Review: CXNats winning Team Edition Challenge Dune, from sand to ice

If you’ve been keeping up with our USA Cross Nats coverage you may have noticed that new US champ Stephen Hyde rolled across the finish line on a set of Challenge’s latest file tread tubular tires – the Dune. OK to be fair, he walked across the line after a crash in the last off-camber turn hobbled his bike with a broken derailleur hanger and a front flat. Nonetheless, we’ve been testing those same tires since not long after they were introduced at Sea Otter, and as we first learned from past British CX champ Helen Wyman in her tire selection criteria the Dune is capable in much more than the sandy terrain that its name belies…

Tech Details

When we found out that Challenge had a new file tread design I was very curious to try it out. Its last predecessor the Grifo XS had been the first file tread tubular that I was really happy with. And with their most recent hybrid file Chicane Challenge broadened its usability, and then the Baby Limus reiterated a successful formula of making small modifications to update and improve their existing cross tires, rather than starting from scratch.

The Dune keeps the same pyramid file tread down the center as the Grifo XS, but replaces the low dots and half moons of the Grifo with a new set of slightly offset square blocks. With more height and stronger straight edges than it predecessor, the Dune promised more grab when you leaned it into soft turns while retaining the same fast-rolling on the straights. Offsetting the new squares a bit farther down the shoulder also offers more cornering stability & support than the thinner Chicane/Limus shoulder, so the grip continues when you lean it even on hard surfaces where it can’t dig into the surface.

At the same time as the new Dune tread, Challenge had another novelty that we discovered when we looked into the tech in detail back at Eurobike. All of their cyclocross tubulars were now being made available to us regular riders/racers in a Team Edition S corespun cotton casing like the pros use – including the Grifo, Baby Limus, Limus, Chicane, and now Dune. But unlike those boutique made-in-Europe tubulars that often cost twice as much as the Thai-made Challenges, these new T.E. tires got that extra S denoting that their pale cotton sidewalls were pre-sealed with a thin layer of latex giving them similar durability and resistance against rot like their polyester brethren, without having to mess with AquaSeal.

By sealing the casing as it is constructed, the tires are better protected, with no gaps in protection. It also is said to not affect how the tire rides, so you get the full benefit of the pale and flexible 320tpi cotton for a supple feel with crazy grip on command down into super low pressures.

With the new Team Edition S designation also comes a slightly softer rubber compound, which performs better in the wet and especially below freezing temperatures. Softer rubber is sometimes heavier, but the Dunes we tested weighed in on our scale at 439g which is just about 30g heavier than claimed weight, and saves weight over the SuperPoly tires thanks to thinner and more fine casing.

Impressions in Different Conditions

Having ridden the Grifo XS on and off road and raced it in a wide range of conditions, it became a tire that I learned to appreciate on everything from dirty cobblestones and dirt roads to racing on dry grass and packed snow. But with the new Dune’s updated shoulder knobs I was hoping for a bit broader application.

With a name like Dune presumably coming from the classic Dutch & Belgian World Cup Cross races going up, down & across the sand dunes along the North Sea, I thought sand was the best place to try out the new tires. So I took them to the dry sandy and dirty cobblestone roads northeast of Prague and tried to do a fair share of sliding around.

The brand new sharp pyramids did a predictable job of moving the loose sand out of the way to reach down to the hard surfaces below. That worked on hardpack dirt as well as on cobblestones and you can see in the photo above that riding on a hard surface the top of the file treads stayed clean while the loose stuff got pushed aside. Cornering on asphalt, cobbles, or hardpack the Dune felt a bit more confident as you lean over onto the squares, a significant change from the Grifo side which are less constant and reliable feeling.

On rides and races where the sandy sections get mixed in with dirt and hold a bit more moisture, the file section of tread tended to pack up a bit, giving the tire a slower feel and at times more of a sense of slipping & sliding under power. It certainly isn’t a tire to use in the mud.

But at the same time wet sand & dirt didn’t seem to build up much and naturally got squeezed off to the side, never accumulating higher than the square shoulder blocks. That essentially meant that even though you could slip a bit in a straight line, leaning over into the corners and those shoulders dug back in to offer some reliable grip.

I raced a couple of times in proper dry, deep & loose sand as well both in above and below freezing conditions. Running relatively low pressures (~23-25psi for my 80kg weight) the tires floated well and straight through the deepest sections without the shoulder squares producing much drag to eat at my momentum. When I had to power more through the sand though turns and climbing, the center tread and flexible casing did an admirable job at finding grip and the shoulder squares made steering as functional as I could hope.

