Time trial bike frame size

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I've been told that when looking for a time trial frame, to look for a frame slightly smaller than what you normally use. I ride a 56 road bike so would getting a 55 or 54 frame be the way to go? The riding position is what allows a slightly smaller frame to be better than your regular size. Is this true?

I've been told that when looking for a time trial frame, to look for a frame slightly smaller than what you normally use. I ride a 56 road bike so would getting a 55 or 54 frame be the way to go? The riding position is what allows a slightly smaller frame to be better than your regular size. Is this true?Yeah, the way you fit a bike with aero bars is a bit different in terms of top tube length which may be complicated by very steep seat tube angles found on some TT and tri bikes.

Check out some articles on fitting tri and TT bikes like this: http://www.slowtwitch.com/mainheadings/techctr/bikefit.html

or:
http://wealltri.com/2007/07/09/triathlon-bike-vs-road-bike/

I generally ride a bike with a 55-56 cm top tube and ride a TT bike with a 54 cm top tube and probably could have gone a size smaller as even with the really short head tube I still need a steep drop stem to get as low as I like. But don't use my numbers as guidelines, fitting a TT bike involves several tradeoffs in terms of flexibility, ability to generate power in a low position, aerodynamics, and ability to see up the road if you get very low. And depending on whether you like a steep angled saddle forward position or a more neutral saddle position things will change including overall cockpit length and whether or not your knees clip your aero armrests when standing. You've really got to ride a few to figure out what will fit you best.

Good luck,
-Dave

I've been told that when looking for a time trial frame, to look for a frame slightly smaller than what you normally use. I ride a 56 road bike so would getting a 55 or 54 frame be the way to go? The riding position is what allows a slightly smaller frame to be better than your regular size. Is this true?

No, not really. In order to reach tri/TT bars, the seattube needs to be steeper. So when you put your knee in the proper place with reference to the BB, you essentially have a shorter top tube but not necessarily a shorter seat tube. Get the frame that fits, with consideration that you need to be able to reach the tri/TT bars and still be comfy..ie, not have the bars way below the saddle(which you may have with just a smaller frame). TRi/TT frames are specific in this regard, not just smaller road frames.