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  1. #1
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    175's v 170's?? (for AM riding)

    Starting to believe that for AM/Enduro type trails 170mm cranks are the way to go...

    Watched some dude reviewing a 2018 Giant Reign & he was having a dig @Giant for spec'ing 175mm cranks on an Enduro mule i.e. he was getting lots of pedal strikes.

    I've experienced similar on two AM type steeds.

    Initially on my Nukeproof Scout 290 I was running 175mm cranks & got several random pedal strikes on my first few rides. So, I changed the cranks out for 170mm Zee's.

    Pedal strikes gone ^^

    After last nights ride (650b Enduro bike w/ 175mm cranks) on good AM type trails. I was again getting random pedal strikes & again I'm thinking of shortening things up by 5mm's.

    175mm v 170mm cranks for AM/Enduro... What say you??

    Anyone run shorter??

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  2. #2
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    Quote Originally Posted by targnik View Post
    Starting to believe that for AM/Enduro type trails 170mm cranks are the way to go...

    Watched some dude reviewing a 2018 Giant Reign & he was having a dig @Giant for spec'ing 175mm cranks on an Enduro mule i.e. he was getting lots of pedal strikes.

    I've experienced similar on two AM type steeds.

    Initially on my Nukeproof Scout 290 I was running 175mm cranks & got several random pedal strikes on my first few rides. So, I changed the cranks out for 170mm Zee's.

    Pedal strikes gone ^^

    After last nights ride (650b Enduro bike w/ 175mm cranks) on good AM type trails. I was again getting random pedal strikes & again I'm thinking of shortening things up by 5mm's.

    175mm v 170mm cranks for AM/Enduro... What say you??

    Anyone run shorter??

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    You really think 5mm makes a difference with regard to the pedal strikes? 5mm isn't much. Just look at a ruler. Crank arm length is a matter of bike fit, not performance.

    I run 165, 170, 175 amongst three bikes currently. Aside from different power it takes to pedal each, no difference in pedal strikes.

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  3. #3
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    Quote Originally Posted by Timothy G. Parrish View Post
    You really think 5mm makes a difference with regard to the pedal strikes? 5mm isn't much. Just look at a ruler. Crank arm length is a matter of bike fit, not performance.

    I run 165, 170, 175 amongst three bikes currently. Aside from different power it takes to pedal each, no difference in pedal strikes.

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    Don't think.... Know ^^

    We'll wait for some educated people to join the conversation ;-P

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  4. #4
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    I ride 170 as a matter of course on a bike I build plus go for thin platforms. It's all part of setup with priorities for mountain biking terrain instead of setup for road riding where efficiency is a higher priority.
    170 is slightly easier but you can use gearing to vary that.

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    If 1/2 of 1cm is causing you to have rock strikes I think you need to focus on your pedaling technique.

  6. #6
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    I went to 170s on one of my bikes for fit purposes more than anything...but less worry about pedal strikes is a nice bonus!

  7. #7
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    Quote Originally Posted by stonant View Post
    If 1/2 of 1cm is causing you to have rock strikes I think you need to focus on your pedaling technique.
    Then you don't know. It's not surprising; most bikes are designed a bit conservative here and you have to go out of your way to have a bike where mandatory pedal strikes are part of the experience for an expert. In some environments even an expert will never see the downsides.


    5mm is totally perceptible. Strikes that knock you off line become just annoyances, and grazing strikes don't happen. The roadie world is much more obsessed with power/efficiency than we are, and all the studies i've read have come to the conclusion that so long as your gearing is appropriate then crank arm length doesn't affect power in any meaningful way.

    That said, i'm running 175s on both my bikes and have excessive pedal strikes cuz i fkn love my old-ass 175mm gravity lite cranks. I designed the hardtail for 650b, so when i get around to building a 650b wheelset for it that extra 7mm of radius will fix the issue. With my FS i enjoy that low LOW BB height way more than i'd appreciate fewer pedal strikes and i don't care enough to buy new cranks.





    I think that crank length is kind of bullshit, to slightly change the subject. In the roadie world there have been several efforts to create algorithms to determine crank length based on legs, and they all seem to come to the conclusion that if you're a completely average male cyclist you can gain a <1% advantage by tweaking crank length between the readily available 165-175, but if you're an average woman or really tall like me then the range of available crank lengths is just totally irrelevant to you. It makes sense from a mass production sense- more than 15mm variation in crank length means differing BB drops are necessary for different frames. Not worth it when marketing, purchasing, and engineering are intertwined.
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  8. #8
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    Im only 5'7, 175's are too long. So are 170's for that matter, but I ride them anyway.

    I got our daughter 160's, which I thought would be great for her (they are) and figured they'd be silly short for me... but I rode around on her bike and they feel kind of great. I think a lot of people ride cranks that are too long.

    170's are just so much easier and cheaper to find than 165s, otherwise id be on 165's on all my bikes.

  9. #9
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    I went from 175 to 170 for the same reasons

    5mm additional clearance significantly reduces pedale strikes, since most pedal strikes are more like "glancing blows"

    especially on bikes with a low bb the difference will be felt immediately

  10. #10
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    Quote Originally Posted by Steel Calf View Post
    I went from 175 to 170 for the same reasons

    5mm additional clearance significantly reduces pedale strikes, since most pedal strikes are more like "glancing blows"

    especially on bikes with a low bb the difference will be felt immediately
    This would make sense if the height of all rocks sticking out of the trail were the same. They're not.

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  11. #11
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    180's

    I've got long levers

    Rocky, tight NE riding

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    5mm can effect pedal strike, for sure...common sense.
    If you have a rock that is just hitting the pedal at 175, if you change the crank to 170 you will no longer hit that rock.....

    However....in a real life situation does that effect me personally, NO.
    I try to keep both my pedals level in rough trail or adjust the height of the side I think might hit something.

    You do get more torque with a shorter crank as you will have to rotate less to complete a full rotation, cadence may also increase.
    It will help reduce range motion at the knee.

    With all being said, I believe the crank length is there to help taller and shorter people feel more comfortable riding a bike

  13. #13
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    Quote Originally Posted by Carlos Vicente View Post
    ...You do get more torque with a shorter crank as you will have to rotate less to complete a full rotation...

    I disagree.

    Longer levers = more torque.

  14. #14
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    5mm is anything but negligible when talking about DH pedal strikes. To illustrate this let the air out of your shock, then angle your cranks to simulate likely riding positions. You'll see just how low your bb is when deep in the stroke, and how little wiggle room your pedals actually have in those deep travel situations.

    DH cranks are short for a reason. You do lose leverage as you shorten your cranks. I would say go as long as you can unless DH pedal strikes are an issue. No sense in giving up leverage unless you really need clearance on the DH. If the strikes are on the climbs, even super short cranks will require strategic pedaling. A fast hub and some ratcheting will get 180 cranks up better than 165's pedaling mindlessly, but there's little you can do to get 180's down cleanly.

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    Quote Originally Posted by Miker J View Post
    I disagree.

    Longer levers = more torque.

    Yes, you are right my mistake.
    The longer the crank more torque when pedaling down stroke as you have a longer arm to push down

  16. #16
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    I switched to 170's on all my mountain bikes. Just feels better on my upper leg when one leg is down weighting a pedal and during a pedal stroke. A benefit is significantly less pedal glances on rocks, roots, etc. 1/5th of an inch doesn't sound like much till you consider a BB height going from 13.4" to 13.2". Same thing.
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  17. #17
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    Quote Originally Posted by Miker J View Post
    I disagree.

    Longer levers = more torque.
    On a mechanical device or machine, sure. When you factor in human biometrics, then definitely not!

    My legs go out of the ideal angle to apply power with 175's. 170's too for that matter, but its getting closer to what works.

    I can apply better, smoother power for longer with a shorter crank. The mechanical leverage difference stops mattering if it doesnt work with your body.

  18. #18
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    Quote Originally Posted by One Pivot View Post
    On a mechanical device or machine, sure. When you factor in human biometrics, then definitely not!

    My legs go out of the ideal angle to apply power with 175's. 170's too for that matter, but its getting closer to what works.

