Originally Posted by
Steve B.
Only solution outside a speed sensor would be to modify the cycle computer wheel diameter setting until they match.
This will get you close (or closer), perhaps. But it's unlikely even an exact fix on one ride will carry over to the next. Fix 0.5% low, next ride will be 0.1% high. Best solution is to get them "close enough" and then change your expectations so "that close" is acceptable.