Bike Wheel and Spoke Adjustment
Among the most basic components of a bike, the wheel set is among the most important. But in order to understand how to maintain and adjust the wheel, it is a good idea to familiarize yourself with the basic anatomy of the bicycle.
A typical bicycle frame is made up of two triangles: the main triangle that connects the seat, handlebars and pedal assembly, and another that goes from seat to pedals to rear hub.
The back wheel connects to the bike frame, and the front wheel is connected to the fork, a structure that fits over the front wheel hub and is connected to the head tube, a structure that holds the handlebars.
Bike Wheels
Most bicycle wheels consist of four components:
Hubs
A hub connects the wheel to the axle. Ball bearings in the hub reduce friction between the wheel and the axle. Some bikes don't use hubs, particularly single speed bikes. In this case, the wheel is attached directly to the bike frame.
Spokes connect to the hub to the rim of the wheel.
Spokes
Spokes are thin wires that connect the hub to the rim. They rely on tension for their strength. At the end of each spoke, a nut is used to adjust the amount of tension in the spoke.
As a general rule, the more spokes a wheel has, the stronger it is. But if their tension is adjusted properly, bicycles with as few as 10 or 20 spokes can be sturdy and efficient.
Rims and Tires
The rim is the round part of the wheel that serves as a base for the inner tube and tire. In certain bike models, rims also provide a braking surface.
Most rims are made of an aluminum alloy. However, higher end bikes feature carbon fiber rims. Older bikes may have steel rims.
The type of rims on a bike also indicates which type of tires it requires. Clincher rims are the most common. They work with clincher tires, where an airtight inner tube is clinched by the rim and surrounded by the tire. A third component in clincher rims is needed if the rim has spoke holes: a rim strip. This covering protects the inner tube.
Many bike riders like clincher rims because they allow a high level of air pressure within the tire. They're also considered easier to repair or replace in the case of a leak.
Tubular rims work with tubular or sew-up tires (also called "tubs"). In this style, the tire is sewn up into the shape of a tube, then attached to the rim with glue. Tubular tires don't always have a separate innertube.
Tubular rims are more labor-intensive when it comes to repair. The process entails removing the tire from the rim, opening it, patching it, sewing it back together, and gluing it back onto the rim. Clincher rims have become the industry standard for consumer-model bikes. But specialized riders still use tubular rims in certain cases.
Maintaining Bike Wheels
Two major bike maintenance jobs involve the wheels: fixing or replacing a tire, and truing the wheel. Experienced cyclists who have the right tools perform these jobs at home. Most wheel maintenance and repair jobs are considered intermediate or advanced projects. You should watch a pro do the job a few times before trying it yourself.
Truing is a process that adjusts tension on spokes to keep the rim straight while the wheel spins. The tension is adjusted by turning the nuts at the end of each spoke, commonly called "nipples."
To adjust the tension, you will need the proper wrench size. Most nipples are square, but their sizes vary. The wrench must fit the nipple perfectly. A wrench that does not engage properly may damage the nipple when you turn it.
Professionals aim to create a balance among lateral true, radial true, rim centering and spoke tension. When lateral and radial true are not correct, the result is a wobbly wheel. Brake pads can also be affected.
If rim centering is not adjusted properly, the back wheel does not follow the front wheel, causing handling problems.
Spoke tension is also important. Low spoke tension puts too much stress on the wheels. Excessive spoke tension may damage the rims or hubs.
Standard Wheel Alternatives
The wheel described above is the most common type. But some bikes don't use a typical wheel. BMX bikes, for example, have cheaper, simpler wheels made of plastic, which use a lower air pressure.
Higher-end racing bikes feature wheels made of carbon fiber. The advantage to these wheels is that they're lighter and have a minimizing effect on aerodynamic drag.
Disk wheels are also meant to reduce drag, but they're a bit heavy. Some riders find bikes equipped with disk wheels hard to handle in windy conditions.
Bike wheels play a vital role in braking, efficiency and comfort. Therefore, knowledge about wheels is important for any rider who takes cycling seriously.
Resource
Bike Repair Online (n.d.). Introduction to Bicycle Wheel Hubs. Retrieved April 17, 2008, from the Bike Repair Online Web site.
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