The warm weather here in the Ohio Valley has allowed me to ride outside the past few days. I've been enjoying my new Lemond Buenos Aires WSD - it is a sweet, sweet ride. However, I noticed last night that the muscles in my lower back and pelvic region were quite sore. I've had the new bike to the bike fitter. When I ride I don't feel stretched out, bunched up, etc - things really do feel good on this bike so I don't think it is a fit issue. Could this be due to the change in geometry of frames (I've been riding a 1985 Univega Grand Turismo)? Does the change in geometry cause me to use muscles differently?