The Gravel Slayer

The Gravel Slayer

At the point I center-punched the granite block I wouldn’t have admitted to you I was out of control. To admit such a thing would require me to even agree with that statement … or lie. I didn’t think I was out of control, but really, I was at a point where gravity and the particular terrain of the fire road had led me to that hunk of rock which was, to use game show terminology, about as large as a good-sized loaf of bread.

I’d avoided some rocks that were perhaps not as big or as threatening as this one, but it hadn’t occurred to me that those choices were narrowing my options. Suddenly, I spy through the leaves a true red alert obstacle.


I stayed upright, but the pain that shot through my shoulder was enough to make me see a flash of light. I began to pull over because the pain was so great that I didn’t think I could continue to control the bike down the descent and, honestly, I assumed that any impact of that much force would just automatically result in a flat.

I should back up a second. When I first began exploring dirt roads and paths on my road bike back in the 1980s, I did so without much concern. My corner of the South is as devoid of rock as Times Square is of grazing cows. When I began lurching down dirt roads in New England, I did so on a road bike with tubular tires, not the 32mm clincher tires I’d been riding on my touring bike. The combination of smaller tires and exposed granite taught me to pick my line with care, to ginger my way through the most neglected sections.

It never occurred to me that at some point I might own a road bike that would allow me to charge through such stuff in the big ring.

We call that failure of imagination. I’ve been guilty of it here and there. What’s beautiful is how our eyes can be opened to new possibilities and suddenly we adopt a new normal. Now I ride terrain that would have been difficult to pass on a 26-inch wheel mountain bike at any speed, let alone sans freins.

The challenge I face now is finding that balance point between a tire big enough to allow me stampede through terrain that would pinch flat traditional road tires instantly while not going so large that I lose my ability to accelerate. The upcoming Old Caz is the perfect illustration of this point. The opening descent of Willow Creek is just rocky enough that I typically see close to a dozen riders pulled over on the descent, fixing flats. My bike isn’t as light as theirs, but I roll on by.

Since their return to the market, Clement has made its greatest inroads in the cyclocross and gravel segments. I previously reviewed the the LCV (and open tubular), the USH X’plor and the MSO X’plor. The large MSO has been one of my two favorites for gravel riding due to its 40mm width. Last summer Clement announced a tubeless version of the MSO in a 36mm width.

So I pulled over, let the pain subside and then pressed the heel of my hand on the tread. No flat.


Scratches head through helmet.

I turned to my friends, “Ready?”

On that ride, I proceeded to center punch another four or five rocks. Each of the impacts was hard enough that A) I felt the rim contact the rock, B) had I been running tubes inside the tires, they would have suffered snakebite flats for sure, and C) I was amazed that I didn’t manage to cut the tire casing.

Let me be clear: I don’t like pounding wheels into rocks. I don’t deliberately abuse products. The job of a reviewer isn’t to see if you can break something. The task is to see how it holds up under reasonable use. This means not putting the bibs in the dryer on high for two hours. It also means attempting to roll over stuff and not just pound into it like a two-wheeled football player.

But I was having too damn much fun to slow down. Of all the possibilities in this diverse world, I wasn’t going to choose slowing down unless it was thrust upon me with a flat. And that flat never came.

That ride taught me a couple of things. The first was that I need to run 40mm tires if I’m going to try to ride like that. Even 36mm tires aren’t quite enough for some of the rocky trails around here. Noted. Of course, I performed a thorough inspection of the wheels and tires when I got home. Other than some sidewall scuffs, I couldn’t find any damage to either the tires or, more impressively, the wheels. Surely there was at least one ding in the rim. Nope. So the second thing I learned was that I didn’t need to do any further rides on those wheels to be able to write the review. Not that I stopped riding them, mind you.


We laughed at that
There was a time when I laughed at any tire that was 700C and more than 25mm wide. It was a snobbery directed at any tire that I didn’t consider high performance. Of course, the X’plor MSO is a high-performance tire. Funny how perception can evolve. Clement worked hard to make sure this would be a true tubeless tire, with a super-precise bead for a consistent and accurate fit in order to prevent burping or blow-off. The MSO is unusual among gravel tires in that its assembly of small knobs roll with the smooth procession of water through a rain gutter. It’s arguably the most organic-looking tread among gravel tires. Yet it’s no problem to propel up to speed and on dirt, it grabs like tires with much more aggressive knobs.

