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My thoughts on seat position, crank length, and cleat position
Hi Everyone,
I think I have finally settled into a position I am comfortable with and I hope will allow for maximal power output and maximum efficiency at sub-maximal power outputs. In other words, improved endurance. First a summary of my situation, then a description of my "solution" and thoughts on why it seems to work. My inseam (varies by time of day, compression of meniscus?) seems to be 95cm, my feet are size 50 (305mm long). When I was in my 20's I weighed about 93 kg (205 lbs), was rather fit, and didn't have any problems with comfort even on long rides. I used 177.5mm cranks on my road bike, 180's on the time-trial bike. I used LeMond's inseam x 0.883 for seat height with a little downward fudge for crank length. Knee slightly forward of the spindle. Way stretched out with a long top-tube and the longest Cinelli stem I could find. After a 10 year hiatus I bought a new bike and started riding again. Once I got down to 105kg I started experimenting with positioning to find an optimal setting. My hands had problems with numbness, but I attibuted that to overweight upper body, and rough pavement. My new bike had 175mm cranks. As my weight dropped to 100kg, the numbness persisted, and I figured I had to do something about it. So I moved my saddle slowly rearward to get weight off my arms, as well as raised the bars, and moved them rearward. I tried a very large range, and the numbness improved but did not go away. But pedaling always felt sub-optimal. Standing was a waste of time, and on flats in a tuck I kept slipping forward on the saddle. On seated climbs I would ankle quite a bit and slide my butt bones all the way off the rear of the saddle. I had my cleats set very neutral, but thought I'd try moving them back to compensate for my large feet, in an attempt to make my pedalling feel more normal. I didn't notice any real change except my monster ankling on steep climbs wasn't as effective. I became intrigued by the "proportional cranks" argument and set about thinking how it could benefit me. It didn't take much to convince me that proportional makes sense, and were worth a try. The difference has been amazing. It took a while to get the seat height right, and I ended up trying all sorts of crazy combos until I found what felt right. When I measured the height it corresposnds to 109% of inseam from seat to pedal spindle. Coincidently a magic number touted my Ed Burke and others. I also found my knee was right over the pedal spindle. Another coincidence factor. Everything seemed to be so "normal" that I tried moving my cleats back to right under the ball of my foot. Again everyting seemed to just click. I have a pet theory that the conventional wisdom of large feet benefiting from reaward cleat position is just a kludge to overcome what is actually people using cranks that are too short. The issue isn't large feet, the issue is the long legs attached to those feet!Now in a tuck I don't side forward, and ankling up steep climbs I don't slide back at all. I shove back a bit, but not any more than can be taken up by the slack in flesh. My bars are slighlty higher than they were relative to the seat (about 1cm) but are now 2cm further forward. My fore-aft balance on the bike seems much better and the numbness in the hands is gone. And even standing on climbs feels good. Instead of feeling as though I was teetering on top of a flag pole, I feel like I get good solid strides. But the real fun came when I went to measure my power on a long hill. At the peak of the season a few months ago on 175mm cranks I measured my output at almost 290 watts by plugging values into analyticcycling.com. Yesterday with my 195's I calculated over 300 watts, despite having not ridden so much in the last 6 weeks. And it was pouring rain so my clothes held some unknown mass of water, which lets me know the output is even a little higher. (My wife gave me one of those looks when I said I was going to traipse through the house in sopping wet gear to weigh myself, so the exact weight is unknown for now...). I know there are studies showing that crank-length has almost no bearing on power output, but I think they maybe did not study a wide enough range. Or perhaps I just am lucky. I haven't been on any rides longer than 110km with the new cranks, so I don't know how it will play out endurance-wise. I think the key is juggling the variables of power (speed), cadence, and pedal force. The extra leverage afforded by using cranks that are not drastically undersized allows a lighter force to be applied to achive a given power at a comfortable cadence. Cadence and force obviously play into eachother, and when you can't get them to jive, it isn't strange that it feels funny, or that power is sub-optimal. This lighter force at least in my case more than makes up for the greater pedal distance and pedal speed required for a given cadence. So my new fit seems pretty normal: seat height (from bb) = (inseam x 1.09) - crank length seat fore-aft: knee over spindle cleats: neutral But it is all only possible by using cranks of length 20.8% of inseam. Are there many folks using cranks 20.8% of inseam who also have seat position set similarly, but are of a scale that results in more normal length cranks like 172.5? Joseph |
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#2
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My thoughts on seat position, crank length, and cleat position
Well, almost. I have a 33" inseam (838mm) and use a 175 crank, which is
