What do you do when the cones of your wheel worn out (worn out = show signs of a pit/groove from the bearings resulting the hub to not spin smoothly)? Your either replace the cones with new ones, or as many people do nowadays, buy a new wheel! The problem is, that cones are not that hard to pit, especially if if you ride often on a rough terrain or if you ride a loaded bike. Few weeks ago, a friend of a friend gave me for free his expensive wheels, because he bought new ones after he noticed the worn out cone symptom (problematic wheel spinning)!
The factors that causes hub cones to pit are many, and although you can prolong their lives by maintaining them regularly, sooner or later you will have to buy new ones, or buy a new wheel! Before you do that, please continue reading!
Giannis‘ creative thinking found an easy and free solution by asking the radical question “why not repair them?”. He proved that this can be done with only a drill, a piece of sandpaper, a nail and a dremel grinding bit. He even put the repaired cones to the test for a year (about 14.000 kms) and the cones seem to be holding up perfectly!
Here is how he did it :
John Tietjen in the comments wrote about his way (which I think is brilliant):
Thanks for your suggestion. I do a lot of old bikes, and finding cones is always a big pain. There is an improvement on this technique, as follows: instead of fixing the cone in a vise, and then grinding on it with a stone, which may not be done very evenly, it is easier to make a fixed rounded grinding surface and then attach the cone to a rotary (drill or dremel tool) to machine it.
Prepare a cylindrical grinding surface by wrapping (double sided tape works well to adhere) the sandpaper around a shaft (I used an old shaft from a quick-release hub). You can use 100-150 grit, depending on how much you are going to grind off). The final grinding surface should have approximately 3/10″ diameter, which roughly matches the radius of curvature of the cone. Clamp the “grinding surface” into a vise.
Prepare the cone for grinding by locking it with the lock nut onto an axle shaft at the end (with the bearing surface facing out), then tighten the other end of the shaft into the chuck of the drill.
Now the drill becomes a rotary tool, and you can press the cone which is being continuously turned by the drill against the grinding surface with the shape of the cone fitting against the contour of the grinding surface, and work the cone until the pits are gone, and the cone maintains its shape as it is being “turned” continuously to remove as much metal as necessary.
The cones I “machined” this way came out great, almost like new, and it saved me a lot of grief trying to either find at the LBS or order on line, not to mention the money.