    I can apply better, smoother power for longer with a shorter crank. The mechanical leverage difference stops mattering if it doesnt work with your body.
    Wonder if there is a relation to leg length. My inseam is 34.25" and I seem to be able to push about 2 teeth higher out back with the longer cranks.

    However, our trails are almost never a sit and spin matter - almost all out of the saddle grunts.

    Now that I come to think of it, those rare times I'm on my mud bike doing back roads, I had come to realize spinning did seem better on shorter cranks.

    So, like most everything, I guess the correct answer is, "it depends..."

  19. #19
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    I switched from 175 to 170 on all my bikes. Less pedal strikes and easier on my knees wished I had done it years ago. I am 5'9" with a 30" inseam.

  20. #20
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    According to my research, most people would be better served with shorter cranks. The angle of the knee and the biomechanics involved produce more power with shorter cranks, even taller people like me (6' 3").

    Also, shorter cranks (yes, even 5mm) can significantly reduce pedal strikes. Most of my pedal strikes are barely clipping rocks and roots. Add 5mm to those and they become more significant events. The worst crash I have ever had was a pedal strike I never saw coming. If I was on 5mm shorter cranks, that may have been enough to save me.

  21. #21
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    I went from 170's to 135mm....I'm rolling in the floor....
    Attached Thumbnails Attached Thumbnails 175's v 170's?? (for AM riding)-dscn3367.jpg  


  22. #22
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    Quote Originally Posted by mountainbiker24 View Post
    According to my research, most people would be better served with shorter cranks. The angle of the knee and the biomechanics involved produce more power with shorter cranks, even taller people like me (6' 3").

    Also, shorter cranks (yes, even 5mm) can significantly reduce pedal strikes. Most of my pedal strikes are barely clipping rocks and roots. Add 5mm to those and they become more significant events. The worst crash I have ever had was a pedal strike I never saw coming. If I was on 5mm shorter cranks, that may have been enough to save me.
    Well said (typed)...

    I was using 175's on my Nukeproof Scout 290 & getting pedal strikes in unusual places, on familiar trails.

    Going to 170's sorted out the problem.

    Will likely go to 170's on my Reign.

    If I had perfect pedaling technique like others I could see 5mm not being an issue.

    But, I'm human & no Sam Hill...

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  23. #23
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    Quote Originally Posted by targnik View Post
    ...Anyone run shorter??

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    Short answer, No.

    I am only 5'8" and prefer 175mm. In October I was in Sedona and broke my 29er with a day left in my trip. So I rented a 27.5 w/170mm cranks. First thing I noticed was on the short punchy climbs, that is Sedona, it was a little harder to lay down power. I am a 60 rpm spinner and start to bounce out of the seat at 90 rpm so that probably has something to do with my preference.

    Second was that 27.5 on 2.6wt tires makes the bike about as stable as a 29er. So last month I built a 27.5 with 175 cranks. First ride out on a beginner/intermediate trail I had 10+ pedal strikes where i had none before. Took me some time but I am down to 1 strike on that trail, I've had to change my technique in spots with more momentum or more ratcheting.

    I don't think it's unreasonable to go to 165mm cranks on bikes with low BBs, which now a days is all of them.

  24. #24
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    I'll take more leverage for 175 Alex....

    -----------------

    A 2001 study by Professor Jim Martin (yes, this debate has been raging for a while) sampled tested power output in training cyclists using cranks of between 120 and 220mm in length. It found that maximum power changed by less than four per cent. If there’s all but a negligible difference in power, how else are shorter cranks aiding our performance?

    McCann explains: “Mainly, the benefits include better RPM, and this can improve pedal torque and help to eliminate any ‘dead spots’ in your pedalling action.”
    Cavell adds: “For a given gear, to maintain peak power your cadence will increase as crank length decreases.”

    Are shorter cranks better? - Cycling Weekly

    ------------

    Personally the last thing I want to do is increase cadence while pedaling through steep/rough/loose terrain. Ya all can do what you like though.

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    Quote Originally Posted by EatsDirt View Post
    I'll take more leverage for 175 Alex....

    -----------------

    A 2001 study by Professor Jim Martin (yes, this debate has been raging for a while) sampled tested power output in training cyclists using cranks of between 120 and 220mm in length. It found that maximum power changed by less than four per cent. If there’s all but a negligible difference in power, how else are shorter cranks aiding our performance?

    McCann explains: “Mainly, the benefits include better RPM, and this can improve pedal torque and help to eliminate any ‘dead spots’ in your pedalling action.”
    Cavell adds: “For a given gear, to maintain peak power your cadence will increase as crank length decreases.”

    Are shorter cranks better? - Cycling Weekly

    ------------

    Personally the last thing I want to do is increase cadence while pedaling through steep/rough/loose terrain. Ya all can do what you like though.
    Then shift gears.....

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    Quote Originally Posted by Haymarket View Post
    Then shift gears.....
    Cavell adds: “For a given gear, to maintain peak power your cadence will increase as crank length decreases.”

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    Quote Originally Posted by EatsDirt View Post
    Cavell adds: “For a given gear, to maintain peak power your cadence will increase as crank length decreases.”
    Exactly. For a GIVEN gear...meaning one shift and you can spin the same cadence you were spinning and maintain same power output. It’s just a change in ratio....look at a gearing calculator and you can see how crank length affects gearing.

  28. #28
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    Quote Originally Posted by Haymarket View Post
    Exactly. For a GIVEN gear...meaning one shift and you can spin the same cadence you were spinning and maintain same power output. It’s just a change in ratio....look at a gearing calculator and you can see how crank length affects gearing.
    You think power comes for free despite the decrease in leverage?

  29. #29
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    Sure U will have more torque, if UR standing on the pedals. When UR knee cap is in UR chest, out of the torque range. With shorter cranks, U can spin faster or push a harder gear. U breathe better, keeping knees out of chest...Been riding 135mm for yrs, and 125mm on road bike. No problems.
    Quote Originally Posted by Carlos Vicente View Post
    Yes, you are right my mistake.
    The longer the crank more torque when pedaling down stroke as you have a longer arm to push down
    Last edited by ladljon; 12-18-2017 at 03:54 PM.

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    Any leverage losses are regained by shifting gear, so as long as the cranks don't cause fit problems, that argument is moot.

  31. #31
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    Quote Originally Posted by Len Baird View Post
    Any leverage losses are regained by shifting gear, so as long as the cranks don't cause fit problems, that argument is moot.
    Then you're increasing cadence for the same power output so it's not a totally moot point. However, people with shorter legs have to increase step frequency to run at the same velocity as a taller person so maybe the shorter cranks will be more natural for a shorter person anyway.

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    Your really not increasing cadence. The cadence speed is the same, but the distance for the longer cranks is greater,(more knee and hip flexor) therefor needing more oxygen per revolution...this is not noticeable in small 5-10mm shorter, become more so 15-35mm differences.
    Quote Originally Posted by jeremy3220 View Post
    Then you're increasing cadence for the same power output so it's not a totally moot point. However, people with shorter legs have to increase step frequency to run at the same velocity as a taller person so maybe the shorter cranks will be more natural for a shorter person anyway.

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    Quote Originally Posted by ladljon View Post
    Your really not increasing cadence. The cadence speed is the same
    Not if you're in a different gear. Read the post I responded to.

  34. #34
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    Quote Originally Posted by ladljon View Post
    Your really not increasing cadence. The cadence speed is the same, but the distance for the longer cranks is greater,(more knee and hip flexor) therefor needing more oxygen per revolution...this is not noticeable in small 5-10mm shorter, become more so 15-35mm differences.
    Cadence is crank RPMs. How exactly do you get the same cadence when you shift gears?

  35. #35
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    A bigger chainring is more leverage too. An oval chainring increases leverage during the power stroke. The crank is part of a series of levers (inc chainring, cog, and wheel size), that transfers power from your lower body to propel the bike. You can change all the leverage of each in all sorts of configurations, but you can't change the leverage in your legs. You should be more accommodating to that fact and optimize the bike to your body and pedaling style. Sit and spin is better with a shorter crank. Stair-climber-style mashing is better with long cranks.