~20.8%. My saddle height is 737mm, which is what your formula works out to as well, but that is to the top of the seat clamp (or to the saddle rails), NOT to the top of the saddle surface itself. That dimension is a full 50mm higher. I can't imagine riding that much lower, if that's what you are suggesting. Hmmm... wrote in message oups.com... Hi Everyone, I think I have finally settled into a position I am comfortable with and I hope will allow for maximal power output and maximum efficiency at sub-maximal power outputs. In other words, improved endurance. First a summary of my situation, then a description of my "solution" and thoughts on why it seems to work. My inseam (varies by time of day, compression of meniscus?) seems to be 95cm, my feet are size 50 (305mm long). When I was in my 20's I weighed about 93 kg (205 lbs), was rather fit, and didn't have any problems with comfort even on long rides. I used 177.5mm cranks on my road bike, 180's on the time-trial bike. I used LeMond's inseam x 0.883 for seat height with a little downward fudge for crank length. Knee slightly forward of the spindle. Way stretched out with a long top-tube and the longest Cinelli stem I could find. After a 10 year hiatus I bought a new bike and started riding again. Once I got down to 105kg I started experimenting with positioning to find an optimal setting. My hands had problems with numbness, but I attibuted that to overweight upper body, and rough pavement. My new bike had 175mm cranks. As my weight dropped to 100kg, the numbness persisted, and I figured I had to do something about it. So I moved my saddle slowly rearward to get weight off my arms, as well as raised the bars, and moved them rearward. I tried a very large range, and the numbness improved but did not go away. But pedaling always felt sub-optimal. Standing was a waste of time, and on flats in a tuck I kept slipping forward on the saddle. On seated climbs I would ankle quite a bit and slide my butt bones all the way off the rear of the saddle. I had my cleats set very neutral, but thought I'd try moving them back to compensate for my large feet, in an attempt to make my pedalling feel more normal. I didn't notice any real change except my monster ankling on steep climbs wasn't as effective. I became intrigued by the "proportional cranks" argument and set about thinking how it could benefit me. It didn't take much to convince me that proportional makes sense, and were worth a try. The difference has been amazing. It took a while to get the seat height right, and I ended up trying all sorts of crazy combos until I found what felt right. When I measured the height it corresposnds to 109% of inseam from seat to pedal spindle. Coincidently a magic number touted my Ed Burke and others. I also found my knee was right over the pedal spindle. Another coincidence factor. Everything seemed to be so "normal" that I tried moving my cleats back to right under the ball of my foot. Again everyting seemed to just click. I have a pet theory that the conventional wisdom of large feet benefiting from reaward cleat position is just a kludge to overcome what is actually people using cranks that are too short. The issue isn't large feet, the issue is the long legs attached to those feet!Now in a tuck I don't side forward, and ankling up steep climbs I don't slide back at all. I shove back a bit, but not any more than can be taken up by the slack in flesh. My bars are slighlty higher than they were relative to the seat (about 1cm) but are now 2cm further forward. My fore-aft balance on the bike seems much better and the numbness in the hands is gone. And even standing on climbs feels good. Instead of feeling as though I was teetering on top of a flag pole, I feel like I get good solid strides. But the real fun came when I went to measure my power on a long hill. At the peak of the season a few months ago on 175mm cranks I measured my output at almost 290 watts by plugging values into analyticcycling.com. Yesterday with my 195's I calculated over 300 watts, despite having not ridden so much in the last 6 weeks. And it was pouring rain so my clothes held some unknown mass of water, which lets me know the output is even a little higher. (My wife gave me one of those looks when I said I was going to traipse through the house in sopping wet gear to weigh myself, so the exact weight is unknown for now...). I know there are studies showing that crank-length has almost no bearing on power output, but I think they maybe did not study a wide enough range. Or perhaps I just am lucky. I haven't been on any rides longer than 110km with the new cranks, so I don't know how it will play out endurance-wise. I think the key is juggling the variables of power (speed), cadence, and pedal force. The extra leverage afforded by using cranks that are not drastically undersized allows a lighter force to be applied to achive a given power at a comfortable cadence. Cadence and force obviously play into eachother, and when you can't get them to jive, it isn't strange that it feels funny, or that power is sub-optimal. This lighter force at least in my case more than makes up for the greater pedal distance and pedal speed required for a given cadence. So my new fit seems pretty normal: seat height (from bb) = (inseam x 1.09) - crank length seat fore-aft: knee over spindle cleats: neutral But it is all only possible by using cranks of length 20.8% of inseam. Are there many folks using cranks 20.8% of inseam who also have seat position set similarly, but are of a scale that results in more normal length cranks like 172.5? Joseph |
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My thoughts on seat position, crank length, and cleat position
