Wednesday, June 19, 2013

Dustin's Clicky Unicycle

For weeks Dustin's KH 26 unicycle has been making a clicking noise.  It seemed to be getting worse over time.  It's rather annoying and we've both been concerned something was going break or get ruined.

One time before riding, I had tried tightening his crank bolts to the right torque.  That didn't help.  Neither did tightening his bearing holding to spec.  Yesterday Dustin stopped by in the evening and we tried some more ideas.  Before getting too technical, we swapped seats and posts, and then pedals but none of those helped. It wasn't the typical pinging noise I've heard from spokes, but still I tightened all the spokes 1/8 of a turn.  No help.  That was all we had time for.

Later I read a lot of messages on the unicycle forums regarding what sounded like the same problem.  There were many suggestions.  This evening Dustin stopped by again and we worked on it some more and pretty much did everything that was suggested.

First I wanted to further eliminate the possibilities of spokes rubbing. Sometimes spokes make noise when they flex and rub against each other.  So we worked thin plastic spacers between every point where two spokes crossed each other.   The clicking remained.

Then we removed the wheel and took everything off the hub spindle: cranks, outer spacers, bearings, and inner spacers.  On the way home from work I had stopped at AutoZone and borrowed a bearing/gear puller.  It was the first time I'd used a bearing puller.  I'm not 100% sure it was the right model for this application, but it did work fine.  On one side of the hub the inner spacer was very tight and had to be carefully pried off.  The other inner spacer came off with no tools.  I assume this was just because of manufacturing tolerances, though I did file some very tiny spurs on the stubborn spacer.  It still didn't go back on easy, so I doubt that did anything.

With the inner spacers off we noticed some tiny metal filings at the connection between the spindle and hub body.  It looked more like something left over from manufacturing than something generated from friction.  After cleaning everything up we reversed the process.  One forum suggestion was to lube the spindle before putting the spacers and bearings on.  We did this.  We also swapped parts from one side to the other.  Why not.  To seat the sticky inner spacer and the bearings I used a deep socket of the right size and hammered.  I'm not sure if a press is normally used, but this technique worked fine.

After putting the wheel back on the frame and tightening the bearing holders to spec, it was time to put the cranks back on.   First I cleaned the crank holes with a toothbrush.  Then I greased the spindle splines.  I have never done this before because grease seems like a bad idea for parts held together mostly by friction, but apparently it's a not uncommon.  I tightened the crank bolts, put the pedals on, and it was time for a test ride.

Guess what.  The clicking is gone!  So, what was the fix?  It's hard to tell what specifically did it, but for now Dustin and I are glad that annoying click is gone and hopefully gone for good.

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