I am setting up a dedicated tri-bike for up to IM distance races and I am looking at cranks. I do the majority of my training on the road bike, with indoor sessions and limited weekly miles on will be on the the tri bike. I ride 172.5 on my road bike, should I go to 175 on my tri bike or should I stick with 172.5? I think I understand the reason why most roadies go a little longer on their TT bikes, but would this same logic apply with a run afterwards?
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Re: Crank Length [jmh]
[ In reply to ]
We use this simple and utterly unassailable formula for computing crank length to perfection every time. The good thing is, it works for every single person without ever an exception: Where "L" = Crank Length and "I" = Inseam-
L(.45)/67~circumferential quotient (> or <){3.1415(I)} + sinL/time in EDT(body weight)X frame size[age]^29/ 1/2
(.5) divisor= (50/100 [%]) 110/ top tube length/reach-hand lengthX circumferance of forehead+ 2 = "L" (on odd days).
You see, its easy.
Tom Demerly
The Tri Shop.com
L(.45)/67~circumferential quotient (> or <){3.1415(I)} + sinL/time in EDT(body weight)X frame size[age]^29/ 1/2
(.5) divisor= (50/100 [%]) 110/ top tube length/reach-hand lengthX circumferance of forehead+ 2 = "L" (on odd days).
You see, its easy.
Tom Demerly
The Tri Shop.com
Re: Crank Length [Tom Demerly]
[ In reply to ]
Stick with 172.5mm if they have worked for you up to now with no problems. Or, you could use the formula....
Tom Demerly
The Tri Shop.com
Tom Demerly
The Tri Shop.com
Re: Crank Length [jmh]
[ In reply to ]
If you do a net search there are a couple of sites that have either charts or calculators to determine theoretical crank size based upon your inseam. I used to have them bookmarked but don't any more.
Re: Crank Length [cerveloguy]
[ In reply to ]
I looked up three or four of the different sites and got results from 165 to 181.625 (or something like that).
As Tom said, stick with what you're used to, unless you have the time and ability to test the changes in power and endurance from one crank length to another. The problem with that is; how do you know if the new crank length wouldn't be better if you had time to get used to it? I'm told by several people that 175's would be better for me than the 172.5's I ride. I always felt a bit bogged down with 175's...just wasn't able to clear the top as well, but, I never tested the power and endurance changes to know for certain, and I never stayed on them for a long period of time to get fully accustomed to them. Also, as I have been training my hip flexors religiously for the past few months, maybe now the 175's would feel better over the top than they used to. Maybe 180's would be OK. The fact is, I just have a limited amount of time to be messing with it all, so, for now, the experimentation with cranklength will just have to wait.
Stick with what you have been used to unless you have compelling reasons to try something else.
Quid quid latine dictum sit altum videtur
(That which is said in Latin sounds profound)
As Tom said, stick with what you're used to, unless you have the time and ability to test the changes in power and endurance from one crank length to another. The problem with that is; how do you know if the new crank length wouldn't be better if you had time to get used to it? I'm told by several people that 175's would be better for me than the 172.5's I ride. I always felt a bit bogged down with 175's...just wasn't able to clear the top as well, but, I never tested the power and endurance changes to know for certain, and I never stayed on them for a long period of time to get fully accustomed to them. Also, as I have been training my hip flexors religiously for the past few months, maybe now the 175's would feel better over the top than they used to. Maybe 180's would be OK. The fact is, I just have a limited amount of time to be messing with it all, so, for now, the experimentation with cranklength will just have to wait.
Stick with what you have been used to unless you have compelling reasons to try something else.
Quid quid latine dictum sit altum videtur
(That which is said in Latin sounds profound)
Re: Crank Length [yaquicarbo]
[ In reply to ]
I have 170's on one bike and 172.5 on another. Honestly can say that I don't notice the difference.
Does it make sense to recommend the longest crank that doesn't seem to make a difference in the feel of the pedal stroke? Ever try 175's? Or, even longer?
I learned on 170's, but ride 172.5's and don't sense a difference between these two...however, I do sense a difference at 175...again, maybe this sense is insignificant, maybe the length is insignificant, only testing would tell me if there is a measureable performance difference...and then, I still might see different results if given time to adjust.
I wonder if we could tell the difference if we had 165's? I certainly think so, but I don't know.
Quid quid latine dictum sit altum videtur
(That which is said in Latin sounds profound)
I learned on 170's, but ride 172.5's and don't sense a difference between these two...however, I do sense a difference at 175...again, maybe this sense is insignificant, maybe the length is insignificant, only testing would tell me if there is a measureable performance difference...and then, I still might see different results if given time to adjust.
I wonder if we could tell the difference if we had 165's? I certainly think so, but I don't know.
Quid quid latine dictum sit altum videtur
(That which is said in Latin sounds profound)