    It's easier to extend your leg from a less bent position, which is a fact that a shorter crank can take advantage of. If you can leg press 500 lbs many times if you only go from extended position to 1 ft back, but can only leg press 350 lbs if you go from extended to your knee being 90 degrees. Unideal to have a 1 size fits all crank length for people of various leg lengths.

    There's advantages beyond that, with clearance and ergonomics.
    - BBs ranging from 330-345mm are criticized for being low to high (5-10mm isn't as insignificant in these critics' eyes), without taking into account ride height--smaller tires, less sag (esp with lower total travel), more AS, regressive leverage curve, result in higher ride height.
    - Crank length also affects optimal saddle position (height and fore/aft) and be a fitting tool. Shorter crank will allow the saddle to be raised, nice if you're close to fitting the next size up dropper, or if you'd like your saddle higher in relation to the grips.

    If I had the choice, I'd choose shorter. There's just more advantages. I'd determine whether or not to use oval rings using similar logic.
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    Ok...mark a position on a tire, now make a mark half way down on a spoke. Spin the wheel, both marks are going the same speed. The mark on the spoke traveling less distance than the mark on the tire. Ride what you have been program to ride...I will ride my own ride. Ok now put UR finger on each dot and keep the wheel spinning. Which one takes the most energy to keep spinning? Talking about body mechanics, not gearing.
    Last edited by ladljon; 12-18-2017 at 08:30 PM.

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    Quote Originally Posted by dv8zen View Post
    A bigger chainring is more leverage too.
    It's less leverage. Mechanical Advantage= (Number of teeth of output gear)/(Number of teeth of input gear)

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    Quote Originally Posted by ladljon View Post
    Ok...mark a position on a tire, now make a mark half way down on a spoke. Spin the wheel, both marks are going the same speed.
    Ok but if you spun it by grabbing the tire instead of half way down the spoke, you were able to apply more torque with the same force. Go try it, is it easier to spin the wheel from the tire or near the hub?

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    Quote Originally Posted by jeremy3220 View Post
    It's less leverage. Mechanical Advantage= (Number of teeth of output gear)/(Number of teeth of input gear)
    Ok, if you want to use engineering semantics, then a bigger rear cog is more leverage. What use is such increased mechanical advantage? A bigger crank is like a bigger rear cog.

    I was using satire to show how pointless it is to only look at the leverage of the chainring itself, without considering the rest of the series of levers/gears, similar to how people only looked at the leverage of the crank.

    The end goal is efficient power transfer from the body through the entire drivetrain to propel the bike forward. The bigger picture...
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    Quote Originally Posted by dv8zen View Post
    What use is such increased mechanical advantage? A bigger crank is like a bigger rear cog.
    Yes, less force required to maintain the same pedaling cadence. However, like I said earlier people with shorter legs may feel more comfortable with a faster cadence (i.e. shorter cranks w/lower gearing)

  41. #41
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    FWIW, bike manufacturers often spec 170mm carnks on their models with really low BBs. Evil does this on their Calling and Intense does it for the ACV. I was on a pre-release ACV with 175mm cranks a a non-spec headset and I went OTB every other ride on that bike due to pedal strikes. Intense changed to 170mm cranks when they released the bike for added pedal clearance.

    I agree the difference is small but sometimes it's enough...

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    All you guys arguing about cadence and power.... Read some roadie crank length articles and get it out of your systems. It was explored to exhaustion 15 years ago.



    Where i find the crank length thing interesting is gearing correctly to 'step over' features on technical climbs. Good riders will set themselves up to be in a gear where putting a pedal down right in front of an obstacle gives them the momentum to clear it, while keeping their pedals out of the way at the same time.

    With shorter cranks that balance could be messed up. I can imagine pairing longer cranks to larger wheels to taller riders... but that seems to be so esoteric it's absurd. Anyone who has ridden ultra short cranks have an opinion? I've had 200mm cranks and it didn't affect things, but extra long cranks meant i could be even sloppier.
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    How about this to offer and explanation and sum it up....


    Looking at posts from different riders show there are likely different styles of riding.

    One type seems to focus on cadence and serious pedal strikes. XC, pedally type trails ridden in that "sit and spin" style is where a shorter crank probably has the greatest benefit. It is almost as if these folks are taken by surprise by that rare, and thus deadly pedal strike.


    The other type of rider is likely to be ok with longer cranks on techie, steep, trails where out of the saddle grunts and maneuvering are the norm. Ratcheting the pedals and trialsy type style seems common here, as opposed to the "sit and spin" type rides. The rare times I do sit and spin I'm using a very low cadence, high gear approach. A fast, sit and spin cadence, at high speed, would almost certainly result in a rapid, catastrophic OTB event. Personally, I have multiple small pedal and crank strikes per ride, and this is the norm in our exceedingly rocky NE conditions. Look at most pedals and cranks around here and you will see the scars. My DH bike's chain ring protector is worn to a nub.


    Different horses for different courses.

    As always, it's all about the trail.

  44. #44
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    Quote Originally Posted by Miker J View Post
    How about this to offer and explanation and sum it up....


    Looking at posts from different riders show there are likely different styles of riding.

    One type seems to focus on cadence and serious pedal strikes. XC, pedally type trails ridden in that "sit and spin" style is where a shorter crank probably has the greatest benefit. It is almost as if these folks are taken by surprise by that rare, and thus deadly pedal strike.


    The other type of rider is likely to be ok with longer cranks on techie, steep, trails where out of the saddle grunts and maneuvering are the norm. Ratcheting the pedals and trialsy type style seems common here, as opposed to the "sit and spin" type rides. The rare times I do sit and spin I'm using a very low cadence, high gear approach. A fast, sit and spin cadence, at high speed, would almost certainly result in a rapid, catastrophic OTB event. Personally, I have multiple small pedal and crank strikes per ride, and this is the norm in our exceedingly rocky NE conditions. Look at most pedals and cranks around here and you will see the scars. My DH bike's chain ring protector is worn to a nub.


    Different horses for different courses.

    As always, it's all about the trail.
    I experience glancing blows to pedals and cranks on nearly every ride as well. It's those blows that catch that really suck. In this video I kept clipping the pedals on seemingly insignificant dirt mounds before I ever even hit the chunky stuff this trail (Butcher Ranch, Downieville) is known for. I ended up sitting down and limping the bike the remaining 10 miles because I was so shaken up by the constant pedal strikes.


    After a few more nearly catastrophic crashes which involved bruised ribs and lacerations I now have a healthy fear of strikes. lol
    175's v 170's?? (for AM riding)-10620161850.jpg175's v 170's?? (for AM riding)-106201618449.jpg
    Upside down in the bushes with my bike still on top of me. Full on front flip due to pedal strike. This one didn't hurt.

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    ^^I got thrown from a pedal strike from a Stumpjumper 650 demo when they came out a few years ago. I was pedaling through a large dip in the trail and when the suspension compressed...my pedal hit the ground and I got tossed. With bikes nowadays...I'd rather have that slight bit of a margin than not.

    I'm 5'8" with a 30 inseam and run 170 on all my bikes.

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    Quote Originally Posted by Miker J View Post
    Looking at posts from different riders show there are likely different styles of riding.

    One type seems to focus on cadence and serious pedal strikes. XC, pedally type trails ridden in that "sit and spin" style is where a shorter crank probably has the greatest benefit. It is almost as if these folks are taken by surprise by that rare, and thus deadly pedal strike.

    The other type of rider is likely to be ok with longer cranks on techie, steep, trails where out of the saddle grunts and maneuvering are the norm. Ratcheting the pedals and trialsy type style seems common here, as opposed to the "sit and spin" type rides. The rare times I do sit and spin I'm using a very low cadence, high gear approach. A fast, sit and spin cadence, at high speed, would almost certainly result in a rapid, catastrophic OTB event. Personally, I have multiple small pedal and crank strikes per ride, and this is the norm in our exceedingly rocky NE conditions. Look at most pedals and cranks around here and you will see the scars. My DH bike's chain ring protector is worn to a nub.
    Some of it is also a matter of paying attention, reading the trail, and having a sense of pedal strokes vs. distance. Most of my pedal strikes happen near the end of long rides when I'm just pushing the pedals to make it home and my brain's off in la-la land. I'm not really paying attention and looking far ahead enough, and that's when I hit things with my pedals or bash the handlebars into trees. I'm just mindlessly pedalling along and bam, I've whacked something and I'm down on the ground with no idea what happened.

