I ride multiple bikes and whenever I change between bike profiles on the Edge and start a ride, it recalculates wheel circumference for that bike. There may be other ways to force it to recalculate, but I don't know them specifically. Perhaps forcing it to pair again with the GSC10 will force a recalculation, or switching to another bike profile momentarily and then switching back, or selecting manual wheel input and then selecting automatic, ...etc.