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

October 2014
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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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10 Comments

  1. I weight exactly 178 right now at 6’1.5″ tall. So I’m not fat, but I could be lighter. The year I rode 4000 miles I got down to 163. My girlfriend has threatened that I should not do that. But I once rode at 80 PSI by accident and SUFFERED through 35 miles in March with my buddies whose tires were all properly inflated. I now ride between 120 and 130. So according to your suggestions that sounds about right. I’m also built of rubber, clay and some carbon, Cheetos, a coupla beers a week and meat when it’s served.

    • bgddyjim says:

      This post was inspired by a friend of my wife’s who came to me just beside herself wondering whether or not 80 psi was enough for doing a sprint triathlon… I can only imagine how tough that ride was. Thank you for adding your experience to the discussion.

  2. PedalWORKS says:

    I prefer the 15% tire drop method (http://www.dorkypantsr.us/bike-tire-pressure-calculator.html) that takes into account the rider’s weight, the bike weight, tire size and front/rear weight distribution. This is designed to provide the ideal pressure for cornering and comfort. For me that means 75 front and 116 rear with a 40/60% weight distribution ration on 23s.

  3. My mind immediately goes to the first time I was prepping for a century, going over my bike out in the garage the night before the ride. It was clean, lubed, and I pumped my tires beyond the max pressure so I could go faster the next day. I went inside the house with a smug smile of satisfaction, certain I was ready for a fast ride the next day.

    I thought someone fired a gun outside in my garage… twice.

    Oops.

    I can’t tell how many times I have heard that same sound in the parking lot before a lot of organized ride since then.. and I laugh.

  4. I generally am comfortable with 120

  5. dagowop says:

    I’ve been flirting with different pressures lately and I completely agree with your assessment of us heavier riders. When I was at low pressures (90s) my wheel got banged up badly. My earlier rides were 110-120 and my wheels held up like champs.

  6. my1sttrirace says:

    I’m about 185 and normally run 100-110. If it is a shorter race maybe up to 120. The risk of over inflation in Triathlon is a real thing. If you sit in a transition area on a hot day you can hear the tubes pop one by one.

  7. […] other day I wrote a post about my experience with tire pressure. As a summation, I’ve always maxed out the pressure figuring I was getting […]

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