The tire weighs 425 grams, which runs heavier than the other sizes due to the higher rubber content necessary to make the tire tubeless. And because it’s tubeless, it is a bit more expensive than other Clement tires, at $75.

Unless I lived somewhere with so much mud I needed to re-think my tire choices, The X’plor MSO would be one of my go-to tires. That is, it would be anywhere but where I live now. And this shortfall in performance isn’t something I fault the MSO for. Clement makes a 40mm version, and they will have a tubeless version of the 40 sometime in 2017. Either of those tires are simply more appropriate for all the rock I encounter.


The nuts, the bolts
The Ushuaia wheels weigh in around 1620g, depending on just which axle assembly you use. They come with axle adapters for quick release, 12mm or 15mm in the front and quick release or 12x142mm in the rear. They are available in either six-bolt or center-lock hub designs. Basically, the only bike you can’t run them on is the Specialized Diverge. The rim is wide: 26mm on the outside, but 23mm inside, wide enough to help prevent tire squirm when you run really low pressures. The rear rim features an asymmetric profile to reduce wheel dish and improve wheel strength.

The wheels are built with 28 spokes front and rear with J-bend spokes. The upshot is that if you break a spoke, it will be easy to replace and you’ll be able to ride home despite the broken spoke. It comes with a Shimano-style freehub body to accept either Shimano or SRAM cassettes.

The wheel set goes for $650 and not only do they come with all the different axle adapters, valves and tape are included in the package as well.

Carbon fiber dream wheels have driven prices into price points once occupied by whole bikes. I don’t object to that, but I’ll admit that it has helped to skew my perception of pricing for aluminum wheels. I don’t flip out when I see a set of aluminum wheels that encroach upon $1000 territory. And that’s what makes these wheels so remarkable. I was paying $650 for good wheels 15 years ago. These are absolutely the best value in wheels I’ve encountered in the last three years.

Final thought: Just waiting for Clement to introduce the tubeless 40mm MSO X’plor. When they do, cowabunga.

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  1. josh

    funny you brought up old caz. i’m registered this year and am pondering tire choice. nano 40 tubeless or clement mxp tubeless….or even maxxis refuse (shoulder-less micro file tread) 32 tubeless….or a combo of above?

    i’ve only ridden up willow creek a few times and each time was with 25mm slicks.

    1. Author

      You can get up Willow Creek on 25s no problem. If you want to do anything other than nurse your bike down it, go big. I have no intention of running anything smaller than 40.

  2. Emil Gercke

    I’ve used the same tire with great sucess as a trainer tire on my ‘cross bike. I look forward to using it on mixed terrain too. What pressures were you using for your review?

    1. Author

      Pressure varies. If I’m doing more road miles, I’ll bump the pressure up to 50 psi front and 52-53 in the rear. If I’m doing lots of unpaved stuff, or any sort of run through Annadel, I’ll run on the order of mid-30s to 40 front and rear. Honestly, I’m still experimenting.

  3. Dave King

    Great review. I looked for these wheels on the Clement website but they don’t list them – do you know if they are available yet? And why can’t they be run on a Diverge? I don’t have one but I’m curious to know if I can run them with a Scott Addict Gravel CX.


    1. Author

      No, for reasons I can’t explain, the Ushuaias are not yet on the Clement web site, but I am to understand that they are available. You might try asking your LBS to order them.

      The Diverge uses a unique axle standard. While the engineering behind it makes some sense, the complete lack of interchangeability has infuriated a number of owners.

      You won’t have any trouble pairing these with a Scott.

  4. Jeff Klun

    I contacted Clement via email and heard back from that the lastest update for release is April, 2017.

  5. Peter Rhodes

    These wheels are on my “maybe” list for my Niner RLT. I have a set of 32 hole grail rims on it now. So far my favorite tire has been 40c WTB Nano race tires…yup, not tubeless ready, but they were awesome tires out here on the gravel roads of Oregon. Right now riding some 40c panaracer gravel kings on that same wheelset and I like them, but I think I like the Nano setup better.

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