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#4
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My thoughts on seat position, crank length, and cleat position
Ron Ruff wrote: wrote: But the real fun came when I went to measure my power on a long hill. At the peak of the season a few months ago on 175mm cranks I measured my output at almost 290 watts by plugging values into analyticcycling.com. Yesterday with my 195's I calculated over 300 watts, despite having not ridden so much in the last 6 weeks. I doubt that difference is really significant considering the variations in wind conditions that always occur... but at least it looks like you are doing alright with the longer cranks. No wind, and I use a hill steep enough that for my speed (about 15 km/h, or 9.3 mph) there is no significant wind resistance. If I estimate the weight of soaking wet clothes and rims full of water to be about 2 kg, the calculation gives me 311 watts, vs 289.5 watts I recorded earlier in the season with dry clothes, and shorter cranks. It is of course impossible to say how my fitness has changed, but I'd say it is safe to say that the 7% power increase was achieved at least to some degree by the cranks. I don't think it is possible that they slowed me down, and I am convinced that there is no way I could have gone as fast with 175's. I know there are studies showing that crank-length has almost no bearing on power output, but I think they maybe did not study a wide enough range. The ranges are usually quite large... I think 120-220mm in one test that I recall. Zinn claims that he has many testimonials from people who love their long cranks... but he has tried to show a positive correlation with *performance*, and hasn't been able to do so. He also mentions that he does quite well with 100mm cranks! If you prefer the "feel" of the long crank, you probably won't be significantly slower at least. 120-220 sure covers a lot of ground. Perhaps for certain individuals there are certain lengths that are particularly bad, while most other lengths are just neutral. I wasn't expecting my max power to increase, I was hoping to get better feel and at best flatten out my power-HR curve, if that makes any sense. I was hoping for more efficient sub-maximum output, ie endurance. I don't know how one would measure that. Maybe lactate levels at different power and/or cadences. I intend to take a VOmax and lactate test later this fall. It is at a place where you use your own bike. Maybe I'll bring 2 bikes (175, 195) and see how things compare. Anyone with suggestions on how to measure, or plot this info (and what info to record) to be able to make sense of it all would be appreciated. I think the key is juggling the variables of power (speed), cadence, and pedal force. The extra leverage afforded by using cranks that are not drastically undersized allows a lighter force to be applied to achive a given power at a comfortable cadence. Cadence and force obviously play into eachother, and when you can't get them to jive, it isn't strange that it feels funny, or that power is sub-optimal. This lighter force at least in my case more than makes up for the greater pedal distance and pedal speed required for a given cadence. You will have a bigger circle to move your leg around... whether or not this is "better" than simply pedaling a little faster with the same force (and a shorter crank), seems to be an individual thing. I think this is the whole key to it. The individual preference of relation between force and pedal speed. When one is pedalling along in a gear that feels too light, why does it feel too light? Likewise what makes a gear feel too heavy? Somehow 170 seems to have been settled upon, but why? Are there many folks using cranks 20.8% of inseam who also have seat position set similarly, but are of a scale that results in more normal length cranks like 172.5? My inseam is 33.5 in (85mm), seat height is 36.25 in (1.08x), and cranks are 172.5mm (20.3%). If I used 175s I'd be just about there. Sounds pretty close to me, considering how imprecise inseam measurment is. I wouldn't mind trying 150s and 190s... just to see what it felt like. http://www.hscycle.com/Pages/adjustablecrankset.html But $450 might be a bit much to satisfy your curiosity... Joseph |
#5
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My thoughts on seat position, crank length, and cleat position
joseph.santanie wrote:
No wind, and I use a hill steep enough that for my speed (about 15 km/h, or 9.3 mph) there is no significant wind resistance. If I estimate the weight of soaking wet clothes and rims full of water to be about 2 kg, the calculation gives me 311 watts, vs 289.5 watts I recorded earlier in the season with dry clothes, and shorter cranks. It is of course impossible to say how my fitness has changed, but I'd say it is safe to say that the 7% power increase was achieved at least to some degree by the cranks. I don't think it is possible that they slowed me down, and I am convinced that there is no way I could have gone as fast with 175's. Lots of variables and uncertainties there. How accurate are the Analytic Cycling formulas? How accurate were your estimates and assumptions? How much was due to psychological factors (similar to new bike syndrome)? And also, you changed several things besides just crank length. But hey, if it feels more comfortable, and you're riding better, don't fight it! Art Harris |
#6
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My thoughts on seat position, crank length, and cleat position
Me if you look back at the figures I posted earlier. Interesting.
