I’ve got a fit question, maybe more of a sizing question, that I’m curious what the fitters on the forum would say. For the sake of discussion, let’s assume my current bike fits properly and I’m just looking to replicate it on a different bike.
If one were to ‘size up’ on a bike to get a higher stack height, how much shorter of a stem to account for a corresponding increase in reach would be acceptable? I’m considering getting a more aero frame for road racing, and of course most aero frames have fairly low stack heights. I’m currently running a 56 cm Aethos with a 90deg 120mm stem, w/ 20mm of spacers. Looking at the Tarmac SL8 as an example, going up to a 58 would get me an extra 26mm of stack, with only 7mm more reach. I’m thinking that the 58 would work without any spacers and a standard -
6deg stem. The question would be to drop to an 110mm, or even 100mm stem, to get the reach roughly equal.
Is there any particular reason I shouldn’t do this, or would it make more sense to just get a 56cm SL8 and run the same spacer stack? (fwiw, the geometry for the original Aethos and the SL8 are identical, so I know the 56 would work, but would like to do away with the spacers). Would a 100mm stem be cutting it a little close?