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The Tire Pressure Revolution

Posted April 06, 2015 06:43PM by Skye in the Cycling Forum

Skye
Skye Skye Nott
@TheStaminist   Skye Nott Staminist.com
Location: Vancouver, Canada
Joined: 2 years ago   Posts: 495

Really interesting article by Jan Heine over at Bicycle Quarterly about the rolling resistance for tires with various pressures.

The common wisdom is that higher pressure and narrower tires offer less rolling resistance, but their tests showed a surprising result that flies in the face of a lot of "pro" advice over the last few decades: Tire pressure has almost no effect on a tire's speed

The second half of the common wisdom about narrower tires would seem to be contradicted by the pro peloton moving from 23mm to 25mm tires lately. I doubt they would move to wider tires if they were slower. You would think the extra rotational weight would make a difference, but maybe the increased comfort and puncture resistance are worth it. However, during some race interviews at a Middle Eastern event recently, many pros were still running 140 psi. Surprisingly, many did not know their tire pressure; they just leave it up to their mechanics. Of course, latex tubes do lose pressure so if it's a particularly long stage, it will be quite a bit lower at the end of the day, and the roads in that part of the world tend to be brand new and as smooth as billiard tables.

"The variations are much smaller and hard to predict – they depend on the tire as much as on the road surface – so the take-home message is that tire pressure doesn’t matter enough to worry about it. Inflate your tires enough that they don’t collapse when you corner at speed, and you have found the optimum pressure for your tires. It’s that simple."

Read the full article here

So what do you think? Have you changed to wider tires and lower pressure? Have you felt a difference in rolling resistance or comfort?

Webmaster - Staminist.com

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tire pressure speed testing.jpg

Skye
Skye Skye Nott
@TheStaminist   Skye Nott Staminist.com
Location: Vancouver, Canada
Joined: 2 years ago   Posts: 495

Listed to this recently and it reminded me that I was experimenting with dropping my pressure, and that for some reason I stopped around 90-100psi...

CyclingTips Podcast, Episode 9: Rethinking road bike tire sizes and pressures

Can’t quite allow yourself to believe that a 30mm tire at 70psi might be faster than a 23mm one at 100psi? Okay, but do yourself a favour and have a listen to what Poertner and Heine say about it — and keep an open mind, because what you feel, and what the numbers tell you, don’t always go hand in hand.



Based on Frank Berto's tire pressure chart, I've started running my Vittoria Corsa 25c tires at 80 psi front and 88 psi rear

No issues so far (ie pinch flats) and it smooths out cracked and rough pavement considerably

Vancouver, Canada 5 2

Sep 12, 2016
1:26 pm

290 m
29.8 km

1:06:02
27.1 km/h

 
195 W




Note in the chart below the weight listed is per wheel. I've seen some people extend the chart to the right, but that shouldn't be necessary. To get a really accurate number you should balance on the bike in your normal position (ie on the hoods) with a scale under each wheel to get a % difference in weight distribution front to rear, but I just guessed something between 50/50 and 45/55 (more weight & therefore more pressure in the rear obviously)

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berto-tire-pressure-chart.jpg
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