The rear fender started its life as a blank I ordered.

In retrospect, I think I should have made sure to order a fender for rigid frames, because I think this is meant to be a softtail fender, which is why its radius is a bit too big (it's meant to live above the tire so the suspension has room) as well as being kind of flat across the top instead of formed to the profile of the tire. But I thought, what the hell, the rear tire needs to be able to slide backwards to take up chain slack as the chain wears, so a perfect hugger shape wouldn't be the best anyway. Plus with a fender as short as I want, who cares if the shape is a little off?
Originally I planned for the fender to cover the tire all the way down to the lower crossbeam on the frame. Problem is there's not enough room between the tire (in its forward position) and the top crossmember on the frame to fit a fender, plus there's already not quite enough room between the engine and tire for the jackshaft and battery box, plus you would have to cut out a wedge from the fender to make room for the chain which is kind of ugly, plus the radius of this fender makes fitment impossible to begin with. So the decision is easy: fender starts at the seat.
And for the fat-tire look, I want the fender to stop at the top center of the tire. (Also this lets the tire slide directly back without getting any closer to the fender). So a short fender is in order. Short enough that my one blank could make 2 fenders. Perfect to give me the confidence to tear into it knowing that when I screw up I can start over for free.

After careful consideration and measuring to really make sure I wanted less than half the blank fender...you don't want to find out you want slightly more than half and end up with 2 pieces of useless metal... I finally bit the bullet and cut it in half. A cut-off wheel on a grinder made quick work of it.
To fit it snug against the frame I had to grind some curves into it. I used tape to mock up the shape I wanted to get a proper look at it before making cuts.
A fender is supposed to protect the rider from road debris, but this fender is only going to protect the tire from getting my ass caught in it.

I tied a pen to the axle so I could draw a curve that matched the arc of the tire. I put the tire in the middle of its travel range and rested a spacer on the tire to make sure the fender was sitting with enough gap between the tire. I drew a line that would expose the sidewalls, and would make the tire fit pretty well no matter what position it was in. Using the grinder again, I did a rough cut to approach but not quite touch my line.
I didn't finish the work, thinking I should try to get the fender mounted properly before finishing. But if we don't get that welder going soon, and I run out of other stuff to do, I'll finish it off.

email: mikebike@rocketcar.net