I notice slowman always recommend 650c on frames smaller than, say 55. Well, maybe I am showing my newbie tri bike knowledge here, but my dilemma is this…I agree about the size but many of the bike companies do not advertise the kits as such. I am a 5’6", average torso and legs, 135 lbs., male. I ride a 52cm Road frame. I am purchasing a tri bike this season. I am looking at the QR Tequilo, Cervelo P2K and Litespeed Tachyon. My frame size with any of these would be 51 (??), but non of them spec the bike with 650c at that size, only 700 (except for the SL Cervelo which runs more $). Is it possible to swap out the 700’s for the 650’s? Is the frame geometry on the P2K SL any different than the P2K with 700’s? Would going to a 49cm frame be to drastic?
For what it’s worth I’m 5’8" with a short torso and ride a size 48 Cervelo (Dual) and it fits me well with the exception of a lot of seatpost showing. Are you running your own numbers or have you had a fittting done? If not get fit first you may find that you will be better on the smaller bike.
Sounds like you need to get together with a good fitter. Someone who knows fitting and tri bikes will be able to help you decide which bike is best for you (see Slowman’s article on the difference between the standard bike shop and bike fitters who also sell bikes – title was something like “Just Some Guy”). If you let us know what part of the world you live in, people here can probably give recommendations.
I think when Slowman wrote his rec, tri bike builders were using 650s for more sizes. The market has driven manufacturers away from 650s, for reasons that many on this site will say have nothing to do with the performance of 650-wheeled bikes.
If you can’t find what you need in stock, a custom bike might be a good call. I’m roughly your size, bought a new road bike last fall, but looked closely at Guru and Yaqui for a tri bike. If you go the Yaqui route, I hear that the builder (Ves Mandaric) will also act as your fitter.