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  1. #1
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    looong cranks?

    i know a few of you are running extra long cranks, ie, longer than 180mm. i am playing with the idea of such a setup, but don't want to have super-heavy profiles on my bike if it can be avoided. any more light- to moderately beefy stuff out there?

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    Quote Originally Posted by uphiller
    i know a few of you are running extra long cranks, ie, longer than 180mm. i am playing with the idea of such a setup, but don't want to have super-heavy profiles on my bike if it can be avoided. any more light- to moderately beefy stuff out there?
    I'm 6'6" tall and I'm pushing 250lbs. I reality-test parts with the best of them.
    I'm running 180mm cranks on my SS...they are the Race Face variety and have been solid and problem-free since October. That being said, my last set of 180 cranks were the cheapo Truvative Stylo's which lasted a good 6 months with no problems till I sold them on mtbr for $60. Some hate those cranks. They did flex alot, but I never had issue with them. I'm not sure the 3lbs is worth it for the Profiles.

    Also, I know Sparty and Shiggy love those 180+ lenghts for cranks.. but I think that all the rain they get up there does strange things to them. At my height, with my leg length...180 seems to just on the limit for me. Any longer, it seems the circle my leg would make would be so large that it would become combersome. The added leverage and length of the 180 seems just right. With a nod to fairness, I have never ridden cranks any longer than that.

    I've beaten my RF's to death and they've let out not even a whelp...yet.
    Also, Hugh, Andy akaRut, and many others have had great success with them. Okay, not Andy akaRut... but lot's of others...

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    Guess who

    Tim,

    As you know I've got lots of experience with extra-length cranks. I started off with Bullseye 202mm cranks on my custom CoMotion mountain bike back in '92. I now have four bikes with extra-length cranks, two with 202mms and two others with 195mms. FWIW my inseam is 36".

    The first thing I would tell anyone who's considering extra-length cranks is that they are bound to feel weird (maybe more like wrong) until you've ridden them for a few months. When I took possession of my new CoMotion back in the spring of '92, at first I thought I'd made a terrible mistake. The bigger pedaling circle felt cumbersome as my legs were not used to it. The whole bike felt sluggish. Frankly it took me all summer to get used to it. But after that, I found that I could climb things that nobody else I rode with could climb (I assume due to the increase in torque, or more specfically, the ability to meter out the application of that torque through a longer lever), and every time I got back on a bike with traditional length cranks (180mm or less) I felt like I was riding a kiddie tricycle. "Short" cranks made me feel like the power I'd become accustomed to disappeared. My point here is that the learning curve is by no means instantaneous but perseverance can be well worth it (it was in my case).

    Some people have stated that they think that long cranks plus a higher gear offers no advantage over shorter cranks and a lower gear. It's not that simple. It has more to do with crank length being proportunate to rider size. I'm at work so I can't give you the link I have to a Zinn web-article about long cranks, but maybe you've already read it or maybe somebody will come along and link it to this thread before I get the chance to do so myself.

    Here is a source for long cranks that are doubtless lighter than Profiles:
    http://www.hscycle.com/
    Click on "crankset."
    I have not tried these.

    While I'm not saying that extra-length cranks are for everybody, I'll say that personally I never want to go back to anything shorter than 190mm.

    --Sparty

    Quote Originally Posted by uphiller
    i know a few of you are running extra long cranks, ie, longer than 180mm. i am playing with the idea of such a setup, but don't want to have super-heavy profiles on my bike if it can be avoided. any more light- to moderately beefy stuff out there?
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  4. #4
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    Zinn link here

    http://www.velonews.com/tech/report/...es/5257.0.html


    Quote Originally Posted by Sparticus
    ...give you the link I have to a Zinn web-article about long cranks, but maybe you've already read it or maybe somebody will come along and link it to this thread before I get the chance to do so myself.
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  5. #5
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    My experience with crank length

    I've posted this before but here goes

    I've read all the crank length articles I could find. All the articles discuss geared bikes so I think they are useless. They all try to come to the conclusion. Longer cranks provide more torque but that arm length is irrelavent because you can change gears to compensate ( see sheldon Brown, Zinn etc).

    But we're talking about SS. And making the most of that one gear.

    here's what I've found in reality testing.
    My leg length determines how long a crank you can use.

    Here's the problem. My legs can only handle so much length. I have a 31" inseam and after trying many sizes, I'm running 175's.

    Anything over 175 and I lose speed and acceleration. I can crank up hills easier and stay seated more but my top speed and acceleration suffer horribly.

