180 cranks or No...?- Mtbr.com
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  1. #1
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    180 cranks or No...?

    Got back on the SS this past week to get back into riding shape. I had forgotten how much I love riding it (the Tracer has been seeing less trail time) although walking along side it is not as much fun. There were too many business trips the past year which hampered my riding time and added 15 lbs to my frame. I have a Schwinn Moab that I converted some time ago (Toyota had a promo with Schwinn some time back and Schwinn passed on a Moab Disc to me). I am currently running 32 x 22 gearing for So.Cal / OC trails and after today's ride in Aliso and up Cholla. I was wondering if 180 cranks would be worth the investment to assist in climbing. I am riding on 175s now and for those familar with Aliso, I have to stop about 4 times up Mathis on the SS but no problems on the gearie. I do plan on going to a twenty niner eventually but want to get my "behind" back into shape first. My goal is to ride the VQ instead of working the aid stations by next year as well as take our annual bike tour with the SS and forego gears (maybe).

    Would 180 cranks help me out? I know it may increase crank to rocks time. I just wonder about spending the duckets ($) versus value.

    Rider: 6 foot / 32" inseam / 215 lbs shooting for 190 lbs
    Bike: Schwinn Moab Disc converted to SS (medium frame)

    PS - Paul rear hub and no quick release. Currently 22t with a 20t waiting in the wings. Pardon the garage mess, we are in the midst of a re-do...
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  2. #2
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    Imo

    At your height...
    175 = no
    180 = yes
    185 - 190 = even better

    This comes from a 6'3", 36" inseam, 190 lb-er (shooting for 183 lbs) who's been riding 195-202mm cranks for 14 years. Once you get used to long cranks, you'll wonder why more manufacturers don't offer them. But be forewarned -- at first they may feel wrong. Stick with 'em while your leg muscles get used to turning bigger circles.

    Then laugh while you climb, climb, climb.

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    Last edited by Sparticus; 01-09-2006 at 09:43 PM. Reason: I love to edit stuff
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  3. #3
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    I ride 180's on all my bikes (road, 'cross, MTB, single or mult-speed), so I'm probably a little biased, but I say go for it. Studies have shown that 5mm more of crank length is equal to 1 less tooth on your chainring, which means that 1) at a given cadence you are generating less wattage with 180mm cranks, and 2) at the same wattage you are going faster than you would be on 175's. Aside from that, common sense tells you that using a longer lever makes any "prying" job easier by needing less force to move something (in this case you and your bike) the same distance.

    Don't listen to all the people who try to tell you that you'll blow out your knees, that's a bunch of crap perpetuated by the bike industry because they don't want to have to make more sizes of crank arms. Just make sure you adjust your saddle position correctly and your knees will be fine.

    As for not being able to spin fast, that is entirely up to you and how much you practice. I can spin my 180's just as fast as I spin the 170's on my track bike, which is about 180rpm max. You can spin any crank as fast as you're physically capable of, you just have to practice and adapt.

  4. #4
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    I'm 6 foot with a 34" inseam and I ran 175's at first (couple years ago) because my other mtb bikes all had them. I ran across a deal on 180s and I've been bit ever since. After the first ride I've only fely weird on the 175s on mtb bikes now. Could never go back. To me it was a definite (even if it was mental only) adavantage to me. I climbed better and just felt more powerful.



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  5. #5
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    Anything under 177.5 feels way to short for me. I run 180s on my fs and ss and 177.5s on my road and cross bikes. I can spin em' or crunch em' no problem. No knee problems in the 15 years I've been doing the long crank thang.
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  6. #6
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    Forgot to add to the first post "any recommended crank arms?" The current bottom bracket is a "octolink LX" but I am more than willing to replace. Again $ to value ratio is a high priority.

    Thanks for all the responses thus far! It looks like 180 for boboso.
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  7. #7
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    What about reasons not to? Anyone have an opinion on that? I am currently in the same situation and I am curious about drawbacks.

  8. #8
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    The Eno cranks come in 180's and are very nice, you can sometimes find older generation Shimano cranks (that use regular chainrings) in 180mm on Ebay, and there are always the various BMX cranks like Profile. Personally, I have a set of Middleburns on my Steelman, which are great cranks and have a lifetime unlimited warranty. If you jump off a cliff and break a crank arm, send it in and get a new one, no questions asked . You'll have to hunt around to find them though, they're rare in the US.

  9. #9
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    i vote NO.

    i'm 6' with 32" inseam. my ss has 175mm and i'd go 170 if i have the money. my cross and fixie both have 165mms.

    shorter==easier spinning. if i need torque, i use a bigger cog. end of story.

