Mick Gets Aero With The DT Swiss GRC 1400

If we step back and look at the cycling industry as a whole, there are two segments that are currently growing like crazy; e-Bikes and gravel. On the latter, we’ve witnessed quite a significant shift from road riders who are making the move over to gravel, as more folks discover the freedom of riding off-road and away from the threat of traffic and dangerous drivers. Of course more ‘mature’ mountain bikers like us have naturally gravitated towards the gravel scene too, since in a lot of ways it’s a lot like early mountain biking, and we dig that.

With more folks heading away from the tarmac, the range of bikes and gear on offer for this new-school-but-actually-old-school style of riding is swelling. Highlighting the extent of the gravel boom, the wheel gurus over at DT Swiss have been investing heavily in the segment with the release of three new complete wheelsets over the past year. The three-pronged attack includes the entry-level G 1800, the mid-level GR 1600, and the top-end GRC 1400 wheels we have here.

The ‘C’ in the name refers to the deep-section carbon fibre rims that DT Swiss has developed in collaboration with its fellow countrymen at Swiss Side. These rims are substantial – they have a 42mm depth, making them properly aero. They’re also quite wide – 32mm externally, with a 24mm internal width that is is perfectly suited for running 35-40c gravel tyres.

To see how these high-end carbon wheels ride, we got a set in just before the Gravel Grit Laguna to fit to our trusty Trek Checkpoint. Here’s how it all played out.

DT Swiss GRC 1400 Spline 42 Wheel Specs

• High-end carbon gravel wheelset
• Available in 700c & 650b sizes
• 42mm deep carbon fibre rims
• 24mm internal rim width
• 32mm external rim width
• Tubeless compatible with rim strips and valves included
• DT Swiss Aero Comp straight-pull bladed spokes
• DT Swiss Pro Lock alloy nipples
• Splined alloy hub shells w/240s internals
• Centerlock spline w/6-Bolt adapters included
• Hub spacing: 100mm (front) & 135/142mm (rear)
• Freehub body: Shimano, SRAM XD and XDR options
• Includes quick releases & thru-axle end caps
• Weight: 1611g
• RRP: $2,849

Setting Up

The test wheels arrived at my workshop in their own individual wheel bags, along with quick release skewers, thru-axle end caps, and a standard Shimano freehub body ready for an 11-speed Ultegra cassette. Because of the modular nature of DT’s freehub bodies, it’s possible to swap in a SRAM XD and XDR body if needed.

It was nice to be able to fit my Shimano Freeza Centerlock rotors straight onto the 240s hubs. It’s such a neat system with just a single lock-ring per rotor, rather than six fiddly bolts. If you are using 6-bolt rotors though, DT Swiss includes adapters in the box. Nice touch!

I ran the GRC 1400 wheels with a thru-axle setup on my Trek Checkpoint SL 5, where they replaced a set of Shimano RS770 wheels. These weren’t exactly terrible wheels – they feature tubeless ready rims made from a carbon/alloy laminate, and weigh in at 1639g for the pair. However, with a 17mm internal rim width, I have found them to be on the narrow side when running high volume rubber.

In comparison, the DT Swiss hoops are much wider with a 24mm internal rim width. This provides a load more support to the tyre beads, particularly when you’re running low pressures with a tubeless setup.

As for tyres, I switched over a pair of Maxxis Rambler 40c tyres, though not until I’d given the beads a good scrubbadub to remove any dried sealant that might compromise the airtight seal. Once cleaned up, the pre-ridden tyres aired up tubeless on the DT rims beautifully with only a floor pump required. Always nice to not need an air compressor.

One thing to note is that the rims come pre-wrapped with tubeless tape, and DT Swiss also includes a pair of milKit tubeless valves. These valves use a one-way rubber seal on the rim-side of the valve, which is designed to stop latex sealant from filling the valve cores and clogging them up over time. You can also utilise the milKit injector syringe, which allows you to insert a thin tube through the valves and into the tyre, to draw out any remaining sealant. That way you can check how much sealant, if any, is currently left inside your tyres, without having to depressurise the tyre and pop the bead off. It’s very clever, though it requires a fairly specific procedure to avoid sealant exploding all over your workshop – follow the instructions, and it’s a neat method for checking and refilling your tyres with sealant when required.

