Most common rear spacing for a 4in fat tire?

[chyaboi]

I am trying to find a 20x4in fat tire bike to convert to an ebike. I have a 170mm rear hub. A lot of retailers don't list this so it's hard to tell if my hub will fit on the frame.

 

[Anton]

I am trying to find a 20x4in fat tire bike to convert to an ebike. I have a 170mm rear hub. A lot of retailers don't list this so it's hard to tell if my hub will fit on the frame.

From what I can see, fat bike rear hubs come in the following sizes: 170mm, 177mm, 190mm and 197mm.

You should definitely reach out to the retailer to make sure your 170mm rear hub will fit onto the frame.