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The Noob’s Guide to Bicycle Tire Pressure: If You Want Speed, How Much Already?!

I’ve dedicated a good portion of my writing to this series, I’ve gotta be working on 50,000+ words, and tire pressure will surely be one of the most heated topics I’ve ever covered, but I’m up for the challenge!  Scroll down for the comments section.

I rode my first 16,000 miles at 130 psi, thinking I’m lighter <170 lbs. so I should get less rolling resistance and more speed, right?  Now, if you’re paying attention, you’re thinking, “But my tires are only rated to 125 psi!?” Yeah, so are mine, but if 125 is good, 130 is better! Folks, there’s a reason I’m a recovering drunk – if one is good, a case is just about right (24 is a case – a dozen is a half-case).

On the other hand, I’ve spoken with less knowledgeable noobs than myself who ride between 80 and 90 because the shop told them to and are utterly beside themselves with whether or not they’re at the right pressure…

Well, I’ve decided to do a few experiments and talk with a few people to get a better understanding – and share my thoughts here.

First of all, when we’re talking about speed…and we’ll keep it to clinchers because most of us won’t have a chase car with a few extra wheels in case we flat…you don’t want to be riding on a squishy tire.  First, your weight matters in this equation.  Lighter cyclists can (and should) ride with less pressure in the tires, not more. My butter zone is between 115 & 120 psi. (I ride 23’s).   Any less and I feel like I’m riding through the mud.  That said, I wrote that I had been riding for years at 130…  This was based on the idea that I’d get better rolling resistance.  In reality, while the ride was much harsher at 130, I’ve found little speed difference at 120 but the ride is a lot more enjoyable because minor bumps aren’t so jarring.  What I’ve found is that because the ride is so much more comfortable at 120, I’m faster because I’m not bracing for bumps every thirty feet.  I can just mash the pedals and go.  At 130, every little crack was a jarring to be braced against.

Where weight comes into this is with the compression of the tire while riding.  Now, I picked this little part of the equation up from one of the mechanics at the shop who is a bigger fella, it’s one of those things that makes sense…  The lighter a cyclist is, the less pressure they’ll need in the tires to achieve decent rolling resistance.  The idea is that heavier cyclists are better off with more pressure in the tires because when they go over bumps, their weight will naturally compress the tires more.  In theory, they’ll have the same ride results as a lighter cyclist at 115 or 120 psi.

Where this can get tricky is with wheel integrity.  I use an extremely lightweight aluminum rim.  While the rear wheel is solid, it can be knocked out of true with a good bump when I’m riding between 125 and 130 psi.  Since I dropped to 115-120, I’ve hit some gnarly bumps and pot holes and the wheels didn’t show the impact.  This is splitting hairs a little bit, the heavier duty your rims are the better they’ll take rough roads.  Such is the price of using lightweight equipment.

Next up would be tire width.  The wider the tires, the lower the pressure.  23 mm tires should be run between 115 and 125 psi while 25’s are between 105 and 120.  I don’t know where 28’s fall out because I don’t ride a cyclocross bike (chuckle).

Now, I’ve heard of people riding 23’s as low as 110 and 25’s at 80 psi but I can’t even imagine wanting that cushy of a ride.  By the time you get down to 80 pounds you really are bleeding speed for the softer ride.  We’re not talking about a cushy ride around the block in this post though folks, no indeed.  We’re talking about cruising in a pack, 25 deep at 28 mph, trying to hold on with your teeth!  This is no time for squishy tires or squishy bikes!  So if you want to rocket down the road, check the max pressure reading on the sidewall of your tire and start there.  If you’ve been eating your Wheaties rather than donuts and you’re already light, knock five or ten pounds off of that and you’re good to go.  If you’re heavier (180+), max it out baby.

Don’t, however, do what I did and overfill your tires.  I’m an ex-drunk, I do stupid stuff from time to time – especially when I encounter a situation where “x” is good.  In those cases, “X” plus a little more must be better.  Stupid is as stupid does Forrest.

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