'Praxis'

First Impressions: Compass Steilacoom High Volume CX Tire

If you’re reading this blog for the first time, you might not know I am a massive tire nerd. Why? Probably because I grew up riding mountain bikes when the discipline was very young (around 1990), and I struggled a lot with tires. Mainly, I struggled a lot with flatting, which, in hindsight, actually had a lot to do with early mountain bike tires being commonly built with light, supple casings. And let’s be honest, I wasn’t the smoothest rider in the world.

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Supple 1.8″ and 2″ tires were fabulous for some terrain, like the wide trails of Gatineau Park (sort of, they were much rougher then than they are now), but less so for the rocky trails of Camp Fortune. The typical narrow rims of the era (the gold standard being Mavic 217s), had a 17mm inner width, which is 2mm narrower than the Woven road rims we use today. On a rigid bike, one didn’t really have to hit sharp or square edges all that hard to puncture.

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For rocky terrain on rigid, then front suspension bikes (with perhaps 2″ travel), tire volume was an important way to increase traction, reduce pinch flats, and have more fun on mtbs. However, mounting a 2.3″ tire onto a narrow rim like the Mavic 217 yielded pretty poor results from a stability perspective, as fairly supple casings tended to fold all over the place at low-ish pressures. So until rim widths grew (which was a painfully slow process), I rode wheel set-ups that were inadequate for my needs for years, and knew it. Ultimately, I resorted to riding downhill tires on dowhhill (Mavic 521) rims all the time, which was the furthest thing from a supple, fast rolling set-up. But I didn’t flat and roll tires all the time. Just sometimes.

Thus, tires, the medium through which we do our fun bike things, have long been a focus of mine, first because they were fraught with issues, then because they opened up new possibilities. Large tires on road bikes did the latter, particularly the Grand Bois tires Jan Heine has sold for years. More recently, it’s his Compass tires that are redefining fun on drop bar bikes. Jan’s latest model, the Steilacoom, marks his first foray into cyclocross tires, and given my experience on other tires from the range, I was extremely curious when he told me he was sending me a pair to try. As a sponsored Compass rider, I am very fortunate to get to ride their tires on most of my bikes. I’ve been hoping Jan would branch into tires with knobs for some time; the time is now!

The Steilacoom is born

Jan surprised me when he said the new tire was 38mm in width. That’s pretty big for a CX tire, and with so much knob, would we want to ride it on mixed terrain? The casing would come in either normal thickness (for Compass, which is thin), or Extralight, which is as thin as it gets. The tire was designed with mud in mind, following Jan’s rationale:

To provide the same traction and comfort, a clincher needs to be about 10-15% wider than an equivalent tubular. Scaling up a 33 mm tubular gets you a 38 mm clincher. This tire still fits into most current cyclocross frames – no need to go “moster-cross” to fit the new Steilacoom tires.

Ok, so the volume makes sense from a ride quality angle, but what about rolling resistance? Would a 38mm tire with fairly deep tread simply roll too slowly on grass and other typical cyclocross surfaces? And would this simple, vintage-looking tread work well in the mud and grass? Jan writes,

When I discussed tread patterns with the engineers from Panaracer [who manufacture the tires], their opinion was succinct: “With knob shapes, it’s mostly about fashion.” I thought about that and realized that the old round knobs made a lot of sense: You don’t want the tread to clog up with mud, so the fewer edges you have, the harder it is for the mud to stick to the tire. A round knob has the smallest surface area for mud to stick.

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The inspiration for the Steilacoom tread. Panaracer’s Porcupine was similar, and MTB mud tires have also tended to use a round tread, spaced far apart.

 

What matters more than the knob shape is their size and especially their pattern on the tire. We placed the knobs so that there are a few more in the center. The square knobs are harder to deform than thinner, irregular shaped ones. This reduces the squirm on hard surfaces. The knobs are placed so that the transition from the center tread to the shoulders is smooth and gradual. The slightly larger shoulder knobs resist squirm during hard cornering. That way, the tire rolls smoother and corners better on hard-packed dirt and pavement. The first rides by cyclocross racers have confirmed this: On pavement, the Steilacoom exhibits none of the sudden breakaway that you get with most other knobbies. Some riders will want to use these tires for mixed-surface rides where they expect significant mud – or for a ‘cross race on a dry course.

