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55cm Road Bike =55cm TT/Tri bike??? (X-post)(5 posts)

55cm Road Bike =55cm TT/Tri bike??? (X-post)Ride-Fly
Nov 14, 2002 1:23 PM
Warning: X-post from the Tri/TT forum. It had 4 views so I thought I'd try here.

I have 55cm Klein Quantum Race which has an effective toptube of 56cm, and use a 90mm stem w/ zero rise (or 90 deg.) Would I need a shorter, longer, or equal toptube in a TT/Tri bike. The bike I have in mind is a 55cm Cervelo P2K which has an effective toptube of 54cm with the seatangle set at 78 deg or 56.5cm with the seatangle set at 75 deg. Do you (experts) think that it would be a good fit, generally speaking?? I always thought that a tri-bike needed to be a little shorter than your normal road bike because of loss of reach you experience from placing your forearms on the aerobars instead of having the your full reach to the hoods or even the drops. Granted the seattube angle is a lot greater so that puts you more forward to begin with but does it offset the loss of reach?? Thanks!!
re: 55cm Road Bike =55cm TT/Tri bike??? (X-post)brider
Nov 14, 2002 1:54 PM
Your title led me to initially think you were talking about seat tube length, which shouldn't change. Tope tube length doesn't necessarily need to change, but the distance to the elbow pads WILL be less than your normal reach. A number of clip-ons put the pads well behind the base bar, and it depends on the length of your arms as to whether you'd need a long stem or something more normal. Longer arms would necessitate a longer stem. Hope that helps.
Check out this site for some great discussion on TT/Tri fit.Ken of Fresno
Nov 14, 2002 8:02 PM
Lots of good stuff here:

BTW, my Lemond road bike has a 56.5c tt with a 110mm stem and my Quintana Roo Tiphoon has a 54c tt with a 100mm stem.

Best of luck,
re: 55cm Road Bike =55cm TT/Tri bike??? (X-post)NikoK
Nov 14, 2002 11:46 PM
That link Ken submitted is really useful. Here´s some info on tri-bike fit too:

your road bike is too big to begin with!!str8dum1
Nov 15, 2002 9:38 AM
90mm stem? In general thats way to short, unless you have severely stunted upper body.

if u get a new bike, how about get fitted this time? Esp with a TT bike the short stem will make the ride very twitchy. I bet you really need a 52 top tube frame with a 120mm stem.

For the cervelo, I'd bet you'd fit correctly on the 52.

All in all i'd get professionally fitted before your drop another 1500$ on a TT specific bike.