Bike wheels are obviously an important part of a bike. They affect what a bike can do and how it’s going to feel for your customers. Low quality wheels will make a bike feel uncomfortable and need replacing much quicker than high end ones. That just doesn’t look good on the bike. Obviously high end wheels drive up the price for both the manufacturer and the consumer too though.
There’s a balancing act between what kind of wheels to put on a bike. Some choices are obvious, you’re not going to be putting down hill mountain bike wheels on a bike maybe for going to work for example. But there are other things to consider. What material should you use for the bearings, what profiles should the spokes have etc.
Luckily for me I don’t have to spend a lot of time with these questions, that’s what our design team does. And for the designers out there this will probably all seem pretty surface level. But for everyone else in the industry it’s good to keep in mind how design choices affect the final product.
The Structure of a Wheel
- The wheel of a bike is made up of five key components:
- Bearings (technically part of the hub but they deserve special mention)
All of these parts work together to create tension, allow rotation and keep the bike comfortable throughout the ride.
The hub is the central point around which the rest of the wheel rotates. The bearings are what allows this. The spokes create tension between the hub and the rim to apply pressure evenly around the wheel. The nipples help to keep strength and tension on the spokes. The rim provides structure and shape while affecting the handling weight and speed of your bike. Each part plays a role in making the right wheel for the bike. And each part has different choices with it.
Bike Wheel Hubs
The hub of a wheel is made up of the axle mounted to the frame, the bearings inside and the shell- where the spokes are attached. There’s plenty of different hubs out there and I’m not going to be covering them all here. Honestly there’s probably a whole article in that alone.
At their most basic hubs are the point around which the wheel turns. All that’s really needed is low friction for it to turn easily. All hubs provide this. Just as long as you aren’t putting a mountain bike hub on a road bike it will do its job.
That doesn’t mean all hubs are the same quality though. The material of a hub matters. Lower end hubs are usually made of steel or aluminium. Which to choose really depends on whether you want to prioritise weight or durability. Steel will be heavier but tougher making it better for country bikes.
For bikes that need to take more punishment like mountain bikes, higher end hubs are better choices. They might be made of tougher materials that still keep weight down, So they’ll take some punishment on a run without upping your wheel’s weight too much.
Bike Wheel Bearings
Like I mentioned already the bearings are really part of the hub. They’re a very important part of it though that will affect how smooth the wheel can turn. When you’re wondering what bearings to put in your bike you are mostly thinking about the style, size and material of the bearings.
The most common bearing type are cartridge bearings. Which are just what they sound like, a one piece cartridge containing the bearings. The cartridge generally has seals which help protect the bearings from any dirt and debris. This means that a cartridge bearing will last longer than loose bearings. However they also can’t be disassembled to be cleaned which means once they get enough obstruction to cause a problem they need to be replaced.
Loose bearings are more associated with lower end models but they aren’t universally bad either. High end loose bearings are still used by a few companies. Rather than a single unit these bearings are- as implied- loose and sometimes held in a retainer to keep them evenly spaced from one another. Because they are loose these bearings can be disassembled and cleaned. They’re not as fool proof as cartridge bearings though since they need to be adjusted, but well adjusted loose bearings can be great.
With size generally the bigger the better. Bigger bearings increase surface contact which allows for a much smoother rotation. Weight isn’t really an issue since even the heaviest bearings won’t add all that much weight to your bike.
A few materials are common in bearings. Various steels, ceramic. The rule of thumb is harder is better. You want to make sure your bearings are durable so they don’t need to be replaced too often. Ceramic is probably the best material for a bike wheel. It’s hard and smooth allowing for high durability and nice rotation.
Bike Wheel Spokes
The spokes will help your wheel keep its shape. Providing tension between the hub and rim they press against the wheel to make sure it doesn’t deform on the ride. They also affect the weight and feel of the wheel. It’s not as simple as some metal bars pressed into the rim though. Spokes come in different shapes and patterns that affect how they perform.
The simplest spoke is straight gauge. This means the spoke remains the same thickness throughout. The big advantage is that they are simple and cheap to produce. This makes them ok for entry level bikes but they are also able to flex less and so can be easier to snap.