    (edit: wrote ring instead of cog. use a bigger cog or a smaller ring, either way.)

  10. #10
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    Sounds like they would work for you fine, and if you think you'd like to try a longer crank, probably will. I am 5' 9" with kind of short legs for my height, but I am very comfortable spinning 180s on a recently built SS. I raced on them for seven years prevously, so I already knew this, but I believe it is more a matter if your legs will move comfortably with the extended range of motion (larger spin circle). If it does not excede your maximum range of motion, you are no worse off and with more leverage. They will feel diffeent at first, but that is because you are using muscules differently than before, and you will get used to it. It's like any kind of workout. You will become better acclimated to the motion and extend that range the more you push it.

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  11. #11
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    Uh, using a bigger chainring LOWERS your torque. It's like trying to accelerate your car from a full stop in second gear.

  12. #12
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    Dude, isn't this the single speed forum? On a ride you don't have access to different gears.
    Quote Originally Posted by weather
    i vote NO.

    i'm 6' with 32" inseam. my ss has 175mm and i'd go 170 if i have the money. my cross and fixie both have 165mms.

    shorter==easier spinning. if i need torque, i use a bigger cog. end of story.

    (edit: wrote ring instead of cog. use a bigger cog or a smaller ring, either way.)
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  13. #13
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    Just my half penny worth, but would a longer crank not increase toe overlap on a 26inch wheeled bike?

    Not as much of a problem on a 29er I suspect. At 6'2" with size 47 feet, toe overlap is always something I need to be aware of.

  14. #14
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    Size 48 shoe, no toe overlap on even the tightest 29" geometry XL frame.

    ALL cranklengths take getting used to. I've got a 39"+ inseam, and typically have 180mm on all offroad bike, 175 road (I'm cheap). recently built up a bike with my ancient 185's, and they take some getting used to for sure. But, the few instances where I found myself in low rpm climbing a steep, it was a-ok. I'm pretty sure that if I only rode one bike (more like dozen in fact), I could get used to 200mm and longer. Do take a month of regular riding into account to fully get used to a length change.
    When comparing very similar 29"ers back-to-back, one 175mm, one 180mm, both me and my buddy (175mm rider himself) agreed that the 175mm sucked at any high-power low-rpm situation. We were fighting voer the 180mm bike, a heavy rigid, where the 175mm was my new bling proto bike, go figure.
    I intend to put another ancient 185mm set on some bike again, to get more and more 185mm mileage and train my legs on it. I am completely convinced more knee angle is better. The naturally lower ideal rpm might also help pedal more "round", thus more efficient. Lance-style, ya know...
    After a few 185mm rides, mixed with 180mm and 175mm rides, I'm still very much getting used to it. with headwind (80-90rpm?), it's seems tiring. Drafting a couple roadies nearer to 100rpm, it was heaven on earth. 185mm really it too for me to get into more detail, the difference with my 180's (90% riding time) is too little.

  15. #15
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    I'm 6'2" and looking at going to the 180's for my SS.
    Someone above mentioned adjusting your seatpost height. Would you raise or lower your post to accept the longer arms? The way I see it the distance to the BB is the same so why the different post height? Thanks

  16. #16
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    Lower...

    Your crankarm will be 5mm longer, so the saddle will need to be adjusted lower to compensate. (Your foot don't spin on the BB)

  17. #17
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    formula

    The 'old coot' in dirt rag in one issue that I cannot find right now had some formula that determined your correct crank arm size. I did the calculations( I am 5 4 with a 30 inch inseam) and my proper crank arm length was something around 165mm. I am sure it is somewhere on the website. So I don't know, I am building a new bike right now( gunnar ruffian 26") and I ordered the 170 mm cranks(eno). I also ride a track bike w/ 165mm. Are there any smaller folk out there rockn' larger cranks? Is it just preference?

  18. #18
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    Quote Originally Posted by KONA_in_SB
    Dude, isn't this the single speed forum? On a ride you don't have access to different gears.
    dude, learn to change out your freewheel or your chainring. it's actually easier than changing crank arms.

  19. #19
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    Blowing out your knees is not crap. Just ask all the cyclists who have experienced knee problems from pushing too big a gear, especially while seated. SS crankarms can be longer than road or geared MTB arms because we ride them different. Standing on climbs is the norm and puts less stress on the knees, thus you can use longer arms. If you don't like to stand, SS riding will be difficult and longer crank arms can do some damage. A person better gear lower, including shorter crankarms, if standing is not their thing. Longer arms also help on the downhills, you won't spin out as soon. Thus, in general, longer arms are good for SS, unless you don't like to stand and climb.

