Tire Pressure

I'll join the "never run max pressure" chorus....because (hrrmph) it is right :)

Seriously. If you won't believe Sheldon Brown, try the guys over ad Road Bike Rider.

You want your tires to have enough pressure to avoid pinch flats and no more. For most riders (and they're basing their logic on avg male weights) 90-95 is plenty.

If you run a high pressure, your bike will bounce over little bumps (oh, like say chip seal). You get the impression that you're moving, but, in reality, your wasting energy bouncing up and down instead of rolling forward.

If you run a lower pressure, your tire can deform around those small bumps. You don't lose energy bouncing up and down and you get the side benefit of a more comfortable ride.

The Road Bike Rider guys will also say you're less prone to puncture flats if your tires can deflect around some of the road debris. If the tire cannot deflect, the glass will go through the casing.

Hmmm... riding at lower pressure seems to make sense. I've always done 100-110 psi, but I am soooooooo flat prone. True the choices of where I have to ride suck and I end up on roads that have lots of crap on the side. But I ride with DH most of the time and I am always the one with the flat. I might try the 90-95 psi and see if I could ride a few weeks without a flat!

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Originally Posted by tctrek

Hmmm... riding at lower pressure seems to make sense. I've always done 100-110 psi, but I am soooooooo flat prone. True the choices of where I have to ride suck and I end up on roads that have lots of crap on the side. But I ride with DH most of the time and I am always the one with the flat. I might try the 90-95 psi and see if I could ride a few weeks without a flat!

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I also got to thinking - it might make a difference depending on the brand of tire. I ride Conti's and they seem to have a rather soft rubber in contrast to, say, Michelins. So, maybe my 120PSI is similar to a 100PSI Michelin in terms of comfort and handle-ability...? But, I'm probably going to lower my PSI because the roads are hot & heat increases tire pressure.

I've been riding 100PSI on any tire I put on my bike. I seldom have flats. When I do, I have 2 new tubes in my seat bag along with my bike tools. Usually I give my flat tire to a friend who will use it on his rides. I'm too lazy to fix a tube. :)

I do suggest that you always carry 2 tubes with you. Also, if you put "baby powder" on them, it will make it easier to put on the rim.

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Originally Posted by indysteel

I have never had a flat of any kind. I guess I've been lucky thus far.

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Wow! I want your tires! What are you using?

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Originally Posted by redrhodie

Drift--I patched a flat a couple of weeks ago, and it (the patch) failed this week. What did I do wrong? I used a self stick patch, and sanded the tube lightly, as per the instructions. The hole was on a seam, which is where the air ended up escaping from under the patch. Should I have sanded more, or used another kind of patch?

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A few years ago the owner of my LBS sold me some of those self-stick patches, saying they were fantastic. Most people around here, including him, are primarily mountain bikers. I used one on my road bike, and it failed. Tried a few times, and they always failed the same way. The sticky part isn't strong enough, and the air (at road bike tire pressures) forces a path out to the edge. It just creeps along, following the path of least resistance. I don't think you did anything wrong - and it chose the seam to travel along, as the easiest path, but I'm pretty sure it still would have failed.

I haven't used them in 10 years, so maybe they've been improved, but those things really should be labeled with a maximum suggested pressure, in my opinion. Give me the old kind (with the glue that sometimes evaporates out of the sealed tube :rolleyes:) any day! I think I have the self-stick kind in my mtb seat bag, but never again on the roadie.

Does the "never inflate to max" apply to tubeless tires too?

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Originally Posted by makbike

Does the "never inflate to max" apply to tubeless tires too?

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even more so, I believe. and they run at much lower pressures. I was a 115 - 120 psi on tube tires and 90 - 95 on tubeless.

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Originally Posted by Skierchickie

Give me the old kind (with the glue that sometimes evaporates out of the sealed tube :rolleyes:)

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drifting...

