Tuesday, June 5, 2012

First Flat

Tomorrow is the start of the Park Ave Weeknight Series races and I plan to attend and ride muni.

So this evening I decided to tighten my cranks and make sure my uni is good to go.  As soon as I took it off the hook in the garage, I noticed the tire was flat.  Crap.  I figured it was a pin-hole leak caused by some thorn or nail I must have run over.

I took my wheel off and removed my tire.  I still haven't gotten around to posting about the weight saving changes I made to my uni over the winter, but here's a sneak preview.  I'm using a lightweight tube made by Schwalbe.  It's lightweight because it's thinner, and maybe a less durable rubber.  When I removed the leaking tube from my tire I found it looking all worn.

Worn Tube
I inflated it outside the tire a bit but didn't see, hear, or feel any obvious leak.  I'm assuming there are some tiny holes within the worn areas, but for now it's not important to me.

I had a second Schwalbe tube so I installed that.  It was kind of a pain because I screwed up a bit.  I put the wheel on backwards first.  Duh, right?  Somehow it can be tricky when the uni is upside down.  Once I switched it to be correct, I noticed an obvious foolproof way to get it right every time.  My cycle computer sensor and magnet are only on one side.

One other problem I had has been haunting me for a while.  For some reason the wheel sits in the frame a bit cockeyed.  It's slight, but it can be seen when looking at the distance between each brake pad and the rim wall.  There's no adjustment for the rim position in the frame.  The hub bearings just sit in bearing holders that get tightened down. It could be caused from minor manufacturing variations in the frame, bearing holders, bearings, the wheel build, or an accumulation from all of these.  I did notice that with the wheel in backward, it centered itself very well, but I can't ride my geared hub that way.

In the past I've just tried to put pressure on the rim while I tightened it it an attempt to take advantage of any play available.  It helped a touch. But this time a cut a super thin piece of flat rubber to shim one bearing holder, so the bearing in the side sat the tiniest but higher.  This worked well.

I rode my reassembled uni once around the block.  It seems to be running fine.  I'll check my tire tomorrow morning and hopefully it will be holding air.
I'm a little nervous heading into a race tomorrow with these changes, but it will likely be fine.

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