  20. #20
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    "Longer arms also help on the downhills, you won't spin out as soon"?

    you gotta be kidding me.

  21. #21
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    You're pedaling bigger circles.

  22. #22
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    larger circles==>exaggerated movement==>your center of gravity moves around more==>harder to spin.

    btw, if you are thinking a larger circle will make you pedal less rounds, you've made a mistake in your reasoning. think again.

  23. #23
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    Anomie: As for not being able to spin fast, that is entirely up to you and how much you practice. I can spin my 180's just as fast as I spin the 170's on my track bike, which is about 180rpm max. You can spin any crank as fast as you're physically capable of, you just have to practice and adapt.

    Then why not have 190mm or 200mm cranks?

    IMHO, the length of the crank should be optimal for your body geometry, not for leverage. Use the cog or chainring size to manage torque or leverage. In other words, use a crank length that allows your legs to work at their optimal power output. That output is always a compromise between speed (spin) and power (leverage).
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  24. #24
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    Quote Originally Posted by weather
    "Longer arms also help on the downhills, you won't spin out as soon"?

    you gotta be kidding me.
    Perhaps the comment was based on the assumption that with longer cranks the rider will also utilize the ability to run a higher gear. I've done this personally, but it's ineffective on a true downhill, where I'll coast regardless. However it can be helpful on a trail like the 26 mile long McKenzie River Trail (heading downstream), where I can run a tooth or two higher than my buds.

    Hey, occasionally every little bit matters.

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  25. #25
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    Quote Originally Posted by serious
    IMHO, the length of the crank should be optimal for your body geometry, not for leverage.
    we have a winnah!!!

  26. #26
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    Quote Originally Posted by serious
    ...IMHO, the length of the crank should be optimal for your body geometry, not for leverage. Use the cog or chainring size to manage torque or leverage...
    Leverage (lever lenth) and gear ratio are not exactly comparable. Although each can be used as an approach to solving the same problem, they accomplish different things in different ways.

    Quote Originally Posted by serious
    Then why not have 190mm or 200mm cranks?
    That's exactly what I do. I have a couple bikes outfitted with 195mm cranks and a couple outfitted with 202mm cranks.

    Look, nobody's saying that long cranks are best for everyone. You are right when you say the individual's body style and preference ought to dictate which length a given rider utilizes. Use whatever you like, but for some body types (ie: mine) you'll never convince me to use a shorter lever and a lower gear. I've done that. It's not the same. Not even close.

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  27. #27
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    The rule of thumb in this case is - "Use what works for you."

    As for me, I'm 5'10" with a 33" inseam in clipless shoes, and I'm absolutely in love with my profile 190mm cranks. Being an ex BMX guy, I was already used to 180mm (the standard in BMX for riders 16 and older), so going a bit longer for a single speed MTB seemed to fit.

    The knee blowout issue might have some merit for roadies who log 500 mile weeks, but for SS off road riding, where I'm standing 75% of the time, I've had no knee issues.

  28. #28
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    Quote Originally Posted by Sparticus
    Leverage (lever lenth) and gear ratio are not exactly comparable. Although each can be used as an approach to solving the same problem, they accomplish different things in different ways.
    Maybe I'm just not following your reasoning, but gears <b>are</b> coupled levers. They're the same thing. You apply a force over a given distance at your input, and you get some other force over a different distance at the output. Depending on your gear or leverage ratio, you can trade off between the two. But there's no free lunch. Whether you go to a longer crank or a bigger cog, you'll spin out faster. Force and distance are always tied together, and you can't get more force without adding distance.

    So for the OP, since he's reasonably tall, I'd say try 180's for a month, and if you don't like it, then sell them here. The only changes: seat will move down a little (no big deal), pedal clearance will decrease (may not matter due to terrain), toes will get closer to the front wheel (shouldn't matter). Unless your area is rocky, there's not much to lose, and you might find that they fit you better. There's no way to find out without trying them.

    If after a month you don't like them, sell them here and use the proceeds to go up one tooth in the back. Either way, you'll spin out sooner. No big deal. That's what has to happen if you want climbing to be easier.

    The other option is to go do squats or plyometrics or pick up speedskating, but that's not fun to argue about over here....

