Singlespeed Conversion - Spacer Calculations
 

I'm going to convert an older Trek to a singlespeed for my wife. It has a Shimano 8-speed groupo at the moment. I'm planning on keeping the rear wheel, so I need to figure out just how much distance I need spacers to cover. I'll be keeping the spacers that are part of the cassette and I'll be keeping one of her sprockets. Is there an easy way to figure out how much space is left to be filled in before the lock ring?

You will need more than those spacers. Find an old cassette and break it apart. That should give you more than enough. You can also check with you LBS, they may just give you some (mine did). Good luck