Thursday, July 17, 2008

How to true a wheel, Nepali-style

I went yesterday to a "real" (i.e. retail) bike shop to get a chain--I twisted a link on my way to visit some friends (of mine, of Tom's, and of the shop's) and I needed one anyway for the kids at P.A.--whose class started before RugMark's--to practice taking apart and putting together. 

It was raining when I got to the shop, so the guys inside invited me to sit down and wait it out, which I did, happily. I'm beginning to develop a sense here of which storms will last 20 or 30 minutes and which ones will last all day, and this looked like a passing shower. One of the big signs is when the rain starts; similar to living in the Midwest during thunderstorm season, you get a lot of afternoon showers that clear by nightfall, but if it starts in the morning it will probably go all day.

In any case, the shop had a bunch of Nepalis in it, probably 5 or 6, plus me, which made for a lot of cheerful squeezing back and forth in dim light between gray metal shelves stacked haphazardly with greasy bicycle pieces, mostly held in plastic bags ripped open. The only kid working--probably no more than 19--was working on a wheel with a pretty good hop in it, which had a couple of broken spokes.

First he replaced the spokes, which actually took a good bit of time--the wheel was 4-cross and had probably 40 or 44 spokes. That's a lot, more than you need, and (as an aside) from everything I've read 3-cross is actually stronger. The kid kinked the spokes a little finagling them into place, but while I think I probably could have kinked them less, getting them in without any kinks at all would be really, really hard. He put them in the right place--over  and under the other spokes correctly--though.

He then gave them a good initial tightening and put the wheel into the truing stand, which in Nepal is a contraption without the caliper arms at the bottom that American/European stands usually have. Instead you get 4 legs , with an old spoke twisted around one pair--it's this spoke you move up and down to judge whether the wheel is true. The mechanic at the shop actually just put his thumb on the bent spoke so that the wheel grazed his nail, and used that to determine lateral true. (Radial true, with this tool, is pretty easy.) He found the spot he want to work on, determined the length of the hop, and marked it with a finger.

Then he picked up a metal mallet with one hand and then a sledge with the other, and bracing the sledge against the rim, hammered it back into true.

After he had done that a couple of times he checked the spoke tension with his fingers, and tightened the spokes that had become loose with his hammering. He continued for a few more spots on the wheel, but it had stopped raining and I paid for the chain (200 Rs., about $3 USD) and walked back home.

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