The only thing more difficult than decoding wheel brands’ model names (DT Swiss ARC 1100 DICUT DB 62?? Really?) can be choosing the right rim depth for the right situation. Initially, triathletes operated under the “more is more” mantra that said you should always run 80mm wheels, no matter what. For a while it was even “disc or die” when triathletes loved disc wheels for every possible occasion. Even today some of that traditional cut-and-dry thinking still stands even amongst those who should know better and have access to basically unlimited options. (One example sticks out to me when I saw a pro rack of bikes at a low-level, super hilly local race on crazy rough and technical roads and most had disc wheels.) Sure there’s a lot of machismo around wheel selection, the same machismo that likely drives the majority of Corvette sales, but there’s also a lot of misinformation around wheel-depth choice. Without digging into the deep wind tunnel numbers behind each depth for each wheel, we’re going to take a look at a quick and dirty guide for those looking to purchase their next wheelset or for anyone with a few options already at their fingertips to hopefully avoid embarrassing themselves like those pros at the local tri a few years ago.
Ain’t No Mountain High Enough
This may seem obvious, but it needs to be said: Not every wheelset is appropriate for every course. Look at my sassy example above. For this course with 2,300 feet of climbing in 30ish bumpy miles, more than a few sections with grades between 7-13%, and plenty of technical descents on the brakes, a disc wheel is not appropriate. Sorry, it’s just not. For a course like that, all but the strongest of cyclists should be running somewhere in the 50-65mm range. For any course that has a majority of ups and downs with few flats, think mid-depth; for anything like 70.3 Nice, with 4,500 feet of climbing over 56mi., you’d want to go less, like 30-50mm. It’s rare, however, that you’d want to go under 30mm for a non-draft tri unless there were non-course-related reasons. Now, if you’re on a flat course like IMFL or IMAZ (though, you should also account for the turns on IMAZ), or something rolling, you might want a disc wheel or something around 80mm, depending on your abilities (we’ll get to that later).
Turn! Turn! Turn!
This is important too: The elevation gain of the course is a huge factor, but the amount and severity of corners are also worth factoring in. If you’ve got tons of tight 90 degree turns, that means you’ll be slowing down and speeding up quite often. If you’ve got a big heavy disc underneath you, it’s going to take a lot more torque (which hurts your legs quite a bit for the bike and the run) to get back up to speed. On the other hand, if you’re an amazing bike handler and the turns are sweeping, or the course rolls gently, that momentum you maintain with a disc wheel around corners and up and down rollers will actually help you—assuming you’re not featherweight, and you’re not a weaker cyclist.
Blowin’ In The Wind
Courses aside, the next factor you need to look at when determining wheel depth for a given day is weather conditions. In windier conditions, it’s true that a lighter rider (or someone with less experience) will be blown around more with a deeper wheelset—with the front wheel playing a far far bigger role than the rear. In fact, many heavier riders (like above 160lbs.) can still run a disc rear wheel, even in all the but the windiest conditions and still maintain control. A rough rule of thumb for moderately experienced riders is you should stick with a mid-depth front wheel (40-60mm) when crosswind speeds go above 15-20mph; heavier/more experienced riders can get away with more, lighter/less experienced riders should exercise more caution. Don’t forget, you can still run something deeper (50-80mm) in the rear and shallower in the front if crosswind conditions pick up on race day, and you shouldn’t have too many problems unless you’re riding particularly slowly.
Are You Experienced?
Bike handling skills and experience definitely come in a close fourth when it comes to choosing a wheel depth for race day. The more time you spend on a deep wheelset, the more you’ll be able to naturally handle the side forces you might experience from crosswinds in a race. I’ve seen pros ride in an aero tuck on 40mph downhills with 30+mph gusts on 80mm front and rear wheels—they stay relaxed, let the winds move them a little, and then lean into the rest. I’ve also seen pros completely freak out in 15mph steady side winds with 50mm wheels, and come off the bike a tense wreck, unable to run well at all. How do you get better at this? It’s easy: Ride with deep wheels often. The best deep-section riders—the ones who will get a ton of advantage in crosswinds with deep wheels on—are almost completely relaxed because they train with those wheels often. They have great bike splits because they can handle a deep wheel on a flat course, and they come off the bike ready to fly without any fatigue from holding on for dear life. Yes, I know it’s not super cool to do training rides with 80mm wheels, but there is a purpose aside from just putting up good Strava segments—you’ll be ready when things get hairy on race day. Similarly, there are more than a few strong arguments that wheels like a disc wheel don’t even give any advantage at all when ridden below a certain average speed—Enve, for example, even narrows their own buyer market by saying anyone who averages under 27mph shouldn’t be riding their disc at all!
