Road Bike Wheels: What to Know
Road Bike Wheels: What to Know
With a long list of tangible benefits, it’s no surprise that optimizing rolling stock is one of the most popular modifications a rider makes. The road bike wheels on a bike really keep you moving and have a considerable impact on the quality of your ride. Of course, the drivetrain pushes you forward, and the frame has a major impact on ride quality, but the wheel is the first element where the bike feels road vibrations, surface imperfections, and terrain changes.
One of the most important properties of a wheelset is the role it plays in translating your efforts on the bike into results on the road, so matching the right wheelset for your riding style is important because having a reliable The wheels still deliver sound level performance.
So before you buy a shiny new set of hoops, read this buying guide for everything you need to know about road bike wheels.
Anatomy of a Wheel
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A bicycle wheel consists of four main components, all of which affect weight, performance and durability. Upgrading (or downgrading) these components can affect ride quality, your effort output (speed) and braking performance, so it’s worth taking a look at each component and how this relates to improved road performance.
Rim: The rim of the wheel is located on the outside of the wheel and serves two main functions; securing the tire and providing a braking surface (for rim brake bikes, not bikes equipped with disc brakes). Rim width affects tire width, which can have a major impact on rider comfort, and the material of the braking surface also affects braking performance.
Hub: The hub is in the center and provides the axis of rotation. Inside each front and rear hub are the axles that connect the wheel to the bike. On the rear wheel, the hub has splines to which the cassette is attached. The chain of the bicycle is wrapped around the sprocket of the cassette and, together with the crankset and shifter, forms the bicycle drivetrain that propels it forward. In addition to propelling the bike forward, all road bike wheels (excluding fixed wheel bikes) will use a rear hub with a “freehub” mechanism that allows the bike to coast.
Spokes: The material that connects the hub to the rim. The number of spokes on the front and rear wheels will vary, with the rear usually having more spokes for strength and stiffness. More spokes generally mean a stronger wheel, but that comes with a weight loss. The spokes are made of different materials and have different shapes to optimize strength or improve aerodynamics, sometimes both. The most common spokes are made of steel wire, but shapes and diameters can vary widely.
Nipple: The spokes are attached to the wheel by special nuts called “nipples”. The nipples are important for adjusting the spoke tension, which will “truly” the wheel, making it straight as it spins.
What is a good wheel?
Choosing a good wheel depends largely on its intended use, however, while it is difficult to pinpoint all aspects, ideally a good set of wheels will be durable, have reliable hubs, provide inspiring Braking, stiff power delivery and light weight.
Lightweight wheels maintain rotational weight by having a shallow rim profile and low spoke count. Aside from the overall weight savings, one of its side benefits is comfort. Deeper wheels are fast, but ride quality is often described as “harsh”, in contrast, lightweight wheels generally offer good compliance. A good lightweight wheelset will usually be under 1,400 grams, some very light wheels will be under 1,000 grams!
Aerodynamic wheels are designed to be as fast as possible by reducing drag. Aerodynamic wheels are typically greater than 40mm deep at the rim and also become wider. That speed does come at a price, as deep-section wheels are more susceptible to crosswinds, which can make them difficult to handle, and the extra material does add weight.
Wheelsets that are less performance-focused often have properties that make them more suitable for everyday use or general training. Compared to carbon fiber, the aluminum braking surface provides better performance in all weather conditions, the higher spoke count is used for strength, and the rim width is wider to accommodate larger tires. Due to these characteristics, weight increases with premium wheelsets, usually between 1,500 – 1,800 grams.
Wheelsets designed for load travel or frequent use under heavier riders (120kg+) are often hand-built with higher spoke counts of 32 or even 36 spokes. With extra strength, this form of wheel typically weighs over 1,900 grams.
Most entry-level wheels will feature aluminum rims of varying quality, while premium wheels typically feature rims made from carbon fiber, which saves weight while increasing stiffness.
Aluminum as a rim material provides better braking performance than carbon fiber, which tends to perform poorly in the wet and on long descents because heat builds up during braking. Based on this, some brands offer aluminum braking surfaces mounted on carbon fiber rims. It’s worth noting, however, that these designs are generally heavier than single-material rims.
The shift to disc brakes has really started and is fast becoming the new norm for road bikes. Moving away from rims and traditional caliper braking gives manufacturers some experimentation in terms of frame and wheel design and the obvious benefits of increased stopping power.
Wheelsets using disc brakes do not need to have brake tracks or identify a specific width to accommodate narrow fork and frame clearances. As a result, wheelsets equipped with disc bikes can have improved profiles for improved aerodynamics and performance. The downside is that a disc bike’s wheelset has to be stronger to handle the extra braking force, which means more spokes and specific hubs, which may negate any weight savings or other performance gains. However, the weight saved on the outside of the wheel (rim) has a far more significant impact on its lightness than the weight near the hub.
