Originally Posted by
mstateglfr
1- as already mentioned, but worth repeating- dont move the saddle to reduce/increase reach. The saddle position is to get your legs right. A saddle too far forward or back will affect power and comfort when pedaling.
2- besides stack and reach, is important frame geometry the same between the 55cm and 57cm models? Are the seat tube and head tube angles the same? If not, you need to account for that difference when deciding which to ride. And its also important to compare them to your current bike. Same with fork offset and trail.
Basically, a bike model is effectively 2 totally different bikes between the small and xl sizes. Almost always, those bikes are completely different and will feel different. Often times, the transition for geometry is in the middle of the size lineup, so a 55cm could be different from a 57cm due to the transitioning geometry.
Just consider all that is important. Plugging in numbers to a bike geometry program wont hurt.
The geo of either size in the new bike works for me. It's a bit different than my Tarmac, but that's what I want, it has a longer wheelbase and front center, with a slacker ht angle. So it should be more stable, while still being fast and responsive (relatively low stack and short chainstays), perfect all around road geo imo. The large having a slightly longer wheelbase and front center would be slightly more stable than the medium, theoretically.
I'm running a 10mm collar and 10mm spacer on the Tarmac, but would probably be comfortable without the 10mm spacer. I don't want spacers on the new setup, they look even worse than spacers on a traditional stem. So running just the 5mm collar on the new setup with no spacers, here are the stack/reach differences I would be looking at compared to my current setup on the Tarmac.
Medium - 18mm less stack/13mm more reach
Large - 1mm more stack/22mm more reach
With my long arms and torso, maybe the longer reach would be easier to adjust to than the lower stack? Would probably help me straighten my back out more, I think I tend to round it. lol
Also, can't test ride either bike, they're direct order, but they do have a 30 day return policy, so that's good.