Cyclocross tire choices
Different kinds of bike nerds obsess about different things these days. Road riders can talk about their wattage for hours. Mountain bikers can’t seem to shut up about wheel size. Cyclocross riders, having settled the disc brake discussion now give their full attention to their other favorite topic: Tires.
Forget carbon fiber. The real miracle material for cross bikes is rubber. Pick the right tires, and your bike will hook up in corners and shed sticky mud. Choose poorly and you’ll slide through that same corner or get bogged down by mud-packed tread.
In cyclocross, you’ll be obsessing about tire choices all the time. Most likely, you’ll have multiple sets of tires. You’ll have tires for dry, hard-packed courses. Tires for soft, muddy conditions. Puncture-resistant road tires for doing the work-week commute. There’s a lot of nuance to all of this, so here’s a little guide for all of your considerations:
Foldable tires use Kevlar thread instead of steel wire in the bead
Clincher tires are where we’ll start. When viewed from head on, clinchers are shaped like a “U” and have wire or Kevlar edges (called “beads”) that hook under the edge of the rim and hold the tire in place with an inner tube inside. The easiest tire choice here has to do with those beads. A tire that comes folded up in a box has lightweight Kevlar beads, and a tire that holds its round shape on the showroom wall has beads made from steel wire. Pick a folding tire instead of the cheaper steel beaded version and you can typically save a half pound of weight. For cyclocross, standard clincher tires give you the widest price and performance range, but have some big drawbacks. Clinchers are usually the heaviest option. They require you to run the highest air pressure of all the different tire styles (which makes traction not so good). Lastly, clinchers can suffer the most flats (inner tube pinches, tube cuts from exposed spoke eyelets, punctures from debris in the tread).
The same tire, set up tubeless (with sealant) or with an inner tube.
Tubeless tire sealant bubbles around the edge, sealing the air in.
If you’re comfortable with the idea of clinchers, then tubeless clinchers should be easy to wrap your brain around. Tubeless tires are possible when tires, rims, and rim strips (the tape that protects the inner tube from the spoke holes) are made to exacting tolerances that eliminate the need for an inner tube to keep the air inside. Liquid sealant is used to keep these types of tires from seeping minute amounts of air, but impermeable tire casing and rim strips do most of the work here. Switch from regular clinchers to a tubeless set-up and you can typically reduce your air pressure by 5 to 10 p.s.i. (with no tube to get pinched), which will increase your traction significantly. The tubeless liquid sealant will also work to seal up small thorn and glass punctures. Seems like tubeless tires would be lighter than a standard clincher, but they’re not. Liquid sealant weight replaces the weight of an inner tube, and tubeless-ready tires and rim strips usually weigh slightly more than their conventional counterparts.
Tubular (Sew-Up) tire and a tubular rim
Tubular tires and sew-up tires are different names for the same thing. The oldest type of pneumatic tire, sew-ups are typically made with the casing actually sewn together around an inner tube (except for the Tufo brand, which makes their sew-ups hold air without using an inner tube). This all-in-one tubular tire is then glued onto a tubular specific rim. Tubular tires have the best ride “feel” because the sidewalls are usually more supple and squish around conforming to the ground more readily than clinchers. By eliminating the need for wire or Kevlar beads and the hooked clincher rim walls, tubular tires and wheels will be your lightest option. If you run sew-ups you can also run the lowest tire pressures, usually 20 p.s.i. lower than a comparable clincher. Tubular tires and rims aren’t always the most expensive option, but they usually are. If you are going to spend the money for carbon fiber wheels, the smart choice is to get them Tubular style so you get the lightest weight for your money, and have the best durability during mishaps (if you suffer a flat, the tire will stay in place and won’t expose rim edges to damage while you try to stop). The biggest drawbacks to running tubulars are added expense (get a flat and you’re replacing a whole tire, not just a tube), and added work (properly gluing a sew-up takes time and can be messy).
Tire styles aside, remember that air pressure dictates how your tires perform (rim width can be a consideration too, but no time for that today). Go too low with your air pressure and your bike will wash out in turns, or bottom out on bumps causing rim damage and flats. Tire pressure that’s too high will keep you bouncing off the ground, losing traction instead of digging in.
File tread, dry condtion knobby, multi condition, mud tire.
Lastly, you’ve got tread design to consider. File tread tires (most with shallow, tightly-packed diamond-shaped bumps) are typically the choice for hard packed dirt and dry grassy cyclocross conditions. You can expect slightly taller knobs along the edge of these treads to keep you from sliding out in corners. If off-road conditions are a little softer and you need better traction than file treads, a good multi-purpose tire will have small knobs placed tightly together (sometimes nearly continuous down the center of the tire). These tires work great under most conditions, but become nearly unrideable in sticky mud. A good mud tire will have tall widely-spaced knobs that will dig into the soft surface but will (at least in theory) shed the mud from between its knobs as the tire rotates. My advice: if you feel limited by your handling skills and traction, go with more aggressive tread. If you have great balance and handling but still feel slow, go with shallower tread and lighter-weight options.
If you get this tire thing all figured out, don’t worry. You can still be a cyclocross nerd. You’ll just have to start obsessing about Belgian beer.