These days aero is everywhere and you’re just as likely to see them on a club run or sportive as you are in a time trial or race.
Aero road bike wheels are one of the easiest ways to buy yourself some speed. It’s been well proven that a set of aero wheels can knock minutes off your PB in the right conditions.
A pair of aero rims on a flat course will cut through the air more easily than a normal rim, making them more energy efficient.
Aero wheels used to be the preserve of time trialists and triathletes in their quest for the ultimate aerodynamic advantage. These riders typically race on flat courses and have scant regard to the potential weight or bike-handling penalties.
Why aren’t we all using aero wheels?
There are various potential downsides. The main two being handling and weight. An aero rim uses more material which results in heavier rims. And in crosswinds the rim catches a lot more air than you’d think, making your bike more difficult to control.
Thankfully the growth in popularity has led to a much wider choice in a huge range of variants. Manufacturers are making huge technological developments resulting in more all-round user-friendly aero wheels.
It’s a potentially bewildering choice in fact. Here’s a few points to guide you through the key points to look for when choosing as aero wheel set.
The depth of the rim has a major effect on speed and handling. The deeper the rim the better the aerodynamic properties but also an increase in weight, although material choice can help to offset this in some cases.
There are two basic categories for aero: mid section and deep section. Each has their own advantages and disadvantages.
Mid section rims are anything up to 40mm in depth. These are very common on road racing machines as they are the best of both worlds.
The increased rim depth has aero benefits but they aren’t too deep and are still relatively easy to control and not too heavy. Best for racing on flat and lumpy courses.
Any rim more than 40mm deep is considered to be a deep section rim. Get these rims on the flat in a straight line and they will make you fly.
The large rim depth cuts through the air with less wind resistance meaning you go faster for the same energy output.
The increased profile does make them heavier and boy can they catch the side winds! This makes them difficult to handle. Best for flat time trials and races.
What are they made of?
Carbon is the holy grail of rim material as it is light making for a more energy efficient wheel but there is a greater cost.
There are two types of braking surface: alloy or carbon. Alloy braking surfaces use a standard brake block. Some carbon rims also come with an alloy braking surface meaning you can use standard blocks.
If you are using all carbon rims then you must use carbon specific brake blocks as they don’t damage the rim and they also work a lot better.
The fewer spokes the more aero the wheel. But too few will make the wheel weak so take care – especially if you are a larger size.
Generally aero wheels have 18-20 spokes in the front and 24 in the rear. Bladed spokes will help cut through the air easier but they are more expensive.
If you have a pair of specialist wheels its worth having a few spare spokes as this will make repairs much quicker, especially if you are unable to visit to your usual mechanic.
Nipple placement on the rim – exposed or recessed – will affect servicing and repair but there aren’t any real performance differences.
Tub or clincher?
The clincher system is what most people think of as the “normal” system. Rims with lips and tyres with beads. Clincher tyres have come a long way in recent years but they are still heavier than a tub.
A clincher rim is also heavier than a tub rim due to the lip which seats the tyre using more material. They are much more practical than a tub though. You can simply replace the tube if you puncture making them better for training and all-round use as well as most racing.
Tubular (tub) rims use a tyre which is glued or taped on to them. These rims are much lighter than a clincher and the tubular tyre itself is also lighter than a clincher’s tyre and tube combo.
This makes tubs ideal for racing or weight weenies.
Cyclocross riders also love them as they can run them at incredibly low pressures for better grip without fear of puncturing (there’s no inner tube to pinch). The major drawback is they are very, very difficult to repair should they get damaged.
The latest trend among aero wheel manufacturers is to increase the width of the rim profile to create a more aero shape – especially in conjunction with the tyre.
The rim slightly cups the tyre giving it a more aero profile and less space between rim and tyre. Studies have shown that slightly fatter tyres can be used, for increased comfort and grip, without any aerodynamic sacrifice with a wider rim (we’re talking micro millimetres here).
Hubs can often get overlooked when choosing aero wheels as the focus tends to be on the rims but you shouldn’t ignore them.
Compatibility with your current gear system is a must and also checking if they are as future-proof as poss. Are they 11 speed compatible? Are you contemplating disc brakes in the years ahead?
Which aero wheels should you buy?
Occasional rider – A shallower rim will suit those starting out or the occasional rider as the rim is stronger, easier to control in windy conditions and descents, and cheaper to buy and repair.
Regular riders will feel the benefit of a mid section aero rim as they get the aerodynamic properties with only a little weight penalty. A mid section rim is also easier to control as it will be used on lots of different types of terrain and weather conditions.
Racers – Deep section rims should only be used for racing or time trialing as they can be tricky to handle for even experienced riders in cross winds. The aerodynamic benefits on a flat course with no wind are impressive but to get the best out of them you have to really push them. They do roll nice in the right conditions though…