How Do I Do The Cyclocross? (Part 4 in a series)
Tires and Tire Pressure
Dave Severn sort of stole my thunder on this topic by asking the question on Facebook, but this is one of the best topics in all of CX to completely nerd out about. There’s a so many types of tires and opinions on what works best. Remember, what works for one rider might very well not work out as well for you. If you have OCD tendencies, this is the CX topic for you to obsess over.
There are three different types of rims and tires used in Cyclocross.
Standard Clinchers are a standard tire with an inner tube and a hook and bead. They are the most common, the easiest to fix should a flat occur, and they have the most options as far as tires go. They are also heavier, have higher rolling resistance, (due to the tire and tube being seperate pieces) and must be run at a higher tire pressure to avoid pinch flatting. The advantage to clinchers is that you only need one (ideally two, so you have spare wheels in case you flat mid-race) wheelsets, and you can switch tires easily for different racing conditions. Plus they can be the cheapest option.
Tubular Tires have a built-in innertube, and are attached to the rim with tubular glue, in a process that is best left to people who have glued tires to rims before. This makes them super complicated to replace should you flat them. They are also the most expensive option. The good news is that it’s more difficult to flat them, because of the different rim shape. You can bottom out a tubular tire and rim, that is, feel the rim itself contact the ground when you hit a bump, and suffer no ill effects, an event that is usually fatal to the tube in a clincher tire. This means you can run Tubulars at insanely tire low pressures, which gives you more traction, as the tire will conform to the ground rather than bounce around. This also works as additional shock absorption. Plus, you can put Stan’s tire sealant in them, both as a prophylactic measure, as well as to seal a small hole after a flat. Plus, tubular rims and tires are lighter than clincher rims, tires, and tubes. Plus, all the Pros use them. But, if you want to have options as to what tread you want to run, you’re going to need to buy more wheels- it’s basically a process that takes a day to properly glue a tire onto a rim. (You don’t have to work on it for the entire day, smart apples, you just have to apply glue to it for a few minutes, let it dry for a few hours, repeat, install tire, let the glue dry.)
Tubeless Tires are tires that don’t use an innertube, as the name would suggest. For best results, you should use them with a rim and tire that are both designed specifically for tubeless, although you can make most rims and tires into a tubeless system. The tubeless system relies on a special valve and rim strip as well as sealant inside the tire to seal the gaps and pinpricks, so there is a measure of flat prevention built into the system. Tubeless MTB tires are pretty much universally used by most riders who race MTB or just go fast, but the narrower CX versions by and large haven’t worked as well, despite what the manufacturers of tubeless tires and rims will tell you. It’s not difficult to find stories of rider’s suffering from the dreaded burp (when a tubeless tire suddenly loses a little air.) While you can run lower tire pressures than you can with clinchers, they are still higher pressure than you can with tubulars, and the chance for race-ending losses of pressure makes the tubeless option a risky choice.
I’m by far not the only person that feels that if you’re even remotely serious about CX, tubulars are the only way to go. The ability to run super low air pressure is a massive increase in performance for your bicycle. A tire at 24psi that will not pinch flat is going to corner, brake, accelerate, and climb better than a tire at 40 or 45 psi that potentially could pinch flat. If you’re skinny, you can run even lower pressures, so you have even more traction.
Last season was my first on tubulars, and there is a bit of a learning curve with them. You should train as well as race on tubulars, so that you get used to how they perform- they are that different. By training on them as well, you can dial in your ideal tire pressures in situations that aren’t a race, and won’t cost you an entry fee by guessing too high or low on your tire pressure. However, they do require more TLC than clinchers, and they are more fragile. You can cut the sidewall on rocks, for instance. Most CX courses in Florida don’t have a lot of rocks, but there are notable exceptions to this- Picnic Island in Tampa for one.
If this is your first season racing CX, you should go with clinchers. I recommend having two sets of wheels at your disposal on race day, so you don’t end up watching your race should you flat. One set should have a Grifo type intermediate tread, and the other is up to you. Personally, I like the speed of a Grifo XS type file tread, particularly on the rear wheel. You might not like the compromise of having relatively little traction, in which case, a set of wet treads is great for your spare set of wheels. Mix and match, trade with your friends, find out what you like best. Personally, I am probably going to race this most of the races this season with a Grifo (intermediate tread) front tire and a Grifo XS (file tread) rear.
What tire pressure you run is based on how much you and your bike weigh, and how you ride your bike. There are 140 pound guys like Jason Guillen who ride like they weigh 180, and there are 220 pound guys who ride like they weigh 160lbs. Obviously there are also 220 pound guys who ride like they weigh 320, too. Basically, for clinchers, you should start at about 40psi front/45psi rear and roll around your practice area a little bit. If you’re bouncing all over the place, take out a little air. If you’re feeling like the rim is going to bottom out, add more pressure. You might want to invest in a digital tire pressure gauge, they are surprisingly inexpensive. You basically want to get the tires hard enough that you don’t pinch flat, but soft enough that you don’t lose any fillings from all the bumps and ruts. What makes the tire pressure question even more complicated is that the perfect pressure changes every week. Temperature, course style, and precipitation are all a factor. You’d want a softer pressure for a course like 2012 Tampa Riverfront, that was all grass and turns, than you would for a course like 2012 Melbourne Day 1, with its long straightaways on smooth dirt roads.
image from Embrocation
- roll fastest on pavement and hard pack
- great in dry sand (and snow!)
- decent traction in dry grass
- not great in wet grass
- bad in mud
- not for the inexperienced cyclist
image from Embrocation
- You must have a tire of this type
- good if not excellent in most conditions
- perfect traction in dry grass
- good traction in wet grass
- rolls slower and wears faster on pavement
image from CX Magazine
- more aggressive tread = more traction
- great in wet grass and some mud (and snow!)
- still provides great (too much?) traction in dry grass
- most rolling resistance
- will wear out if used on road
There are also true mud tires, but I’m not going to discuss them here because you don’t really need them here in Florida. We simply don’t have that much mud. Yes, we have a couple of courses that have one or two mud sections on them, but not enough that the heavier, slower mud tires would help you.
There are obviously many more tire brands than Challenge. Some other tires that are popular in FLCX are Clement (clinchers and tubulars), Michelin (clinchers), Schwalbe (clinchers and tubulars) and Vitoria (clinchers and tubulars). There are also FMB and Dugast hand made tubulars, if you’re feeling really fancy.