    Some folks also have a hard time getting a sense of where their pedals are and how to get them to where they should be at a given point on the trail. For me it's 2nd nature, I can spot an obstacle 30' down the trail and know where my pedals will be if I pedal into it along with what adjustments I need to make if I want to pedal into it with the cranks level, left side up, right side up, or whatever the required position is to make it over. I don't have to think about it, it's instinctive and I just know. Some folks are like me, some need a second or 2 to think about it and make it happen, and others really struggle with it, we're all different.

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    This was a timely thread, as I just snapped my 175 XX1 cranks and they are the same cranks i have been on for all the 4 years I've been riding cuz I moved them from a previous bike.

    Anyways I'm going to try 170 cranks even though I'm 5 11. I did a few online calculators and it would appear to be a better fit for my body type and I'm getting several symptoms of too long cranks, describes me to a tee. Eager to try it out. But I also have some 175 cranks on order just in case.

    I do pedal strike all the time but I don't really consider it that big of a deal. It's just less of them would really help on the technical climbs.

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    Last edited by Suns_PSD; 12-23-2017 at 10:51 AM.

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    Mmm....

    I'm 5' 11" 1/2 & possibly concur - that 170's may just be a better fit ^^

    Zee/SLX 170's are on my 2018 hit list ;-)

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    Quote Originally Posted by targnik View Post
    Starting to believe that for AM/Enduro type trails 170mm cranks are the way to go...

    Watched some dude reviewing a 2018 Giant Reign & he was having a dig @Giant for spec'ing 175mm cranks on an Enduro mule i.e. he was getting lots of pedal strikes.

    I've experienced similar on two AM type steeds.

    Initially on my Nukeproof Scout 290 I was running 175mm cranks & got several random pedal strikes on my first few rides. So, I changed the cranks out for 170mm Zee's.

    Pedal strikes gone ^^

    After last nights ride (650b Enduro bike w/ 175mm cranks) on good AM type trails. I was again getting random pedal strikes & again I'm thinking of shortening things up by 5mm's.

    175mm v 170mm cranks for AM/Enduro... What say you??

    Anyone run shorter??

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    To get back to what the OP asked....From all my readings we aren't doing it but crank length should be matched to the rider. I'm 5'7" with stumpy legs so why would I run 200mm cranks as an extreme example? I'm short so I should match my cranks to my stumpy legs. I have found for me that 165mm is the most comfortable. I believe you'll find most bike manufacturers run 170-175mm cranks as they'll suit the most broad range of riders.

    So I think you should work out the best cranks for you and ignore the rock strike issue. Don't get me wrong They aren't fun but it's about the majority of your riding not those odd times you glance off a rock.

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    Quote Originally Posted by Timothy G. Parrish View Post
    Crank arm length is a matter of bike fit, not performance.
    Pretty much what this guy said!!!! Performance is also a factor but the FIT comes first.

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    I had to order new cranks as my old ones just broke.

    I started reading about crank lengths and ended up reading this link:

    BikeDynamics - Bike Fitting Specialists - Crank Arm Lengths

    ...that puts me in 170mm cranks, even though I'm 5'11" and frankly those fitment rules are for road bikers.

    I hope to get a real ride and report back later today what I think on the 170mm crank I just installed. All of my mountain bike experience is on 175mm cranks and I can definitely feel that they are different on the street test ride, but not in a bad way.

    I will say that I do hit my pedals on really rough climbs and this often impedes my forward progress. If the shorter cranks reduced this it would help me clear more obstacles for sure. But mainly I want to feel more efficient and comfortable overall. That will be the determining factor for me.

    I also bought 175 cranks and will imply sell which ever ones I chose not to keep.

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    pedals

    Maybe off topic but I found pedals make a pretty big difference.

    I have some large sharp flats and seemed like I was getting severe pedal strikes pretty often, waiting for replacement pins I rode my Shimano M8020 SPD and it all but stopped... even when I did hit it was glancing blows vs that instant stop thud I got with the big flats.

    Im sure being smaller and less wide helps but I think the rounded shape is a big part of it as well.

    Not sure how much of a pain it would be but kinda got me wondering if a thin one sided flat pedal with an rounded bottom edge would be helpful...maybe even combined with a shorter crank (Photoshoped what I am talking about)

    175's v 170's?? (for AM riding)-oneside.jpg

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    I have the Canfield brothers Crampon flat pedals and they use a very thin and narrow design that doesn't grab too bad. It's noticeably less than other pedal designs I've used.

    So after 4 years this very month since I began riding bicycles as an adult (and became completely addicted to it I might add) and the entire time on 175mm cranks, I did my first day on 170mm cranks. My inseam is 32.5" and my height is 5'11". When I ran the calculators the suggestion was in the 171-172.5mm crank length range. I don't think that any high end mountain bike cranks are offered in 172.5mm or I would have bought that length.

    I am riding at a higher level than ever before, climbing stuff I would have never thought possible just 2 years ago, and at times I've been like XC guy fast on the in between slightly smoother sections, really able to put the power down and maintain speed and pulling away from others I have always ridden with or behind. The places I ride have very chunky, rough, at times slow going terrain, at least at my skill level. Although we don't have huge mountain climbs here we have nasty rocky climbs with many ledges and loose rocks that are very tough for most to climb. And I still get hung up on a regular basis, way more often than I would like. I guess I would mostly describe it as if I hit a rough section with as much momentum as I can muster, but at some point I am wishing I was in a lower gear and am standing on the pedals and unable to continue and end up coming to a complete stop. That and not being able to pedal at the right moment due to rocks is how 95% of my failures on climbs occur. This is a common symptom of too long of cranks, kind of being the first in your group to stand on a climb trying to keep the cranks spinning. Some of the other symptoms such as knee pain, does happen to me on occasion, but I can't blame that on cranks when I've blown that knee out 2x.

    When I first went out on the 170 cranks, it just felt weird, like I could not stand and just will that bike to get up to speed like really quickly how I like to do. My legs felt like they were doing little circles. However almost right away I cleared two section I have never cleared, mostly due to pedal strikes in the past, but also the old 175 cranks just stalling out on me. That was cool.

    I had to stop 3x and raise my dropper post about 4 mm, and also slide my seat forward about 2-4mm to fit the new cranks. At this point, the bike started to feel much more normal to me and I quit noticing them as much.

    I could tell I was pedal striking a lot less and I definitely preferred having my feet closer together when my feet were horizontal over drops and really rough terrain. It might only be 5mm more ground clearance, but it reduced rock strikes for me and honest 60%+.

    Towards the end of the ride I cleared like 4-5 obstacles I've never cleared. This is a trail I know well and before today, I wasn't really getting better at these obstacles, I had given them a good run many times before and I just figured I needed to be more fit or something. Where i use to stand on the pedals to work my way through really chunky stuff and I would get stuck on 175s, the 170mm cranks would just begin to spin under the same conditions and the bike would go!

    Overall I consider it a notable improvement, but still a slightly odd feeling sensation. If I was a XC racer with my body dimensions I would stick with the 175s. Something about those big windmill cranks take longer to get spinning but it felt like the lower cadence had more momentum once they were doing those large slow rotations.

    For my terrain (slow and chunky often) and personal build, I wish Sram made 172.5mm high end cranks as I think that would really be my ticket. Anyone under 5"11" riding chunk needs to be on a 170mm or less crank imo. I'm shocked they don't even make a 165mm crankset for small and medium bike riders.

    That all said I think the 170mm cranks are a notable improvement overall for me and I'll be sticking with them. I simply could clear more of the features that I prefer. I also hope that after a couple of more rides I feel just as momentum fast on the in-between smoother sections as I did on the 175s.

    It's always fun to find some improvement in bike performance. It's hard to try it all because of money/ time/ what you are use to. But I've been able to try lots of new stuff out on my bike and I've been pretty tickled with the overall performance improvements I've experienced. Tires, wheels, brakes, bars/ stem, grips, cassette, dropper lever, seat, and now crank arm length can all make small, but quite notable improvements in your bike fit and performance if you are a sensitive rider as I am.

