How to easily repair your pitted hub cones!

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 :

First tighten the one end of the axle in the drill chuck
First tighten the one end of the axle in the drill chuck

 

And then tightens the cone onto the locknut in the other side of the axle
And then tighten the cone onto the locknut in the other side of the axle

 

And then he wraps a nail with a piece of sandpaper (shouldn't be too rough) to make the cone curve smooth as a glass. The nail is used for the sandpaper to have a small curve and also to be easier to apply force on the right spot.
And then he wraps a nail with a piece of sandpaper (shouldn’t be too rough) to make the cone curve smooth as a glass. The nail is used for the sandpaper to have a small curve and also to be easier to apply force on the right spot.

 

 

Afte a year of hard riding and about 14.00 km the old cone looks as new!
After a year of hard riding and about 14.00 km the old cone looks as new!!!

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.

 

 

 

 

 

 

 

 

14 Comments Add yours

  1. Michael S says:

    Sounds really great! But wouldn’t you need to refurbish the opposite face as well? Does it all fit together then, balls and all?

    1. Bicyclosis says:

      Hello Michael,
      If the other cone is fine, you can leave it as it is. Yes, everything fit together again as before! Even if you ‘repair’ the cone few times (I doubt it will need an other repair for the next years), it will still fit perfectly in the hub.

  2. John Tietjen says:

    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.

    1. Bicyclosis says:

      Great explanation John, thanks for sharing! I will add it to the main article so others can see as well.

      1. John Tietjen says:

        Another thought: I’m going to try it next on pitted bottom brackets that aren’t worn too badly; although I know most bikes have sealed BB’s now, I fix a lot of older (cheaper) bikes for a local youth organization and am always trying to save a few bucks to keep the bikes rolling.

  3. John Tietjen says:

    For clarity, my suggestion should have read “quick-release skewer” to make the grinding surface–it has a diameter about half the axle shaft which will match the cone diameter better when wrapped with sandpaper.

  4. Marco Norswede says:

    Thanks for this idea! Great post! I, too, have suffered in trying to find the cone I need. What a nightmare. Luckily I have a small metal lathe. Since the cone is fairly hard, I didn’t try machining it with tooling. It does hold and spin the axle very smoothly. I then wrapped a phillips screw driver with 220 (Good quality) and paper. After about 20 minutes of running it in the channel, scratches disappeared. I love the can-do attitude of bike people. thanks again.

    1. Bicyclosis says:

      Glad you liked it Marco! I wish tricks like these were more well known so people can’t buy wheels whilst they can easily fix their old ones!

  5. Drew says:

    This process just saved me, twice! Finding compatible cones for old bikes sure is a pain!

    I used a variation of this that helped save some time and (I think) improves quality. I used a Dremel tool with a grinding bit to help remove material until the pits were gone. The Dremel was mounted to a bench using a vise or the Dremel drill press stand so that I could use my cordless drill to spin the cone. With both tools spinning, it was easy to take off the material necessary and still maintain the curvature needed.

    For sanding and polishing, I used drill bits to hold the sandpaper so that I could match the curvature more easily. I taped the flutes so they would not get damaged in my vise (which has notches for holding round parts), then taped sandpaper to the non-fluted part of the shafts. Double-sided tape would have been nice, but masking tape works fine so long as you leave enough sandpaper exposed for a sanding surface. With the bit held in the vise with the drill point downward, it was easy to gently sand the cone and inspect my work as I went.

    After grinding, sanding, re-grinding (there was still a small pit left), and re-sanding, I used a polishing wheel on the Dremel to put on a nice shine. Now the resurfaced cone looks better than new!

    Thanks again so much!

    1. Bicyclosis says:

      Hey Drew, thanks a lot for your tips, very helpful! This process saved me twice as well!

  6. Ed McGuigan says:

    Great tip guys. Just came here to look to buy replacement cones. Definitely think that spinning the cone and not the abrasive in the best approach as regard an even application of abrasion. One of mine is quite badly pitted and I suspect it is due to poor adjustment. I didn’t have any cone wrenches in the past so it was probably loose. I love repairing stuff rather than junking it. I was going to build a new hub into the wheel if I hadn’t been able to get the cones.

    1. Bicyclosis says:

      Hey Ed, please try it before buying new hub or cones. I’ve fixed many cones this way since this article posted

  7. Mick says:

    This is so cool. Finding bike parts is getting difficult even for re-use. I can afford to replace it and always prefer to repair. This is such an awesome idea. Thank you!

    1. Bicyclosis says:

      Hello Mick, I am very glad you found it helpful! Sorry for the delay, this blog is not so updated anymore!

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