I am refurbishing a 79 R100RS and was in the process of changing the final drive from a low ratio sidecar one to a more normal one. All was going well until I found the rear wheel wouldn't turn. Huh? Took everything off and checked the final drive and it is just fine, but learned that in some odd cases the castings/nubs inside the hub part of snowflake wheels interfere with the final drive. My friend, Wirespokes, says this occurs once in a while and is due to either an earlier wheel and a later final drive or vice versa. Anyhow, anyone else run into this and if so, is there an easy way to figure out how much metal to take off the wheel hub nubs so everything spins as normal, or do I just keep messing with interference marks until things are good? Sorry if this isn't clear - kind of an odd problem that doesn't lend itself to proper nouns.