I bought a trek Marlin 5 with 29 inch wheels. I was wondering if I could switch the 29ers with 27.5 inch wheels. I would prefer the 27.5 inch wheels for some 20-30 foot jumps I've been hitting. Would I be able to switch the wheel sizes without ruining the bikes functionality?
If you have disc brakes, all you need to do is find a new set of compatible disc wheels (i.e. the rotor will mount to the front hub, and the rear hub has the right rotor mount and freehub compatible with the number of speeds you want), and you can swap to a different wheel size.
Obviously, your tires need to clear the frame still, and the bike will handle a bit differently.