    ~ take care

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    My shop accidentally ordered 175 to replace my 170's that I broke.

    I barely, barely notice a difference. That's on my Enduro.

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    Quote Originally Posted by Sidewalk View Post
    My shop accidentally ordered 175 to replace my 170's that I broke.

    I barely, barely notice a difference. That's on my Enduro.
    Some people are like that, they can ride well on anything and not know the difference.
    The fastest guy I know doesn't check his tire air pressure with a gauge, has never set his suspension sag, will hit any ledge drop without even looking at it, and is the best climber I've ever seen.
    That ain't me!

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    I'd like to see mfg's offer 160-165s for the XS, 165s for S, 165/170s for the med, and 175s for L and XL. Heck, some of those sasquatch guys would probably love a 180, since it's proportional to their geometry.

    I have borrowed my wife's 165s and I like them. My knees don't hurt as much (I'm 5'9"). I run 170s now, 175s hurt my knees a lot.

    Yes you lose leverage with the shorter arm, you get it back with a gear change. Duh.

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    Quote Originally Posted by UtahJohn View Post
    I'd like to see mfg's offer 160-165s for the XS, 165s for S, 165/170s for the med, and 175s for L and XL. Heck, some of those Sasquatch guys would probably love a 180, since it's proportional to their geometry.

    I have borrowed my wife's 165s and I like them. My knees don't hurt as much (I'm 5'9"). I run 170s now, 175s hurt my knees a lot.

    Yes you lose leverage with the shorter arm, you get it back with a gear change. Duh.
    36" inseam here. No strong opinion about the superiority of proportional cranks (having owned long cranks i think they're a waste of mental energy), but i'm positive that it's less important than BB height and ground clearance. I don't know if i'd want longer cranks if they came with a higher BB........ I certainly wouldn't want longer cranks if the BB height wasn't adjusted accordingly, and the FC wasn't being scaled up with my own height.

    I think for production complete bikes it makes more sense to stick everyone on 170s and tune the suspension (and geo) so we're all experiencing the same clearance and travel use. Like all you shorter folk, i'm perfectly fine with turning circles with 165s.
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    Even though you lose some torque leverage going to smaller cranks while using the same gear, I think you end up with a faster cadence/ rpm overall. However your legs are not moving any faster just because the circle is a bit smaller. So maybe you turn more circles, but the speed your feet are going is the same as with larger cranks at a lower cadence.

    That's just my feeling anyways. I was concerned I'd feel more tired on smaller cranks but that wasn't the case.

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    This leverage/torque loss is equivalent to shifting your gearing range towards further to the high end. It's very slight, smaller than going from a 11-45 to a 10-42. You can drop from 175 to 165 and retain the same gearing if you switch to a 2t smaller chainring.

    175's v 170's?? (for AM riding)-21cawyj.png175's v 170's?? (for AM riding)-wjlzcwy.png
    -175 crank with 11-42 and 10-50

    175's v 170's?? (for AM riding)-ywzfipk.png175's v 170's?? (for AM riding)-c66vmlr.png
    -170 crank with 11-42 and 10-50

    175's v 170's?? (for AM riding)-r4sghz6.png
    -165 crank with 11-42

    The drivetrain is a series of simple machines. Pulleys exert leverage, equivalent to their radius, and the rear cog's "leverage" is equivalent to the crank's leverage.

    If I thought I could use more high end on a 1x10, and it was cost prohibitive to go with a cassette with 10t or 9t, and a bigger chainring would affect my susp (less anti-squat), and I could only fit so big of a wheel/tire in the frame, I'd see shorter cranks as an option, weighing all the pros and cons.

    If you really want crank leverage/torque, due to being a masher, I'm sure these guys would love to sell to you:


    - supposedly, it flexes on your power stroke to get longer. It's like the new tweener option between short and long cranks. Like the oval chainring of cranks for people who don't spin.

    You shouldn't really be losing/gaining anything related to power. If you settled into particular gears in the past, with new length cranks those same gears should just feel slightly harder w/shorter crank (slightly faster if you maintain same RPM) or slightly easier w/longer crank (slightly slower with same RPM). Ground clearance is super valuable, esp with low BBs.
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    I did find that even though it was a minor amount, only 5mm, I do like the climbing better on my Enduro. So while I barely notice it on the chunky descents and crank strike about the same as before, it does help with the climbing.

    I will likely go with an E*13 cassette for the better range when my current one wears out. I am pushing a 35 pound bike with 29" wheels and 160mm travel up 5000+' climbs, with a 32T chainring. But I need the 32 for descending, so...I mash the cranks a lot.

    I can really feel the short cranks on my old steel roadie. Really hard to get some good leverage on them. But very handy on tight crit type riding with friends as I can pedal through turns, and the gearing range is plenty wide enough that I don't need the leverage (though, the original 42T front hurts when I'm in the mountains).

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    Quote Originally Posted by UtahJohn View Post
    I'd like to see mfg's offer 160-165s for the XS, 165s for S, 165/170s for the med, and 175s for L and XL. Heck, some of those sasquatch guys would probably love a 180, since it's proportional to their geometry.

    I have borrowed my wife's 165s and I like them. My knees don't hurt as much (I'm 5'9"). I run 170s now, 175s hurt my knees a lot.

    Yes you lose leverage with the shorter arm, you get it back with a gear change. Duh.
    This would make so much more sense! There are no production bikes that come with 165s, not even women's XS models. My small Ibis came with 175s, which is absolutely ridiculous for a bike designed for a 5ft tall rider. I ended up swapping the crank arms out for 165s because my knees hurt with the long cranks, and as a side effect I now get fewer pedal strikes.

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    Quote Originally Posted by mahgnillig View Post
    This would make so much more sense! There are no production bikes that come with 165s, not even women's XS models. My small Ibis came with 175s, which is absolutely ridiculous for a bike designed for a 5ft tall rider. I ended up swapping the crank arms out for 165s because my knees hurt with the long cranks, and as a side effect I now get fewer pedal strikes.

    Sent from my SM-T800 using Tapatalk
    Jen, how tall are you? I'm just shy of 5'7" with 175 crank arms on my new bike. Trying to decide 165s or 170s instead.

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    Quote Originally Posted by alh View Post
    Jen, how tall are you? I'm just shy of 5'7" with 175 crank arms on my new bike. Trying to decide 165s or 170s instead.
    I would go straight to 165mm cranks. My wife made the switch from 170 to 165 on both her bikes and would have gone 160 but not many options in that length. She is 5'1"

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    Quote Originally Posted by mahgnillig View Post
    This would make so much more sense! There are no production bikes that come with 165s, not even women's XS models. My small Ibis came with 175s, which is absolutely ridiculous for a bike designed for a 5ft tall rider. I ended up swapping the crank arms out for 165s because my knees hurt with the long cranks, and as a side effect I now get fewer pedal strikes.

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    There are some roadie formulas for calculating ideal crank length... 9.7% of leg length i think for example??

    Anyway, the formulas end up suggesting 165-175 lengths cover average 5'8-6' riders, where a 5' rider will be better suited to something like a 145mm crank.

    My impression is that you can have excessively long cranks and once they're not too long then it doesn't really matter.
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    Quote Originally Posted by cmefly View Post
    My wife made the switch from 170 to 165 on both her bikes and would have gone 160 but not many options in that length. She is 5'1"
    Did she end up raising the saddle by about 5mm to keep the same leg extension at the bottom of the pedal stroke? I've thought about shorter cranks for my wife but don't want to raise her saddle any higher since she already has issues with how high her saddle is off the ground.

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    Quote Originally Posted by jeremy3220 View Post
    Did she end up raising the saddle by about 5mm to keep the same leg extension at the bottom of the pedal stroke? I've thought about shorter cranks for my wife but don't want to raise her saddle any higher since she already has issues with how high her saddle is off the ground.
    Yes, We both raised our saddles when we went 5mm less on the crank arms. I ride 170mm now and my knees feel better for it. Get your wife a dropper post and get her in the habit of lowering the seat as she comes to a stop if that is the issue with saddle height. My wife found when using the shorter crank her legs were in a better position to apply power when going over obstacles. Her legs were not having to go to as extreme of a high and low on the stroke. That 5mm made a big difference for her as the cranks were easier for her to turn over.

