I was wondering if a 2017 road glide 21 in front Rim will fit my 97 sportster custom?

 

Zack, when you say 'rim', do you mean the entire wheel? I think you will find that the stock size for an RG front wheel is 19", not 21", unless the wheel you are looking at is a custom one. As for doing a wheel swap, your ’97 wheels use 3/4" ID tapered roller bearings, whereas the RG uses 25mm ID bearings. In addition your bike uses smaller OD brake rotors than the RG, so they will not match your callipers. It is possible that the RG wheel can be made to fit, but it is not a simple bolt-in.