Track Crank Length
- Thread starter Lasalles
- Start date
Lasalles said:
In general physics suggest that several factors that come into play.
1.) Length of tibia.
2.) Length of fumer.
3.) And the ratio of the above and total lenght of leg.
4.) Along with Seat position. Angel of pelvis.
Best Power etc Bla Bla Bla Physic Physic Bla Bla.
================================================================================
In real terms it boils down to the following.
1.) Almost all short riders will most likely always be best served by 165 mm cranks. (rider < 5'5")
2.) Taller riders will be best served somewhat longer cranks most of the time. (rider > 5'8")
3.) Loss of significant power through body contact. A rider who's upper leg contacts their body at the top of there peddle stoke will prefer a shorter crank. In other words (Huge thighs or short fumer/long tibia then shorter cranks eq good).
4.) No one wants to lift the back wheel off the wood (shorter cranks and higher BB eq safety). However 180mm cranks with a 4.0 cm BB drop could be just about as safe as a 5.5 cm BB drop with 165mm cranks Remember 1cm is 10mm.
5.) Not to many people will feel to good about spinning 1000 miles in pre season with 180s only to switch to 165s on opening day at the track. (Comfort,training,better spin,etc eq better power)
6.) Lower BB is a little more stable. Do you need to face off and jockey for position during a sprint at low speed or is you race greater than 11 seconds. Then again bike handling skills could make up of that.
7.) Yes shorter cranks are generaly better for higher cadence spin and peek power. However pushing real hard at a cadence above 115 is going to snap up all your O2 befor you heart can even react. How long is your race???
I think that the short crank fad is over unless you are short, massive or you race is under 2 minutes.
If you are as proportional as the Leonardo Da Vinci's statue of David and do not already have a preference then take your hight in cm (example 170cm and convert that to 170mm) vola in the ballpark give or take about 2.5 mm, not so hard after all.
Read the following.
I have big thighs , I am short, and cannot move my seat any further forward. I would gladly trade my set of 170mm Miche cranks for a set of 165mm Miche cranks. For that matter I would trade my entire De Bernardy Thron 53cm bike in great condition for a 49cm to 51cm bike with 165 mm cranksets in great condition.
Any takers: [email protected]
Finally got to have a go on the boards yesterday at Dunc Gray. Was great fun. I have to say, though, that the crank length did crack me a bit. I ride 175s on my road bike and have found them to be the best for me (having ridden bikes with 170s and 172.5s before). To step back to 170s on one of the velodrome's spares threw me a bit more than I thought it would. It felt very strange pedalling in such small circles. Even though I was turning only 88in, it seemed to take more out of me at comfortable cruising speed. I know that no one really cruises in track racing.
Anyway, the upshot is that I now like track riding and I'd lik to do a bit more riding to get used to things a bit more. I just don't know if I'd be able to get a frame which would have enough BB height for some 172.5s or 175s so I can feel more comfortable.
Anyway, the upshot is that I now like track riding and I'd lik to do a bit more riding to get used to things a bit more. I just don't know if I'd be able to get a frame which would have enough BB height for some 172.5s or 175s so I can feel more comfortable.
If I want to ride bigger gears then surely I would need bit of extra leverage to get any acceleration at all. Physicaly I would have thought that the bigger your gear the longer you need to get up to speed, unless you can generate a greater torque which can be achieved through stronger legs or through longer cranks. Torque is reduced in shorter cranks and hence so must acceleration. That's my understanding through physics. We can agree to disagree on this point.ed073 said:
Aside from this. I just think that it would be a pain in the **** after doing all the road training on 175s (which I am most comfortable and fastest with) to have to readjust a couple of times a week to 170s. The weight of evidence and the experience of others seems to be that you try to keep your road and track cranks as close in length as possible. I know that people have run 175s or even 180s in pursuits, and I am pretty sure I would do the same. I just don't know how safe a set of 175s would be in a scratch or points event on the banking. Maybe I could limit myself to 172.5s
Im just waffling on now.....
I raced my whole road career after junior ranks on 175s and never had the slightest problem switching to 170s for the track. There was no re-adjustment as such, just road and track.
Similar to what a MTB racer would feel I guess, going from his road bike to his MTB.
Similar to what a MTB racer would feel I guess, going from his road bike to his MTB.
tafi said:
On the velodrome crank length would only be a problem when you are going slow on the banking. That does not happen in tt, keirin, derny, scratch, elimination, pursuit or points races. Only in sprint, more so match than derby, and remotely in madison.
Crank length has been the matter of some debate for years. Results of testing I saw were that a rider was most efficient in the crank length to which the body had adapted. Changing lengths had an negative impact on efficiency. It would be obvious that a change of length altered joint angles sufficiently to bring muscles into play differently.
I used 175s on road & 170s on track. I use only 175s now for both, well at least 5 years now, and have benefited at the track.
