I've heard that the "conventional wisdom" is to typically fit a cx bike one size lower than the road bike you ride.
This has been largely to the higher bottom bracket that many cx bikes have?
I purchased a Felt F1X cx bike a few years ago (c-list) as a beefy road bike for commuting/training in Seattle's lousy weather and roads; not for racing. Hadn't gotten much use out of it due to terrible brake chatter, but now that that's solved, looking to ride it a lot more. My road bike is a 54cm Cannondale R800 which fits great. The Felt is 56cm, and tends to feel "big", but in a hard to define way. Maybe "perched" is a better description, due to the higher bb. Measured standover is 2" higher on the Felt. It's a little longer than the Cannondale as well.
My inseam is 33.5"; I'm 5'11", so long in the leg and short in the torso for my height. Currently looking to use a cross bike as a long distance training or even light touring bike; racing is a possibility. If the Felt is not a great fit for me and for these uses that's fine, I'll sell it; its replacement would be another cx bike or perhaps a light/sport tourer.
Most important requirement for this bike is as a fun/comfortable ride over century+ distances, and versatility. Could very well be a sport touring bike is the logical choice, but might like to preserve the racing possibility. Good relaxed geometry cx bike could be a very good option--suggestions?
Obviously, vitally important that the bike for this use fits well; but what criteria is applied to cross bikes for fit that might be different/same to road bike criteria, and why? How do your road vs cross bikes sizes compare, or is that even particularly important? What should I be looking for regarding fit re: this Felt or its replacement, and cx bikes in general? Did you apply different criteria re:distance/commuting vs racing for your cx bike, perhaps even owning one for each purpose?
Much appreciate the insight.