I’ve read the slowtwitch bike chooser and still am lost…
I need (read: want) to upgrade my frame from my 5 year old KM40. 5’7" female, very flexible but with large (dinosaur-sized according to Tom D.) femurs. I like an aggressive aero position and am very comfortable but continue to slide far back on the saddle. I am positioned as well as can be on the Kestrel, but I still feel I’m shifting around to get more power. I ride 650s but don’t know if I should look at 700s. Main focus is IM distance. Money isn’t the main object here–getting the right bike for me is…
I also ride a lot of hills, and am going to buy an inexpensive road bike this spring to complement my training.
Short of actually going to someone that can put their eyes on you, see you pedal, etc., see if Ves Mandaric will give you a recommendation of acceptable geometry. I don’t even know if he does this for his non-customers…maybe he’d agree to consult with you for a fee. Maybe I’m way off base even suggesting you try, only Ves could tell you that. He certainly nailed my geometry requirements over the phone when provided with measurements of various parts of my anatomy. Couldn’t hurt to ask him. Again, this is if you don’t have a trusted, experienced fitter within your reach.
If you’re constantly sliding back in the saddle in order to generate more power then perhaps you’re riding too steep of a seat tube angle. Seems a lot of people sacrifice power for aerodynamics. Never sacrifice power.
Big clue here: “shifting around to get more power”
This may not be entirely fit related. Often times riders refer to a sensation as being “planted” on a bike. This sort of hazy vernacular describes the notion that forces are in balance on the bike and the rider does not need to move to exert leverage against the opposing forces of the pedal stroke.
In other words: Your upper body creats a frim platform from which to exert drive forces against the pedals.
Picture this: A huge crane lifting large loads but mounted on a flimsy base. Recipe for disaster.
Now here is the quandry- a short torso, long leg, long femur fit has this enormous muscular engine, but little torso to oppose these muscular forces against the pedal stroke, Consequently, they are shifting around on the saddle constantly. It isn’t a matter of not finding the sweet spot, it may be a matter of not being able to hold the sweet spot.
I am a 5’8" female with a bike racing background and very long femurs and short torso. My road bike is a 57cm with 700cm wheels. I bought a tri bike a few years back for IM racing that had a very steep seat tube angle and 650 wheels. I could not get comfortable on that bike nor could I ever generate any power. SO, David Greenfield from ELITE got me on a 58cm/700 wheels T-Class and I have never been happier. I’d be happy to speak more in depth with you about this if you want to!