    The problem is my knee rises too much at the top of the stroke. If you're looking from the side, my leg rises way above level and I have a terrible DEAD spot in my stroke. I stretch etc to no avail. They are just too big. It's too bad cause if I could spin em I would love em. The extra torque is nice on the hills. 175's are probably a tad too big really but anything smaller and I lose more than I gain. Remenber crank length has a doubling effect. If the cranks are 5mm longer. You lower your seat 5mm to adjust and this makes a 10mm (5mm lower seat + 5mm longer crank) difference at the 12 oclock spin position. If you've got long legs, no problem. If they're shorter like mine it's a huge noticeble change.

    170's feel like I have no torque. I can definitely spin faster but suffer on hills more. 180's great on slow hills but slower eveywhwere else. I would really like to try 177.5's but haven't had a chance yet.

    So here's my final analysis: Run the longest crank you can spin. Your legs will adjust over time to spining a bigger circle but you can't fix a "mechanical dead spot". Try spinning the cranks with one foot on a trainer. If you can't pedal a realatively full circle the cranks are probably a little too long. If they spin easy, you could go to a longer crank without much difficulty.

    Cheers,

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    That's not all

    If you really want to get the most from long cranks, build a custom frame around them. The phenomenon you cite about your leg being bent at the top of the stroke must be dealt with. Not only do your knees feel like they are going to hit your chest on the upstroke (at first), but don't forget that your feet's relative distance from the BB will be Xmm farther forward. Both my extra-length custom frames have steeper than traditional seat tube angles in order to address the foot's farther forward position (I believe one is 75° and the other is 76°).

    On my stock frames I use a Race Face XY seatpost with the offset reversed.

    Because the seat angle is steeper, two other adjustments need to be made: chainstays should be shortened and top tube should be lengthened. In addition, because of the longer front center measurement these adjustments cause, a head angle that is 1/2 to 1 degree steeper than normal helps quicken the bike back up.

    I would urge anyone considering extra-length cranks not to judge them until they have ridden a bike that was designed specifically for their use for at least three months of hard riding.

    That is a big investment to make just to find out whether or not you like extra-length cranks.

    --Sparty


    Quote Originally Posted by Rockdogger
    I've posted this before but here goes

    I've read all the crank length articles I could find. All the articles discuss geared bikes so I think they are useless. They all try to come to the conclusion. Longer cranks provide more torque but that arm length is irrelavent because you can change gears to compensate ( see sheldon Brown, Zinn etc).

    But we're talking about SS. And making the most of that one gear.

    here's what I've found in reality testing.
    My leg length determines how long a crank you can use.

    Here's the problem. My legs can only handle so much length. I have a 31" inseam and after trying many sizes, I'm running 175's.

    Anything over 175 and I lose speed and acceleration. I can crank up hills easier and stay seated more but my top speed and acceleration suffer horribly.

    The problem is my knee rises too much at the top of the stroke. If you're looking from the side, my leg rises way above level and I have a terrible DEAD spot in my stroke. I stretch etc to no avail. They are just too big. It's too bad cause if I could spin em I would love em. The extra torque is nice on the hills. 175's are probably a tad too big really but anything smaller and I lose more than I gain. Remenber crank length has a doubling effect. If the cranks are 5mm longer. You lower your seat 5mm to adjust and this makes a 10mm (5mm lower seat + 5mm longer crank) difference at the 12 oclock spin position. If you've got long legs, no problem. If they're shorter like mine it's a huge noticeble change.

    170's feel like I have no torque. I can definitely spin faster but suffer on hills more. 180's great on slow hills but slower eveywhwere else. I would really like to try 177.5's but haven't had a chance yet.

    So here's my final analysis: Run the longest crank you can spin. Your legs will adjust over time to spining a bigger circle but you can't fix a "mechanical dead spot". Try spinning the cranks with one foot on a trainer. If you can't pedal a realatively full circle the cranks are probably a little too long. If they spin easy, you could go to a longer crank without much difficulty.

    Cheers,
    disciplesofdirt.org

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  7. #7
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    Quote Originally Posted by Sparticus
    If you really want to get the most from long cranks, build a custom frame around them. I would urge anyone considering extra-length cranks not to judge them until they have ridden a bike that was designed specifically for their use for at least three months of hard riding. That is a big investment to make just to find out whether or not you like extra-length cranks. --Sparty
    Well said, Sparty. It's a lot of work for something that "might" help.
    Do your custom frames also bump the BB a bit higher to offset the pedal strike issue or do you just develop a dancer-like cadence to get over stuff.....

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    Oops

    An elevated BB... yup. I guess I musta thought that went without saying.

