Originally Posted by
Unca_Sam
The OP is looking for advice converting a MTB to gravel and CX use, not necessarily for singletrack. So far the advice provided is to pay attention to TT lengths to avoid getting stretched out, and that stack heights might be short. Gravel and CX fit are likely not too far from a road bike fit.
Hybrid and mtb sizing are the same concept/approach relative to road bike sizing. Think about your statement and you should see where your logic blew up.