Is it easy to clean and grease the bearings on a back-pedal brake bike?

July 28, 2012 10:31 AM

Can I grease the bearings in a wheel with a back-pedal brake without wrecking the whole thing?

I have an old Dutch bike that I bought for cheap. I just replaced the tire on the back it a fancy new Schalwbe one. I noticed that the wheel doesn't turn smoothly. It feels like the inside is pretty gummed up. I just greased the front wheel and I know enough about bike maintenance to do that easily.

My problem is that the back wheel has a back-pedal brake (a coaster brake). I'm wondering if I open it up will all sorts of parts spring out, ruining my bike? I know that back-pedal brakes aren't easy to mess about with and I don't want to try cleaning it. But can I get at the wheel bearings by just unscrewing the axle nuts, or should I just leave the whole thing alone?

posted by nevan to Technology (7 answers total)

Re-greasing the hub properly involves taking the old gunky stuff stuff out and cleaning it, and replacing it wish fresh, clean grease. But, it's possible that stiffness is because the hub also needs adjustment. Just loosen the axle nuts and adjust the cone on the drive side. The reaction arm will hold it in place.

I'm assuming you have cone wrenches. If not, take it to a shop.

If you want to give the overhaul a rip, Sheldon Brown is the go-to, as usual. There a bunch of links at the bottom with diagrams of common coaster brake hub models.

http://sheldonbrown.com/coaster-brakes.html


Good luck.
posted by sapo at 11:13 AM on July 28, 2012 [1 favorite]

I agree with sapo that the problem is most likely the adjustment of the cone nuts rather than gunk in the hub. You may have disturbed the adjustment when you replaced the wheel.

Here is another Sheldon Brown picture that illustrates the issue. Your hub is slightly different but you get the idea. The two tapered cones squeeze inward on the ball bearings. They should be snug enough to just barely remove the side to side play. If they are too tight, the wheel will not turn freely.

On a coaster brake, the reaction arm is permanently attached to the cone on the left side and you put a wrench on the cone on the right side. The reaction arm is essentially the lefthand wrench. As you rotate the reaction arm you loosen or tighten the cones. What might have happened is that you rotated the reaction arm in order to line it up for installation which tightened the cones. What you should do instead is rotate the entire wheel assembly to line up the reaction arm instead of twisting the reaction arm.
posted by JackFlash at 12:13 PM on July 28, 2012

Nothing's going to say sproiing and jump across the fence to the neighbors, no. Take the ball bearing apart, (if they're pre-assembled bearing cartridges, they need to be replaced when malfunctioning) clean out the gunk, as someone said above, rinse with benzine, check that all the surfaces of the bearing are undamaged and the steel balls still round and complete in number, apply new grease, re-assemble, adjust the cone. Stay away from the brake mechanism inside, some parts of that may not get any grease.

Here are some pictures of the insides: (Dutch blog)
and here's a schematic video of the assembly, in case you'd have to take apart the whole shebang.
posted by Namlit at 12:48 PM on July 28, 2012

If the wheel rolled fine before, it's likely just a cone adjustment needed, as others have mentioned.

If you decide to take apart the whole hub, it will need grease even in and around the brake shoes. Without grease around the brake surfaces, you'll likely damage the hub shell and/or the brake shoes. Single speed coaster brake hubs are generally packed full of grease.

An old Dutch bike likely has a Sachs hub with either the roller clutch (depicted in the blog and video in Namlit's post) or a cone clutch. Either way, they're not very complicated. They are very reliable and will go many many miles without need for service.
posted by 2N2222 at 2:35 PM on July 28, 2012

Namlit's advice is generally good, except please don't actually degrease with benzene. It's toxic and carcinogenic and inflammable and expensive and bad for the environment and unnecessary. It's perfectly sufficient to just wipe the contaminated grease off with a clean rag. If, for some reason not entirely grounded in mechanical necessity, you insist on degreasing the parts, citrus degreaser or Simple Green will do.

Actually, this is the first time I've heard of degreasing with benzene. Kerosene is carcinogenic and inflammable enough for even the most old-school mechanics I've ever met.

Also, everyone telling you to try adjusting the hub first with a cone wrench is correct. Friction due to contaminated grease usually manifests slowly over the course of many weeks, not instantly after a wheel is removed and reinstalled.
posted by d. z. wang at 6:31 PM on July 28, 2012

Just want to say that while a cone wrench is absolutely the right tool for this job, if you're just working on your own bike and you're reasonably careful there's no reason that you can't do this with an adjustable wrench, or channel locks, or pliers, or really anything that'll grab the flat bits on the cone. You don't have to crank hard on it or anything, as others have said you only want it just tight enough to remove play from the axle without pinching the bearings inside.

A professional bike mechanic might recoil in horror if they saw you take a pair of channel locks to your cones, but honestly as long as you're gentle you're not going to damage anything. And in the worst case scenario that you somehow do manage to round off the flat parts of your cones or something, they'll still work just fine.
posted by Scientist at 12:02 AM on July 29, 2012

Sorry 'bout the benzene, turns out to be a translation glitch. What d.z.wang and 2N2222 say.
posted by Namlit at 1:16 AM on July 29, 2012