Road bike wheels – the straight dope

When it comes to upgrades that make a tangible difference to your bike, wheels have to be top of the list. They can have a major effect on three key areas of the bike 1. Weight 2. Aerodynamics 3. Comfort. There’s not one other ‘component’ (use that loosely as wheels are made up of multiple parts) that can change all three in such a strong way.

There’s a lot of information out there but most of it is promotional material from wheel companies trying to sell you something. This guides aim is to give you easily understandable points to help you make sensible decisions on your wheel upgrade.

First things first, let’s break a wheel down and cover off each of the parts. Then move on to how each one can be improved to better your ride. This guide is predominantly for road bikes but the thinking and theory can be applied to most bicycle wheels. The info given is basic overview but routed in the science and my own personal experience.

Rims

Rims come in two basic types. The type you need is decided by the style of brake you have on your bike. Either rim brakes or disc brakes. Difference being rim brake rims have a machined braking track where the brake pads contact. Disc brake rims do not have this as the brakes are connected to the hub. Then we have rim material, the two main types for road bikes are aluminium or carbon. Rims are also available in different widths, depths, and spoke drilling’s but more on that later.

The wheels rim

Spokes and Nipples

Spokes, the little strips of metal that connect the rim to the wheel. They can be available in standard shape (circular cross section) or aerodynamic (flat cross section). Nipples are the nuts used to tension and true the wheels into a usable state, can be alloy, brass, or nickel plated steel. They can be located at the rim or hub end of the spoke depending on wheel design.

Spoke nipple

Hubs

Hubs provide the central point of the wheel build (the spokes affix here before being tensioned to the rim). They house the bearings and axle, and on rear the wheel the freehub body. They are also the point of connection to the frame. Methods of attaching the wheels take on two main types, quick release skewers or the new standard of bolt through axles.

Wheel hub

Bearings

These can either be cartridge or loose bearings. Although, bar shimano, most higher end road bike wheel sets have now have press fit cartridge bearings. Cartridges mean the bearings are fitted as a single part in pre adjusted unit (bearings and races together). Loose bearings are exactly that with adjustments made using the cones attached to the hubs axle.

Loose ball bearings
Sealed cartridge bearings

Tyres

Ok so tyres can be a minefield but for road bikes their are three main types. Clincher (standard tyre and inner tube setup), tubeless (much like a clincher but with a fully airtight construction, tighter rim fit, and sealed rims to allow inflation without an inner tube), and tubular (the tyre and inner tube are a one piece sealed construction and are glued to the rim rather than hooking into the rim bed).

A tyre seated on a rim

Tubes

Inner tubes are used in clincher type tyres to keep the tyre inflated. There are two valve options but for road it is predominantly presta. The other type is the “car type” or schrader valve. Tubes can be made from butyl (standard black rubber) and are able to be patched, latex (lightweight and can be patched but trickier to do so), and polymer (super tough plastic, very light, but not repairable). Benefits of using butyl tubes are that you can add a repair fluid to create self sealing inner tubes, they are cheap to buy, and easy to live with.

A standard butyl tube
A tubolito polymer inner tube

Ok, now we know what’s in a wheel. Let’s look for a few points on how each of these areas can be improved to give you more performance on the bike.

Rim material

Road bikes rims come in two distinct materials. Carbon and aluminium. There are advantages to either material but Carbon is the leader in performance. Due to the strength to weight ratio of carbon it can be made into deeper section rims without any additional weight, or for a much reduced weight over the equivalent sized aluminium rim.

Carbon fibre rim with a dimpled surface

Rim depth

Rim depth can make a big difference to how a wheel performs. If you increase a rims depth you can achieve significant aerodynamic gains. This is due to reduced opportunity for the wheel to create drag as it spins. However increasing rim depth can also increase rim weight and vulnerability to cross winds. This is why you see shallow depth rims on climbing wheels and deep section/disc wheels on time trial and track bikes. With the improvements in carbon rim technology you can almost have the best of both worlds. There are now deep section rim wheels that weigh as little as some wheels designed for climbing.

