DIY Tech Tips

How to Radius a Motorcycle Fender by Raz

This has to be one of the simplest, most effective how-to's I have come across. I was ready to cut slits in my fender, bend and reweld it when I found this how-to by Raz on the JJ. Radius your motorcycle fender to fit your wheels just right with some scrap 2"x4"s.


As you can see this fender does not fit the motorcycle tire at all, there is no side wall clearance and the radius is way off.

So here's what I do to remedy the fit. Lay the fender on the bench, get some 2"x4"s and place the ends of the 2"x4"s on the rolled edge of the fender (if the fender dos not have a rolled edge I don't think this will work as well)
Apply some pressure to the other end of the 2"x4"s, this will push the skirts apart as the fender gets wider the radius will shrink.
Work from one end of the fender to the other moving the 2"x4"s in 3" - 4" increments .
After you have gone from one end to the other check the fit on the tire.........it's not quite there yet.
So repeat the proses again this time pushing the end of the 2"x4"s closer together (or increasing the size of the wood block between them), then check the fit again/
Now that fits pretty good if you ask me. I'm going to shorten the fender so the bit on the end does not matter.
Editor's Note: I used this method to re-radius a 4" duckbill Bates fender and it worked perfectly. I opened it up from 4" to 4-3/4" and it made the radius a bit too tight, so I carefully pressed down on the fender while it was laying on it's side on a wood block, closing it back up to 4-5/8" and it was a perfect fit on my 19" rear wheel. I cut a few different blocks in 1/4" increments to carefully expand the fender, tweaking it to just the right size.