Schwalbe Ultremo ZX Clincher Tire
We'll always need tires. While the investment can make a huge difference in riding performance, helping determine comfort, speed, and road grip, tires are relatively cheap and entirely disposable, so if you're not happy with a set, you ride them until they fail and then try something new. Since they're cheap relative to wheels, that makes them almost fun to try out, except for those few times when a tire doesn't work from the moment we try to mount them.
So it is that we tested out the Schwalbe Ultremo ZX. Schwalbe is a relatively new name to us, though it's a fairly old company. Schwalbe, referring to the bird we call a swallow in German, began as a tire company in 1973, though its roots date to 1901 in Germany. The Ultremo ZX is their high-end racing clincher. The claims are that they're light, low in rolling resistance, and long lasting. Schwalbe has a lighter tire, the Ultremo ZLX, coming in at a claimed 160g, but as the weight savings comes at the sacrifice of a breaker belt under the tread, the benefits of which strike us as being outweighed by the costs.
Once we got our hands on the tires, we weighed them. The claimed weight is 195g, which is pretty light these days for race tires. We weighed our pair at 185g and 188g. Variation is expected, but it's unusual for us to find our tires weigh less than claimed. A good start.
The tires feel soft and supple in hand. Schwalbe starts with a rubberized textile fabric, probably not cotton, or they'd be calling attention to it, that is wrapped around bead cores, in this case Kevlar beads, and then coated with a rubber compound. They lay their breaker fabric, in this case what they call their High Definition SpeedGaurd on top of the material, then they lay the tread compounds on top of that. They use three compounds in the tread, which they call their RaceStar Triple Compound. There is a hard rubber compound in the middle, then a slightly harder compound just underneath the center, then a much softer compound on the shoulders. This is their answer to making a tire that, in their opinion not only lasts a long time, but grips well. The yellow stripes are part of the soft rubber section, but not all—it extends past the stripes on both sides.
Installing the tires on our Mavic Open Pro rims was easy. No tools necessary. We also installed them on a set of American Classic wheels, similarly easy. All the web reports we've found on the tires also remark on the ease of installation.
The tires look big on our rims. When we pulled out the calipers, they measured pretty true to size. On our Mavic's, the tire is 23.01mm wide. On the AC's, the tire measures 23.51mm wide. The appearance of extra height is probably due to the stripes and the tall lettering on the sidewalls.
Recommended tire pressure is 115psi for someone weighing 165lbs. We inquired about this. They treat this as a very rough average. Very rough. Lighter people should start with less pressure, heavier, a bit more. We pretty much went with the Michelin tire chart recommendations, which we estimate our pressure should be close to 105psi. Pumped them up and went. But we did let the tires be and rode them down to 70psi on several occasions before getting out the pump again.
We rode the tire in all conditions. Rain, sun, gravel roads, cobblestones, smooth asphalt, concrete, city streets, country lanes, in training, in racing. Over 2,000 miles as of this date.
In terms of that nebulous "feel" experience, the tires felt on the fast side. We tried to figure out a way to quantify how fast, but they pretty much rolled within the range of faster tires on our standard test track. They also seemed to grip fine in turns and in the rain, but it was pretty much as we expected, we didn't go out to push the limits of the tire, and our normal riding didn't reveal any weaknesses on the road adhesion front.
We've only had one flat thusfar, and that probably the result of a glass-strewn road we tackled. Still, after 2,000 miles plus, the tires are looking the worse for wear, with cracks showing in the sidewalls, and faded logos, and what appear to be small chunks taken out of the tread and some pebbles and glass embedded. Representatives from Schwalbe tell us we're probably reaching the limit of the tire's life, though their claim that their breaker fabric does a good job of keeping embedded sharp objects from piercing through the tire appear to be true.
We looked around for rolling resistance data on the Ultremo ZX. Bike Tech Review doesn't have any. Roues Artisanales has old tires from too long ago. The only test we could find was a test by Tour magazine out of Germany last year. Tour has a well-earned reputation for thorough testing, one that Velo (formerly VeloNews) seems to be trying to emulate. Tour put their review behind a pay wall, but Continental Tire had the article translated into English and posted it to their site. Conti' did it because their tire "won" the test, but the Ultremo, predecessor to the Ultremo ZX, took a strong second, based on the tires wet weather grip (they test-rode the tires in the rain on a 12.5-meter radius turn, the tire held at 32.9kph), sharing top-rated puncture protection and top-rated light weight. It wasn't at the top of the low rolling resistance ranking, but The ZX is supposed to reduce rolling resistance by 15% over the old Ultremo, which improves it considerably. If the 15% is applied to the results Tour obtained, it becomes a very competitive tire on rolling resistance.
Interestingly, in subjective evaluations, the old Ultremo was the best-feeling tire of the test. Tour's testers found it rode very well, giving the feeling of lots of rubber on the road, and it did great in turns, making the transition from straight to turning very predictable and with great grip and it even lost grip slowly at the end of its range, so you could possibly correct if there's an error in your line. As the newer ZX is supposed to ride even better, the testers would probably love it.
We're not sensitive enough to feel to come to the subjective conclusions that Tour testers had. That written, we were very pleased with the Schwalbe Ultremo ZX. It rode well, seemed nearly impervious to flats, and is still going strong, even as the tire is slowly revealing we've taken it to the end of its useful life span.