|Love Your Spin...And Your Spin Will Love you!||BigLeadOutGuy|
Jan 1, 2002 5:51 AM
|Just a random though about crankarm length...I used to use 175 or 180 length cranks...being 6`4`` with i assume are long legs (34` inseam) its kind of assumed you get the longest cranks available to you...well I went against the "norm" and have been using 172.5s and my spin has never been so smooth and my cadence so high. My first assumption would be that its in my head but my vetta tells me my Ave. cadence is lots higher as well as my max cadence. Go figure!
I have heard that shorter cranks make you spin faster...guess its true.
any thoughts? cant wait to get torched with this one =)
happy new year
stay stoked =)
|re: Love Your Spin...And Your Spin Will Love you!||Jon|
Jan 1, 2002 6:23 AM
|Here's something counter-intuitive. I've read that Lance uses shorter cranks on his time |
trial bike than his road bike!
|re: Love Your Spin...And Your Spin Will Love you!||harlett|
Jan 1, 2002 1:37 PM
|i've read lots of recommendations that competitive cyclists use shorter cranks than normally recommended to reduce the dead spot at the top of the cycle, from 9 to 12 o'clock, and to allow a shorter stroke through the strongest leg movement-- |
there is data showing that the shorter the crank, the higher the possible cadence (one being an article in velonews http://www.velonews.com/tech/rev/crank.html )
this would facilitate reaching optimal cadence in the shortest time (one example: accelerating out of corners)
as an endurance oriented cyclist I prefer longer rather than shorter for the leverage it gives turning bigger gears at slightly lower cadences--
there are some newer studies that are dealing with the delicate interaction of a number of variables in arriving at a beneficial crank length and spin-- muscle fiber ratios, femur length, tibia length, foot size, saddle position relative to bb and muscle flexibility-
one of them is: "determinants of maximal cycling power: crank length, pedaling rate and pedal speed" martin, spirduso.eur j appl physiol 2001 may-
much of this, i think, is really finding ones own rhythm and understanding how different muscle groups hand off work to the next set of muscle groups-- practicing and visualizing the muscle groups handing off the work smoothly-- this is not a natural thing for the human body to do-- we need to teach it to do it in a concentrated and relaxing way--
|nice to see you back harlett nm...||cycleguy|
Jan 1, 2002 7:16 PM
|nice words....thank you....nm||harlett|
Jan 2, 2002 12:14 AM
|re: Love Your Spin...And Your Spin Will Love you!||Jon|
Jan 1, 2002 7:49 PM
|My understanding is that the data from studies is all over the place. No one has been able |
to come up with a good generalization. However, peak power is usually attained with shorter
rather than longer cranks, which is why trackies generally go with shorter cranks. They want
to reach maximum cadence in minimum time. Crank length does seem to be an individual
thing, with the determinants being at best poorly understood. I have an 89 cm inseam, but
prefer a 170 mm crank. I'm also a spinner, with perhaps one fast twitch fibre in each leg!
Jan 2, 2002 12:12 AM
|your right it is has been all over the place-- some of the newer studies are coming close to more definitive explanations though-- |
dr. waneen spirduso, director of the institute of gerontology, at the university of texas and professor john martin, dept.of exercise science, at the university of south carolina have found research on cycling and repetitive muscular contraction can serve as a window though which to observe basic muscle function-- two of their past studies and two of their current use crank length as the variation in looking at maximum cycling power and the function of different muscle groups-- the current studies may give some better understanding of the relationships of those things i listed in my first post and give us a better guide to how those variables help us--
one older study into this was: "the effect of bicycle crank-length variation upon power performance" inbar, dotan, trousil, (1983). Ergonomics 26:1139-1146
your also right that at the moment this is individual and minutia without better studies-- and i would hate to replace that notion of finding ones rhythm with all science--
btw.are those last two fibers fast-oxiadative type IIa's or fast-glycolytic type IIb's ? you know that at your age prolonged activity is better than power-- *S*
Jan 2, 2002 6:57 AM
|I'm hoping they're IIAs so that they're trainable. This old dog needs to learn |
|I'd love to try it||McAndrus|
Jan 1, 2002 6:42 AM
|I believe your analysis is correct. I ride 175s and have a 35" inseam. Somebody up on the physics will probably explain it but even a person with high school physics can understand that shorter cranks have a lower rotational mass and thus are easier to accelerate - or in this case, spin.
I'd often thought of dropping to 172.5s just to see if it helps my spin. But this is one of those situations where I'd be conducting a $200 experiment. If they didn't help, there's another expensive mistake sitting on a garage shelf.
And what about power on climbs? What's you experience with the 172.5s versus the 175s? I've read that power climbers prefer longer cranks.
|Me thinks...||Lone Gunman|
Jan 1, 2002 8:09 AM
|that if you took the length of the arc that a 175 crank travels and compared to the distance a 172.5 travels, it will be shorter and if you pedal approx. the same speed/work rate (as a constant for comparison) I'm thinking 172.5 will be faster or more revs per minute, in theory mind you....Anyone seen my pocket protector?|
Jan 1, 2002 10:39 AM
|If your 34 inch measurement is a true cycling measurement, to hard crotch contact in bare feet, you legs are actually short for your height. The 172.5 length is not out of the normal range for this leg length. 175's would be more common though.
I'm 9 inches shorter at 5'-7", with a 32-5/8" inseam. I used 170 cranks until three years ago, when I switched to 172.5. I can pedal either one with reasonable efficiency, but the 170's do encourage a higher cadence. I've ridden 165's and those really let me spin. The trick is to find the optimum combination that will allow you to produce the most power without sacrificing endurance. Power = torque x cadence. Torque and cadence are equal partners in the equation.
When you changed cranks, did you readjust your KOP (move the saddle back)? 2.5mm isn't a big change, but it does place the knee a little further forward, which also enhances spin. Moving the saddle back will tend to slow your cadence if you find that's it's too high for optimum efficiency.
|Is this another case of Armstrongism?||The Conductor|
Jan 1, 2002 11:37 AM
|Back in the Indurain-days everyone was looking for the longest cranks available. Now people think that shorter is better - "that way I will be able to spin like Lance"!
According to the experts in the field of human bio-mechanism, a short-legged riders' pedaling is optimized whith shorter crank-arms, and longer legs delivers the power best through longer ones. But everyone is different, so maybe It's worth a try!?
However, I dont think any other human being can beat Armstrongs cadence going up a mountain at full speed. It's absolutely incredible.....
|The Inseam on the label....No mountains!||BigLeadOutGuy|
Jan 1, 2002 12:52 PM
|Ummmmm...i dont think my legs are too short...I was just going by the inseam number on the tag of my jeans =) I ride a 62 inch frame and have about 2-3 inches of stnad over clearance...Ill go measure my inseam with a tape later!
ya think i got short legs eh? hmmmm
I dunno how the cranks will work on long climbs...where I live there arent any long climbs...but ill keep you informed...Im sure Ill end up somewhere with a mountain =)
|do the measurement this way||CT1|
Jan 1, 2002 3:31 PM
|In bare feet stand over your bike and block up the wheels (evenly of course) until you have significant bar/crotch pressure.
I bet your "bike" inseam length is well over 35" if measured this way.