Bicycle wheel - Wikipedia. Bicycle wheel with wooden rim. Boatinfo requires FlashPlayer 9 or newer to display this document! PIN 7796457-5 4-1994 Workshop Manual 1994 " MD" Models Fuel System VOLVO PENTA! A Shimano Dura- Ace freehub style hub. A bicycle wheel is a wheel, most commonly a wire wheel, designed for a bicycle. A pair is often called a wheelset, especially in the context of ready built . A typical modern wheel has a metal hub, wire tension spokes and a metal or carbon fiber rim which holds a pneumatic rubber tire. A hub is the center part of a bicycle wheel. It consists of an axle, bearings and a hub shell. The hub shell typically has two machined metal flanges to which spokes can be attached. Hub shells can be one- piece with press- in cartridge or free bearings or, in the case of older designs, the flanges may be affixed to a separate hub shell. The axle is attached to dropouts on the fork or the frame. The axle can attach using a: Quick release - a lever and skewer that pass through a hollow axle designed to allow for installation and removal of the wheel without any tools (found on most modern road bikes and some mountain bikes). Nut - the axle is threaded and protrudes past the sides of the fork/frame. Some axles have integrated cam levers that compress axle elements against the fork leg to lock it in place, while others rely on pinch bolts on the fork leg to secure it. Diameters for front thru axles include 2. Rear axles typically have diameters of 1.
Most thru axles are found on mountain bikes, although some cyclocross and road bikes are using them. Thru axles repeatable locate the wheel in the fork or frame, which is important to prevent misalignment of brake rotors when using disc brakes. Unlike other axle systems (except Lefty), the thru axle is specific to the fork or frame, not the hub. Hubs/wheels do not include axles, and the axle is generally supplied with the fork or frame. Female axle - hollow center axle, typically 1. Mountain bikes have adopted a 1. Most bicycle hubs use steel or ceramic ball bearings. Some hubs use serviceable . Both surfaces are smooth to allow the bearings to roll with little friction. This type of hub can be easily disassembled for lubrication, but it must be adjusted correctly; incorrect adjustment can lead to premature wear or failure. ![]() In a . The manufacturing tolerances, as well as seal quality, can be significantly superior to loose ball bearings. The cartridge is pressed into the hub shell and the axle rests against the inner race of the cartridge. The cartridge bearing itself is generally not serviceable or adjustable; instead the entire cartridge bearing is replaced in case of wear or failure. Hub shell and flanges. The hub shell of a spoked wheel generally has two flanges extending radially outward from the axle. ![]() Ust Valve Stem Installation ToolYou can call our headquarters at +49 (0) 731-70 46-0 or send a fax to +49 (0) 731-71 90 89 Please send general inquiries to [email protected]. Each flange has holes or slots to which spokes are affixed. Some wheels (like the Full Speed Ahead RD- 8. Others (like some from Bontrager and Zipp) do not have a noticeable flange. The spokes still attach to the edge of the hub but not through visible holes. Other wheels (like those from Velomax/Easton) have a threaded hub shell that the spokes thread into. On traditionally spoked wheels, flange spacing affects the lateral stiffness of the wheel, with wider being stiffer, and flange diameter affects the torsional stiffness of the wheel and the number of spoke holes that the hub can accept, with larger diameter being stiffer and accepting more holes. The brake disc can be attached in a variety of ways using bolts or a central locking ring. Drum brakes – a drum brake has two brake shoes that expand out into the inside of the hub shell. Rear- mounted drum brakes are often used on tandems to supplement the rear rim brake and give additional stopping power. Coaster brake – coaster brakes are a particular type of drum brake which is actuated by a backward pressure applied to the pedals. The mechanism is contained inside the bicycle wheel hub shell. For information on other types of bicycle brakes see the full article on bicycle brake systems. The rear hub has one or more methods for attaching a gear to it. Freehub–- The mechanism that allows the rider to coast is built into the hub. Splines on the freehub body allow a single sprocket or, more commonly, a cassette containing several sprockets to be slid on. A lock ring then holds the cog(s) in place. This is the case for most modern bicycles. Freewheel – The mechanism that allows the rider to coast is not part of the hub, it is contained in a separate freewheel body. The hub has threads that allow the freewheel body to be screwed on, and the freewheel body has threads or splines for fitting sprockets, or in the case of most single speed freewheels an integral sprocket. This style of hub was used before the freehub became practical. Track sprocket – There is no mechanism that allows the rider to coast. There are two sets of threads on the hub shell. The threads are in opposite directions. The inner (clockwise) set of threads is for a