Thursday, February 26, 2009

Why do my brakes rub on my bike?

A friend of mine asked this question, then I found out my answer might be something worth sharing, as there is a lot of experience here:

I don't know how much you weigh. If you are over 185 you are heavy for the factory made typical sport class wheel which is made for riders with an ideal weight of about 150-170. The bike makers make lighter wheels because the market thinks lighter is always better. Bike buyers do not have enough experience to know this is not always true. The wheels do flex with torque and weight. Also as a wheel wears and is adjusted, sometimes the screws on the spokes and the nipples get looser and then does not stay true as long. Sometimes you can true it up then put a tiny bit of blue loctite in there and that keeps it set. Tighter tension is better, but that tends to pull the nipples through the light alloy rims when you hit stuff espcially if you are heavy and have a hard tail. I used crack rims at the nipple from hitting stuff, worse if tightly tensioned. If you are not hitting stuff because you are always on pavement it is less important, but I had the problems on road wheels too. A guy I know used to build wheels for me and then tension them on the tighter side to make them more true under torque. I think he had a tendancy to overdo it. But then he was in the business of selling replacement rims and wheels so there you go.

There is no way around the rim rub issue. It is just a compromise with design. Very much like a guitar with respect to action height, except you are not beating on the guitar (hopefully). My older bike has rim brakes and even with my weight (175) I get a bit of wheel rub when the wheels are not true and perfectly tensioned. So I just back the brakes off a bit. Of course at some point you back off too much and then you can't get enough pressure to brake as well as you would like, not to mention the brief delay. Another thing. Unless you have the CERAMIC surface rims (expensive enough to make you consider discs) with appropriate pads you will wear through the aluminum rim with the pads eating the rim. There is no way out of it unless you use softer pads then you are replacing them at least monthly which is a pain in the ass. Your wheels will need to be replaced after lots and lots serious riding. I went through a several wheelsets doing that until I got onto disks. One time I used some hard pads and ate a set of wheels in three months. OOPS. Very stupid. Every time I bought a ceramic rim it seems I would pull a nipple through it or dent it on a rock so it would have a bump in it while braking. I stopped doing that and then my wheels would always last until the rim got eaten by the pad, but before I pulled a nipple through it. I could not win. I still have one old ceramic front on my bike in the mountains. It is 7 years old. Pure luck. Of course front wheels have it easy if you ride right.

On my Laguna bike I have disks and they are now perfected. For a while they were unreliable but the technology developed. Still I would use nothing but Shimano (harder to adjust) or Avid hydraulic disks. The other brands are not as reliable. I use Avid Juicy 7s which are amazing. Needs pads maybe once a year, even with my level of riding. Even disks, the rotors can warp or get tweaked a bit from a stick or something and you need to mess with little bends on them to keep centered. Also occasionally align the calipers. But any rub is less inevitable, and the feel is far superior as is the power. I would never go back but its a huge price to upgrade from rim brakes unless you are already buying a new wheel set anyway. Also older bikes may not have the mounting points for disks.

All of the factory wheels are not as good as the best hand built wheels. The last wheel set I bought I got smart. I got tired of those wheel issues. I told the guy to build the lightest training (not racing) wheel he could. He used Hope (UK) hubs, DT (swiss) rims and spokes. They were hand built by a pro and cost me $500 for the set. They have been perfect in three years of heavy riding and I have only needed to have them tesioned twice, and this was just for maintenance purposes, not because they seemed uneven. They are on the heavier side (but NOT a downhill wheel) because I like strong more than I like light. A good wheel set is made by a pro with your weight and riding style as consideration. I have never pulled a nipple through the DT rims. I had that problem with Mavic rims, I think the alloy is softer.

Its also hard to know who is really good at it, like you know just because its handmade does not mean the guy who did it is better than a machine. In that way it is exactly like guitars.

I don't like the brain shocks. They get stiff when they feel no bumps. Then the first bump just kicks your ass. Then it gets soft like a stupid shock again until it goes smooth for a while. I am happy with my stupid shock where my ass does not get kicked at all. It might be ever so slightly less efficient but as I am not racing I don't care. It has a lockout so I can lock it out when I am climbing but actually I don't give a shit and don't bother because I am not racing. You can forget and then start going downhill, hit a rut and crash.

I rode today. My bike shifts crappy too. Time to replace the cables. You have got me thinking about it. Also I need a new rear tire, but they are like $40 and I am cheap so I think I will push it a bit more. Last year I would have thrown that tire out by now.

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