This past winter, I switched mid-season from the IRC Serac CX tires to the Schwalbe X-One Allround, and they ended up have the right type of traction for the final NCCX races of the year. It combined green grass, dry grass, red dirt, fine gravel hardpack, and just a tiny touch of snow and mud in the shadows. In other words lots of good stuff, a little bit of bad stuff. Trouble was, I’m not sure these particular rims were the right ones for the tires…
First things first, they weigh in at 363g and 376g each. Claimed weight is 370g, which averages out perfectly. These are the Tubeless Easy EVO model, their top version, in a 700×33 size, which is the only size offered. As the name implies, they’re designed for all-around use. There’s also an X-One Bite that’s designed more for mud, which is good because mud is not this tire’s strong suit.
The last race of the year had me slowly reeling in competitors until I was sitting in a comfortable 4th place half way through the last lap, possibly able to catch 3rd (he was in my sights the whole time). The course raced through the trees on this manicured gravel path, around a track on the grass, and up and down off camber sections that were also mostly grass.
The opposite side of the field had a mix of our infamous red clay/soil and dry grass. And on the very back of the course, just before we came into view of the final twists, turns and sand pit run-through, was a small patch of snow and a ridiculous muddy section running along the side of a very steep bank. There was a line, but most folks ended up running it.
The X-One Allround uses roundish knobs with siping to bite into the ground and control their flex. Despite the diminutive size of the side knobs, they worked well for me. The center section is ramped and spaced tightly enough to roll very fast, even on pavement.
What I found interesting (and encouraging), was that the tires only packed up with thicker clay-like stuff. The wetter regular mud and other stuff flung free from the openly spaced knobs quickly.
Barring the snow and mud, the Schwalbe X-One Allround had serious grip. After the race, I tried leaning the bike further and faster into tighter and tighter turns on both the dry and the green grass, and it was hard to shake them loose. I gave up before I lost grip because my tests were no longer reflecting real race conditions, and I didn’t want to get hurt. The red dirt sections were a mix of flats, drops into turns and up and down banks, and traction was equally reliable there. Happy so far, but as the race progressed I could tell I was losing air.
I mounted them up to older tubeless-ready Reynolds Stratus Pro wheels, which have a meager 17mm internal width. Why? Because they’re all I had available at the time and needed to get the bike built for a few final races. Schwalbe recommends something like Stan’s Iron Cross with a 20mm internal width, and I suspect this is where the system failed me.
Oddly, the tires weren’t overly round on these rims. If anything, I’m thinking much wider rims would square them off a bit much. But considering the ~30 to 32 psi setting I favor (recommended minimum is 40psi, according to Schwalbe), the narrow rims seemed to give them too many opportunities to burp air. One particularly big burp happened on a fast, downhill, off camber 180° sweeper (the perfect storm for burping a tire, really…this instance happened on a different course than the one pictured here). Other than that the subtle, consistent air loss would sneak up on me until I was squirming the tire on every turn.
I had plenty of sealant in the tires, and I’ve had excellent tubeless results with Schwalbe’s road and mountain bike tires. So I’m not blaming the tires, I’m blaming the set up. While they held air, the tires proved an excellent race partner. And I never had much problem with the front, so I suspect with wider rims, they’d have maintained pressure to the end. On all but the last race, they held enough air for me to finish strong.
That last race? By the time I came off that muddy hillside, there was no air in the rear tire and I was spinning the rim inside it anytime I tried to accelerate. And turning was imprecise to say the least. But the tire never came off the rim, even as racer after racer passed me in the final stretch and I ended up 7th.