Top a shallow section climbing rim, bottom a 50mm deep aerodynamic rim

Rim width

Now rim width has become a big talking point in the last few years, and could easily be a whole blog post of its own. Manufacturers have switched on to using wider rims to give performance gains in both grip and aerodynamics. A wider rim profile changes the shape of the tyre by moving the side walls away from each other and essentially flattening out the tyres contact patch to the ground. increasing the contact patch increases the grip as more rubber is contacting the ground. This also increases the tyres feeling of stability as the tyres cross section from being more balloon shaped to being more dome shaped. This reduces the propensity for the tyre to roll in corners and allows you to run slightly lower tyre pressures. Another gain from changing the cross section of the tyre is aerodynamics. When the rim and the tyre have a more matching shape (transition between tyre to rim), air flows better and reduces drag (this is a very basic description and would be far better detailed by an aerodynamicist but it works for this piece!).

A cross section of a carbon disc rim showing the measurement for rim width. Here we have a 30mm internal rim width and 35mm external rim width.

Spoke count and length

Spokes are quite often one of the most neglected parts of the wheel for performance gains. Spokes can have a huge effect on performance of a wheel and one of the reason why you see a very low spoke count on road bike wheels. The benefits of low spoke count wheels are less weight and reduced aerodynamic drag. This is where deep section wheels really benefit, reducing the length of the spokes greatly reduces the opportunity for drag. Also the increased strength of deep section wheels allows for a further reduced spoke count. For more performance gains wheels can also be fitted with aerodynamically shaped spokes to pass through the air even more efficiently.

Nipples

Nipples can actually be a source of some fairly heavy gains on wheels. Especially in aerodynamics. Spokes can cause a fair whack of turbulence and drag if the are exposed outside of the rim. Traditional nipples poke through the rim allowing them to be tuned and tightened externally. This makes them easy to service but not aero friendly. To overcome this issue a few of the big spoke manufacturers have come up with the hidden or internal nipple design. Simply by reversing the fitment so the threaded section no longer protrudes outside of the rim. They now are inside the rims cavity. The downside being that to true the wheel the tyre/tube/rim tape must be removed.

Internal nipples

Bearing type

To make gains in a wheel bearing, generally, the best option is to reduce friction via the hubs and bearings rubber seals. This is where most drag is caused. There are other options like ceramic bearings but the gains versus the expense are negligible. For most road cyclists a high-quality set of steel bearings with low friction seals will be more than adequate. But where every second counts and every watt is needed then ceramic bearings can provide the edge.

A diagram of a hybrid ceramic bearing. For cycling this is the type you would used. Steel track construction with a ceramic ball bearing. Although the gains are negligible.

How to choose the wheels for you

Some examples then, if you are a 75 kg rider and most of your rides are under 50 km long and with elevation gains around 500m, Then a good recommendation would be a set of 50mm deep section carbon rims built with a low spoke count (say 20 front and 24 rear). But if you were 100 kg rider and most of your riding is in tough hilly areas or mountains a suggestion would be a set of shallow, maybe 25/30 mm rims, with a higher spoke count at say 28 spokes per wheel.

That essentially translates to (as a basic rule of thumb!) if you want to go fast on the flat go aero or deep section wheels. If you ride in the mountains go lightweight wheels. If you weigh less then go for lower spoke count, if you weigh more go higher spoke count (wheel manufacturers usually give rider weight guides with their wheels).

Really it’s just a case of applying the knowledge above to your situation. See what others are riding in your area and look for the type of gains you want to make. If you want to get fast uphill then look at making the wheels as light as possible, if you want to go fast on the flat then look at what you can do to reduce the aerodynamic drag. Then have a hunt around the multitude of wheel manufacturers to find your dream set!

Here are some example manufacturers

Hunt

U.K. brand Hunt have a reputation for good wheels at a great price point. Offering a wheel to suit all riding types and situations. HUNT.

Zipp

When talking road bike wheels Zipp would be classified as one of the best manufacturers in the world. Made in the USA with the highest quality components. ZIPP.

Mavic

French manufacturer has almost been making wheels as long as they have been round! Proven technology and a wheel for all adventures and abilities. MAVIC.

Winspace

A relatively young brand, Winspace are a China based company making super high performance wheels to rival the best at very competitive prices. And achieving great reviews from real engineers and aerodynamicists. WINSPACE.

Rinasclta

Another Chinese brand proving that Chinese made product can be, and mostly is, good quality. Rinasclta in the main do business as a silent partner for other brands but do sell own product via their website. Owning a factory in China they can guarantee the quality, and being factory direct the price is very competitive. RINASCLTA.

There you have it, a rough guide on how to choose your road bike wheels. If you hear anything contrary to the above it might just be marketing spiel…. So scrutinise your purchase well. Investing in a well made set of wheels that match your riding style and personal performance is well worth it. Good luck and feel free to ask away!

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