Upside is they were free. Downside is that free doesn't actually mean free. Firstly I had to buy a new freehub because these were for a campy drivetrain. So there's $80. Secondly, tubular tires are expensive. Those MXPs I was planning on using are $130 a piece for the tubular version (at retail, but still that's over $100 a tire). And you can't change them easily so whatever you pick has to work for all the races. So while I like the tread design of the MXP, with the nice chunky cornering knobs, the price had me looking at other options. Challenge and vittoria for example have $100 msrp tubulars so that's what I was looking at.
The standard multi-purpose cyclocross tread is the "grifo." That's the name of Challenge's tire but there are other brands with a nearly identical tread. It looks like this:
I just don't like it though. Those little dots and half moons just seem kind of ineffective as cornering knobs. The MXP is an update to that tread with more substantial side knobs. I really like these and didn't want to go backward to the old version:
But like I said, pricey. Challenge has a few other tires with more side knob though. There's the Limus mud tire, but mud tires all the time are generally not ideal, as they roll slower on hardpack and grass. The chicane file tread uses the same edge knobs with a slick center. Given the amount of grass we race on these days, with two on a golf course and two more at big sky brewing, at least one of these, as a rear, was something I strongly considered
However, I already had the happy medium, and my wheels came with a grifo-xs file tread on the rear, so it seemed like having three file treads and just swapping one for another might not be the best course of action. The XS worked well out at the golf course, and those little half moons and dots provided more grip than I expected, but I wanted to play it safe for the end of the season, especially since it could get a little wet and slick, and the old thunder is pretty rough and loose.
That left one more tire from Challenge, the Baby Limus:
The baby limus is a lower profile version of the limus mud tire. It keeps the same side knobs, but has shorter center and intermediate knobs to roll faster. They claim it is good as an intermediate that can handle mud, and itt seemed like a good way to maximize cornering grip while still getting a fairly fast rolling tread. Plus Toby and Dave are on these so I can't have made too bad of a choice.
I decided to glue them myself, and it would up not being too bad. Key thing is get those wheels CLEAN. As clean as I thought it needed to be, it wasn't good enough on the first try. I must have had some goo gone residue still on the wheel and the glue didn't stick in a few places. So get some acetone and scotch brite and clean rags and scrub the hell out of it before your first layer of glue goes on. Anyhow, my tires haven't come off I guess I did it well enough. I'll probably make a tire-gluing post, but does anyone really want advice from someone who's only done it once?
So how are they? Pretty good. I've raced with the old grifo xs rear and a baby limus front twice at the golf course, but only once last week at old thunder with a baby limus front and rear, so need to spend more time on them. The big things is that there's a lot of grip and they seem to be fast and they like less pressure than a clincher. I was even cornering faster than a few really good bike handlers out there, and making up time on Rob around the lumpy hairpins (but going too slow in a few other spots). Up the steep bank ride-up, I could pedal as hard as I wanted and the rear hooked up and pushed me forward. The happy medium was slipping in the same situation. I also got in a bit of a slide on some leaves and was able to catch it and stay upright, so you can slide a bit without hitting the deck and that gives you confidence to push.
The thing I have not quite figured out is pressure. At the golf course, I ran 32psi the first time, and went up to 34 in the front the second time out because I kept hitting rim on the sharp edges going in and out of the sand. Tubulars are more tolerant of bottoming out than a clincher, but the consequences of a flat are greater so it's something I'm trying to avoid. The golf course is smooth and grass is grippy, so out there higher pressure is fine and lowers rolling resistance. Old thunder, however, is not smooth. You want to be right on the edge of as low as it will go to absorb all those lumps, but also keep enough air in them for cushion against the rocks. I was going to start at around 30-32 but Alex sent me out on course to practice at more like 27. I would up racing at 27f, 29r, and it was more than enough. Previously I've used a higher front to rear difference. With the old clinchers, 33/39 was the split I used. But in cornering and braking I'm starting to wonder if i really want the rear that much higher, so I'm trying to keep them closer. On the MTB I now only have a 1 psi difference front to rear. And then 33 psi was the lowest I'd go in the front with a clincher, but in a tubular of the same size that is way too firm. I'm not entirely sure what the mechanism there is that makes the tubular feel the same at a lower pressure.
Personally I worry more about how the tires feel than what the specific number is, and then use the gauge to be able to set them in the same place every time. What I look for is that feeling where the tire is grippy and compliant, but not flopping around or bottoming out too often. That goes for cross and mtb. On the road I am a little less picky and just go by the gauge on the pump, but a bigger tire at a lower pressure is more sensitive to small changes. 5 psi in a 23 would be hard to notice, but 5psi in a mountain bike tire is a huge difference. So, get yourself a good digital gauge (I recommend the topeak d2), and try things out.
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