Hey Team!

This week will be a geek episode again! Tires and tire pressure. I’ll start with the research then explain how to figure out your best air pressure!

The latest testing has shown that a wider tire is actually faster than narrower. The days of 700x23cm pumped to 120psi are long gone. Now that we have the ability to test rolling resistance and vibration loss. We learned fairly quickly(2012) that a wider tire is faster. In 2012 though, we only really knew that changing the shape of the contact patch(hence the wider size) was less rolling resistance, we still didn’t know much about air pressures yet. In the last five-eight years we also learned lower air pressure also makes us faster and with a knock on effect of not fatiguing us as fast. There’s two things at play here. 1) the human brain is horrific at interpreting speed and 2) lower air pressure allows for more control, thus we can comfortably go faster. What we interpret as "speed" is really just high frequency vibration. When we pumped our tires to 120psi and everything rattled we felt like we were going fast. Smoother is faster.The analogy i’ve been using to customers is think about driving on the highway in an old pick up truck. 75 mph feels fast. The truck is rattling and vibrating and you feel like you’re going super fast. however, do that same 75mph in a cadillac. The stable smoothed out ride usually ends up with you not even realizing you’re going 75mph. same speed, two completely different feels. Apply that to the bike. a wider tire with lower pressure allows for a smooth stable ride allowing you to go faster. The biggest benefit isn’t even from the increase in speed. By having a more supple ride, you dont fatigue as fast, staying fresher longer. More speed. A wider tire/lower pressure also allows for harder cornering with the improved traction. Again, you can carry more speed into and out of corners, not having to accelerate as hard as often resulting in less fatigue and more speed. For myself, I’m running 700x30c tires, at 71psi front and 73 psi rear at 225 pounds body weight. I saw an increase in speed on my "B" bike, with it being a heavier bike, a slower wheelset and slower tires by swapping to 30’s. The "A" bike has also gotten this upgrade and it’s crazy how much faster it is.

Figuring out your pressure is easy! I have used and swear by the Silca Tire Pressure Calculator. it asks for some specific inputs in a convenient drop down menu style site. I’ll add the link to the bottom of this email. I prefer the silca calculator for one main reason: it gives you the best suggested starting pressure no matter what. Remember my PSA on hookless? Silca asks you to understand the gear you’re running and whether or not you can or can’t run those pressures is up to you to know. While this is scary, I appreciate knowing what my best pressure is regardless. I can make a decision based on tires and such knowing that that is the optimal air pressure. The other key to using the calculator is taking an actual measured width of your tire, not the printed size on the tire. On my wheelset, 28’s measure 29.5mm, and 30’s measure 30.2. In my personal testing, I’ve found the silca pressure to be dead center of a 10psi range. For me meaning i can go down to 65psi and up to 75psi with no loss in performance, and i can make the air pressure choice based on course. Watermelon crit? 68psi, somerville? 72psi.

What I haven’t touched on yet is the tires themselves, rolling resistance and tubeless vs inner tubes. All of these have a huge impact on rolling resistance. Bicyclerollingresistence.com is your best place to see what tires you’d like to try. While the exact rolling resistance won’t translate to outdoor, the order of tires does(the vittoria is still faster than the continental etc.) I’ll speak in broad strokes for this. Tubeless and a latex tube are equal from a rolling resistance standpoint. TPU is next followed by traditional butyl rubber. For speed sake, tubeless or latex is the best bet. TPU is good for weight. butyl is as its been for a hundred years.

Hope this helps with getting your bikes ready to ride outside! Hit up Pop’s for the latest tires!

https://silca.cc/pages/pro-tire-pressure-calculator