I recently installed some Velo Orange aluminum fenders on my Trek 311. I’ve been riding this bike a lot this year and it’s had a set of Planet Bike plastic fenders on it since I built it up in its current configuration back in January. I tend to think of aluminum fenders as higher quality and more “permanent” than plastic fenders, which is why I made the change. But after I installed the aluminum fenders I got to thinking about the differences between plastic and aluminum and the relative advantages and disadvantages of the two types. I’m not sure one type is any better than the other, they’re just different.
For instance, plastic fenders are probably a better choice if you frequently lock your bike up in crowded bike racks where the bike is likely to get banged around. Plastic fenders resist the unavoidable scratches and dents that would have aluminum fenders looking old and beat up in no time. If a plastic fender gets crunched against a rack or another bike, it will usually just snap back to its original shape while an aluminum fender might end up rubbing against a wheel until bent back in shape.
Aluminum fenders tend to offer better coverage which means they keep you and your bike drier and cleaner. This isn't entirely a function of the material. Plastic fenders could be made longer offering greater coverage, but none of the commonly available plastic fenders (SKS and Planet Bike) come in sizes as long as the commonly available aluminum fenders (Velo Orange and Honjo). I suspect that this is partly because aluminum is stiffer and therefore more stable in the longer lengths and less likely to flop around. A plastic fender would probably need to be made heavier or would require additional stays if it were made as long as most aluminum fenders.
Of course there are also aesthetic arguments for aluminum or for plastic. Aluminum fenders just look right on some bikes while plastic looks right on others. It's just as hard to imagine a classic René Herse with plastic fenders as it is to imagine a Trek Madone with hammered aluminum fenders (though I'm sure both have been done).
|1950 René Herse porteur|
One of the arguments I often hear in favor of plastic fenders is that they're easier to install. In general I'd agree with this, though I think it's not as much a function of the material (plastic vs. aluminum) as it is a function of design. Honjo and Velo Orange fenders are designed to be installed more permanently as an integral component of the bicycle while SKS and Planet Bike plastic fenders are designed to be easily added on as an accessory. You generally won't have to modify much about a plastic fender to get it to fit reasonably well on your bike assuming the bike has room for any fenders. With an aluminum fender, be prepared to do a little bending, drilling, cutting and cursing.
Each time I install a set of aluminum fenders I learn another trick or two that makes the job a bit easier and results in a better quality installation. It still usually takes me more time than installing a set of plastic fenders, but some of these tricks at least remove difficulty-of-installation as a significant factor in deciding which type of fenders to install on a bike, so I thought I'd share some of what I've learned.
- Install one contact point at a time working your way from one end to the other. For instance on the rear fender, attach the fender to the chain stay bridge first, then at the seat stay bridge, then the rear fender stay.
- After each point is attached, work on “shaping” the curvature of the fender to match the arc of the tire from that attachment point to the next. In other words, once you’ve attached the fender at the chain stay bridge work on shaping the curve of the fender only between the chain stay bridge and the seat stay bridge. Once you’ve got that section nicely matched, then attach the fender at the seat stay bridge and begin shaping the fender from the seat stay bridge to the fender stay.
- The curve of the fender can easily be “shaped” by either squeezing the edges of the fender toward each other or away from each other at the point where you want to adjust the arc. Squeeze the edges together to increase the radius of the fender arc (make the curve flatter), and pull the edges outward to decrease the radius or make the curve tighter. A little flexing goes a long way, so go easy. Adjusting the arc in one spot will affect how the fender fits in the adjacent spots so it’s best to make tiny adjustments working along the length of the fender and then go back over it a couple times. It’s sort of like truing a wheel.
- Once installed, there should be no tension in the fender. Sprung tension is what causes fenders to crack. In other words, the attachment points shouldn’t be holding the fender in the correct curvature, they should only hold the fender on the bike.
- Use leather washers and rubber spacers between the frame and the fenders to reduce noise and the likelihood of cracks.
- Use nylon lock nuts or locktite on nuts and bolts to keep them from vibrating loose.
- Never, ever embark on a fender installation job without beer.
|Squeeze the edges together to increase the radius|
|Pull the edges apart to decrease the radius|
Those with sharp eyes have already noticed that the rear fender line on my Trek isn't quite perfect. Other than the fact that I'm not a perfectionist and could best be described as a "hack" when in comes to bike wrenching, there are a couple of reasons (or excuses) for this. First, these fenders had been installed on another bike previously and were removed because the rear fender cracked at the seat stay bridge (due to my faulty installation job). I patched the fender back together with a couple of pieces of sheet aluminum and some nuts and bolts as you can see below.
It's not the most beautiful patch job in the world, but it's quite sturdy. While the patch holds things together well, it limited my ability to shape the fender to match the arc of the tire perfectly.
Also, since the Trek has horizontal dropouts, I decided to leave some extra room near the chain stay bridge so that the rear wheel could easily be removed and reinstalled without having to let air out of the tire. I've seen other fender installations that solve this problem by attaching the fender to the chain stay bridge with a spring gizmo so the fender follows the arc of the tire but can be pushed forward when needed to remove and reinstall the rear wheel. I've used this approach before and it does look better, but in my experience it always results in a fender that rattles and eventually cracks. For a randonneuring bike, I'm interested in the simpler, more indestructible approach even if it isn't quite as pretty.
So far this installation seems to be solid and totally rattle free. The 400k and 600k brevets coming up in the next few weeks will be good tests.