July 03, 2018
Just 8 weeks 'til cyclocross season! Time is flying. Last week we looked at the pros and cons of tubular, tubeless, and traditional clincher tires for cyclocross racing and training.
Hopefully you've made your selection, so with 8 weeks to go lets take a look at how to maximize your new tires for optimal performance by finding the right tire pressure.
How important is tire pressure for cyclocross? Critical! Katie Compton has said that she can feel the difference just .5 PSI makes in the handling and performance of her race bike! Lower pressures can mean better grip, but only to a point, because too low risks punctures and damaging your rims.
So how do you find the right pressure? A great starting point for setting PSI is the "Helen Wyman" method, used by the multiple time British National Champion and her mechanic Stefan. For tubular tires, they advocate rider weight in pounds, divided by 10, plus 5. So for myself, a 160 lb rider, their formula yields 21 PSI. That's pretty close, I usually start with 25 PSI, then let air out during course inspection, then race at 20-23 PSI, depending on conditions. (For clinchers, Wyman suggests adding 10 PSI instead of 5.)
After using the Wyman method to establish a starting point, are you bouncing over rough terrain or slipping in loose corners? Try lowering the pressure. Are you bottoming out the tire on the rim, or can you feel the tire "folding over" during aggressive cornering? Raise it. Don't be afraid to experiment.
Setting tubular tire pressure
Of the 3 tire types, tubulars offer the ability to run the lowest possible pressures without the risk of pinch flats, so you can be more aggressive. You might even want to bottom out the tire once or twice a lap to squeeze out even more cornering grip. It's possible to get away with this on tubular rims, since they don't have a bead hook to damage, but it's not magic - keep in mind you can still damage the rim.
Setting tubeless tire pressure
Riders with tubeless systems will typically need a bit more pressure than they might run in a tubular, especially for bigger, heavier riders who can create a lot of side load during cornering. Some tubeless tires can "burp" at low pressures - the time to discover this is during training, not racing! You should know the lower limit of your tubeless tire before the first race.
Setting clincher tire pressure
Clincher tires will need the highest PSI of all tire types. Too low and you risk the "snakebite", or "pinch flat" type of puncture - that's why the Wyman tips suggest 5 PSI more than with a tubular tire. As with a tubeless tire, try lower and lower pressures during training until you pinch flat - then you'll know where the limit is for your weight and riding style. Using latex inner tubes can help mitigate some of the downsides of clincher tires with tubes.
Regardless of your tire selection, always start with a course inspection on race day. You may wish to ride slowly, inspecting the course details, and then faster laps at race pace. During those faster laps, it's OK to stop and add or remove air. I recommend carrying a small handheld gauge with you during warmup for this purpose. You might even need to re-adjust prior to your race due to changing weather or terrain.
See you next week when we check in with just 7 weeks to go!
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