This is really two questions:
Some bikes are always going to be faster than others with a given rider over a given terrain. Weight; geometry; stiffness vs. flexiness of frame, wheels and components; suspension setup if any, etc.
If you're making no progress, bike fit could be contributing, even if it's a theoretically go-fast bike. But I think the fit would have to be pretty far off, and very uncomfortable, to keep you from making any progress at all, and you would know it. It's more likely something in your training or nutrition IMO. Or possibly in your expectations. What exactly are we talking about? Have you been stuck at 29.9 km/h for the whole six months? Or ...?
Last edited by OakLeaf; 07-29-2010 at 03:46 AM.
Speed comes from what you put behind you. - Judi Ketteler