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    Quote Originally Posted by alh View Post
    Jen, how tall are you? I'm just shy of 5'7" with 175 crank arms on my new bike. Trying to decide 165s or 170s instead.
    I'm 5'2" with a 30.5" inseam (cycling inseam, not trouser length). I probably would have gone for 160 if I could get them, but that would have involved a lot of messing about with my drivetrain components. Going from 175 to 165 was a simple crank arm swap, I didn't even need to change the bottom bracket. I also had to raise my seat post in order to maintain the proper leg extension.

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    I'm 5' 3.5" with a 29" inseam (trouser). My 2017 EX-8 27.5+ has 175mm and a 10-42 11 speed. What crank length would you go with? 165 or 170? My LBS wasn't keen on the 165 but that seems more appropriate based on this thread. Trail and ST riding.

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    Quote Originally Posted by Dr Evil View Post
    I'm 5' 3.5" with a 29" inseam (trouser). My 2017 EX-8 27.5+ has 175mm and a 10-42 11 speed. What crank length would you go with? 165 or 170? My LBS wasn't keen on the 165 but that seems more appropriate based on this thread. Trail and ST riding.
    165 would be my choice

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    Quote Originally Posted by Miker J View Post
    I disagree.

    Longer levers = more torque.
    R

    ^^this. I swap longer handles on my fishing reels for more cranking power and slower cadence. I feel that I can apply more torque with my 175mm cranks vs. 170 on the same bike, and it has helped me clear some technical climbs this year.

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    "torque" is the combination of the lever (crank arm), crank angle, front ring, and rear cog force, into the rear tire diameter.

    With a fishing reel, do you have a gear to deal with too, or is it direct drive?

    If you use a shorter arm, a gearing change will result in the same torque at the rear wheel. But you are correct in having more torque with no other changes. However a front ring swap, or being in gear 9 vs 8, accomplish the same thing.

    Ie: I guarantee you'll have more "torque" with a 26 front ring and 165 crank arm, than a 30T front ring and 175 crank arm. It's the combination which matters. Heck, even a 28T/165 will out torque a 30T/175. The crank arm lever difference is only 3% or so, the 2T ring change is closer to 7%.

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    Good post UtahJohn. Other people judging crank arm length as if they were speaking of its use on a unicycle. xD
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    Wow

    Just stumbled upon this thread about crank length. I've been riding long cranks since 1994 (202mm Bullseye cranks) on a custom Co-Motion mountain bike. One of maybe a dozen or so ever built by that very successful tandem & road bike company but that's another story.

    Anyway I rode those 202mm cranks for a few years and then got a few sets of 195mm cranks for my various mountain bikes. These days I'm riding comparatively short cranks -- 185mm. These seem like the sweet spot for my 36" inseam.

    Because I've been riding excessively long cranks for over two decades, I've stepped in countless internet debates over crank length as regards fit and biomechanics and tangentially, torque, gearing and power transfer discussions. For a while I feared I might never get that smell off my shoe.

    After all these years I've come to this conclusion which I believe with all my soul. Crank length doesn't matter. Period. Ride whatever feels best to you.
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    Buy a High engagement rear hub and practice when to not pedal. This will let you run whatever crank arms you like.


    I have always run 170s because I have a 29 inch inseam. Also, moving up to 175s would put my Thighs 1CM higher into my stomach and make. No thanks.

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    I tryed 165 and liked it. I do have shorter legs and from 170 i noticed less strikes. My actual inseam with a book shoved up against my perneum standing in a hallway barefoot was 31. I wear a 30 inseam jeans pant an i like 165.. It helps whem you bust airs and do ET's phone home. Lol jk

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    I just had my second ride on 170 cranks after years on 175. I'm never going back. And I'm not a short guy. I'm just clearing stuff that I've been trying to clear for 2 years and I could not do it, I thought I needed to be more fit but I'm going right up the same stuff with just a crank change.
    It felt a little funny on the first ride at first, it's all completely normal on this ride, I couldn't even tell that the circle was slightly smaller.

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    Road bikers including sprinters producing huge bursts of power often use shorter cranks. There are top pro sprinters on 170's. In my size with a 32" inseam 172.5 is standard on most bikes. One size lower will be 170. one size higher 175.
    I think the fears of losing torque or power at all are unfounded. Plus its not huge differences in all these factors, and you can quickly adjust to a range of sizes.

  78. #78
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    Quote Originally Posted by Len Baird View Post
    Road bikers including sprinters producing huge bursts of power often use shorter cranks. There are top pro sprinters on 170's.
    All pushing a much higher cadence then that of your typical mtb under normal max power conditions.

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    Quote Originally Posted by EatsDirt View Post
    All pushing a much higher cadence then that of your typical mtb under normal max power conditions.
    Exactly, EatsDirt.

    Imagine a stuck bolt and a short wrench.
    If you can break it loose, you’re more likely to bust your knuckles.
    With a long wrench, breaking the bolt is easy.
    I employ long cranks and have noticed that I clean steep up sections that riders on shorter length cranks don’t.

    I’m not saying the longer lever saves energy, just that it metes that energy out differently. Personally I like the longer lever but like I said before, in the end it all comes down to personal preference.

    I will voice one more opinion about crank length. If someone turns to shorter cranks to avoid pedal strikes, that may be a bandaid instead of fixing the root problem. The truth may be their bottom bracket is too low. Bike fit should trump everything else. Right-size your cranks, then get a frame that accommodates that length crank. Proper length cranks are a matter of bike fit. Just as wheel size, handlebar width, even grip diameter and brake lever size are matters of bike fit. Why should the frame be the only thing that gets larger for taller riders or smaller for shorter riders? Everything should change.

    But everything doesn’t change on production bikes because it would too expensive for bike companies to change everything throughout the size lineup of the bikes they offer. That’s one reason I build up my own bikes.

    These are my opinions. We each have to make our own way. Everybody do as you will.
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    Quote Originally Posted by targnik View Post
    Starting to believe that for AM/Enduro type trails 170mm cranks are the way to go...

    Watched some dude reviewing a 2018 Giant Reign & he was having a dig @Giant for spec'ing 175mm cranks on an Enduro mule i.e. he was getting lots of pedal strikes.

    I've experienced similar on two AM type steeds.

    Initially on my Nukeproof Scout 290 I was running 175mm cranks & got several random pedal strikes on my first few rides. So, I changed the cranks out for 170mm Zee's.

    Pedal strikes gone ^^

    After last nights ride (650b Enduro bike w/ 175mm cranks) on good AM type trails. I was again getting random pedal strikes & again I'm thinking of shortening things up by 5mm's.

    175mm v 170mm cranks for AM/Enduro... What say you??

    Anyone run shorter??

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    I have a 2016 Giant Reign and found the 175's a bit long....changed to 170 and the pedal strikes where better.....then put DMR v12's on instead of the Crankbro's candys....back to pedal striking

    i have 175's on an OLD XC bike and have almost no issues but i would say the BB is higher.....165's on the DH bike feel a bit short

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    2 points: I have seen guys with shorter cranks clean sections because they didn't spin out (less torque). Also, you comment that their bottom bracket is obviously too low, but they may view yours as being too high, and suffering handling because of it. You could lower it a little if you didn't use the long crank arms. :-p

    Everything is a compromise.


    Quote Originally Posted by Sparticus View Post
    I employ long cranks and have noticed that I clean steep up sections that riders on shorter length cranks don’t.

    I’m not saying the longer lever saves energy, just that it metes that energy out differently. Personally I like the longer lever but like I said before, in the end it all comes down to personal preference.

    I will voice one more opinion about crank length. If someone turns to shorter cranks to avoid pedal strikes, that may be a bandaid instead of fixing the root problem. The truth may be their bottom bracket is too low. Bike fit should trump everything else. Right-size your cranks, then get a frame that accommodates that length crank. Proper length cranks are a matter of bike fit. Just as wheel size, handlebar width, even grip diameter and brake lever size are matters of bike fit. Why should the frame be the only thing that gets larger for taller riders or smaller for shorter riders? Everything should change.

