New bike sizing help
I'm trying to pick a size for a 2026 Supersix Evo. My current frame is slightly too big, but I've gotten the fit to work fairly well. That bike's fit data is:
2006 Lemond Croix de Fer, size 53
From BB to 80mm width of saddle: x19.8cm, y61.3cm
from BB to handlebar center: x44.15, y61.5
The Supersix in 50/52 has stack: 52.0/53.2, and reach 37.9/38.3, and comes stock with a 90mm stem, 0 offset seatpost.
My main issue with the Lemond is the reach has always been too long. I'm running an 80mm stem right now, which has helped, but I've considered dropping that down to a 70. I think in either size Supersix, I'll need to swap for a setback seat post. The stack height will be shorter for sure on the 50, but I think it's an overall better fit, and I think my body will be happier with a shorter stack height if I have sufficiently short reach. The 50 also comes stock with 165mm cranks, which is what I currently use.
I think the 50 makes more sense but I'm getting a bit lost when I start calculating seatpost angle, headtube angle, stem length, etc.