I’ve used Michelin’s downhill mud tires in the past, which were on the narrow side, about 2.1″, and used pointy, square treads. In the right mud, they were incredible. Jan’s rationale for using a squared lug design makese sense, as a pointier one ends up squirming a lot on hard surfaces, which is dangerous.

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Michelin DH Mud, 2.1″, uninflated.

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Set-up

With extra rubber on the ground, it’s hard to say how much energy is lost to friction compared to a 33mm tire, but one thing is certain: flatting a clincher is far less of a hassle than flatting and potentially destroying a tubular. The current generation Woven carbon clinchers I have, 45mm deep, have a bead shelf that made mounting the tires easy. I was actually able to push one bead up and over the ‘retaining hump’ that runs parallel the rim’s sidewall. The bead climbs up and over this hump, settling down and against the sidewall. By pushing the bead over about 2/3 of the rim, I was able to put the other bead on, then air up the tire with a floor pump, one handed! This was a revelation, amazing! I used about one scoop of Stan’s sealant and Woven’s tubeless valves, and the tires sealed completely and easily, holding their air overnight with no significant loss in pressure. I tried rolling the tire off the rim at 10psi, failed to, and thus headed into the race with confidence that only a puncture from a sharp rock would cause a problem. So, mounting these tires tubeless can be a simple affair, provided your rims have a good tubeless design.

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The diagram shows the retaining hump as less pronounced than it really is, or seems to be.

Performance

My first test ride was in a local park. Riding over on pavement was surprising; the tires didn’t feel slow at all. The tires had a unique feel, unlike any others I have ridden. I was able to ride them at fairly extreme lean angles on grass, and climb steep grades. The traction was very uniform. which didn’t surprise me, as the treads follow a steady progression from centre to shoulder. In contrast, some tires have a more pronounced shoulder knob, with minimal transition knobs. These tires are fun, because they carve lines, but there’s such a thing as too much of a good thing. A ‘sharp’ tire will tend to cut grass right out of the ground, which leads to loss of traction and crashes. So a tire like a Clement PDX, for example, is sharp, which is good for cutting through mud into firmer substrates, but less ideal for grass. Their MXP is better suited to that, though I find a somewhat sluggish-feeling tread. I still have some of these, both tubulars and clinchers, and they have served me well.

The Steilacoom tread puts a lot of rubber across a large surface area, creating a unique squeaking sound on the grass! Weird! Cool! I couldn’t get them to break free, but I could get them to start to fold over around 25psi.

Before trying them out in a race, I took the tires out for a fast, hilly trail ride in Gatineau Park. As I tend to do, I rode them as fast as I could down every descent, including one that has a nasty rock in a compression. I struck it so hard, not having seen it, I thought I’d perhaps broken my wheel. Nope. Instead, my tire took two very small punctures: one on the shoulder, the other lower, above the bead. This is a classic ‘tubeless snakebite.’ My sealant couldn’t fix it, so I installed a tube to finish the ride. Back home later, I patched it, remounted the tire, and aired it back up. Lovely! I thus learned the tire’s limit. At 38mm, the volume isn’t large enough for square-edged impacts at 50kph, unless you run perhaps 40psi. Knowing the tire’s limit, I now adjust my speed and lines appropriately in order to get the most out of it over the course of a whole ride or race, rather than being able to cope with the one nasty feature, which I can simply ride slower. This is the strategic approach to choosing tire pressures.

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I opted to race the Steilacooms at our first Eastern Ontario Cyclocross series race at the Calabogie ski hill about 45 minutes from Ottawa. This venue is sandy, and bears a resemblance to the Gloucester GP track in how it breaks down. Rocks get unearthed. There are even some firmly embedded rocks to avoid, making this a course that can eat tubulars in particular, tires in general. I’ve noted that increasing pressure doesn’t really help, as knobs seem to tear when they hook up on embedded rocks. Better to leave the fancy tires at home and rock the tubeless Steilacooms!

I went with 27-28psi in both my tires for the race, slightly up from what I did course training at after bottoming the front on a hidden rock in the sand. I knew this would make for slower rolling on all the rough pedaling sections, but flatting is slower still. I had no idea how much of a hit I’d take on the fast, smooth sections, but I was really enjoying shredding the sand sections on tires that made my bike feel more like a mtb than usual. It was fun!

