Sun Ringle Düroc SD37 Pro Wheels | For Rim Dingers

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We sent David ‘Dinger’ Hayward out to beat up these Sun Ringle Düroc SD37 Pro wheels, available as both a rim only or complete wheelset option. Will his reputation as a wheel bruiser be dented, or will it be the wheels that take the damage?

Sun Ringle Düroc
Production model.

Specs and Set Up

The main feature of these is the rims, at 37mm wide with a 35mm internal width, they’re beefy and suitable for plus tyres if you so desire. They arrived pre-taped, which is always a pleasure (despite it being easy, for some reason taping rims remains one of my least favourite bike jobs). Also in the box were valves and a couple of small bottles of sealant.

Sun Ringle Düroc
Yay! Pre taped!

For this wheel set, Ringle has reintroduced Super Bubba hubs, with the rear having a clever new feature they call “Clok’d”. It refers to the pair of ratchet rings in the hub shell, with the freehub having two rows of corresponding pawls. Indexing notches in the hub shell allow you to align the ratchet rings two ways. For maximum strength, line up the teeth to engage all six pawls at once. Alternatively, you can offset them, engaging three pawls at a time and halving the engagement angle to make it just 4 degrees.

In the 8 degree setting, during testing, they found that chains would break before the hub did. I ran this wheelset in the 4 degree setting for most of the time, and had absolutely no problems with skipping, no matter how much I mashed. This higher engagement does technically lead to slightly higher drag than the 8 degree one – I didn’t notice though.

Just beware when you’re reinserting the freehub and don’t accidentally pull on it, or you’ll end up with pawls falling out, like me. D’oh.

Ringle has also reintroduced Bubba hubs, which are available after market and have standard flanges for J-bend spokes. Super Bubba hubs are straight pull, and only come in wheelsets such as this. The spoke nipples are brass, which I much prefer for any wheels that are going to lead a hard life – or perhaps end up anywhere near road salt in winter. I’ve had too many alloy nipples shear or round off in the past, which its to say: two.

Absolutely everything in this wheelset also uses the same 6902 bearings: the front, the rear, and the freehub. Lovely to see a thing standardised like this, the fewer tools and parts you need to look after a thing, the better.

Available in 29in or 27.5in, I rode the 27.5 wheels on a Nukeproof Mega 275c. It actually had two sets of these wheels, a pre-production set, and a production set that came later on – the obvious difference between the two was purple anodising on the free hub, and consistently coloured rim tape. Weight of the bare wheelset is 2048g, which pleases me because it’s a power of two.

Hotlines sent the bike with 2.6in WTB tyres, which I found quite baggy and hard to set up, even with a high volume track pump and a charger pump. I think this was a combo of an unusually baggy tyre, wide rim, and high air volume. The 2.6 rear tyre was excessively sticky on road climbs anyway, so I replaced it with a 2.4 Onza Ibex and had a much easier time seating that. The 35mm internal width definitely makes tyre inserts easier to work with, should they be your thing.

At 28 spokes each, you’d be forgiven for having doubts over their toughness. Time to ride.

The Ride

For some of this test I was also testing tubeless rim inserts, but I made sure to run them on plenty of rides without, and give them a good beating too. It’s a solid and direct feeling wheelset – in fact, I’d never have guessed it was a 28 spoke one.

Sun Ringle Düroc
Tyre damping is significantly changed

Most of my riding until now has been on narrower rims, with an internal width of 25 – 30mm. Does the extra 5mm on offer here really make a difference? Yes. Tyre damping is significantly changed by the higher volume, allowing very slightly lower pressures and giving a little more protection against dings. I didn’t get to run them in any bike-park like corners, but wider rims also increase tyre support for that too.

The Düroc SD37s have fared better than most wheels I’ve run (even the ones I don’t destroy have tended to end up with flat spots… through ProCore). These SD37s have had much less protection than I usually give to a wheelset nowadays, and come out with no damage.

Sun Ringle Düroc
Super Bubba

This has included a high speed front flat in a rock-filled gully, leading to multiple big dings as I came to a stop. On another descent, I’ve been experimenting with different lines in a pair of alternating corners, and one grassy line concealed an enormous sniper rock. It rang that front rim like a chuffing bell, and I was incredulous to find the bike still rolling, they tyres still up, and at the next gate, absolutely no signs of any trauma to the rim.

Sun Ringle Düroc
Dinging but not denting

In all, they had a lot of miles put on them over Summer and Autumn, by me and several other riders, and didn’t balk in any way at all. By the end of the test they were still true, still undinged, and still spinning freely.


This is a chunky wheelset, able to take plus sized rubber or get your standard 2.4in tyres up to a higher volume. The clever ratchet system also makes them versatile. I’ve rarely beaten a wheelset as hard as I did these Düroc SD37 Pros, and with or without rim inserts, they laughed it all off.

Sun Ringle Düroc

Review Info

Brand: Sun Ringle
Product: Düroc SD37 Pro, 27.5in
From: Sun Ringle / Hotlines
Price: Front £329.99 , Rear £499.99, £119.99 rim only
Tested: by David Hayward for 4 months

David started mountain biking in the 90’s, by which he means “Ineptly jumping a Saracen Kili Racer off anything available in a nearby industrial estate”. After growing up and living in some extremely flat places, David moved to Yorkshire specifically for the mountain biking. This felt like a horrible mistake at first, because the hills are so steep, but you get used to them pretty quickly. Previously, David trifled with road and BMX, but mountain bikes always won. He’s most at peace battering down a rough trail, quietly fixing everything that does to a bike, or trying to figure out if that one click of compression damping has made things marginally better or worse. The inept jumping continues to this day.

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