Dyna Glide ModelsSuper Glide, Super Glide Sport, Super Glide Custom, Dyna Glide Convertible, Super Glide T-Sport, Dyna Glide Police, Dyna Switchback, Low Rider, Street Bob, Fat Bob and Wide Glide.
you can't just pop a 21 inch front wheel on a stock street bob front end... problem is with the hub and spacers.... you'll have to lace up a 21 inch to the street bob hub
unless, of course, you're going to put a wide glide front end on
1. Buy a laced wheel that fits the midglide front.
2. Buy billet wheel that fits the midglide front.
3. Switch entire front end to W/G, many wheels available for this setup.
4. Check out jsbridgew entire thread on fitting a 21" rim to bob hub.
How deep are your pockets?
I went the W/G route and bought a 21X3.25 and stock W/G spacers. Everything fit up perfectly.