Depends (that’s helpful- isn’t it ..LOL
I generally change bag or at least empty bag before starting out. On short putts locally, the bag has never been an issue.
At the end of long runs or a full day of riding I’ve had, in the past ,a blowout or two. I wear a two piece and have had the bag separate. I wear Ostomy Secrets boxers and they hold the bag in place till I visited the men’s rooms.
My ostomy is also at belt level and it seems; being in the seating position, with the vibrations for long periods of time -somehow the snap locking device comes undone.
So now I stop more often and empty it and /or check the snaps whenever I stop( for gas or a break). This seems to work for me. Haven’t had any issues for a while now
I’ve never had an issue with the appliance coming undone
Hope this helps