My experience through the 60 minutes of racing was overwhelmingly positive. I didn’t feel at 100% physically at the start, yet I had my best cx race I can remember, finishing closer to a few adversaries than ever before for 4th overall in the Senior / Master 1 race. I felt very confident in my bike’s handling, and never once had the thought that my tires were slowing me down. This was pretty shocking, in hindsight, given the conditions were about as far from ‘mud’ as one could come. Instead of worrying about smashing rocks, I focused on refining my lines, figuring out where I had to recover, and where I had to attack. Without the nagging fear of flatting, I could just have fun racing my bike. I loved it. 

After the race a number of riders walked their bikes to their cars with flats. I rode mine, and I couldn’t say that I paid a high price for that pleasure. Given the course was about as fast as they come (over 28kph average speed fastest lap), I can’t say these are ‘slow conditions only’ tires. I’ve been told TIm Johnson recommends choosing your tires based on your riding style, rather than track conditions. Sure, everyone needs mud tires when it’s muddy, but what about when it’s dry and fast? Perhaps riders who have more corning skill can use file treads and gain some speed on the straights. Perhaps the same rider can gain some time in the corners and work less on the straights with more aggressive tires? The average rider will benefit from having more traction when they want it, which tends to be all the time. The additional volume and overall versatility of the Steilacooms make them a tire I would, and already have recommended to others. At 38mm and surprisingly fast-rolling, they will serve well in the cross races and trail rides too, given they have so much more volume than 33s. For certain, the tires are not UCI-legal, but this is a non-issue for the majority of cyclocross racers in North America. 

But?

As in every aspect of life, there are trade-offs when it comes to performance. The extralight version of the Steilacoom tire should be considered similar to a high quality FMB or Dugast tubular. All these tires use as little material on their sidewalls as possible, which is what affords them extremely supple, energy conserving performance. This is achieved by using very little rubber encasing the threads of the tires. When off-road tires are folded over hard under the rider, the sidewalls take a beating. Eventually, their threads break, and the tires die. Tubulars, being glued on, can be run at very low pressures, which allow them to fold over a lot. This means many riders only get one season, if that out of their tires. The Steilacooms, being tubeless, will not likely be run as low as tubulars. However, if my set-up is any indication, some riders will be able to run them quite low, probably down around 20psi. I will experiment with this when I can on tracks without sharp impacts, and monitor their wear closely, as should any rider taking pressures really low. But bear in mind that as a tubeless tire, they might actually ride a little faster at a given pressure than a tubed tubular, due to the lower hysteretic losses one gets by eliminating the inner tube from the system. I have no data on this, but 27psi in these tires might roll as smoothly as a lower pressure in a tubular. Might. One thing is certain, they ride well in the high 20s, and that’s lower than most have been using in other tubeless CX tires out there.  

Very happy with today’s cyclocross race at Calabogie, the first of our Eastern Ontario series. I’m working on better pacing through the early laps, and trying to race hard through the middle 20 minutes, which I tend to find the hardest. Until I dropped my chain (more of a flexy bike phenomenon than anything else), I was in third and feeling good. @derrickstjohn passed and I couldn’t get to him, but it was closer than I’ve been before. Wheels and tires were fantastic, exactly what I hoped for. Great grip and rolling, and no punctures! Meanwhile a number of tubulars were destroyed. Sad. Looking forward to a solid week of training through Sunday’s Madison. #cyclcrossishere #destroycx #wovenprecisionhandbuilts #compasstires #steilacoom #easternontariocx
A photo posted by Matt Surch Ⓥ (@cyclosomatic) on

I can’t tell you how stoked I am to have a clincher wheelset worth racing now that I have these tires. Keeping up three pairs of tubulars is expensive, time consuming, and a PITA. If riding clinchers means I can preserve my fancy tubulars for the races where I really need them (UCI races), great, I can have fewer tubulars. Yes, it would be cool if 33mm tires like the Steilacooms were available, but the market is so small for such tires right now, I can’t see myself trying to convince Jan to do that. Yes, I’d love to ride awesome tubeless clinchers for UCI races, but how many riders are out there thinking the same? If you are one of them, let us know!

I’ll race these again at the Madison in Renfrew this weekend, and experiment with incrementally lower pressures each lap. Should be a fun experiment under real race conditions, and it might even rain! Come back for more.

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