Riding The Gravel Grit Laguna

Along with a bunch of local trail riding, the GRC 1400 wheels were first put to the test during the Gravel Grit Laguna – one of my favourite events from the past year. Not only is it held in a beautiful location around the Olney State Forest, partway between Sydney and Newcastle, it’s also held over a weekend with the option for camping and many opportunities to hang out with your riding compatriots. That aside, it’s just a really fun and chill day out – a far cry from many of the serious road and MTB races that we’re used to seeing.

Due to the threat of bushfires, the 2019 edition of the Gravel Grit Laguna was limited to a shorter 67km route. There was a huge array of different bikes being ridden, from gearbox enduro bikes, to retro rigid mountain bikes, to super-boutique titanium gravel specialists, anything and everything was fair game.

With the DT Swiss wheel upgrade, my Trek Checkpoint showed a dramatic improvement in almost every regard.

On the dirt, while the GRC 1400 wheels weren’t a whole lot lighter than the RS770s, they felt a lot lighter, which boils down to a few different things. Firstly, the build is tight. DT has used 24 flat-blade aero spokes per wheel in a 2x lacing pattern, and they’re beautifully tuned with little flex present. The 240s hubs are also silky smooth and roll along with very little drag.

Likewise, the rims don’t exactly catch the air either. Just like it would on an aero road bike, the 42mm deep rim profile allows the wind to glide over it seamlessly. You’re unlikely to feel this at slow speeds, but get the bike up to 25km/h and above, and the difference between these and the Shimano wheels that came off the bike is stark – there’s significantly less drag, and that allows you to go faster. Of course you don’t reap the full benefits with a tyre that’s wider than the rim itself, so those who are chasing as much speed as possible on smoother hardpack roads, consider running a narrower 32-35mm wide tyre.

One thing I also found was that because they’re so wide (for a road/gravel rim), the blunt profile is also more resistant to side winds, so you don’t get bashed around as much. Then again, most of my gravel riding is in the forest amongst the trees, where you’re not subjected to the same coastal gusts that you’d experience out on the open road.

With that big hollow carbon rim, I did notice a lot more noise with the GRC 1400 wheels compared to the RS770s. Changing gears, you could hear and feel the reverberations of the chain clunking into place. Likewise, coasting with the Star Ratchet gives it a whole new voice. It isn’t unpleasant at all – there’s a very high quality feel and sound about these wheels, though you may end up being ‘that guy’ if you’re riding in a bunch. On the bike path, there’s no need for a bell to warn pedestrians of your proximity – freewheeling for a moment proved to be equally effective.

But the main aspect I noticed with the GRC 1400 wheels is just how much smoother they are. The extra width at the rim bed helps to plump up the tyre volume, allowing for a drop in pressure without sacrificing stability. I was running 31psi on the rear, and 30psi on the front, down from 35psi on the RS770s, which is a healthy difference and really not that much higher than a full-on MTB setup.

On crappy road surfaces and on rough gravel tracks, they soak up the vast majority of imperfections without hassle. There were some pretty sketchy descents during the Gravel Grit Laguna, where my rear wheel in particular was subject to a pounding as rocks tumbled underneath the tyre. Despite having smacked the rims plenty, including on some surprise potholes, I never flatted once.

Flow’s Verdict

Lightweight, responsive, smooth, fast. The DT Swiss GRC 1400 is as premium as it gets for a gravel wheelset, and the ride quality shows it. Wide tubeless rims make such an improvement to a gravel bike, but they often come with a weight penalty. Not so here. The deep profile of the GRC 1400 rims don’t just slice through the air, they’re also very lightweight and responsive, especially given their size. The added width gives fantastic support for running 35-40c gravel tyres at low pressures, and I certainly won’t be going back to narrow rims anytime soon.

Of course the high-end performance comes with a high-end price tag. For around a third of the price, DT Swiss offers the alloy GR 1600 wheelset, which is a fair chunk heavier at 1811g (claimed). The GR 1600 also misses out on the aero benefits of the deep-section profile, but they do get the same 24mm inner rim width and they’re ready to roll tubeless too. Those wheels run on 350 hubs, which are still top-quality units, making the GR 1600 exceptional value for $949.

But for those who want a serious upgrade for your current gravel bike, then wheels are no doubt the best place to do it, and I’m struggling to think of a higher quality wheelset than this.

Mo’ Flow Please!

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