Originally Posted by
tangerineowl
For the stack, I'd want it to be the nearly the same, to 10mm taller. I wouldn't want a stack that is more than a couple mm lower.
For the reach, I'd want it to be no more than 5mm longer. Up to around 7mm shorter would be fine (difference can be made up with a slightly longer stem). That shorter margin in the reach may find you with the front wheel closer to your toes (check the front-to-centre distance if listed in the geo chart).
Thanks.
Currently comparing two different bikes to my current, one has 9mm longer reach and 21mm shorter stack while the second bike has 8mm shorter reach and 11mm shorter stack (but allowing a little bit of leeway as I am comparing my bike's measured values vs officially posted specs online).
Looking at that second bike, one size up, gets me 14mm longer stack and 1mm longer reach.
Sounds like the second bike might be a closer fit than the first one.