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Back 11.12.2018

Talking Tire Pressure for Cyclocross and Gravel

Zipp engineering technician Lewis Henrickson in action on the cyclocross course. Photo by Kent Baumgart

Quarq TyreWiz Proves Useful for Zipp Engineering Tech Looking to Dial in Pressure

Tire pressure matters. In June, we interviewed triathlete and Zipp design engineer Ben Waite about tire pressure for road riding. Now we chat with cyclocross racer and Zipp engineering technician Lewis Henrickson about tire pressure for CX and gravel.

Henrickson fell in love with cyclocross soon after discovering cycling. Growing up playing football and hockey in Michigan, he embraced cold weather and rough and tumble physical challenges. So it’s little wonder he was drawn to cyclocross racing and gravel riding. At Zipp, Henrickson works with Zipp’s engineering team developing new wheels. The team started using Quarq’s TyreWiz, a device that measures and displays real time tire pressure as you’re riding, in its product testing.

INTERVIEW ON TIRE PRESSURE FOR ON-PAVEMENT ROAD RIDING

Henrickson has been pairing TyreWiz with Zipp 202 Firecrest Tubulars (for cyclocross) and 202 Firecrest Tubeless (for gravel). Here’s what he’s learned:

What were your first impressions of TyreWiz?
When I first heard about it, I thought why do I need this to know what pressure I’m riding? I have a pump. You think you know after so many years; ‘I like 100PSI for road, always ride 100PSI for road.’ For gravel and cross it’s a little bit more experimental with all the different conditions. Guestimating how much air you let out or if you have to let any out. When I started using TyreWiz, that’s where it started changing the game. You use a different pump, you’re going to get a different reading. That can be pretty huge. When you’re using TyreWiz, you always know exactly what pressure you’re going to.

Many times you go on a ride and you realize this is too much pressure, I want to let out a little bit of air. You can look at your phone or Garmin and get a live reading of how much air you’re letting out. You start to thinking, ‘I rode this road and dropped my pressure down, so next ride I’m going to start out at this pressure.’

How much thought do you put into tire pressure for cyclocross?
For cyclocross, pressure is huge—1 or 2 PSI (0.069 to 0.114 bar) one way or another helps determine your traction. The course could be bone dry for your warm-up laps. By the time your race comes, everything could be super slick out there. The ruts are getting dug in. The corners are getting ripped up. So, if you’re able to get out there with TyreWiz, you can do some fine tuning, such as ‘I’m going to dial it down a little bit before the race.’ Then you just look and see exactly what your pressure is, and you can duplicate that with your pit bike. After the race, you can write down the conditions and record what pressure you rode to keep a log of what you’ve done.

Have there been races where you realized you picked the wrong pressure and didn’t get the traction you need? Or, conversely, you knew you hit the ideal pressure and were gaining on people in tough conditions?
When you start racing, you worry you aren’t putting enough pressure in. You usually go on the higher side, and you’re getting bounced all over. You learn and adjust it and find that sweet spot for you. You can tell on a lot of courses. On a technical course with a lot of turns and a rock section or root sections, you’re just gaining on guys with the proper pressure. You’re doing less work than they are, too.

What pressures do you use for cyclocross?
I’m about 160 pounds (72.6 kilograms) and ride tubular cyclocross tires with a high TPI (threads per inch) for a more supple ride. I’ll start with 30 PSI whatever the conditions, and I’ll do a practice lap and gauge it from there. If it’s a dry hard packed course I’ll go to 27 (1.86 bar). If it’s muddy, I’ll get down to 23 (1.59 bar). But you definitely don’t want to get down too low to preserve impact protection for wheels.

Whether it’s for cyclocross or gravel, what pressure considerations do you make for cold-weather (below freezing) riding?
If you’re commuting or going on a long ride, you’re probably going to fill your tires in the house. It’s 67 degrees (19 Celsius) or wherever you have it set, and then you’re going outside in 30 degree (-1 Celsius) weather. If you have TyreWiz, just fill up your tires and put your bike outside and then just watch. You can just sit inside looking at your phone and see live data that you dropped 5PSI or something. You can correct that before you go out on the ride.

What’s the coldest temperatures you train in?
Freezing (32 degrees Fahrenheit, 0 Celsius)! Anything below that, it’s trainer weather. Sadly, I think all the years of playing pond hockey for hours on end and getting frostnip have made my hands, and feet pretty weak against the cold.

What has been your experience using TyreWiz on tubeless tires for gravel riding or cyclocross training?
That’s what I’ve used it on mostly… As you get into wide rims and tires and all these different shapes, you really start thinking about being more adventurous with pressure. If I drop pressure is it going to be squishy? Is it going to be more comfortable? I run tubeless on gravel exclusively and for cyclocross training. For my training, I’ll leave the Zipp office with 40PSI (2.76 bar) and ride on roads over to the CX course at the IndyCyloplex a few miles away. Then I’ll let some air out so I’m not bouncing all over. Before I leave sometimes I’ll whip out my minipump and put a little extra air in for the way back since it’s all paved.

Any final advice for ‘cross and gravel riders looking to learn more about what tire pressure works best for them?
When you’re deciding what PSI to start with, definitely default with either the rim or tire spec. I always go higher with pressure and then work my way down. I’ve found it to be easier that way. Let out a little bit of air and see how it feels and go from there.

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