Time trials, criteriums, club road races, even sportives, in all manner of events, we’ve seen deep section wheels — from the ranks of the WorldTour peloton to recreational riders on the local club run. But what advantages do they offer in the real world? More importantly, is there a universal benefit for all of us?
“Generally, deep-section wheels offer significant aero drag benefits over traditional shallow rims so that a rider can go faster for the same effort, or the same speed for less effort,” says Chris Yu, Specialized’s head of aero and tech.
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His thoughts are echoed by Kevin Quan, director of engineering at wheel firm Knight Composites, who explains: “Deeper wheels experience less drag. For instance, a 95mm-deep rim could save a rider up to 35 watts versus a box rim in a 40km time trial.
All good, then — it sounds like a no-brainer. Except, Quan then adds a warning: “The disadvantage is the added side-forces, which demand additional bike-handling skills.”
Yu’s take on the potential drawbacks follow similar lines. “With deeper wheels, some riders may feel susceptible to crosswinds, since they will generate more side-force than a shallow wheel,” he says. “Deeper wheels are also heavier than shallower wheels. Plus, due to the fact that deep wheels are almost always of carbon construction, they tend to be much more expensive than a traditional shallow alloy rim, which obviously makes them costly to replace in the event of an accident.”
Crashes aside, wheels take the brunt of any impacts when riding on rough roads. And with fewer spokes, as is often the case with aero wheels, they can be harder to straighten if they go out of true.
In at the deep end
With the pros and cons understood, the key now is getting to grips with the ideal time to use a deep-section rim.
Yu suggests: “In any discipline where speed is a priority, a deep-section wheel would be beneficial. This includes time trials, crits and road races, even ones with moderate climbing.”
By the same token, if you’re targeting a 100-mile sportive, and the course profile is flat, you might also benefit.
Quan adds: “Of course, the time trial is the natural discipline for a deep-section rim, but riders may also benefit with deeper rims in a criterium. This is because deeper rims are also much stiffer than shallower ones.”
So are we essentially looking at a wheel that only suits racers? “If a rider is comfortable handling deep wheels in everyday conditions — namely exposure to crosswinds — there’s no reason why they couldn’t be used for everything from racing and organised rides to training.”
But how deep is too deep? Both our experts agree that there’s no need to go much deeper than 60mm. For a criterium, Quan reckons: “I would suggest a 35mm or even a 65mm-deep rim, depending how close the overall frame weight is to the race minimum.”
“Crucially, this really depends on the type of terrain your riding takes place on,” says Yu. “But generally a good all-around rim depth is in the neighbourhood of 60mm. This depth is enough to reap the majority of aero benefit while still maintaining reasonable weight, stability, and ride feel.”
There is one place where they won’t help, though; Yu points out that a deep-section rim isn’t going to be much use to you if you’re planning a weekend in the Alps. “For riders who tackle mixed terrain or climbing, having lighter, shallow wheels would probably be a better option,” he advises.
As with so many advances in the world of cycling tech, deep-section wheels won’t help everyone, despite the compelling evidence supporting their effectiveness.
Yes, if you’re regularly racing in TTs, are watts-obsessed or are starting out in circuit racing, and — crucially — you can afford them, then dive in. If you derive your cycling thrills from riding up mountains, or you simply don’t have the disposable income to splash out on a second set of wheels, don’t panic — we reckon you’ll be just fine.
Do you need deep section rims?
Yes: Kevin Quan, Director of engineering, Knight Composites
“Deep-section wheels experience less drag when the wind blows from any angle besides head-on. I recommend regular practice on deep-section wheels in varying conditions. With practice, most amateurs should be able to handle 65mm-deep wheels with ease. Serious competitors should be able to handle 95mm wheels and full discs with just a few months’ experience.”
No: Chris Yu, Aero and racing R&D lead, Specialized
“It depends on the type of terrain. For riders who tackle mixed terrain and do an occasional hill-climb or spend their time climbing mountains, having a lightweight, shallow-section wheelset would be a better option. Also, deeper wheels are heavier and tend to be more expensive. However, for someone who almost always rides on rolling or flat terrain, or where speed is a priority, deep-section wheels would be beneficial.”