In the deep turns I still often felt like I was on the edge of my wheel washing out, but it never totally happened. While it doesn’t necessarily feel like being in complete control, I definitely was going faster than those around me through the loosest sections and was able to carry more speed through the deep ruts that many of the others around me had resigned themselves to run. Riding wasn’t always fastest, but it gave me a bit of a confidence boost (and more time on the bike at my max heart rate!)

Most recently winter has taken over and I have put more time on the Dunes in snow and ice. Where they have unexpectedly shined has been with temperatures right around freezing where snow cover has made it hard to guess whether there would be ice or damp grass underneath.

I haven’t been as impressed by the Chicane that often feels to me like it is two opposite extremes, compromised by being together except for very specific conditions. I had used it a bit as it was a better option on wet grass or snow vs. most file treads like the old Grifo XS that just slid all over the place in the wet.

The Dune though seems to offer a better matched straight line and cornering grip that gave me confidence and predictable sliding on either the wet grass under snow or patches of ice. Sure if it gets proper muddy you’ll be out of luck, spinning you wheels and unable to put power to the ground on the straights. But on a course right at the freezing point or a race with few enough riders to not churn up the mud too bad, the loose spots will be in the corners and that’s where the Dune shoulder squares will offer confidence inspiring traction.

I already had expected good performance in the deep freeze kind of snow riding that is either packed tracks or the white stuff hiding lot of full on ice beneath it. It seemed counter intuitive at first ride many years ago, but file treads in the snow are like velcro, just tons of tread surface area grabbing the powder. And really like in soft sand, you don’t want big side knobs which will just chew up the track surface and throw it at your bike and drivetrain.

Then when you hit the ice, it’s again a case of the more rubber against the ground, the better chance of staying upright. Again you want smooth transition to the side knobs. You want to avoid cornering on ice, but inevitably you’ll run into frozen ruts, where it is still best to keep low profile side knobs and as much sticky rubber on the ground.

In the cold I think I most appreciated the softer rubber of the Team Edition tires. I don’t feel like there is that much difference in tire compound that I would be able to quantify, but the tires grip and make me feel comfortable with that traction.

Final Thoughts

OK, that’s a lot of words about a couple of file tread tubulars. To sum it up, the Dunes are a predictable file tread tire with a smooth feeling transition to stable shoulder knobs that offer support and positive grip in the corners. Those simple characteristics make the Dune a surprisingly versatile tread. While they don’t suit muddy conditions, they outperform most other fast-rolling cross tires I’ve ridden once the ground starts to get damp or even wet.

Combined with the T.E. S casing they make a supple tire that offers ample grip and pretty solid security. They even have Challenge’s single layer puncture protection strip (PPS) under the  tread to protect the latex tube inside from flats. Sure that was no match for the 10cm/4″ nail that I picked up in the junkyard section of the Rad Race cross race at this year’s Vienna Bike Show. (No, it didn’t buff out.) But as a testament to the versatility of the tire, instead of trying something else, I bought myself a replacement so I could keep racing on them.

One of the things I learned riding my previous sets of file treads was that it could be a blast getting fast and loose with a tire outside of its comfort zone. I still feel like that holds true with the Dune. Getting used to a tire that you can slide through turns is a lot of fun and good cyclocross training. But the Dune has a much wider application than its name implies.

Sure it does great in the sand, and for any race I’ll be doing anytime soon with significant amounts of sand, this is the first tire I’d reach for. But if you read our feature on Helen Wyman’s method for picking cyclocross tires, you’d have seen the name Dune pop up as a viable first or second option for 6 out of 11 of the different course terrain categories. So when Stephen Hyde switched to the Dunes mid-race before taking the men’s Elite National Championship win on the snow covered and frozen course in Hartford, I was certainly not surprised.


18 thoughts on “Review: CXNats winning Team Edition Challenge Dune, from sand to ice

  1. Interesting to see how different the tire selection was between Stephen and Katie who was on a Clement PDX/BOS mix, lots of knobs. And the course conditions really didn’t change that much between those last two races.

    1. I would bet it has something to do with rider comfort getting loose. If you watched Hyde, he clearly slid around in a few sections going fast. But he never seemed uncomfortable to let the rear break away a bit. Maybe Compton just wanted more security and was fine with a little extra resistance?