    But everything doesn’t change on production bikes because it would too expensive for bike companies to change everything throughout the size lineup of the bikes they offer. That’s one reason I build up my own bikes.

    These are my opinions. We each have to make our own way. Everybody do as you will.
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    Quote Originally Posted by UtahJohn View Post
    Everything is a compromise.
    Agreed. One of the things I love about cycling is we each get to decide what works best — for us. We’re free to prioritize our choices when building up the machine we want to ride. Cheers!
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    Quote Originally Posted by scottzg View Post
    No strong opinion about the superiority of proportional cranks (having owned long cranks i think they're a waste of mental energy), but i'm positive that it's less important than BB height and ground clearance. I don't know if i'd want longer cranks if they came with a higher BB........ I certainly wouldn't want longer cranks if the BB height wasn't adjusted accordingly, and the FC wasn't being scaled up with my own height.

    I think for production complete bikes it makes more sense to stick everyone on 170s and tune the suspension (and geo) so we're all experiencing the same clearance and travel use. Like all you shorter folk, i'm perfectly fine with turning circles with 165s.
    x2....tried 185-165mm cranks and the one thing I didn't see mentioned here is downhill fatigue in the legs (mostly front quad), longer cranks can put more of a strain on that front leg....I definitely don't have to switch my front leg as often w/ the shorter cranks due to less leg burn
    All barks have been rendered into english...

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    Quote Originally Posted by UtahJohn View Post
    I have seen guys with shorter cranks clean sections because they didn't spin out (less torque).
    Counterpoint: I see guys trying to spin too low a gear up tech sections and fail (wheel spin, bounced off line, etc) where a bigger gear/lower cadence promotes less wheel spin and the ability to lurch up over obstacles with precisely timed half cranks etc.

    To each their own.


    Quote Originally Posted by UtahJohn View Post
    Everything is a compromise.
    Agree. Seems to apply to pretty much everything in life...

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    I don't like this game of "longer is better" or "shorter is better" and people going too far with it. Going as long as possible before it becomes too much of a problem seems to be too simple-minded of an action. Enduro racers were cutting back to 740mm bars this year, prompted by some challenges in some courses, and some just kept 'em without moving back to longer ones. Surely, one can learn of this sweet spot without experiencing going too far in either direction? I personally recently learned that 30mm stems compromises a lot in terms of handling on my current bike, and that the sweet spot is around 45-50mm. Someone mentioned that Greg Minnaar said to match your stem length to fork offset, and I wonder if that's just coincidence... technically, 10mm of stem length is worth 20mm of bar width in leverage.

    People talk about spinning vs mashing, and relating it to crank arm length... can't you just shift gears if one pedaling strategy doesn't work in a particular section? xD
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    Quote Originally Posted by dv8zen View Post
    People talk about spinning vs mashing, and relating it to crank arm length... can't you just shift gears if one pedaling strategy doesn't work in a particular section? xD
    Go get a road bike. Put on 170 cranks. Go climb, ride the flats, etc. Then with the same bike and gear ratio, put on 175 cranks and repeat. Report back.

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    Quote Originally Posted by dv8zen View Post
    I don't like this game of "longer is better" or "shorter is better" and people going too far with it. Going as long as possible before it becomes too much of a problem seems to be too simple-minded of an action. Enduro racers were cutting back to 740mm bars this year, prompted by some challenges in some courses, and some just kept 'em without moving back to longer ones. Surely, one can learn of this sweet spot without experiencing going too far in either direction? I personally recently learned that 30mm stems compromises a lot in terms of handling on my current bike, and that the sweet spot is around 45-50mm. Someone mentioned that Greg Minnaar said to match your stem length to fork offset, and I wonder if that's just coincidence... technically, 10mm of stem length is worth 20mm of bar width in leverage.

    People talk about spinning vs mashing, and relating it to crank arm length... can't you just shift gears if one pedaling strategy doesn't work in a particular section? xD
    Solid post.

    Can you clarify how running the ultra short stem negatively affected your bike handling? I've been trying to understand what people are so adamant to run ultrashort stems. I run a 60 personally but I did it to extend my effective reach. Are you saying that when you have a longer stem, it gives you more leverage over the bars, and therefore makes the bike more twitchy? Trying to understand.

    I'm 5-11 and run 740mm bars, I think it's a perfect fit I've tried the longer bars I just don't get it. I even have a spare set of carbon fiber 740 bars on the shelf and I can't sell them because people seem to think they are too short.

    Also I did another ride on my slightly shorter cranks, and I'm a huge fan. It's not that this is the only change, but over the last 6 months I went from being a pretty weak climber to a darn strong climber. The 170 cranks was certainly part of the puzzle for me. It was a big part actually.

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  88. #88
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    Quote Originally Posted by FJSnoozer View Post
    Buy a High engagement rear hub and practice when to not pedal. This will let you run whatever crank arms you like.


    I have always run 170s because I have a 29 inch inseam. Also, moving up to 175s would put my Thighs 1CM higher into my stomach and make. No thanks.
    Me, too, 29" inseam. But I have relatively longer torso so I'm actually on a medium Yeti (felt better than the small).

    Quote Originally Posted by Suns_PSD View Post
    I just had my second ride on 170 cranks after years on 175. I'm never going back. And I'm not a short guy. I'm just clearing stuff that I've been trying to clear for 2 years and I could not do it, I thought I needed to be more fit but I'm going right up the same stuff with just a crank change.
    It felt a little funny on the first ride at first, it's all completely normal on this ride, I couldn't even tell that the circle was slightly smaller.

    Sent from my SAMSUNG-SM-G891A using Tapatalk
    How tall are you @Suns_PSD? Think I will start with 170s as that's what I have on my road bike. My knees do hurt with the 175s but thought it may be other things...

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    Quote Originally Posted by Suns_PSD View Post
    Solid post.

    Can you clarify how running the ultra short stem negatively affected your bike handling? I've been trying to understand what people are so adamant to run ultrashort stems. I run a 60 personally but I did it to extend my effective reach. Are you saying that when you have a longer stem, it gives you more leverage over the bars, and therefore makes the bike more twitchy? Trying to understand.

    I'm 5-11 and run 740mm bars, I think it's a perfect fit I've tried the longer bars I just don't get it. I even have a spare set of carbon fiber 740 bars on the shelf and I can't sell them because people seem to think they are too short.

    Also I did another ride on my slightly shorter cranks, and I'm a huge fan. It's not that this is the only change, but over the last 6 months I went from being a pretty weak climber to a darn strong climber. The 170 cranks was certainly part of the puzzle for me. It was a big part actually.

    Sent from my SAMSUNG-SM-G891A using Tapatalk
    There's many types of turns. There's quick banked turns, longer high speed bermed turns, sharp 90d turns in soft dirt, sweeping flat turns, long arcing turns, chicanes (zig-zag turns), uphill switchbacks, downhill switchbacks, off-camber turns with deadly exposure, etc. and a skilled rider has a large pool of various skills that they can opt to use for each based on the circumstances. Twitchy might compromise with stability in long arcing turns, while it can help with flat ground turns where you're upright and in the saddle, squeezing between trees and boulders, or getting your tire to thread some needle-like line. Going too far put me out of the comfort zone for certain types of turns, and decided I'd rather have a compromise that wasn't biased more to one type. I was "understeering", going wide off of the trail, on bigger sweeping turns, possibly due to correcting my angle from being too tight. Even putting over 100 miles to adjust my steering sensitivity didn't really do much to correct it. Going to back to 45mm (was using 50mm before 30mm) and pretty much I don't think about steering*, and instead think about refining my technique for different entry speeds, to push for even more speed to connect one turn to the following section. *no longer have probs going wide off the trail

    There's also an issue with knee pad clearance with stems. On banked uphill switchback that is fast and sort of flowy, my kneepads were banging into the bar's controls as I was pedaling with my bars turned a little past 45d. This was the clinching factor in deciding that 30mm wouldn't work on my current bike. The bike has 20mm more ETT/reach than my last bike. My last bike I ran with 50/60mm.
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    Quote Originally Posted by alh View Post
    Me, too, 29" inseam. But I have relatively longer torso so I'm actually on a medium Yeti (felt better than the small).