A huge benefit is the performance of carbon fiber wheels, which typically have poorer braking performance compared to wheels with aluminum brake rails. Disc brakes allow the performance benefits of carbon fiber wheels to be maintained (or improved) without compromising braking performance.
Wheels designed for use with disc brakes should not be confused with aerodynamic “disc” wheels, which form a single piece from the hub to the rim to reduce wind turbulence in time trials.
Wheel Size: Width and Depth
The rim width and depth of a wheel largely determines how it rides and feels.
The trend in modern rims is to be wider, resulting in better aerodynamics and improved comfort through greater tire air volume. This coincides with the move to larger tires, which are said to improve (reduce) rolling resistance and comfort by running at lower pressures.
Rim width can be measured internally or externally, which can provide some confusing numbers. Generally, if a brand refers to a number followed by a “C”, this is an internal measurement. By current standards, narrow rims measure internally less than 15mm, while wide rims measure internally greater than 17mm. When measured externally, anything under 19mm is considered narrow, while anything over 22mm can be considered wide.
While closely related, the outer rim width will primarily affect the aerodynamics of the wheel, while the inner rim width will affect comfort, rolling efficiency or tire shape.
The depth of the rim affects the aerodynamics of the wheel and the handling of the bike. In general, deeper rims are more aerodynamic, but also harder to handle, as they are more susceptible to crosswinds than shallow rims. The extra material required also results in a harsher ride that doesn’t offer as much compliance as the shallower wheels. It’s worth noting that not all deep rims are created equal, and the exact profile varies widely from brand to brand. The best options manage to achieve fast speeds while being well controlled in crosswinds.
Deep section wheels typically measure at least 40mm from rim to nipple, with some extending to over 80mm.
The total number, shape and material of spokes on the wheel will vary. A high spoke count (there are a lot of them) adds sturdiness and durability at the expense of weight. The spokes come in a variety of materials, including steel, aluminum, carbon fiber, and titanium. Steel spokes are by far the most common.
The number of spokes on the front and rear wheels will vary, with the force applied (driving force and additional weight load) the rear wheel has more spokes. Typically, lightweight front wheels have between 18-24 spokes, and rear wheels have between 20-28 spokes. This is in stark contrast to the early days of wheel manufacturing, when the front wheel had more than 30 spokes and the rear wheel had more than 40 spokes. With improvements in materials and manufacturing processes, the number of spokes has been reduced, saving weight without compromising performance.
Flat spokes, often referred to as “blade spokes,” offer some small aerodynamic gains compared to round spokes. While more expensive, bladed spokes also help save weight without sacrificing strength.
Normal spokes are “straight pull” or “J-bend”. “Straight-pull” spokes have no bend at the head and require a specific hub, “J-bend” spokes are a more traditional option, with a 90-degree bend at the hub end that looks like a “J”.
The benefits of straight-pull spokes are; more precise alignment, stiffer, more responsive wheels, and reduced weight. The downside to straight-pull spokes is that many companies make proprietary spokes and hubs, which means sourcing replacement spokes can be time-consuming and potentially expensive. J-bend spokes are generally easier to replace and come close to straight-pull spokes in terms of quality and strength.
Butt or “butt” is the term you’ll encounter when looking at round spokes. Simply put, butting is the process of changing thickness, so a double-butted spoke will provide two different diameters along its length. Butted spokes are generally stronger and more durable than straight gauge (one diameter) spokes because they help to better relieve stress fatigue.
The freewheel is located on the rear wheel hub and has two functions: drive the rear wheel and make it slide. The fixed hub also drives the rear wheel, but doesn’t coast, requiring you to pedal the entire time the bike is moving.
Manufacturers have different hubs, so be sure to check your gears are compatible. Both Shimano and Campagnolo splines use a spline system to connect the cassette to the spline, but differ in diameter and spline type, which means they are not compatible. SRAM cassettes work with Shimano hubs, but not Campagnolo.
Most of the new wheels on sale are 11-speed compatible and feature wider hub bodies to handle wider-spaced 11-speed cassettes. They are also backward compatible with 8, 9 and 10 speed cassettes just by using washers. However, older 8, 9 or 10 speed hubs cannot fit an 11 speed cassette (except Campagnolo wheels/cassettes).
As the cost of a wheelset has risen, so has the quality of the components used. For bearings within the hub, they typically range from steel to ceramic. A good ceramic bearing is rounder, smoother, and harder than an equivalent steel bearing, thus reducing friction and improving performance. However, a good steel bearing will usually last longer and perform better than a cheap ceramic bearing.
