Join Date: Feb 2006
Location: Driving the pace in the crosswind
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Originally Posted by Phatman
Thats usually not the case. Generally, the seat tube is what determines the size of a bike. A TT bike with real TT geometry should have a similar seat tube to your road bike, but a shorter top tube. With that said, I went a size smaller on my TT bike to get a bit more saddle to bar drop since I'm stupidly flexible. I ride a 58 road bike and a 56 TT bike.
To the OP, that's weird. They SHOULD keep things the same.
A TT bike will have a steeper seat tube thus shortening it relative to standover height. In addtion, the Top tube shortens. So, no, they should not keep things the same for the reason outlined above. In addition, because of the position one tends to achieve being the same as though you were in a road bike "drop" position, the top tube is lower on the triangle to accomodate a lower stem, and thus both the top tube and seat tube are shorter. We are not talking about randomly assigned "small, medium, and large" but actual numbers whose values have real meanings.
Last edited by DrWJODonnell; 12-08-08 at 06:01 PM.