You raise an interesting point. With the rubber cement, it's immediately obvious when it's gotten so old that it's dried up. With the self-stick patches, you don't know until you go to use one. Or you wind up discarding them just because a certain amount of time has passed and they could be stale.

Yeah... I guess if my second spare tube has failed, either my riding buddies have already left or they'll be willing to wait an extra 90 seconds or so for the glue to dry, even though it does seem like fer-frickin'-EVER even when you're doing it at home with no time pressure. :p

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Originally Posted by Skierchickie

Wow! I want your tires! What are you using?

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I use Vittoria Rubino Pros.

I have a friend who sent me a bunch or articles showing that lower psi is better than high psi. There is no measurable increase in rolling resistance but your ride is smoother and more comfortable. In fact lower pressure is better for when you hit bumps, because your tires roll over them more easily so your momentum keeps going forward instead of being interrupted by the bump. If I can find them I'll post the articles here, but I have to warn everyone that they will make your eyes glaze over -- it's very dry reading.

Anyway, I used to keep my tires at 120 psi. I agreed to experiment with lower pressure and I'm averaging the same speed at 110 psi. One of these days I will drop it to 100 psi and I won't be surprised if it makes no difference in speed. I also mentioned the experiment to the mechanic at the LBS and he said he wouldn't go above 100.

I'd think you'd need a power meter and laboratory conditions to really know the difference. Most everyone I know says they can feel the difference in rolling resistance - myself included - but of course that's subjective, even for individuals using a power meter outside.

But it's well known that higher tire pressure always increases fuel efficiency in cars. There's just a tradeoff in traction on imperfect roads, that becomes more apparent the worse the road gets.

I would think that the theory is no different for general road riding than it is for racing or mountain bike riding - the smoother the road surface and the better the traction, the higher the pressure should be for best efficiency. There's never any "one size fits all" for tire pressure. It's just that paved roads are more uniform than unpaved trails.

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Originally Posted by OakLeaf

I'd think you'd need a power meter and laboratory conditions to really know the difference. Most everyone I know says they can feel the difference in rolling resistance - myself included - but of course that's subjective, even for individuals using a power meter outside.

But it's well known that higher tire pressure always increases fuel efficiency in cars. There's just a tradeoff in traction on imperfect roads, that becomes more apparent the worse the road gets.

I would think that the theory is no different for general road riding than it is for racing or mountain bike riding - the smoother the road surface and the better the traction, the higher the pressure should be for best efficiency. There's never any "one size fits all" for tire pressure. It's just that paved roads are more uniform than unpaved trails.

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Yes I thought the same thing but my friend is a persistent statistician. And really, I've actually tried it and am riding the same speed without working harder.

So, I ran lower pressure today, 108 instead of 118, and I felt like my brake was rubbing. I actually stopped and checked to see if my brake was rubbing, then I remembered it was the tires.

Hard to say if I was any slower. I don't use a computer, and although my time was a little off, I did get a few more red lights than usual. Maybe that was because I was slower. Eh, I'm going back to 118. I didn't like how it felt.

I'm with Red. I keep my tires at 120 and I have had 2 flats in 10 years. Generally, the roads here are OK; no chip seal. I do feel the bumps, but, to me, it's part of riding. I also ride Contis, and I've never seen anything about 120 being "dangerous." My DH has different Contis that are actually rated up to 135, which is what he uses.

While I stand amazed at the depth of TE knowledge and the number of women with strong technical degrees, unless one of you must-run-high-pressure people fess up to not being lawyers, but, instead are physicists or mechanical engineers....well, one last time for the masses (like the 100 pound woman I met who has been struggling to get her tires up to 135 pounds when she needs only 90)

Here's Michelin's guide:
http://www.michelinbicycletire.com/m...rpressure.view

And, the latest Jim Langely blog where he tells a reader named Pam (ok, fess up which one of you sent the question :rolleyes:) that at 220 pounds she'll need more than he and then references the Bicycle Quarterly article:
http://jimlangley.blogspot.com/2010/...nder-best.html