In addition to the bearing material, proper lubrication also affects how they roll and the amount of friction they generate. Friction in the bearings reduces performance and slows down the wheel. Excessive friction can occur if the bearing is not properly lubricated, if debris or other substances enter the bearing, or if the bearing is high pressure flushed away from its lubricant. Here, higher-quality hubs offer improved element sealing, allowing them to roll smoother and longer.
The lower the viscosity of the lubricant, the lower the friction, but the result may affect durability.
Bearings can be cartridge (sealed) or loose ball (cup and cone). A cartridge or sealing system has an inner and outer ring with bearings between them, all enclosed in a single unit. The cartridge bearing is then pressed into the hub shell with the shaft going through the middle. A sealed bearing is a single unit, and if worn, the entire bearing frame needs to be replaced, but this is fairly inexpensive.
The most common on Shimano products and entry-level wheels are loose ball or outer rings and tapered bearings. Cup and tapered bearings have multiple parts and loose bearings. They are not enclosed like cartridge bearings, but instead have loose ball bearings sandwiched between a fixed outer ring (usually part of the hub shell) and an adjustable tapered inner ring threaded to the shaft. If the bearings wear out too far, they can wear down the hub surface, causing enough damage that the hub needs to be replaced completely. On the positive side, they are easy to maintain to prevent this from happening. To maintain such a hub, you need several special thin wrenches called “cone wrenches”.
It’s worth learning about the three different tire types that fit your wheels, as they require specific rims. The tires will be “clincher”, “tubular” or “tubeless” and the wheel will specify which tire is compatible with. Most road bikes available for sale will come with clincher tires that require tubes to hold air.
The most common form of tire currently used on road bikes. Unless otherwise stated, it is a reasonable assumption that any new bike purchased will have clincher tires. Clincher tires will need an inner tube to inflate and hold the air, while the tire will have a steel or Kevlar bead around the edge to hold it in the rim.
Small tubes also use inner tubes, but in a very different way. The inner tube of a tubular tire is sewn directly onto the tire and then glued or glued directly to the rim. Professional racers almost exclusively use tubular tires because they reduce weight, enhance rolling resistance and road feel. In the event of a puncture, it is also possible to ride a tubular with relatively little risk of the tire rolling off the rim.
The downside to tubular tires is that it takes a lot of work to install the tire onto the rim in the first place, and if you get a puncture, changing the tire is laborious. Add in the price of this tire and it’s certainly the best item for a racer.
Tubeless tires have long been used on mountain bikes and are slowly making their way into the world of road cycling. Trek has equipped most of its road bikes with “tubeless” rims since 2015, while Giant has exclusively offered tubeless tires on high-end models since 2017.
As the name suggests, tubeless tires do not require a tube, but rather attach to a specific rim design, creating an airtight seal. This is a technology very similar to modern cars and motorcycles.
Tubeless tires are considered superior to clinchers because they create less friction, which improves rolling resistance, can travel at lower pressures, improve comfort, and are said to offer better puncture protection. To prevent punctures, tubeless tires can use a liquid sealant, which can be inserted into the tire to help seal immediately in the event of a small puncture. For more information on tire types, how they affect road performance, and how to choose the right tire, check out our ultimate guide to road bike tires.
Factory vs Handmade
While many “factory-built” wheels are technically hand-built, the characteristics of each wheelset are quite different.
Factory-built wheels are mass-produced to precise specifications and often feature proprietary spoke and rim designs. They are designed to be purchased off the shelf or paired with a manufacturer’s bike. Extensive research, development and marketing means these wheels dominate the field. Such as Shimano, Mavic, Fulcrum and Zipp wheels.
Instead, hand-built wheels are unique, featuring custom individual hubs, spokes, nipples and rims. Handcrafted wheels are custom creations to meet the exact preferences and needs of the rider.
‘True’ wheels: True means your wheels are tracking in a straight line, with no deviation. If your wheel is incorrect, it can rub against your brakes or negatively affect the handling of your bike. Adjusting the spoke tension is something any local bike shop can do to make your wheels feel real.
Replace Brake Pads: Worn brake pads reduce braking performance and can damage your rim or yourself if the rim is not working properly. On most bikes, changing the brake pads is a simple process that you can do yourself with a small Allen key and a new set of brake pads.
Clean your bearings: Your hub bearings may need to be cleaned and re-greased on a semi-regular basis. The exact time frame will depend on your wheel quality, number of rides and riding conditions. Unless you’re well versed in bike maintenance, this is probably the best job your local bike shop does, but be sure to mention that if you think it might be affecting your wheel performance, send it to them when you’re using it for regular service.
Check your rims: Every time you brake with a rim brake, your rims wear out. This friction can eventually lead to thinning of the rim, which can weaken the structural integrity of the wheel if not taken care of. To avoid this, inspect the rim regularly for visible grooves and keep an eye out for rim wear indicators, which are usually a small hole or groove in the rim to show the amount of material remaining.
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