So I have a problem. I have a 1979 xr500 and I want to change to a 21" front wheel. I thought I could just buy a 1982 21" front rim and just slap it on. That is a BIG NEGATIVE. So I need to take my hub and put it into the 21" rim. What I need to know is what size spoke will I need or how do i figure it out? Can I use the spoke's from the 1982 21" rim?????? Also will I need any special tools. Sorry guys but I need your wisdom. I love my old thumper.