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Tuesday, December 28, 2010

Getting Your Bearings

This is what happens if you don't replace your wheel bearings in a timely manner. Notice the side-of-the-road environment. Actually I was lucky because as the bearings began to fail I was barreling down the freeway in the midst of a lot of traffic. Fortunately I had plenty of warning as the back wheel began a slow but persistent wobble that gave me time to bail out.

The main reason that most people don't think about wheel bearings is that they rarely fail and that they are perceived to be hard to replace. Compared to changing spark plugs this is generally true. Compared to being stranded on the side of the road with a bike you can't even push this is not so true.

Diagnosis: First, with the wheel off the ground, rotate the wheel a few turns and see if you can feel any resistance. If there is even the slightest "grinding" or "crunchy" feel to it you need go no further. Time for new bearings. You may need to take off the drive chain on the rear wheel to properly feel the bearings.

Next, grab the wheel at 3 o'clock and 9 o'clock and see if you can move it back and forth. That is, can you push at 3 and pull at 9 and get any movement? Try again at 12 o'clock and 6 o'clock. Get a friend to hold the handle bars when you test the front wheel.

Still OK? Now check the odometer. More than 30,000 miles or more than 2 years on a dirt bike and it's time. Sure, your buddy had a 1964 Wackistan Zoomer that he's never changed a thing on but so what. Bearings, like tires, should be considered a consumable items.

Now comes the hard part; Changing the bearings. Or is it? Just because you've never done something and it seems pretty mysterious doesn't mean that it's impossible or even that difficult if you're patient.

First, find the size of your bearings. It will be something like 10x35x11 and will be etched into the side of the bearing. This means ID:10mm x OD: 35mm x W: 11mm. Bearings are all standard and you can buy them online or at a local bearing specialty supplier. Every town of any size has at least one. Tell them that you want sealed bearings for motorcycle wheels and they can match you up at ~¼ of the dealer price. The same place may also carry the seals you need, otherwise get them from the dealer.

Don't be bashful about going to a bearing supplier. I paid dealer prices for years because I thought those places only wanted to deal with big time customers. Actually, I think they enjoy hearing about my attempts at restoring bikes. Many of them ride bikes too and I've always found them ready to help.

Tomorrow: How to actually change the bearings.