    Interestingly, I have not found that a higher than normal BB diminishes the quality of bike handling whatsoever. I've also not found any difference in the way extra-length cranks effect the various disciplines of off-road cycling, ie geared or SS. I even have one of my sets of 202mm cranks on my commuter (an '00 Gary Fisher X-Caliber frame), although I don't think I'd want to go longer than 180mm on a true road bike. Pavement is so smooth and grades are less extreme.

    --Sparty

    Quote Originally Posted by Padre
    Well said, Sparty. It's a lot of work for something that "might" help.
    Do your custom frames also bump the BB a bit higher to offset the pedal strike issue or do you just develop a dancer-like cadence to get over stuff.....
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    sparty,
    thanks for the tips, esp the enlightening info on bike geometry for longer cranks. apart from the higher bb, that's all stuff i never would've thought of, the steeper seat angle makes a lot of sense.
    i get why the top tube needs to be longer, essentially because you are leaned farther forward due to the steep seat angle, but why shorter stays and a steeper head angle?
    my brother, 5 feet 8 or so and with relatively short legs, rides his old clark-kent F14 with its std-height 11.75" bb with 180s.
    do the higher bb and shorter stays make the front end easy to lift when standing? seems like it would be the case.
    sheesh. i just naively thought it would be a case of throwing longer cranks on the bike and hitting the trails.
    tim

  10. #10
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    Geometry

    Quote Originally Posted by uphiller
    ...why shorter stays and a steeper head angle?
    Tim,

    Of course frame geometry is an individual thing, so personal choice should be your guide. Personally, I've always liked the way short-stay bikes handled -- they seem a little quicker and sportier to me. Because of the steeper seat angle on a long crank frame, the rider's butt is moved farther away from the rear axle when seated. The shortened stays remedy that. I've not experienced any front-end lifting problems while standing on my long-crank customs. Perhaps that's because the long TT makes an extra roomy cockpit -- easier to move around.

    That long cockpit also makes the whole bike feel a bit longer, which I notice in turns (think of a sports car vs. a bus). A slightly steeper head angle makes the steering feel more nimble, although this can be taken too far. My CoMotion has a 73° head angle, and that's too much. ˝ degree steeper than normal is plenty of compensation.

    A good frame builder should help you with all this.

    What are you up to?

    --Sparty
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  11. #11
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    Quote Originally Posted by Padre
    I'm 6'6" tall and I'm pushing 250lbs. I reality-test parts with the best of them.
    I'm running 180mm cranks on my SS...they are the Race Face variety and have been solid and problem-free since October. That being said, my last set of 180 cranks were the cheapo Truvative Stylo's which lasted a good 6 months with no problems till I sold them on mtbr for $60. Some hate those cranks. They did flex alot, but I never had issue with them. I'm not sure the 3lbs is worth it for the Profiles.

    Also, I know Sparty and Shiggy love those 180+ lenghts for cranks.. but I think that all the rain they get up there does strange things to them. At my height, with my leg length...180 seems to just on the limit for me. Any longer, it seems the circle my leg would make would be so large that it would become combersome. The added leverage and length of the 180 seems just right. With a nod to fairness, I have never ridden cranks any longer than that.

    I've beaten my RF's to death and they've let out not even a whelp...yet.
    Also, Hugh, Andy akaRut, and many others have had great success with them. Okay, not Andy akaRut... but lot's of others...
    The weight difference between the Profiles and a Race Face / Truvativ / etc crankset is a bit over one pound and well worth it in my book.
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    Quote Originally Posted by uphiller
    sparty,
    thanks for the tips, esp the enlightening info on bike geometry for longer cranks. apart from the higher bb, that's all stuff i never would've thought of, the steeper seat angle makes a lot of sense.
    i get why the top tube needs to be longer, essentially because you are leaned farther forward due to the steep seat angle, but why shorter stays and a steeper head angle?
    my brother, 5 feet 8 or so and with relatively short legs, rides his old clark-kent F14 with its std-height 11.75" bb with 180s.
    do the higher bb and shorter stays make the front end easy to lift when standing? seems like it would be the case.
    sheesh. i just naively thought it would be a case of throwing longer cranks on the bike and hitting the trails.
    tim
    I used 185 cranks (up from 180s) on a stock VooDoo frame. The only adjustments I made where to move the saddle down and forward and to swap to a slightly longer stem. It took me about three weeks to adjust my pedaling for the longer cranks. I also learned to automatically "ratchet" to avoid hitting my pedals and hit them less than I did with the 180s.
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  13. #13
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    hey guys,
    thanks for all the tips, all this is stuff i never would've thought of on my own.
    sparty-
    i am in germany on a grant to study history, and am also torturing myself with thoughts about what i'll do when the grant is up in august. german is sometimes strikingly similar to english, and then other times so strikingly divergent.
    i, too am a short chainstay guy, my current custom geared mtb has 16" stays. it makes the front end so much easier to lift, and the steep seat angle helps keep the front wheel down when i'm climbing seated.
    later,
    tim

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    to those of you in the know- one last question (i think).
    -i seem to remember someone mentioning how well bikes with long cranks work in conditions with good traction. how do these bikes ride when traction isn't so hot?

