20 Jul 2017
Getting to grips with wheels terminology
Essentially your wheel comprises a rim, hub and spokes. Vision explain how the structure of each results in very different ride characteristics, with a guide to current wheel tech terminology…
The rim is the outermost part of the wheel, which the tire mounts to. The tire unit is fitted to the rim via three main methods: clincher, tubular or tubeless.
Vision’s Metron 40 SL Clincher is designed to accommodate an inner tube and tyre. It’s easy to fit and fixing a puncture is easy. A tubular tire, which you’d use on Vision’s Metron 40 SL, for example, features just the one unit, which you glue to the rim. This is the professional and keen amateur rider’s choice as it’s lighter than clinchers and can be inflated to higher pressures. Then there’s the new kid on the block – tubeless. Tubeless is a hybrid of clincher and tubular. It’s only one unit, though fits into a recessed rim. It’s also filled with sealant in case you puncture.
Rim material is usually aluminum or carbon. Alu is durable, as is carbon, though that’s also lighter. Rim depth’s also important with studies showing that the deeper the rim, the more aerodynamic a wheel, as it produces a sort of sail effect. Vision’s Metron 81s feature an 81mm rim and are designed for time trials. They’re fast, though are generally reserved for TTs rather than road as they’re slightly trickier to handle especially in the wind. Then you have a wheel like the Metron 40s, featuring a 40mm rim. These are less aerodynamic but that shallower rim saves weight, meaning they also excel in the mountains.
Spokes connect the rim to the hub, ensuring your wheel runs nice and true. Wheels vary on how many spokes they feature – in general, the greater the number, the stronger they are, though this adds weight – and how they’re laced. Spoke patterns are commonly based on how many times a spoke crosses other spokes as it flows from the hub to the rim.
A classic lacing pattern to add strength and durability is ‘three cross lacing’, where one spokes crosses three spokes from hub to rim. Why? Well, the greater the number of spokes a spoke crosses, the more tangential (less straight up and down) the spoke angle. This has been proven to cope with the intense twisting forces exerted on the wheel during braking and accelerations. It’s why a wheel like Vision’s Team 30 Comp, which is designed to rack up training miles, features a 16 three-cross spoke pattern on the driveside of the rear wheel. (You’ll often find the driveside of the rear wheel features this three-cross pattern because of the extra force applied by the sprockets and chain.) Two-cross is, again, as the name suggests.
Radial is another popular choice and is seen on the non-driveside of the Team 30 Comp, as well as the front wheel. Why is down to radially laced going directly from hub to rim, meaning you can use shorter spokes. It’s not as strong against twisting forces but saves weight and is more aerodynamic so is good for racing, too. Hence, 18 of them are used on the front wheel of Vision’s aero beauty, the Metron 81.
This is the innermost part of the wheel, which the spokes attach to. Through its center is a thru-axle (more common on mountain bikes) or quick-release lever (more common on road bikes), which attaches the wheel to the bike. The front hub is simply designed to let the wheel spin; the rear hub’s a touch more complex and larger as it houses the bike’s transmission, like sprockets and rear derailleur. Most hubs feature a mechanism to let you freewheel, though some are intentionally designed not to like those seen on fixed-wheel bikes.
More wheel terminology
A spoke nipple holds the spoke to the rim; you inflate the tyre at the valve, which is either Presta (commonly road) or Schrader (commonly mountain bikes); and carry a puncture repair kit and mini pump with you on every ride in case your ride reaches an abrupt halt!