Did the longer cranks solve the catch in your pedal stroke by the way? wrote in message oups.com... Hi Everyone, I think I have finally settled into a position I am comfortable with and I hope will allow for maximal power output and maximum efficiency at sub-maximal power outputs. In other words, improved endurance. First a summary of my situation, then a description of my "solution" and thoughts on why it seems to work. My inseam (varies by time of day, compression of meniscus?) seems to be 95cm, my feet are size 50 (305mm long). When I was in my 20's I weighed about 93 kg (205 lbs), was rather fit, and didn't have any problems with comfort even on long rides. I used 177.5mm cranks on my road bike, 180's on the time-trial bike. I used LeMond's inseam x 0.883 for seat height with a little downward fudge for crank length. Knee slightly forward of the spindle. Way stretched out with a long top-tube and the longest Cinelli stem I could find. After a 10 year hiatus I bought a new bike and started riding again. Once I got down to 105kg I started experimenting with positioning to find an optimal setting. My hands had problems with numbness, but I attibuted that to overweight upper body, and rough pavement. My new bike had 175mm cranks. As my weight dropped to 100kg, the numbness persisted, and I figured I had to do something about it. So I moved my saddle slowly rearward to get weight off my arms, as well as raised the bars, and moved them rearward. I tried a very large range, and the numbness improved but did not go away. But pedaling always felt sub-optimal. Standing was a waste of time, and on flats in a tuck I kept slipping forward on the saddle. On seated climbs I would ankle quite a bit and slide my butt bones all the way off the rear of the saddle. I had my cleats set very neutral, but thought I'd try moving them back to compensate for my large feet, in an attempt to make my pedalling feel more normal. I didn't notice any real change except my monster ankling on steep climbs wasn't as effective. I became intrigued by the "proportional cranks" argument and set about thinking how it could benefit me. It didn't take much to convince me that proportional makes sense, and were worth a try. The difference has been amazing. It took a while to get the seat height right, and I ended up trying all sorts of crazy combos until I found what felt right. When I measured the height it corresposnds to 109% of inseam from seat to pedal spindle. Coincidently a magic number touted my Ed Burke and others. I also found my knee was right over the pedal spindle. Another coincidence factor. Everything seemed to be so "normal" that I tried moving my cleats back to right under the ball of my foot. Again everyting seemed to just click. I have a pet theory that the conventional wisdom of large feet benefiting from reaward cleat position is just a kludge to overcome what is actually people using cranks that are too short. The issue isn't large feet, the issue is the long legs attached to those feet!Now in a tuck I don't side forward, and ankling up steep climbs I don't slide back at all. I shove back a bit, but not any more than can be taken up by the slack in flesh. My bars are slighlty higher than they were relative to the seat (about 1cm) but are now 2cm further forward. My fore-aft balance on the bike seems much better and the numbness in the hands is gone. And even standing on climbs feels good. Instead of feeling as though I was teetering on top of a flag pole, I feel like I get good solid strides. But the real fun came when I went to measure my power on a long hill. At the peak of the season a few months ago on 175mm cranks I measured my output at almost 290 watts by plugging values into analyticcycling.com. Yesterday with my 195's I calculated over 300 watts, despite having not ridden so much in the last 6 weeks. And it was pouring rain so my clothes held some unknown mass of water, which lets me know the output is even a little higher. (My wife gave me one of those looks when I said I was going to traipse through the house in sopping wet gear to weigh myself, so the exact weight is unknown for now...). I know there are studies showing that crank-length has almost no bearing on power output, but I think they maybe did not study a wide enough range. Or perhaps I just am lucky. I haven't been on any rides longer than 110km with the new cranks, so I don't know how it will play out endurance-wise. I think the key is juggling the variables of power (speed), cadence, and pedal force. The extra leverage afforded by using cranks that are not drastically undersized allows a lighter force to be applied to achive a given power at a comfortable cadence. Cadence and force obviously play into eachother, and when you can't get them to jive, it isn't strange that it feels funny, or that power is sub-optimal. This lighter force at least in my case more than makes up for the greater pedal distance and pedal speed required for a given cadence. So my new fit seems pretty normal: seat height (from bb) = (inseam x 1.09) - crank length seat fore-aft: knee over spindle cleats: neutral But it is all only possible by using cranks of length 20.8% of inseam. Are there many folks using cranks 20.8% of inseam who also have seat position set similarly, but are of a scale that results in more normal length cranks like 172.5? Joseph |
#7
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My thoughts on seat position, crank length, and cleat position