Being a cheap **** (and now living an ocean away from the nearest velodrome), I ride my track bike on the road. It has 165 cranks and feels like riding a bloody circus bike, particularly when trying to kick up a hill. I'd like to put some 170+ cranks on there, but it really isn't a big enough problem to justify throwing money at.
The only time my pedals touch the road is when I'm already on my way down anyway.
The only time my pedals touch the road is when I'm already on my way down anyway.
On my first track bike i had 170mm cranks but after it was stolen my next one had 165mm cranks and i never got used to them if i ride the track again i will invest in will go back to 170mm,s
I use:drewjc said:
Track Racing & Track Training: 165mm Superbe Pro cranks with Toe Clips and Duegi Shoes ( rock solid, high cadence performance) from (79in rollout to 104in rollout)
Road Training Bike : 172.5mm Campagnolo Daytona Alloy Cranks & Look ARC Clipless pedals ( bomb proof) on a 9 speed gearset
Road Racing & TT : 175 mm Campagnolo Chorus & Dura Ace Clipless Floating ( flight and might) on a 10 speed gearset
I am 189cm tall and have high femur over tibia ratio .....
bottom line...on DISC with banking of 42Degrees 165s are superb to permit slower tactics and sharp turns for high acceleration sprints down the bank and ultra smooth high cadence above 150rpm
on the road for training the mid 172mm cranks make me work out and , give me smooth high cadence training (110-120rpm) and very smooth recovery (100rpm) plus the heavier bike/tougher load gives me a stronger prep for races.
In road races and TT the 175s deliver great leverage and increase wattage, at modest cadence as at high cadence over 120rpm my long legs start to bounce me around , hence from 100 to 120 , the 175s optimise my output and save me going into the red.
This mix of cranks works for me...guess it depends on your physiology and needs.....
good luck
Lasalles said:
165 record pista on the street
one is 2004 and the other is 1974
one is on a paramount and the other is on a keirin frame which will soon be swapped out for NJS approved cranks.
Clipless atacs or mks clips.
no pedal strike ever.
barely any overlap
There is mounting evidence to suggest that thigh length and crank length are linked/tied together. There appears to be an optimum range of motion (arc) for each individual. Imagine a person with a thigh length (using "fit kit" methods) of 355mm (me), to get over 175mm cranks my thigh would have to move through an arc of 59.07deg (simplifying to exclude lower leg movements). "Joe Average" with a thigh of 420mm would only have an arc of 49.25deg. It is a fact that the person with the shorter leg can have muscle attachments the same distance from the pivot point as the person with the longer legs. Therefore poor old short a___ has to contend with the extra energy expended through the need for a greater amount of muscle contraction. It should also be noted that even though you change the leverage by changing crank length, the effects on acceleration shouldn't change by the same percentage. eg, 170mm cranks are 3.03% longer than 165mm cranks. I don't have any figures for this next part, but remember that your legs get stronger the closer they get to straight, at the bottom of the stroke the knee bend will be the same on both cranks. But at the top of the stroke, there will be less knee bend with the shorter cranks, therefore your mechanical advantage on the longer cranks will be less than the 3.03% gained by the difference in crank length.
I have an unusually short thigh, so after having raced for 27 years on 165mm cranks and being extremely quick off the mark but with pretty poor top end speed, I decided to get 160mm cranks specially made (at 35 years old). I am still, at 44, doing the same times for the flying 200 as I was when I was a MUCH fitter 25 year old on 165mm cranks. I am even pulling out PB's for a standing 500. I really should have done weightlifting as a sport (from a biomechanical perspective) but enjoyed cycling FAR FAR better.
I have an unusually short thigh, so after having raced for 27 years on 165mm cranks and being extremely quick off the mark but with pretty poor top end speed, I decided to get 160mm cranks specially made (at 35 years old). I am still, at 44, doing the same times for the flying 200 as I was when I was a MUCH fitter 25 year old on 165mm cranks. I am even pulling out PB's for a standing 500. I really should have done weightlifting as a sport (from a biomechanical perspective) but enjoyed cycling FAR FAR better.
Fixey said:
In this study it is proved, submaximally, there is no additional metabolic cost as a result of increased or decreased crank lengths:
http://jap.physiology.org/cgi/content/full/93/3/823
VeloFlash said:
In that study all the efforts were measured while in the saddle/seated and track racing includes many _maximal_ efforts.
As some experienced people have already mentioned here, 5-10mm can make some useful differences for the intended races.
WarrenG said:
As there are no studies at maximal or supra maximal efforts there are no references to support a contrary view that there exists a greater metabolic demand at maximal plus efforts by using longer cranks. If there is no differentiation in demand at sub maximal efforts why cannot it be extrapolated to higher efforts?
I have a n=1 support that changing crank lengths up by 5mm to your normal road length will improve track times. My times against the clock at the track improved or was it from the placebo effect or different training?
