Friday, December 15, 2017

DIY - refinishing bicycle components

Sometimes you have to take matters in your own hands. As I wrote a while ago, I'm not particularly fond of the decision of major bicycle components manufacturers to offer their products exclusively in black finish. Too often we are left with little choice and if you are looking for a particular part for your bike, you can have it in black... or not have it at all. Typically, hubs, pedals or headsets are offered in multiple colors but handlebars, cranksets or even worse - derailleurs, are usually black only.

Because I'm working now on a new bicycle project, I need components that are not black but polished silver. That turned out to be quite difficult, especially considering some limitations I have to deal with. Therefore, I decided that if component makers are unable to provide what I need, I have to make it myself. Sort of.

The parts I want to use on my bike but don't have silver, polished finish I'm looking for are:
  1. My old Sugino OX601D crankset and chainrings. They are silver but with dull, bead blasted finish.
  2. TRP brake adapters (and all other adapters too). Come only in anodized black.
  3. Shimano RD-7800-GS 105 rear derailleur. A modern rear mech that's 11-speed compatible and comes in "silver" option... with a  black pulley cage.
The plan was to strip off black anodizing, sand and polish surface enough so it looks nearly mirror-like. Normally, you would want to use a tumbler or vibrating polisher to this type of work but since this equipment can be pricey and I have no access to it, I had to rely on less high-tech methods to get the finish I was looking for.

Fortunately, I have some work space in my basement and access to several handful tools. I found out that the best procedure is the following:
  1. Bead blast off all black anodizing.
  2. Sand with 400 grit paper.
  3. For tight corners use cushioned paper or pads. Those hard to reach areas can be sanded using steel brushes on Dremel tool (Very gently! Dremel is a high-speed tool and will erode aluminum surface if pushed too hard). 
  4. Sand with 600 grit paper.
  5. Sand with 1000 grit paper.
  6. Sand with 1400 grit cushioned pads. At this point parts will already have nice shiny finish.
  7. Polish with buffing wheel and emery compound.
  8. Finish with buffing wheel and white rouge compound.
My Sugino cranks in their original finish.

And after hand polishing. Minor scratches are still visible but overall I'm quite satisfied with this result.

This process takes time and patience but results are rewarding. I have now polished parts I was looking for. The original finish is gone and most tiny scratches are nicely blended in. This could be likely taken even further going down to finer grit sanding paper but I think it's unnecessary. These are bicycle components after all. They will get some new scratches in normal use so it's a bit pointless to make them look like a clean mirror.

Time to put it all together.

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