Art Harris wrote: joseph.santanie wrote: No wind, and I use a hill steep enough that for my speed (about 15 km/h, or 9.3 mph) there is no significant wind resistance. If I estimate the weight of soaking wet clothes and rims full of water to be about 2 kg, the calculation gives me 311 watts, vs 289.5 watts I recorded earlier in the season with dry clothes, and shorter cranks. It is of course impossible to say how my fitness has changed, but I'd say it is safe to say that the 7% power increase was achieved at least to some degree by the cranks. I don't think it is possible that they slowed me down, and I am convinced that there is no way I could have gone as fast with 175's. Lots of variables and uncertainties there. How accurate are the Analytic Cycling formulas? How accurate were your estimates and assumptions? How much was due to psychological factors (similar to new bike syndrome)? And also, you changed several things besides just crank length. But hey, if it feels more comfortable, and you're riding better, don't fight it! It is a well graded 6% road, and I weighed myself in full kit with my bike before each ride. Assuming that alanyliccycling.com is at least consistent, the "only" variables are weather, weight, and crank length. The first 290 run was done before I even thought about larger cranks, and it was an improvement over 260 watts from earlier in the season. At the time I was very pumped, so that result was as good as it was going to get, in other words the 290 wasn't artificially low. The second run definitely had a positive psychological element from everyting feeling so right with the longer cranks, but I still think the cranks had a huge physical effect. But I'll take it any way I can get it! Joseph |
#8
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My thoughts on seat position, crank length, and cleat position
Lee Hurd wrote: Me if you look back at the figures I posted earlier. Interesting. Did the longer cranks solve the catch in your pedal stroke by the way? Yes, the stumbling, catching sensation is gone. I think that feeling had something to do with the range of knee flexion (or whatever it is called) as related to degrees of crank rotation during the power stroke. Seems several folks fall comfortably into the 109%, 20.8%, kops range. Joseph |
#9
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My thoughts on seat position, crank length, and cleat position
tlarwa wrote: Well, almost. I have a 33" inseam (838mm) and use a 175 crank, which is ~20.8%. My saddle height is 737mm, which is what your formula works out to as well, but that is to the top of the seat clamp (or to the saddle rails), NOT to the top of the saddle surface itself. That dimension is a full 50mm higher. I can't imagine riding that much lower, if that's what you are suggesting. Hmmm... So your distance from pedal spindle to seat-top is about 115% of inseam? I wouldn't even be able to reach the pedals with a setup like that. Is your inseam measurment accurate? Are you particularly limber, such that a very straight knee angle and extended foot isn't a problem? Joseph |
#10
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My thoughts on seat position, crank length, and cleat position
For another data point, I also tried using a longer crank. I have an inseam
of about 96 cm, so I tried a 190 mm crank. This is a bit shorter than the formula, but I was afraid that a longer crank would have too little ground clearance on turns. I started out with a 175mm crank. The longer crank felt good for a while - especially on climbs - but I eventually (a few months later) had a lot of calf pain in both legs. I tried different seat heights and cleat positions, but nothing solved the problem. I went back to the 175mm cranks and the pain subsided. I then decide to try the 190mm cranks again and very quickly had the calf pain back. I then gave up. Leg pain was one of the warning I heard about long cranks. They were right.... for me.... I may have been slightly faster on climbs with the longer crank, but my average speed never changed much - maybe 3-4 minutes out of a 4 hour hilly ride. In the year since the change back to the 175mm crank I have been changing my cleat position and seat height in an effort to optimize my position. I now have the cleat on the ball of my foot and the seat is at about 108%. I plan to try 109% when I get a new seat - the old one has started to bother me. Based on what I have heard from the coaches comments (web page searches) the bicycle manufacturers' offering, and my own experience, I suspect the scaling may be more like the square root of leg length rather than linear with leg length. Moment of inertia scaling? Anyway, that is my story. Good luck with your experiments. Bob Morris wrote in message oups.com... tlarwa wrote: Well, almost. I have a 33" inseam (838mm) and use a 175 crank, which is ~20.8%. My saddle height is 737mm, which is what your formula works out to as well, but that is to the top of the seat clamp (or to the saddle rails), NOT to the top of the saddle surface itself. That dimension is a full 50mm higher. I can't imagine riding that much lower, if that's what you are suggesting. Hmmm... So your distance from pedal spindle to seat-top is about 115% of inseam? I wouldn't even be able to reach the pedals with a setup like that. Is your inseam measurment accurate? Are you particularly limber, such that a very straight knee angle and extended foot isn't a problem? Joseph |
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