The modern bicycle wheel is a great example of elegant simplicity in engineering. It has remained largely unchanged over the last century when advances in metallurgy and the invention of the pneumatic tire gave rise to the current wheel model. The use of thin metal spokes allows wheels for much stronger interlacing designs than the traditional radial lacing found in older wooden wheels. More recently double-walled and triple-walled rims have greatly increased the strength of wheels by providing extra internal bracing.
A good bicycle wheel usually consists of an aluminum hub and rim connected with stainless steel spokes. The spokes are bent and beaded at the hub end so they can be threaded through the hub flange. At the rim end they are threaded to fit into beaded nipples that are inserted through the holes on the inside of the rim (covered by a rubber or cloth band to protect the tube). Wheels can be laced in many patterns, with the most common being known as 'cross 3' because each spoke crosses three others. Spokeless carbon fiber wheels have also been developed, but their benefit remains unproven, and catastrophic failure (shattering) is much more dangerous than on a traditional wheel (tacoing).
Basic wheel properties
Spoke Tension
Adjusting spoke tension is the means of adjusting all subsequent properties. Nevertheless, a good place to start wheel maintenance is simply feeling all your spokes and tightening any ones that feel extremely loose. Good spoke tension will help keep your wheel strong and safe from incidental damage. Be careful not to over-tighten though. A good rule of thumb is that all spokes should have similar tension with the drive-side spokes possibly being slightly tighter on a rear wheel.
Wheel Trueness
The most basic aspect of wheel condition. The gist of this is how smooth the edge run runs along the brake pads as possible. The truer the wheel, the tighter the brakes can be adjusted without rubbing. Learning how to true a wheel properly is what sets apart the true bicycle mechanic from the cheap hack. This is the next logical step after learning to change tires, adjust brakes and derailleurs, and perform other basic maintenance. After this you can go onto rebuilding hubs, replacing drivetrains, and installing new forks!
Wheel Dish
This is how centered the wheel is over the hub. You should not have to worry about this unless you bought a lemon of a bike or it is really old and poorly maintained. Either way, this procedure can screw up the trueness, so it's better left to the professionals, at least until you are really confident with your truing abilities.
Wheel Roundness
Roundness is the measure of how far every point on the rim is from the hub. If a wheel is out of round, it is either because it has been smashed flat in some spot, or because somebody who didn't know what they were doing built your wheel. Regardless, riding on a wheel that's out-of-round is a jostling experience to say the least. More often than not wheels like this are too far gone to fix. Ask your local mechanic.
Wheel Building
Building a wheel is something that should only be attempted by a serious gear head. The cost of the parts of the wheel are not much less than a pre-built wheel anyway, so you should only really need to do this if you have an expensive rim or hub that you want to reuse. Aside from selecting the right spokes and lacing pattern (you can get help for that), the tricky part is getting all the above properties right. This tends to require a lot of incremental tightening to get everything well-balanced. Wheel building skill is one of the surest signs of a true bicycle expert. See Sheldon Brown's Web site below for a very good guide.
Tools for working on bicycle wheels:
Further resources:
- The Bicycle Wheel by Jobst Brandt
- Widely regarded as the authoritative resource on building and maintaining bicycle wheels. Some consider the author to be overly opinionated in his denouncement of newer wheel 'advancements', but unlike most proponents of novelty technologies he backs up his claims with physics.
- Sheldon Brown's Wheel-Building Guide at http://www.sheldonbrown.com/wheelbuild.html
- Sheldon Brown is a long time bicycle enthusiast whose Web site contains the most comprehensive overview of bicycle maintenance anywhere on-line. A great source of free information, this site hearkens back to the early days of the Web when quality content was the driving force instead of flashy graphics. We all here can appreciate that, right?