track sprocket and the outer (counter- clockwise) set is for a reverse threaded lock ring. The reverse threads on the lock ring keep the sprocket from unscrewing from the hub, which is otherwise possible when slowing down. Flip- flop hub – Both sides of the hub are threaded, allowing the wheel to be removed and reversed in order to change which gear is used. Depending on the style of threads, may be used with either a single- speed freewheel or a track sprocket. Internal geared hub – the mechanism to provide multiple gear- ratios is contained inside the shell of the hub. Many bicycles with three- speed internally geared hubs were built in the last century. This is an extremely robust design, although much heavier than more modern designs of multi- gear- ratio arrangements. Modern hubs are available from three- speed to 1. Some wheels use both an aerodynamic carbon hoop bonded to an aluminum rim on which to mount conventional bicycle tires. Metallic bicycle rims are now normally made of aluminium alloy, although until the 1. These rims cannot be used with caliper rim brakes. The cross- section of a rim can have a wide range of geometry, each optimized for particular performance goals. Aerodynamics, mass and inertia, stiffness, durability, tubeless tire compatibility, brake compatibility, and cost are all considerations. If the part of the cross- section of the rim is hollow where the spokes attached, as in the Sprint rim pictured, it is described as box- section or double- wall to distinguish it from single- wall rims such as the Westwood rim pictured. Triple- wall rims have additional reinforcement inside the box- section. Aluminum rims are often reinforced with either single eyelets or double eyelets to distribute the stress of the spoke. A single eyelet reinforces the spoke hole much like a hollow rivet. A double eyelet is a cup that is riveted into both walls of a double- walled rim. Clincher rims. These tires have a wire or aramid (Kevlar or Twaron) fiber bead that interlocks with flanges in the rim. A separate airtight inner tube enclosed by the rim supports the tire carcass and maintains the bead lock. If the inner part of the rim where the inner tube fits has spoke holes, they must be covered by a rim tape or strip, usually rubber, cloth, or tough plastic, to protect the inner tube. An advantage of this system is that the inner tube can be easily accessed in the case of a leak to be patched or replaced. The ISO 5. 77. 5- 2 standard defines designations for bicycle rims. It distinguishes between. Straight- side (SS) rims. Crochet- type (C) rims. Hooked- bead (HB) rims. Traditional clincher rims were straight- sided. The rim provides a shallow circular outer cross section in which the tire lies instead of flanges on which tire beads seat. Tubeless. Universal System Tubeless (UST), originally developed by Mavic, Michelin and Hutchinson. Road Tubeless rims, like UST rims, have no spoke holes protruding to the air chamber of the rim. The flange of the Road Tubeless rim is similar to the hook bead of a standard clincher rim but is contoured to very close tolerances to interlock with a Road Tubeless tire, creating an airtight seal between tire and rim. This system eliminates the need for a rim strip and inner tube. Increasingly common are tubeless tires conforming to the UST (Universal System Tubeless) standard pioneered by French wheel manufacturer Mavic in conjunction with tire manufacturers Hutchinson and Michelin. In 2. 00. 6, Shimano and Hutchinson introduced a tubeless system for road bikes. Original bicycle wheels used wooden spokes that could be loaded only in compression, modern bicycle wheels almost exclusively use spokes that can only be loaded in tension. There are a few companies making wheels with spokes that are used in both compression and tension. This is normally at the rim end. The hub end normally has a 9. Double- butted spokes have reduced thickness over the center section and are lighter, more elastic, and more aerodynamic than spokes of uniform thickness. Single- butted spokes are thicker at the hub and then taper to a thinner section all the way to the threads at the rim. Otherwise, the nipple ends wear a hole in the tube causing a flat tire. In 2. 00. 7, Mavic introduced their R- Sys, a new bicycle spoke technology that allows the spokes to be loaded in both tension and compression. This technology is promised to allow for fewer spokes, lower wheel weight and inertia, increased wheel stiffness, with no loss of durability. However, in 2. 00. Mavic recalled R- Sys front wheels due to spoke failures leading to collapse of the entire wheel. Some spokes are hollow tubes. Stainless steel spokes are favored by most manufacturers and riders for their durability, stiffness, damage tolerance, and ease of maintenance. BMX bikes commonly have 3. Lowrider bicycles may have as many as 1. On the other hand, the reduced number of spokes results in a larger section of the rim being unsupported, necessitating stronger and often heavier rims. Some wheel designs also locate the spokes unequally into the rim, which requires a stiff rim hoop and correct tension of the spokes.
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