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Spin K2 Carbone XLR38 25mm Fat Boy Clincher wheels



Deliciously fast and smooth carbon clincher wheels at a great price and weight

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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Spin's K2 Carbone XLR38 25mm carbon fibre clincher wheels offer bags of speed with a fat rim profile reminiscent of a Zipp or Enve but at a fraction of the price, making them an ideal upgrade for anyone looking to invest in their first deep section carbon heels.

The all-carbon rims are 25mm wide at their widest point, with a toroidal rim profile. It's the way most rim manufacturers are going, as it's commonly accepted to be faster in a greater range of yaw angles as well as being more stable in crosswinds than the previous generation of narrow V-shape rims. They certainly feel fast in testing and hold their own against more expensive wheels.

One easily detectable benefit of the wider rim is that the 23mm Schwalbe One tyres I fitted actually measured 25mm across, providing the benefits of a wider tyre with no weight increase. This also produces a nice seamless rim and tyre profile – no light bulb effect here – which produced a very stable tyre and was a noticeable benefit through hard cornering, such as in a criterium race.

Spin offer a choice of rim depths. At 38mm, these are the shallowest option. It's a good all-round option, more stable in windy conditions than a deeper rim, and obviously lighter as well, so ideal for hilly terrain. A deeper rim might be more aero, and better suited to heavier riders and flatter terrain, but I think the 38mm is the perfect choice for a wider range of applications.

The rims are laced to Spin's own SPN Precision hubs. These hubs are diminutive in size and the HyperDrive freehub produces instant engagement and a pleasing sound when freewheeling, without the excessive noise of some hubs. It's an 11-speed freehub with a spacer provided if you're running a 10-speed setup. Any problems Spin might have had in the past with hub reliability are firmly in the past; these hubs were utterly reliable.

These wheels feature Sapim CX Ray aero bladed spokes, 20 in the front wheel and 24 in the rear. Spin build all their wheels at their own facility in the UK and it's testament to the build quality that I have ridden these wheels through some very unfavourable conditions and rough roads, and the spokes are still showing good tension, and the wheels still very straight.

The wheels weigh 1,465g for the pair. That's 655g for the front and 810g for the rear. It's a very competitive weight, certainly for the price. You won't get much lighter unless you're prepared to spend quite a lot more money.

Braking performance has been an issue for carbon rims in the past, but with the supplied QuickStop Black Shadow brake blocks, there were no issues with braking. In fact, braking was excellent and up there with the best braking carbon rims. No noise, no drama, no fuss, just solid and dependable braking all of the time. That's good to know if you want to ride the wheels all of the time, every day. With this level of braking, there's really no reason why you can't.

They're fast and fun wheels to ride. They accelerate very quickly, with nice response when sprinting out of the saddle, and no detectable flex at extreme lean angles. Get them up to a fast cruising speed and they feel wonderfully stable even in blustery cross winds. Over rolling terrain they exhibit a nice nippiness when cresting rises and swoop through steep descents. What I wasn't expecting was for them to be as sublimely smooth as they proved to be.

There has been a rapid rise in the choice of carbon fibre clincher wheels at the £1,000 mark and it can be difficult to differentiate between them. Spin have a good few years behind them, and it's nice to know they build all their wheels by hand in the UK. These have a thoroughly modern rim design echoing that of more expensive wheels on the market, but at a fraction of the price and with fantastic speed, reliability and dependable braking performance. That they look good too makes them easy to recommend.


Deliciously fast and smooth carbon clincher wheels at a great price and weight

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Make and model: Spin K2 Carbone XLR38 25mm Fat Boy Clincher wheels

Size tested: black,700c

Tell us what the product 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?

K2 Carbone XLR38s deliver ultimate speed, lateral stiffness and stable handling in all riding conditions thanks to their 25mm superwide section, 38mm deep 3D Toroid aero rim profiles.

The superlight forged & machined alloy hubset from SPN Precision features HyperDrive 48-point fail-safe engagement and is 11-speed ready. And for wheels this fast, only the finest aero bladed Sapim CX Ray spokes will do.

Tell us some more about the technical aspects of the product?

Weights (average, grams):

Front 655 / Rear 810 / Pair 1465

Rim Width, Depth (mm) & Profile:

25 wide x 38 deep / 3D Toroid

Spokes Front - 20 Radial:

Sapim CX Ray

Spokes Rear - 24 Two-cross:

Sapim CX Ray Drive / Sapim Laser NonDrive

11 Speed Drivetrain:

Shimano/SRAM standard, Campag Optional

What's In The Box:

Rim tape, QuickStop carbon brake pads, Quick Release skewers

Rate the product for quality of construction:
Rate the product for performance:

Excellent ride and handling performance especially when considering the price, with state-of-the-art toroidal rim shape.

Rate the product for durability:

Brilliant durability through the testing period.

Rate the product for weight, if applicable:

They're not the lightest but they're not bad for the money.

Rate the product for comfort, if applicable:

Surprisingly smooth over rough roads.

Rate the product for value:

There is a lot of choice at the thousand pound mark. These comfortably tick all the boxes and are an excellent choice. There aren't that many wheels at this price with the latest toroidal rim shape that is doing the rounds at the top-end of the aero wheel market.

Tell us how the product performed overall when used for its designed purpose

Really good performance in all aspects.

Tell us what you particularly liked about the product

Easy speed and good braking, easy to live with on a daily basis. Shallow rim is good in the wind, and means you don't need to shop around for inner tubes with long valves.

Tell us what you particularly disliked about the product

Nothing really to dislike, they performed flawlessly.

Did you enjoy using the product? Yes.

Would you consider buying the product? Yes.

Would you recommend the product to a friend? Yes.

Anything further to say about the product in conclusion?

While there's a lot of choice at this price, these wheels easily make a strong argument for their selection over other carbon wheels at this price, as they're clearly head and shoulders above just about everything else at this price point.

Overall rating: 9/10

About the tester

Age: 31  Height: 180  Weight: 67

I usually ride:   My best bike is:

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: road racing, time trialling, cyclo cross, commuting, touring, mtb,


David worked on the tech team from 2012-2020. Previously he was editor of and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds, and you can now find him over on his own YouTube channel David Arthur - Just Ride Bikes

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