      1. Wonder about Driscoll’s tread selection. Hyde has the straight power, but I wan’t to know what tire the bike handler chose, who really only needed one more lap to make the catch. Jamey was putting in fastest lap by a few sec over Hyde for the last three I believe.

  2. Limiting factor on the US CX Nats course was speed through corners. No matter what tire you had there all were slow. Time could be made in the straights and that’s where the Dune excels.

  3. I know I was hard on Challenge on the Wyman post, and admittedly need some experience with the “new” Challenge. Can’t blame me for giving up them after I had a coat rack full of delaminated treads from 1st/2nd rides one season spilling into the next to send back for warranty. Major fail! Time heals all wounds though, hopefully.

    File treads are the norm for my region so I’m gonna have to give these’s Dune a whirl. With a skeptical eye of course 😉

  4. I’m curious if any manufacturer really offers a winter rubber compound, or if they are all considered winter compound? In cars there is a major difference in grip between winter compound and even all season compound, once the temps drop much below freezing.

    1. Tom, Continental makes the tire you’re envisioning. The Top Contact Winter II uses a true winter rubber compound derived from that used in Conti’s studless snow tires for cars. This isn’t just a soft rubber compound…it’s a true winter rubber. It’s basically useless above 55 degrees F or so.

      More importantly, it uses tiny tread elements (Conti calls them lamellae, while Bridgestone touts their microcells for their car tires) to provide thousands of edges.

      These are commuting tires: stiff casing, wire bead, reflective sidewall. I think Conti is insane not to sell a fat bike tire with this tread and compound. They could also do a CX tire with lamellae and side knobs. That would be the only tire to use in conditions like this year’s nationals.

      The narrowest model is labeled 700×37, which would make it illegal if the labeling were accurate. But my pair measures 33 mm wide when mounted to Stan’s Grail rims, so they’re technically legal. I run mine tubeless at about 35 PSI, which is maybe nuts. I had one blow off at 70 PSI when I was seating the bead, but no problems so far at half that pressure.

    2. We’ve been told by a couple of manufacturers in the past (including Challenge) that they do not tend to make season-specific rubber. They do often use different durometers to deliver increased grip or lower rolling resistance, depending on user preference or application.

      1. Cory, thanks for the update. I don’t mean any disrespect to you, but I find the manufacturers’ comments cute. Of course they “tend not to offer season-specific compounds.” There is only one tire on the market with such a compound, and Continental makes it. The comment describes the current state of the market, but it doesn’t address whether such compounds would make a useful difference. And the Conti bike tire is proof that winter compounds make a useful difference.

        I called out the difference between low-durometer standard compounds and true winter compounds explicitly because many people and some companies (including, evidently, Challenge) don’t fully understand the difference.

        But then again, I’m an engineer, and we tend to get hung up on things like quantifiable improvements. 🙂

        1. Just to be clear, winter compounds and micro-tread-features are a package deal. You don’t get the full benefit without both.

        2. Jason, I spectated at Nats this year, which as you know was seriously cold. I had good Vibram sole hiking boots on, and absolutely could not keep my feet underneath me on a gentle traverse section. Made me think that there needs to be a true winter compound if they want any grip in conditions like those.

          1. Tom: Yes, exactly.

            Regarding Cory’s comment below, I’m not sure he understands how different the material properties are for a true winter compound. Silica replacing carbon black is common in bicycle tires and has been for years. Note that this is not the same thing as embedding glass in the tread compound. I know the UCI banned glass and studs; this is different.

            Dugast and FMB don’t have the expertise in-house to develop a true winter compound and to fabricate a tread wtih microcells. It’s not because they’re a bit dim or because it’s rocket science; it’s just something large car tire companies (with legions of chemical engineers) do well. But again, “softer rubber” is not the same as a winter compound. To use the British expression, it’s chalk and cheese.

          1. Thanks for the link to the glass-impregnated Dugast story. I’ve seen glass-impregnated rubber used for shoes before, but usually the glass is much, much finger than that in the Dugast tread. It look like they crushed some glass by hand and threw it in the mold before they shot the tread. Glass-impregnated rubber is a thing, but I think Dugast’s was home-brewed. I might be wrong, but that’s my first impression.

          2. The glass is much, much finer than in the Dugast tread. Not much finger, much finer. Go home, autocorrect; you’re drunk.

  5. Not for nothing but didn’t Hyde fall 3-4 times….his straight away speed was all but scrubbed with the yard sales he participated in.

Leave a Reply