|
 | |
Building a bicycle wheel The simple, the elegant, the intimidating Part 1 of 2 If you've ever taken the time to really look at a bicycle, you would probably agree that it is as beautiful as it is practical. Look a little longer and you will see that no single part on a bike is more elegant and functional than the traditional 32-spoke wheel. Its elegance is due in part to the geometric arrangement of the spokes - as complex as a snowflake - maintaining a perfect roundness. The ancient Greeks viewed this shape as sacred due to its difficulty in achieving. But a wheel has more than surface beauty. Like the perfect human form, it is beautiful and svelte, but also hard working, low maintenance and strong. Those 32 spokes, weighing next to nothing, can support a rider weighing 250 pounds or more. A wheel, like an attractive member of the opposite sex, both attracts and intimidates. If you have never been intimidated by a bicycle wheel, you will be the first time you assemble one. It seems like there are so many more ways to get it wrong than to get it right. Yet with a couple of hours, some basic tools and an adventuresome spirit, a bicycle wheel can be built successfully. I laced up my first wheel about 10 years ago. I attended a class offered by a local bike shop. I don't remember a lot of the details other than everyone in the class was able to get their wheel built. At least that's how I remember it. (By the way, take advantage of any classes offered by your local bike shop. Their employees can answer your questions and you can benefit from their experience. It's one of the best ways to learn more about your bike as well as get to know the staff at the bike shop on a more personal level.) My interest in wheel building re-emerged a couple of months ago when I purchased a cyclecross bike with a rear wheel bent in a crash. It wasn't taco shell bent, but it was bad enough that I wasn't able to true it by adjusting the spokes. I happened to have another wheel with a good rim and a worn-out hub, so I decided to pair the good hub with the good rim. Having successfully completed a wheel rebuild project a decade earlier, I had confidence I could do it again. If it didn't work, I figured I could take the components to a shop to have it done professionally. All I had to lose was a few hours of my time and a bit of my pride. The first step in wheel building is to obtain all of the right parts. A wheel consists of a hub, rim, spoke nipples and spokes of the right length. My project was relatively easy, since the replacement hub and rim were the same diameter as the old ones. Because I was planning on using the same spoke pattern, I was able to reuse the spokes from whichever wheel I preferred. Had either the hub or the rim been of a different diameter, or if I had decided to change the spoke pattern, I would have had to do some math to figure out what length spokes to use. The only special tool I needed was a spoke wrench that can be had for about $5. If you have questions, take one of your spoke nipples to a bike shop to make sure you get the right size wrench. The devil in the details Before tearing into things, start off by making some observations and decisions. You will need to decide if you want to use straight diameter spokes or butted spokes. Most spokes on quality wheels are double or even triple butted. That means that the spoke diameter changes over the length of the spoke. A double-butted spoke will have two diameters and a triple-butted spoke will have three diameters. The change in diameter is sudden, not gradual, so it's easy to see and feel the transition in diameters. The thicker diameter will be toward the ends of the spoke where the stresses are more concentrated. Butted spokes trim off some rotational weight without sacrificing strength, but they do cost more than single diameter spokes. Take a look at your spoke nipples. If you plan to reuse them, make sure that the corners are not rounded off. If they are, they will be difficult, if not impossible, to adjust. Replace any that are damaged. Thread a spoke nipple onto a spoke to make sure that it fits. Notice that the spoke enters the nipple about an eighth of an inch before it begins to touch the threads of the nipple. Also, note that both have normal right-hand threads. Be sure to take a look at the spoke arrangement on an assembled wheel. Note how every other spoke comes from opposite sides of the hub and angles up to the rim. Thus, when you tighten a spoke nipple, it will pull the rim left or right, depending on which side of the hub the spoke is attached to. This feature is what allows a rim to be trued. If a portion of the rim is rubbing on the left brake pad, locate a spoke nipple in that area that is attached to the right side of the hub, then slightly tighten it and slightly loosen the nipples on either side of it. Oftentimes, an eighth or quarter turn is sufficient to correct minor rubbing problems. Of course if a large portion of the rim is rubbing on a brake pad, be sure to check that the wheel is centered properly before adjusting the spokes. There is one difference between a front wheel and a rear wheel that is worth noting. Because the rear wheel of a multispeed bike has to have a gear cluster mounted to it, the drive-side hub flange is offset from the center of the hub less than the left-side hub flange. (The hub flange is the portion of the hub that has holes drilled in it to accept the spokes.) Therefore, the spokes on the drive side of the hub are closer to vertical than are the spokes on the left side. This affects wheel truing. A spoke from the drive side will need to be adjusted slightly more to get the rim to move. This is not true for the front wheel because the hub is symmetrical. Many bike wheels utilize a cross three spoke pattern. This means that each spoke crosses three others on its way from the hub to the rim. Crossing spokes adds lateral (side to side) strength at the expense of some additional weight. Crossed spokes are slightly longer and longer spokes weigh more. Notice how every other spoke on each side of the hub is splayed out in one direction and the others are splayed out in the opposite direction. I find it helpful to make a sketch of the lacing pattern so that I can refer to it if I don't have another identically laced wheel to refer to. A wheel can also be laced in a cross two pattern or laced radially. Radially laced wheels aren't particularly common, and they will probably look odd to you when you first see one. On a radially laced wheel, the spokes run straight from the hub to the rim directly without crossing any others. Personally, I'd be reluctant to ride a bike with radially laced wheels because I don't think they're strong enough to be safe. Make these observations and commit these concepts to memory, and you'll be ready to remove some spokes. But I'll give you a month. In the June issue, I'll provide step-by-step instructions for building that wheel. I expect you to be ready. Byron Kuster is happily married and teaches in a Minnesota state prison. He bikes to work year-round.
| |
Back to the top Waupaca Publishing: 717 Tenth Street * P.O. Box 152 * Waupaca, WI 54981 © 1999-2008 Site last updated 07/01/08 Designed by PBW | |
|
