Fender Theory

Timbone

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i am going to make a front fender. I want it to be as tiny as possible but it needs to be effective. One of the worst things about riding without fenders on wet roads is that the front wheel picks up water and throws it over the top right into my face.

To be effective, how far does the fender need to cover the tire to prevent this? 12 o'clock to 3 o'clock?
 
i am going to make a front fender. I want it to be as tiny as possible but it needs to be effective. One of the worst things about riding without fenders on wet roads is that the front wheel picks up water and throws it over the top right into my face.

To be effective, how far does the fender need to cover the tire to prevent this? 12 o'clock to 3 o'clock?
Depends on the distance between the tyre and fender because the spray direction is tangential...
Draw a tangential line at a right angle to the radius from the tyre surface to the position on your bike frame where you want the protection to start.

The front/end of the fender is less easy to predict. It depends on how quickly the tyre sheds it's water/mud, and the speed you're riding, and how much spray is acceptable. So I would say the tangential line from the front should be horizontal or preferably sloping downward.

IMG_20171101_142102.jpg
 
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Wald make strong bicycle fenders, seek no further. Mud flaps can be found in abundance.
 
Looking from the left side of the bike:
Front: 12 to 4
Rear: 9 to 3

Water comes off at a tangent to the tire. On the front the area from 12 to 2 makes a vertical wall of water that you have to lean to one side to avoid going blind. 2-4 dirties your bike, 3-6 soaks your shoes.

On the rear the 12 to 3 gets your ass wet right at the crack, very uncomfortable and embarrassing, and the 9 to 3 dirties your bike and shoes.
 
Excellent advice and info, guys. I did numerous google searches and found nothing as simple and direct as this. Motorcycle builders just stick stuff on!
 
No sense reinventing the bicycle fender, if you are wanting strength and security Wald and Worksman are hard to beat.
I'm done, I will say no more.
 
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