just had a look at my tool the front bearing adapter will hold a 17.30mm od bearing when you push it out, i needed to make one to suit 18mm for my sirio and nova bearings hope that helps

"Isn't heating up the crankcase the better method, or will this tool not cause damage in the bearing insertion process? I'd love to change bearings without going into the kitchen again, not to mention getting my fingers burnt every now and then..."

Cheers.

no need to heat up,removes and installs bearing with no damage to case