Is shorter better......Crank length?

[SwissVan]

So went for a bike fit (Retül based) and when I told the dude I use 175mm cranks he said he generally prefers 172.5 length cranks for triathlon.....

 

From my perspective I've been using 175 forever and hesitant to change now, BUT it did make me think that perhaps a 2.5mm shorter crank might help open up the thigh / upper body angle.....

 

So any theories and what size do you ride with?

[travisza]

so much info on slowtwitch on this...dont have the exact link but pretty sure its somewhere on the front page

[travisza]

http://www.cervelo.com/en/engineering/ask-the-engineers/crank-length.html

 

http://www.slowtwitch.com/Tech/Crank_arm_lengths_for_tri_727.html

 

Just two I found quickly

[Andymann]

I'm busy doing some research on this - just for my curiosity, and this video has been the best source of information so far - well worth a watch.

 

 

From what I understand (and again it's just from what I have read), because of the geometry of some TT frames, and the need for an aero position, it is very difficult to get the same hip angle as you would on a road frame (generally your hip angle is more closed on a TT frame than on a road frame because of the aero position) and therefore your power output will drop slightly from what you are able to put out on a road frame. Changing the crank arm length opens the hip angle and you therefore restore your power output, but importantly while still retaining the aero position which is beneficial for Triathlon.

[Red Zone]

I ride a 175 on my road and MTB and 172.5 on my TT bike, I didn't notice any difference to my pedal stroke, it feels exactly the same but apparently it does allow for better fit and aero position. I am 1.8 m tall if that helps

[SwissVan]

I ride a 175 on my road and MTB and 172.5 on my TT bike, I didn't notice any difference to my pedal stroke, it feels exactly the same but apparently it does allow for better fit and aero position. I am 1.8 m tall if that helps

 

Currently I don't feel I need to change from 175, its just the bike fit dude planted the damn seed.

I fitted an Adamo saddle this weekend and so far EVERYTHING feels pretty good so I will keep things as they are before changing anything. I'm still using my road bike converted to tri......don't really want to change the cranks just for tri sakes

[Red Zone]

Currently I don't feel I need to change from 175, its just the bike fit dude planted the damn seed.

I fitted an Adamo saddle this weekend and so far EVERYTHING feels pretty good so I will keep things as they are before changing anything. I'm still using my road bike converted to tri......don't really want to change the cranks just for tri sakes

I wouldn't think that going 2.5 mm shorter is going to make a material difference, perhaps going from 175 to 170 yes, but I'm no fit expert, the science seem to have concluded that shorter cranks are the way to go for optimum fit and performance. So decide if you want to get 100 dialed in. If I was still riding my road bike with clip on bars and some minor adjustments to the saddle I wouldn't fuss with a shorter crank, I have done plenty of tri's like this, no problems at all. Its probably a better return if you spend the cash on an aero lid than a shorter crank in terms of gain.

['Dale]

Saw a similar thread a few days ago

 

Optimal is what the fitment recommendations say.

I have not upgraded (similar spec) and it is okay.

 

If you prefer windmilling and would like improve your accelerations then get 172,5mm.

 

 

[jcza]

I have no idea whats on MTB or roadbike - guessing its 175

[SwissVan]

Saw a similar thread a few days ago

 

Optimal is what the fitment recommendations say.

I have not upgraded (similar spec) and it is okay.

 

If you prefer windmilling and would like improve your accelerations then get 172,5mm.

 

Windmilling? is that Dalespeak for spinning

 

That's the thing, he never said I should change to 172.5, just that he generally recommends it....

Its IM I'm aiming for so accelerations = not belangrik

[SwissVan]

I have no idea whats on MTB or roadbike - guessing its 175

 

Yeah that's the best approach, don't let it smokkel with you... if it works don't fixit

[obree]

SV what type of question is " is shorter better" obviously longer is always better...

Having said that I have changed from 200mm on my road bike to 180mm. no difference in power output at all. seems like these days shorter is the new trend, read on british TT forums, lots of guys going for 160mm cranks, for exactly the reason you quote, better hip to torso angle and you can get lower. dont know if an IM athlete wants to ride radically low for 180km....

[obree]

for IM my recommendation is always do what ever will preserve the legs for the run.....

['Dale]

 

 

Windmilling? is that Dalespeak for spinning

 

That's the thing, he never said I should change to 172.5, just that he generally recommends it....

Its IM I'm aiming for so accelerations = not belangrik

 

Windmilling is a term coined by Lancey Armstring.

 

*clears throat*

[SwissVan]

 

SV what type of question is " is shorter better" obviously longer is always better...

 

 

Its worded to attract people like you to the thread...

[SwissVan]

for IM my recommendation is always do what ever will preserve the legs for the run.....

 

Yeah that's the goal, comfort and efficiency first