    How tall are you @Suns_PSD? Think I will start with 170s as that's what I have on my road bike. My knees do hurt with the 175s but thought it may be other things...
    I'm 5'11" with I think a 31.5" inseam.
    Check out the Bike Dynamics UK website. They have some pretty sophisticated formulas for calculating the correct crank length for your body. It put me at about a 171-172 crank as being ideal for me.

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    As far as why the shorter cranks are working well for me, I'm just guessing that for your feet to move the same speed you're carrying a little faster cadence because the size of the circle is a bit smaller. It doesn't feel like I'm spinning faster. I think that extra cadence just carries me over stuff, that's my guess. It honestly feels like I have additional torque like I have more power but I know that's not the case with a shorter lever.

    I rode out at a place today, and granted I haven't been there in a long time. But there's a long series of climbing switchbacks that go on for 10 minutes or so, and I recall I could never even come close to making it in the past. I was dabbing getting stuck on the switchbacks, feeling exhausted. Well twice today I just motored right up it. Now for certain cranks are not the only thing that has changed about my mountain biking. For the most part other people are slowing me down on climbs lately, including riders that are just better all-around riders than I am . This part is pretty significant to me, because I was just always the poor climber, I was always the guy having to walk. It's just not the case anymore.

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  92. #92
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    Quote Originally Posted by Suns_PSD View Post
    I'm 5'11" with I think a 31.5" inseam.
    Check out the Bike Dynamics UK website. They have some pretty sophisticated formulas for calculating the correct crank length for your body. It put me at about a 171-172 crank as being ideal for me.

    Sent from my SAMSUNG-SM-G891A using Tapatalk
    Thanks, will take a look.

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    Quote Originally Posted by Suns_PSD View Post
    Can you clarify how running the ultra short stem negatively affected your bike handling? I've been trying to understand what people are so adamant to run ultrashort stems. I run a 60 personally but I did it to extend my effective reach. Are you saying that when you have a longer stem, it gives you more leverage over the bars, and therefore makes the bike more twitchy? Trying to understand.
    There's three components that I can think of, effective lever length(ELL), fore/aft weight position and hand position along the steering arc. A setup with long stem/short bars and a setup with short stem/long bars where the ELL (distance from your hands to steering axis) is equal, should be about equally twitchy (same 'steering speed'). One advantage of short stem/wide bars is that you can keep your body center of mass nearly the same as with long stem/short bars by keeping the effective reach the same but when you are applying force to the bars it's easier to lift the front end (you're more in a deadlift form with the short stem) and you're less likely to go OTB since the bars you're putting your weight on are further behind the front wheel. The last thing, which I don't see mentioned much, is hand position along the steering arc. Ever see a modern race car steering wheel? Most are not wheel shaped anymore because racing drivers always position their hands at 9 and 3 o'clock for the greatest control. You're not going to see a racing driver with their hands positioned together at the top of the wheel (i.e. long stem/short bars) for the same reason you wouldn't position your hands that way to open a wheel valve, you'd put your hands opposite of each other. With a given ELL wider bars give greater control. That of course doesn't mean everyone should run 1000mm bars, it has to work ergonomically too. Also, stems can get so short that the backsweep of the bars causes your hands to move behind the steering axis with increases ELL just like running a longer stem would.
    Last edited by jeremy3220; 01-01-2018 at 09:45 AM.

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    Quote Originally Posted by alh View Post
    Me, too, 29" inseam. But I have relatively longer torso so I'm actually on a medium Yeti (felt better than the small).



    How tall are you @Suns_PSD? Think I will start with 170s as that's what I have on my road bike. My knees do hurt with the 175s but thought it may be other things...
    I do too. I'm barely 5'9 and my wingspan is a lil over 6'. (34 sleeve) I typically ride smalls that come in 16" with a setback of 25mm on the seat. Mediums always feel boarderline too large.

    I'm curious which Yeti you are on. I may build a 4.5 this year, and I think I could go either way. When I sit in the small, it feels like my current bikes which is pointing me towards a small again. But that's with wide bars and I know when I go down to a narrow bar, things could get more cramped.






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    Quote Originally Posted by jeremy3220 View Post
    There's three components that I can think of, effective lever length(ELL), fore/aft weight position and hand position along the steering arc. A setup with long stem/short bars and a setup with short stem/long bars where the ELL (distance from your hands to steering axis) is equal, should be about equally twitchy (same 'steering speed'). One advantage of short stem/wide bars is that you can keep your body center of mass nearly the same as with long stem/short bars by keeping the effective reach the same but when you are applying force to the bars it's easier to lift the front end (you're more in a deadlift form with the short stem) and you're less likely to go OTB since the bars you're putting your weight on are further behind the front wheel. The last thing, which I don't see mentioned much, is hand position along the steering arc. Ever see a modern race car steering wheel? Most are not wheel shaped anymore because racing drivers always position their hands at 9 and 3 o'clock for the greatest control. You're not going to see a racing driver with their hands positioned together at the top of the wheel (i.e. long stem/short bars) for the same reason you wouldn't position your hands that way to open a wheel valve, you'd put your hands opposite of each other. With a given ELL wider bars give greater control. That of course doesn't mean everyone should run 1000mm bars, it has to work ergonomically too. Also, stems can get so short that the backsweep of the bars causes your hands to move behind the steering axis with increases ELL just like running a longer stem would.
    Yep, steerer to grip length is the measurement that matters. Every 10mm of stem is worth 20mm of handlebar.

    What problem does having hands behind the steering axis cause? I've tested this, not with a 0mm/10mm stem like Mondraker testers did, but with a stem pointing backwards, and didn't really notice any steering issue besides the one caused by new body positioning.

    Do race car drivers twist their arms in sharp turns, or is their steering sensitivity turned up? I can't even manage turning the wheel any more than 2/3 of a revolution. xD

    OTB is caused more by lag in the front end, from flexy parts. The force of a wheel suddenly stalling in a nook, and having all that force wound up in fork flex, tire and wheel flex, and handlebar and headtube flex, will give enough time for your body's inertia to continue moving forward. People back then countered it by just getting low and behind the bars. New XC bikes with stiffer parts do a lot better than bikes with the same geo back in the day, less punishing to casual upright position.
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    Quote Originally Posted by dv8zen View Post
    OTB is caused more by lag in the front end, from flexy parts.
    Seriously? You beleive that "flexy parts" are the cause as opposed to weight bias?

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    Quote Originally Posted by EatsDirt View Post
    Seriously? You beleive that "flexy parts" are the cause as opposed to weight bias?
    Yes, more of a statement than a belief. Ride a cheap bike with the same technique as you ride a modern stiff bike, and you'll see what I mean. Care to challenge it with some science? Newton's First Law is a solid place to start, but I'm open to hearing some quantum theories which seem to contest such laws...
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    Quote Originally Posted by dv8zen View Post
    Yes, more of a statement than a belief. Ride a cheap bike with the same technique as you ride a modern stiff bike, and you'll see what I mean. Care to challenge it with some science? Newton's First Law is a solid place to start, but I'm open to hearing some quantum theories which seem to contest such laws...
    Whoa that's a crazy misdiagnosis! OTB is all about your center of mass relative to the fulcrum... err, front axle. Move the center of mass past the tipping point and you tip over.
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    Quote Originally Posted by dv8zen View Post
    Do race car drivers twist their arms in sharp turns, or is their steering sensitivity turned up? I can't even manage turning the wheel any more than 2/3 of a revolution. xD
    The steering ratios are such that they don't have to turn the wheel more than a max of about 180* (if that).

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    Quote Originally Posted by dv8zen View Post
    Yes, more of a statement than a belief. Ride a cheap bike with the same technique as you ride a modern stiff bike, and you'll see what I mean. Care to challenge it with some science? Newton's First Law is a solid place to start, but I'm open to hearing some quantum theories which seem to contest such laws...
    It's caused primarily by weight distribution.

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