How to build a fender, quick and easy

As promised here is a small instruction how to make a fender from glassfibre quite quick, easy and also cheap. I needed a fender for my Caferacer project and I could not find a one that fitted my front tire, was financially in reach and according my esthetically likes. So I started to make one myself.

I started with measuring the size I would need for my bike. The fork distance was 13 cm. The radius of the front-tire was 35cm. So first I started with a gauge. 13 cm wide and 36 cm high (+ 1cm to get some space between tire and fender).

I cut it out from thin MDF. I also made to big wooden washers that match the side of the gauge. More on that later.

Test if it fits around the tire

Next I took two EPS boards from the hardware store. Luckily the fork space was 13 cm, so I took one 8cm and one 5cm think EPS board. After I cut the 13cm EPS board to have a radius of 36cm on my hot-wire cutter. 

Glued them together with double sided tape. I took away some of the edges so that my gauge would fit easily over the EPS block. After that I placed plaster on it and straightened it with my gauge. So layer after layer of plaster I got a very nice, round shape for a fender (After each layer you have to wet it very well, otherwise the new plaster will dry immediately). So after a couple of hours of forming and a little bit of sanding I ended with a positive mould for my fender.

To have a nice surface to laminate on and to be able to get the fender off the mould without completely destroying the positive mould, I covered it in packaging tape.

I waxed it with release wax about 5 times. Then I started to put on just one layers of 160g/sqm fibre filament first and on top one layer of 40g/sqw fibre filament. With the fine filament on top you get a quite smooth surface. Let it dry for 24 hours. 2 layers is way to less for the fender, but with these two layers the whole thing is very flexible and you can release it easily from the mould.

You end up with a rather smooth surface of the fender. After that I covered the outside with paper and tape and laminated another ten layers of 160g/sqm filament on the inside of the fender. Take care that the very flexible fender stays in shape and straight. I made a small gauge from a couple of wooden boards.

I cut out the finished fender with a circular saw and after a bit of sanding and filling I had a perfect matching fender for my frontire.

The whole thing took me about 3 days and most of the time it was drying on it´s own.