Login required to started new threads
Login required to post replies
I was thinking about this concept and can see it from different sides. I am 5'9" tall with a 32" leg length. I ride a 54 c-c road bike, and a 50 c-c tri bike with a 54 TT. My MTB is 15". I have 172.5 mm cranks on the road and tri bikes and 175 on the MTB. Does it make any sense to consider a 170 for the Tri bike to help encourage sustaining a faster cadence?
Thanks,
Tom
In my opinion it makes sense to stick with the same cranks on all your bikes from a fit perspective. At least, that's what I do. I have 175mms on all my bikes.
Tom Demerly
The Tri Shop.com
I'm about the same height and leg length as you (5'9", 33" inseam)
Personally I think the whole "short cranks to spin" thing is crap for most people. Unless you are way too low and using 180+ cranks then there's no way that you won't be able handle turning longer cranks at race RPM. The reasoning for longer cranks is the same as higher RPM, you end up needing less force per stroke for a given wattage... and therefore have less fast twitch muscle fibre recruitment. I'd also expect there to be neuromuscular gains from using the same length cranks on all bikes...
On an anecdotal note I broke a 175 crank on my training/road bike and put on an old pair of 170's. Even though the difference is small, I suddenly got really really slow on that bike, getting dropped by anyone who wanted to (including my "Cat VII" dad, which hurt)
Last edited by:
Zinc: May 2, 03 7:46
Maybe i am just full of crap, but on one tt bike i have 172.5s on my new TT bike i have 175s On the road bikes i ride (3 different ones) i have 177.5s or 180s.For the last ten years i have ridden the 180s on the road bike more but have gone to 177.5s and i am trying to keep my spin up.All of my fastest times have been set with the 172.5s on the TT bike. I am 6'4 35/36 inseam
Maybe I didn't make it clear... it's possible to turn a longer crank almost as fast as a short one in terms of RPM. The only time this isn't the case is when you end up with your leg hitting your stomach and then the limiter is a mechanical one.
Many people believe that if they can't hold a gear then switching to shorter cranks will magically make them "spin" (whatever that is) and go faster as a result. In reality they end up turning 105+ RPM and scorching their muscles without improving anything. Combine that with 90% of triathletes being wildly overgeared and there's a serious problem here...
Normal crank lengths are "normal" for a reason... for 99% of people they work better.
Last edited by:
Zinc: May 2, 03 12:06
I am six foot with a 32" inseam... I run 172 on the tri bike, 175 on the road and 180 on mymountainbike (higher bb and I want more torque). It all works pretty weel and I do not really notice any difference amongt them.