Touring - Homemade Fenders - How much coverage?

My old bike doesn't have room in front for fenders - no clearance between wheel and unicrown. I can't afford a new bike so I'm thinking of building some fenders before my tour across northern Washington this summer. I've seen the beautiful wooden fenders someone makes. I've built two wooden kayaks and a wood strip camper shell for my truck. I should be able to handle fenders.

I'm thinking of making the front fender in two parts - one in front of the fork and one behind. My question is how far around the wheel do fenders need to be in order to be effective? I want to prevent the wheel flinging water up in my face, especially going fast down a hill.

Suppose the front wheel is a clock face and you're looking it from the right side. Straight up is 12 o'clock, directly towards the rear is 9:00, directly forward is 3:00, etc. How much should the front fender cover?

For that matter, how much should the rear fender cover? (I often used to ride to college in the rain in Bellingham with no rear fender, and am well acquainted with the stripe of muddy spots down my back from water thrown up by the rear wheel.)

I want to prevent the wheel flinging water up in my face, especially going fast down a hill.

Suppose the front wheel is a clock face and you're looking it from the right side. Straight up is 12 o'clock, directly towards the rear is 9:00, directly forward is 3:00, etc. How much should the front fender cover?

For that matter, how much should the rear fender cover?

Without actualy looking at my bike, I'd say my Planet Bike Freddy Fenders cover:
Front - about 1 o'clock to 8 o'clock
Rear - about 4 o'clock to 9 o'clock
I have not ridden this bike in rain yet, but I suspect that my front fender will not completely prevent the wheel from flinging water in my face. I would extend the front fender to between 2 & 3 o'clock for more coverage. Take a look at the picures of loaded rigs thread for ideas on fender coverage.

No matter what material you make them out of, you have the right question before you: How much coverage is practical?

The first pic shows the best, and most practical fenders I have ever seen. Pricey, tho.
The front starts at about 1:30 and covers all the way back to about 7:30. If you strike a straight line from the tire-to-ground contact point, and run the line to the bottom of your chainring, that's the area you want to shield. Centrifugal force will cause the rooster-tail to hit this area so a flap is needed. Trying to clock a fender lower than in the pic will only cause interference on curbs or other objects - even door thresholds. Something flexible will work for you.

The rear fender goes below 9:00. No flap is needed unless you ride ahead of friends and want them to remain so.

The second pic shows my old Zephals with my version of good flaps. The front fender does not cover nearly the same periphery as the Honjo's on the ANT masterpiece. I have found that because the front edge of the Zephals (and very other brand save Honjo's) stops at about 12:00, spray actually flies back and contributes to coating the brakes and lower head bearing area with grit.

The wider and farther away from the tire the fender is, the less spray I notice. I suspect that the closer fitting fenders cause the water to atomize somewhat, while the oversize fenders allow the water to pool back into drops, which tend to fall away rather than vaporize into a fog which I then continually run into.

Just my theory. But, I ride in the Pacific NW, and I get a good deal of experience with rain. So, my advice would be to try and design a set that will give good coverage and not be too close to the tires. Could be a challenge, given your clearance issues. There is a material you could use as a test. It's the corrugated plastic stuff that real estate signs are made of. You could chop it up any way you want til you have a good model, then go mahogany.

My Planet Bike fenders cover the same as the Zephals, and are flapped the same as well.


ANT Rohloff model:
http://i11.tinypic.com/43wzg4i.jpg

My old Trek 830 w/ some serious and effective flaps:
http://i10.tinypic.com/42iyet0.jpg

I measured mine with a digital inclinometer and then converted the results. These are good fenders that have seen a lot of wet weather and let none of it through, no mudguards. In terms of the hour hand, the front fender extends from 8 to 1:30. Or about 30 degrees low at the back and 7 degrees forward at the front.

Here's a reference on building timber fenders if you need any guidance:

http://www.sonic.net/~maryking/wooden_fenders.html

Here is a picture of what the front one looks like a far as width is concerned.