[porfirio]

I've been riding a Trek 2300 (alu. w/carbon seat stays/fork) w/a 105 set-up & a Bontrager Race Lite crank for about 3 yrs. I just purchased a Trek Equinox (full carbon) w/DA throughout for triathlons. The difference is incredible. For example, I've noticed that even on the bullhorns of the Equinox, I experience less pain in the legs going uphill than I do w/the 2300. Since I can't buy a carbon road bike (Equinox was $5K!), I'm wondering if swapping the crank will make a difference. If so, would a 105 vs. Ultegra make a significant difference.

Any thoughts appreciated.

 

[hayduke1972]

Older Bontrager cranksets were three piece set-ups using ISIS splined bottom brackets. It this is what you have than you are very likely to see an increase in stiffness by upgrading to a two piece external bearing crankset.

I don't think a stiffer crank would have anything to do with eliminating leg pain though

 

[JCavilia]

My guess would be that the difference you felt with the new bike is a function of fit, body position, overall flex characteristics of the bike, and gearing. Even if there were a significant difference in crank stiffness (and I'm skeptical of that), I don't see how a stiffer crank would explain your feeling less pain climbing.

Cranks is cranks, IMHO. None of 'em flex enough to make much difference. Maybe some engineer on this board will tell me I'm wrong.

 

[PdxMark]

I experience less pain in the legs going uphill than I do w/the 2300.

Is pain the main difference you're noticing? I really, really doubt pain is a gauge of crank stiffness. I bet the body positions between the two bikes is pretty striking. That's where I'd look to address pain issues.

 

[DavidsonDuke]

Adding on: Crank would be my last choice as to what you're feeling. Isis is not as stiff as the outboard bearings, but it was developed because it was more stiff that the ole square taper. There's just not that much difference. Way too many other variables at play.

And frankly, I don't know why crank flex would lead to leg pain anyway.

 

[porfirio]

My guess would be that the difference you felt with the new bike is a function of fit, body position, overall flex characteristics of the bike, and gearing. Even if there were a significant difference in crank stiffness (and I'm skeptical of that), I don't see how a stiffer crank would explain your feeling less pain climbing.

Cranks is cranks, IMHO. None of 'em flex enough to make much difference. Maybe some engineer on this board will tell me I'm wrong.

Gotcha. I suppose that was a suspect conclusion of mine.

 

[CleavesF]

I say shorter crankarms FTW.

People will say you can't use a certain length for your leg inseam but I disagree. Shorter, is lighter and stiffer.

Obviously if you're 7'11" and you want to use 165mm then forget it, but if you're average height, you'd be surprised how a slight adjustment in your seatpost will do to your cadence.