Butted spokes have a change in thickness. The middle of the spoke is thinner, and so lighter and more flexible. Generally this makes them preferable except for the cheapest bikes. They’re a little more expensive but they’re less prone to failure.
Finally there are bladed spokes. By being pressed into a flat profile. This makes the spoke more aerodynamic but also stops the spoke from twisting and stretching that happens in very light spokes. In terms of performance bladed spokes are generally better but they’re also the most expensive to produce though which makes them less suitable for cheaper bikes.
It also matters how the spokes are connected to the hub. There are two different shapes straight pull and “J” bend. They look like they sound, straight pull are entirely straight. They have great performance but are more difficult to attach and require special tools. This makes them more expensive but many riders feel they have a better transfer of power.
“J” bend spokes are cheaper as they are easier to affix to the hub. This is because the bend prevents them from twisting the same way straight pull do. The bend causes a stress point on the spoke though. If there is a break it is more likely to happen there. How much more likely the spoke is to break though is debatable.
The pattern of the spokes can be broken down into two main types. Crossed and uncrossed. The type depends on whether or not the spokes cross over each other. Uncrossed lacing takes the shortest path between the hub and the rim. Which means less material and an overall lighter wheel. But they aren’t as strong. Crossed lacing patterns on the other hand allow the spokes to support each other making an overall heavier but more durable wheel. One other big difference is that uncrossed patterns put a lot more stress on the hub so the tension may need to be less.
For urban commuter bikes an uncrossed pattern will often be enough. But for mountain bikes or any bike that needs to take some punishment, crossed lacing is probably worth the weight increase.
This one is nice and short. Most of the aspects of the nipple is decided by the spoke. The diameter and length need to be right. The real decision from a design perspective is the material the nipple is made from.
This is going to be either aluminium or brass and both have their advantages. If you want durability and corrosion resistance then go with brass. It’s a tougher metal but it’s heavier. If you want your bike to be as light as possible then fit it with aluminium nipples.
Bike Wheel Rim
The rim is the outer part of your wheel. It affects the weight, the durability and aerodynamics. Depending on what you want your bike to do depends on what kind of rims you want to use. Properties will vary depending on diameter, width, material and cross section.
Obviously the diameter and width of the rims will affect the wheels overall weight. So if you were just to optimise for light weight wheels the smaller the better. It’s not that simple though. The smaller the wheels the more the rider will feel bumps and debris under them. Plus higher diameter wheels are more stable at higher speeds. Wider wheels will increase the weight of the wheel making it harder to pedal but it will also make the wheel more durable.
So while an urban commuter bike might get away with small thin wheels to let the rider get to speed easily and pedal for a long time. Racing bikes might need a bigger diameter to keep stability at high speeds and downhill bikes will definitely need bigger heavier wheels to tackle rough terrain without getting damaged.
The material matters too. Your wheel will probably be either aluminium or carbon fibre. But it could be steel. Aluminium rims are cheaper to produce but they’re heavier. This makes carbon fibre the material of choice if you want to cut weight and increase the speed or readability of a bike. They even allow for wider and bigger diameter rims without increasing the weight. They are however harder for a consumer to get repaired if there is a problem. Because carbon fibre doesn’t bend it is more prone to damage from crashes and that damage usually isn’t fixable at home. If you want to prioritise durability, aluminium is the way to go.
Finally the cross section of the rim matters too. Shallow section wheels are just what they say. They’re strong for the weight and fairly common. They’re a good default wheel for a bike that needs to do a little bit of everything. The cross section is roughly rectangular. As the cross section becomes more triangular you get deep section wheels. Deeper rims are more aerodynamic and they tend to allow for higher speeds. The deeper the wheel the more benefit you gain.
The problem with deep sections is that they suffer in a cross wind. Because the wind is hitting a much greater surface area which can impair your handling quite a bit. As a result lower profiles are often used for anywhere you might suffer cross winds and when speed isn’t a major factor it’s perfectly fine to opt for shallow rims.