Magic Carpet Ride
Of course, the four main considerations above are mostly general and not at all wheel-specific. Some brands have excellent crosswind handling at deeper depths, due to their rim’s shape. I’ve ridden super wide rims that had almost no crosswind issues at deeper depths when compared to other rims, and I’ve ridden wheels that felt like trash in crosswinds, even at 40mm deep, due to super bladed spokes or simply a bad aero fit with the frame. We won’t even get into wind tunnel testing for various rim depths here because that would require a whole other article exploring different brands’ shapes across different depths. The old mantra “deeper is always faster” still doesn’t even apply when you remove factors like wheel weight (elevation gain, grade, cornering, etc.), rider weight/skill (handling, etc.), and conditions (wind, road quality, etc.). Some rim shapes just do better than others in the wind tunnel at various angles, but again that’s a whole other topic. High tech data aside, it’s still super important to think about the factors above when choosing a wheel depth—don’t make me judge you in transition at your next race.
Below are a few of our favorite wheels in each depth category pulled from our recent Wheel Buyer’s Guide:
Wheel Depth: Shallow
Hunt 44 UD Carbon Spoke Disc
$1,440; 1398g, disc brake only, tubeless ready
44mm deep (29mm external width, 20mm internal width)
Despite their price tag, these wheels have some mid-range features, like a low weight, relatively wide rim—externally and internally—and of course the big headline grabber: carbon spokes. Not only do the carbon spokes help shave weight, but they also help smooth out the road (more on that later), and maybe most importantly, they can be adjusted and replaced just like normal steel spokes. Of the few carbon-spoked wheels out there, none are this adjustable AND have a reasonable pricepoint. Of course there’s more to a wheel than just the spokes, and the freehub body ratchets are about as loud as they come (a good thing, generally), as the hubs are decent quality Japanese EZO bearings.
Wheel Depth: Mid
Specialized Roval Rapide CLX Disc
$2,500; 1400g, disc brake only, clincher only
51mm front (35mm external width, 21mm internal), 60mm rear (30mm external width, 21mm internal width)
While on one hand, Enve has looked to reduce the price of their wheelsets by creating a model that has two rim depths that are exactly the same, Roval has made a wheelset with two extremely different shapes for front and rear. The big news on the Rapide CLXs is a front wheel that is not only shallower (this is fairly common) but also substantially wider—not only wider than the rear wheel. The external rim width on the front wheel is a staggering 35mm, something you’d expect to see on a gravel-only wheel, not something made for the road. Even in this roundup of wheels, the next-widest offering behind this Rapide front is still a beefy 30mm, and that’s half a centimeter thinner. The rear wheel on this set is still a very wide 30mm, and both have an internal rim width of 21mm. The thinking behind this anomaly is that a wider wheel helps offset the shallower depth front to improve aerodynamics and handling. An odd side effect is that this wheel is NOT tubeless compatible—another rarity in the lineup.
Wheel Depth: Deep
Swiss Side Hadron Classic 800 Rim
$1,290, 1865g, available in rim or disk, tubeless compatible
80mm deep, 28mm external width (23mm brake track)
Reviewed by: Jonathan Blyer
Swiss Side was catapulted from a relatively unknown brand to the center of the triathlon universe thanks to their back to back appearance on Patrick Lange’s world championship-winning rigs in 2017 and 2018. The roots of the Swiss brand are embedded in F1 racing, so the leap to the carbon, data, and aero-centric world of triathlon was an easy one. Swiss Side has a great strategic alliance with DT Swiss, allowing them to manufacture to very high standards. DT Swiss not only provides the hubs for Swiss Side, they also manufacture Swiss Side rims in their Asian factory.
Wheel Depth: Disc
Ron Aeron X Disc Wheel
$1,245; 1180g, available in rim or disc, tubeless compatible
27mm external width
Though disc wheels for triathletes are rarely considered a “budget” item—given that they’re a race-day only item that only works for certain riders on certain courses and in certain conditions—but the latest from Polish brand, Ron, is about as budget as you can get for a disc wheel. The new Aeron X falls way on the lower side of the weight scale for a disc wheel, more like a disc that costs over twice as much, and still comes with high-end features like ceramic bearings. Ron also offers a tire install service for those who don’t want to deal with the horrifyingly annoying task of mounting a tubeless tire and sealant on a disc wheel (trust us, it’s not something you want to do!). Though it’s available in rim or disc brake options (we tested the disc version), this wheel is best run with tubeless tires at a lower pressure (think <90psi depending on your weight) and disc brakes. With that combination, riders can expect an atypically smooth ride for a disc and the fantastic braking performance that takes a heavy carbon rim out of the equation.