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    Quote Originally Posted by uphiller
    to those of you in the know- one last question (i think).
    -i seem to remember someone mentioning how well bikes with long cranks work in conditions with good traction. how do these bikes ride when traction isn't so hot?
    I have not heard that. I like long cranks no matter what the traction is like. I feel that the longer stroke length lets me control my effort better.
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    ... and if we just ... POVERTY 180's

    longer cranks have a bigger "dead spot"
    Longer cranks hit rocks/roots, if that's your kind of trail
    require pedal up turning
    flexier
    yes, better traction helps, more powerful=more slideout stroke

  17. #17
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    You're confused

    First, the "dead spot" in a circle of one size is no greater than that of another size -- all circles are comprised of 360°. If the dead spot is increased, so is the power stroke.

    Second, longer levers enable power to be meted out in a more measured fashion. While both power and torque are increased as the arm gets longer, so is the ability to deliver that power to the ground in controlled amounts. Imagine a classic lever & fulcrum to illustrate this. The longer the lever, the more control you have over the load.

    Finally, longer cranks only hit the ground more often if you're riding a frame that was not designed to accommodate them, as was pointed out earlier in this thread.

    Cheers.

    --Sparty

    P.S. I admit I don't know what "pedal up turning" is.

    Quote Originally Posted by ioscope
    longer cranks have a bigger "dead spot"
    Longer cranks hit rocks/roots, if that's your kind of trail
    require pedal up turning
    flexier
    yes, better traction helps, more powerful=more slideout stroke
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  18. #18
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    Sparty et al,
    One last question. Really.
    How does one of these steep-angled, short chainstayed, high bb, long crank beasts descend steep stuff compared to your garden variety mtb of the same wheelbase? (By garden variety MTB geometry, i mean 11.75" bb, 71deg head angle, 73 deg seat angle, 16.75" chainstays.) Could you give me a general, subjective take on a machine like this feels on the trail?
    I know I am asking lots of questions, but I am a curious guy and don't want to jump into this without being well-informed.
    Thanks again.
    Tim

  19. #19
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    Quote Originally Posted by uphiller
    Sparty et al,
    One last question. Really.
    How does one of these steep-angled, short chainstayed, high bb, long crank beasts descend steep stuff compared to your garden variety mtb of the same wheelbase? (By garden variety MTB geometry, i mean 11.75" bb, 71deg head angle, 73 deg seat angle, 16.75" chainstays.) Could you give me a general, subjective take on a machine like this feels on the trail?
    I know I am asking lots of questions, but I am a curious guy and don't want to jump into this without being well-informed.
    Thanks again.
    Tim
    My Matt Chester was designed around the 190 mm cranks and drop bars. It has a 13" BB w/ 2.1 tires (I often run bigger), 71.5° head angle (don't know the seat angle),16.5" chainstays and about a 42.25" wheelbase. It is by far the best handling bike I have ridden. Climbs well, descends great, quick handling AND stable. Works for technical trails, too.
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  20. #20
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    I second that

    My Vulture handles most excellently. Trust us on this one Tim, a high bottom bracket is no disadvantage while descending nor in tight quarters. Perhaps the best evidence I can offer in the case of my particular bike is that I finished the '02 Cream Puff (which features over 17,000 feet of climbing AND descending) fourth of nine starters in my class (I was the only one riding SS). The high BB was no disadvantage. Just because my BB/feet might be an inch or so higher, that doesn't mean my center of gravity is any higher.

    --Sparty


    Quote Originally Posted by shiggy©®™
    My Matt Chester was designed around the 190 mm cranks and drop bars. It has a 13" BB w/ 2.1 tires (I often run bigger), 71.5° head angle (don't know the seat angle),16.5" chainstays and about a 42.25" wheelbase. It is by far the best handling bike I have ridden. Climbs well, descends great, quick handling AND stable. Works for technical trails, too.
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    ... and if we just ... BMX 180's on a DS bike

    SPARTICUS... to turn sharply (BMX STYLE) you turn the inside pedal up, and don't pedal in the turn... pedal up turning

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