I used aluminum fenders and don't see the point of risking breaking plastic fenders to do this. The fenders are some generics I bought at a DC swap meet for $10 including hardware. All and all, counting the sheers, the total came to just under $25.
- Aluminum Fenders
- Permanent Marker
- Optional: Pliers or small hammer
Posses a frame that has at least 30mm of clearance between the fork blades, and chain/seat stays as well. My fork had ~35mm of clearance for reference.
Gently place your new front fender between for the for blades and mark each side on the fender with a permanent marker so you know how wide your cuts have to be. Then use your eyes to estimate how deep into the fender you will have to cut out to fit the bike.
Once both sides are marked make your cuts. Remember to always cut short of your marks the first time in case your markings are too big. The whole key here is too make a good even flap. You will not cut out all that you marked. It's a real good idea to file these cuts down. Here's what my final markings and first flap looked like:
Cut 2 pieces of the weather seal that are each long enough to wrap around the fender. Looking back on it now it is completely feasible to use one long piece but no biggy. Now place an end of each piece of sealer under one of the flaps you cut INSIDE the fender. Fold the flap down on top of both of them, I ended up tapping it down with a trim hammer to secure it.
Now wrap each piece of sealer over the outside of the fender and underneath the opposing flap. Be sure to cover the corners as to not scratch the bike. Pictures do a much better jorb of explaining.
Mount your newly improved fender! I also went ahead and put a strip between the fender and it's frame to cut down on noise. Also it's a good idea to do this to where ever the fender mounts to the frame so I put some between the rear fender and it's frame mounts.