Tipping the road.cc scales of truth at just 1415g, the DT Swiss RR 21 Dicut wheels certainly excel when the terrain points skywards, but they aren't just for the weight weenie climbers. With an excellent build quality, top notch components and impressive stiffness they are great all-rounders. A solid performance investment for your lightweight bike.
Acceleration is amazing, especially from a standing start, thanks to the low overall weight of the shallow alloy rims being easy to turn over. Once momentum is gained the RR 21s just continue to accelerate smoothly and rapidly, up until your legs fill up with lactic.
This level of speed gain makes them great for riding in a group as, should there be a break, you can be on it within seconds without feeling like you've wasted any energy anywhere. The instant pawl engagement of the rear hub is something that really stands out.
Climbing, as you'd expect, is where the RR 21s excel, even if you're not exactly a mountain goat yourself. On really short, sharp climbs where I kept the power down out of the saddle I could get a small amount of brake pad rub, but for 99 per cent of the time they feel very stiff indeed.
When coming back down the hill, the braking feels controlled and consistent thanks to the smooth machined rim surface. They don't come with any specific brake pads but the Swiss Stop Yellows I was running certainly seemed a great combination wet or dry.
Shallow rims also mean the RR 21s aren't harsh; they're stiff, yes, but they offer a smooth ride over the rough stuff.
The whole Dicut thing came about in DT Swiss's range a few years ago. The company takes its own products and tweaks them for performance and aerodynamics – a tuning department, if you like.
The most notable area is the hubs. Both the front and rear are based on DT's very impressive 240s models but with the distance between the flange maximised, which, according to DT, is "thanks to the high precision covers which integrate the rotor seal".
In theory, a wider flange increases side-to-side stiffness. I could get some brake pad rub if I really stamped hard on the pedals but overall the RR21s are impressively stiff.
The hubs are paired with DT's own Aerolite bladed spokes which are straight pull and 'nail head' –which means once they are sat in position at the hub they can't twist either when the wheels are in use or being trued, so the very, very minimal aero gains aren't compromised. Being straight pull means they exit the hub, well, straight – no bend – which again should see a little more stiffness.
The 20 radially laced spokes of the front wheel are then attached to the rim using DT Pro Lock aluminium nipples. Corrosion can sometimes be an issue with alloy nipples, but these probably aren't the type of wheels you're going to be crashing about on during the winter months.
The rear uses the same setup but its 24-spoke layout is one-cross, with the drive-side spokes swapped for DT Aero Comps for a little extra robustness. The rear rim is also drilled asymmetrically (offset) towards the non-drive side to reduce the amount of dishing caused by an 11-speed drivetrain, again making the wheel a bit stronger.
Rim width isn't overly wide by current standards at 22mm externally (18mm internally) so those of you who like to ride wider tyres may end up with a slightly more bulbous tyre profile than you'd like. Me, I was happy with the way a set of 23mm Pro-Lite Rutas fitted, with a pretty smooth transition between tyre and rim. Fitting was a doddle too, as was sticking some 25mm Michelin Pro 4s on, although some tyres are a little trickier so you'll need to find the right combination.
The RR 21s are tubeless-ready out of the box if that's a route you want to go down, and tubeless valves are included, as is a washer so that the freehub can take 8, 9 and 10-speed cassettes.
So to price: £649.98 is a lot of money to be laying down on a set of wheels, especially at a price where a lot of people would be looking towards carbon fibre. The only place the RR 21s lose out slightly is in aerodynamics, because of their shallow rim; this was particularly noticeable to me as I'd been running the 40mm-deep Cosine carbons on the bike before. The DT Swisses felt slower on the flat, but in real terms it was minimal unless you're spending all day riding up and down flat dual carriageways. All a bit of moot point really, because if ultimate speed on the flat is your only concern you won't be looking at the RR 21s anyway.
The price reflects the whole package, though. The build quality is exceptional and you can really feel the mechanics of the freehub body working as it engages and snaps into place under hard efforts. If you want a silent freewheel you're best off looking elsewhere, though, because the DT one is a little on the 'clicky' side...
The strength and stiffness from such a lightweight set of wheels is also impressive, especially considering the 110kg maximum rider weight limit. I also like the fact that they aren't overly flashy – well, apart from the bling machined hub flanges.
Overall, I think these are a great long-term investment, which will really transform the speed and acceleration of your bike.
With their impressive build quality and light weight, the RR 21s are fast all-rounders
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road.cc test report
Make and model: DT Swiss RR 21 Dicut Wheelset
Size tested: Black/White, aluminium clincher 21 mm, front, tubeless
Tell us what the wheel is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
DT Swiss says: "If aluminum is your number one choice, then so is the RR 21 DICUT®. Wide, asymmetric, lightweight rims make for an outstanding stiffness to weight ratio. At just 1415 g, this wheelset is both extremely practical and perfect for competitions. The high-quality, 240s-based hubs and the tubeless-compatible rims, which feature a sophisticated waterslide graphics, ensure an elegant appearance and make it easy for you to pick up your next mountain stage win."
Tell us some more about the technical aspects of the wheel?
Spokes: 20 DT AeroLite laced radially
Nipples: Aluminium DT Prolock
Hub: Dicut 240s
Rim: Alloy, 18mm inner width, 22mm outer
Spokes: 24 DT AeroLite/AeroComp laced 1-cross
Nipples: Aluminium DT Prolock
Hub: Dicut 240s
Rim: Alloy, drilled asymmetric, 18mm inner width, 22mm outer
A very well put together set of wheels with quality components.
Low weight sees them accelerate impressively, though I did get a small amount of lateral flex under heavy sprinting.
A solid feel and still running smoothly after plenty of wet rides.
1415g from a stiff alloy wheelset is impressive.
I think you are getting what you pay for here. The spokes, hubs and rims are all quality 'in house' products which build together into a very impressive, solid feeling wheelset.
Did the wheels stay true? Any issues with spoke tension?
Yeah, they are still running as true as the day they turned up.
How easy did you find it to fit tyres?
Depends on the tyres. The only ones I had issues with were also difficult to get on other wheels recently tested.
How did the wheel extras (eg skewers and rim tape) perform?
No issues here at all.
Tell us how the wheel performed overall when used for its designed purpose
The RR21s are designed to work well in the hills and on rolling terrain, and they really do excel here. Acceleration is noticeably impressive, especially that initial kick.
Tell us what you particularly liked about the wheel
The build quality.
Tell us what you particularly disliked about the wheel
Small amount of flex under heavy load.
Did you enjoy using the wheel? Yes
Would you consider buying the wheel? Yes
Would you recommend the wheel to a friend? Yes
Use this box to explain your score
At this price point many are looking to carbon but these DT Swiss hoops highlight why aluminium rims are still a contender. Lightness, stiffness and excellent build quality is what makes the RR21s stand out and judging by the durability you'll be getting your money's worth for years to come.
About the tester
I usually ride: This month's test bike My best bike is: Mason Definition
I've been riding for: 10-20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: time trialling, commuting, club rides, sportives, fixed/singlespeed
With 20 years of road cycling and over 150,000 miles in his legs it's safe to say Stu is happiest when on the bike whatever the weather. Since writing his first review for road.cc back in 2009 he has also had a career in engineering including 3D-CAD design and product development, so has a real passion for all of the latest technology coming through in the industry but is also a sucker for a classic steel frame, skinny tyres, rim brakes and a damn good paintjob.
His fascination with gravel bikes is getting out of control too!