Originally Posted by JunkYardBike
Relatively new to bicycle mechanics, but I've been having fun disassembling/breaking/attempting to reassemble some old bikes.
Now to the point. I have two questions:
First, I decided to overhaul the hubs on a 1993 Cannondale road bike with RX-100 hubs. For all I know, this is the first time they've been serviced. Did some research, found that the most common bearing ball size for front hubs is 3/16. Stopped by a shop before opening hub, asked for 3/16 ball bearings, mechanic said he only had 5/32, but that they use them all the time without problem as a replacement in hubs using 3/16. Disassembled hub - existing balls definitely appear to be at least 3/16 (unscientifically measured against a tape), but to the eye appear much larger than the 5/32s. The shop owner has apparently been in business for many years, and was highly recommended by a friend who has had years of good service there. Thoughts and opinions? Is it advisable to use the smaller size?
Second question. Both cones on the front have almost identical gouges, no bigger than 0.5mm, at one point of the ball bearing pathway (see photo). From what I've read, I should trash them in favor of new cones. Opinions? Also, what could have caused this? The axle appears straight. There was no play in the hub when it was mounted on the fork. Any thoughts, opinions, advice, or flames?
Oh, one more thing. Anyone have a spare set of cones for RX-100 hubs? Top dollar/euro/sterling paid, as long as it's under five of them.
Patrick
Why guess at the proper size of the bearings. Get your self a 1" micrometer and learn how to use it. This is invaluable for all kinds of mechanic work. You'll be able to I.D. the diameter down to thousandths of an inch (or even 10 thousandths if you have the right model of mikes). If you don't feel comfortable with converting thousandths to fractional measurements, the machinist market is flooded with good quality dial calipers, some that are marked on the dial in fractional measurements to simplify things. Its odd that to work on bikes you need BOTH a fractional and metric dial caliper or micrometer. Once you verify the correct size ball bearings then you can deal with the BOZO mechanic who recommended the wrong size and confront him with his bad advice directly because you will no what you need with no uncertainty at all.