  29. #29
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    Quote Originally Posted by dr.welby
    Maybe I'm just not following your reasoning, but gears <b>are</b> coupled levers. They're the same thing. You apply a force over a given distance at your input, and you get some other force over a different distance at the output. Depending on your gear or leverage ratio, you can trade off between the two. But there's no free lunch. Whether you go to a longer crank or a bigger cog, you'll spin out faster. Force and distance are always tied together, and you can't get more force without adding distance...
    They are not the same thing because changing the crank length changes the distance that the force is applied to/during.

    If the pedaling force is applied over ~120 degrees of rotation the distance the pedal moves is ~350mm with 175 arms and increases to ~360mm with 180 arms.
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  30. #30
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    Quote Originally Posted by meloh1
    You're pedaling bigger circles.
    Which means your foot speed is higher for the same rpm. Spinning out should happen at a lower rpm.

    Conversely it means I can maintain a lower cadence on the climbs with longer cranks as my foot speed is slightly higher.
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  31. #31
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    180's: Hell Yeah... ENO Cranks: Hell Yeah.

    I'm 6'2", 32" inseam, 250 lbs. [gave up shooting for lower weight a long time ago] and I have been running 180's on my singlespeeds for 11 years now: no knee problems; more power when climbing and/or standing; and they spin just fine with my 34X20 in fairly steep NorCal terrain [Mt Tam/Marin Headlands].

    As for the ENO Cranks: I've run XTR M900 cold-forged cranks since they first came out, but my wife just got me some ENO 180's for Christmas: very stiff; good chainline; no creaking; crankarms stay tight; and beautifully made to boot. So far, so good. The only bad part is being called a sell-out by your playa hatin' friends for dumping so much bling on a SS...

  32. #32
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    Quote Originally Posted by dr.welby
    Maybe I'm just not following your reasoning, but gears are coupled levers. They're the same thing.....
    I'm not educated in physics, but please bear with me while I try to the best of my ability to explain my opinions/beliefs in lay terms.

    Imagine your cranks are 50mm long. That's about two inches. Even with something like an 14t chainring (or some other very low gear), you'd have a hard time going uphill. There's simply not much leverage with cranks this short, no matter how low the bike is geared.

    Now imagine a bike with a very high bottom bracket and three foot long cranks. (Also imagine a guy big enough to pedal such a bike!) Even with an appropriately large gear, this contraption's leverage would feel completely different than the low-geared bike's 50mm cranks.

    I'm not saying anyone would want either of these extreme examples. What I'm saying is that comparing these isn't appropriate. Changing the gearing is not the same as changing the length of the lever. It feels different and how it feels matters 100% on the bike.

    Are longer levers "better?" No. Individual riders can only speak for themselves.

    Handlebars are levers, too. Some folks prefer narrow handlebars and some prefer wide ones. It wouldn't be right for someone to tell somebody else that their handlebars were "too narrow" or "too wide." Those are individual judgement calls. But saying that changing gearing is the same as changing crank length is similar to implying that using a wider handlebar with a shallower head angle is the same as using a narrow bar with a steep head angle, and this is not the case.

    Maybe the only way to find out which is best for an individual rider is for them to try both, and to do so for long enough that (s)he truly becomes familiar with each before making a decision about which is best for themselves.

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  33. #33
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    Foot speed is not the limiting factor for most people. Applying force while changing direction is more limiting than the actual foot speed. A larger circle allows for smoother direction changes. Pedaling downhill does not require as much force as uphill pedaling so spinning longer arms is not a force issue when pedaling downhill, it's a cadence issue. Try pedaling a fixie with longer and shorter crank arms downhill. I think you'll find it easier to spin a given rpm with longer arms going downhill. This isn't true in most other situations (flats or uphill) because your ability to apply enough force for a given cadence becomes an issue.

  34. #34
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    Quote Originally Posted by meloh1
    Foot speed is not the limiting factor for most people. Applying force while changing direction is more limiting than the actual foot speed. A larger circle allows for smoother direction changes. Pedaling downhill does not require as much force as uphill pedaling so spinning longer arms is not a force issue when pedaling downhill, it's a cadence issue. Try pedaling a fixie with longer and shorter crank arms downhill. I think you'll find it easier to spin a given rpm with longer arms going downhill. This isn't true in most other situations (flats or uphill) because your ability to apply enough force for a given cadence becomes an issue.
    Been there. Not my experience. In fact I find the opposite is true for me.

    On downhills I find it easier to keep up on a fixie with 170 arms vs one with 185, and I normally run the 185s.

    I stall out on climbs sooner with the short cranks.
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  35. #35
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    I agree, shorter cranks make climbing harder but I find spinning downhill easier with longer cranks. What's your leg length? It's not just arm length but arm length as a proportion of you leg length. For everything but out of the saddle climbing some studies have found an arm length equal to 20% of your leg length to be optimum. SS tilts the scales somewhat towards longer arms because of the need to stand when climbing and use a longer lever.

  36. #36
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    Quote Originally Posted by meloh1
    I agree, shorter cranks make climbing harder but I find spinning downhill easier with longer cranks. What's your leg length? It's not just arm length but arm length as a proportion of you leg length. For everything but out of the saddle climbing some studies have found an arm length equal to 20% of your leg length to be optimum. SS tilts the scales somewhat towards longer arms because of the need to stand when climbing and use a longer lever.
    I have seen various formulas that place my "ideal" crank length from 178-210mm. 182-185 feels best to me, geared or SS.
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  37. #37
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    Great discussion... and thanks to all who have provided solid input (good, bad and just plain ugly). It all helps.

    I decided I am going to give the 180s a try. I am checking on some BB measurements and will be going with a deal on some Truvativ 32t 180 with bash ring.

    Once installed and riding, I should be able to tell after a bit if they make a difference in what I was after, improved climbing. Downhill here in So.Cal I am typically coasting and feet are level unless turning.
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  38. #38
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    Quote Originally Posted by meloh1
    Try pedaling a fixie with longer and shorter crank arms downhill. I think you'll find it easier to spin a given rpm with longer arms going downhill.
    i tried, and that's exactly the reason i went shorter on the fixie. and after trying shorter cranks on my CX bikes i'm sticking to 165s rather than 175s on that bike too.

  39. #39
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    Light reading on the subject

    I've read a lot on this subject, including some medical journals. Statistically speaking longer crank lengths increase your likelihood of injury. Here is a good article to start on:

    http://www.sheldonbrown.com/cranks.html

  40. #40
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    And here's some more...

    And here's some more...

    http://www.zinncycles.com/cranks.aspx

    ...plus one crank length formula...

    http://www.nettally.com/palmk/Crankset.html

    ...more of the same fella here, with some old wive's tales...

    http://www.nettally.com/palmk/crwives.html

    ...same guy, but I'm even quoted in this one (I'm the Disciples of Dirt guy)...

    http://www.nettally.com/palmk/crexampl.html

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  41. #41
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    Quote Originally Posted by Sparticus
    Imagine your cranks are 50mm long. That's about two inches. Even with something like an 14t chainring (or some other very low gear), you'd have a hard time going uphill. There's simply not much leverage with cranks this short, no matter how low the bike is geared.
    The leverage will be the same, assuming your chainring is scaled accordingly. It's simple mechanics. The problem is that 2" cranks would be just horrid from a biomechanical standpoint. While the force would be the same, it would feel just so wrong you wouldn't know the difference.


    Quote Originally Posted by Sparticus
    Now imagine a bike with a very high bottom bracket and three foot long cranks. (Also imagine a guy big enough to pedal such a bike!) Even with an appropriately large gear, this contraption's leverage would feel completely different than the low-geared bike's 50mm cranks.
    The leverage would feel different cause you're pedalling 6 foot circles. But again, if you scale the chainring appropriately, the force required will be the same.

    If the force is the same on both setups and you're riding at the same speed, then the foot speed has to be the same. But you will have radically different cadences. The two inch cranks will require you to shift from one leg to the other very quickly. The 3 foot cranks will have a looonnggg power stroke.

    So it really comes down to biomechanics. You may prefer to have that longer power stroke - especially if you have long legs. You muscle make-up may prefer it. Off road and at slow rpms, it might be easier to not have to shift from one side to the other as often. My guess is that that could be the key difference, something I'd like to investigate a bit more.

    Quote Originally Posted by Sparticus
    I'm not saying anyone would want either of these extreme examples. What I'm saying is that comparing these isn't appropriate. Changing the gearing is not the same as changing the length of the lever. It feels different and how it feels matters 100% on the bike.

    Are longer levers "better?" No. Individual riders can only speak for themselves.
    That's they key point - mechanically they are the same but biomechanically they aren't. It's easy to make mechanical predictions but biomechanical ones are pretty difficult.

    So when the OP, wanting easier climbing, asks whether to go to longer cranks or a lower gear, the simple answer is that either will accomplish his goal. But one might work out better than the other, and the only way to find out is to try it. In this case, since he's tall, there's no risk in trying 180's since he would have no problem selling them on this list if he didn't like them. But on the other hand, if he can't afford 180's gearing down will make climbing easier too.

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