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PSI for road bike tires?

esmorin2011-04-08 23:24:11 +0000 #1
So I am having tire floor pump issues.

I bought a Topeak Joe Blow, but couldn't pump my thin bike tires. I asked a guy at a LBS and he said I needed a pump with a smaller air cylinder.

So, I bought a Specialized pump at another LBS today. This one has a narrower pump cylinder, and is much easier to pump. However - my tires are now rock hard (as they should be), but the pump says that I am at 60 PSI. The recommended PSI on the tire says 117. I even check with the Joe Blow, and that gauge also says that the tires are at 60 PSI.

So now I am stumped. I got a pump that worked, and my tires feel right, but the dial says that I am at half the PSI that I should be. Should I keep pumping until I am in that 110-115 range? Will I blow out my tire? Am I neglecting to notice something else?

Has anyone else had pump/tire issues?
aicabsolut2011-04-08 23:28:39 +0000 #2
Yes, keep pumping to around 110, give or take some depending on your weight. It is very difficult to determine road bike tire pressure by feel with your hand. Use the gauge.

However.....when you pump up the tire, is the needle moving up high and then falling back down? Perhaps you don't have a good seal in the pump and aren't getting an accurate reading. You might also hear air leaking from the valve if this is the case. I doubt that the same thing would happen with both pumps, though.
nscrbug2011-04-08 23:38:38 +0000 #3
I'm confused...

I have a Topeak Joe Blow pump and have never had a problem pumping my road bike tires. I don't understand why you were told that you needed a pump with a smaller cylinder...doesn't make any sense to me. I pump my tires up to 115psi before every ride, and DH pumps his to 120...all using our Joe Blow pump...great pump, BTW.

Are you sure that you are turning the little threaded tip on the presta valve all the way to the top of the valve before inserting the pump valve on?
esmorin2011-04-08 23:46:11 +0000 #4
nscrbug, yes, I am unscrewing that little threaded part on the presta valve. And the narrow vs wider pump cyclinder was explained to me this way at the LBS: a large cylinder means that you trying to push a higher volume of air into the tube in one pump, which makes it harder. A narrower cylinder means that you are pushing less air in one pump. So, it would take a higher number of pumps, but the actual pumping would be easier. He was telling me that it's some physics principle. it sounded good to me! And, I have to say that my narrower specialized pump IS way easier to pump.

aicabsolut, at first the needle was going up and then back down, and I resealed the pump and it stopped doing that. And the tube was definitely getting fuller. I was nervous about going any higher than 60, because the tires felt so firm.

So, you ladies are saying I should trust the dial? it seems really unlikely that BOTH my pumps -bought at different shops- would be broken or inaccurate to the exact same PSI - right?
Possegal2011-04-09 00:56:42 +0000 #5
I remember calling my brother in law when I was first putting air in my bike's tires and saying to him - should it really feel like if I put more air in these things may explode? And he said yes.

So I just kept putting air in until the gauge read correctly. And nothing exploded.

You are not alone - I laugh now, but initially I kept thinking you need a dang PhD to put air in your tires. Then I realized I have one, so I just soldiered on.
Biciclista2011-04-09 00:21:38 +0000 #6
depending on your weight you don't need 115 pounds of pressure. Some tires come with a graph, and if you weigh about 120 pounds they tend to show you need more like 90 pounds, much easier to pump to that level. 60 sounds low unless they are larger (wider) tires.
ridebikeme2011-04-09 01:33:48 +0000 #7
I am VERY confused. We use the Jow Blow pumps in the shop, and have for many years... without any problems. Although we own an air compressor in the shop, we pump everything by hand. So you can imagine how many times the pumps are used. We also have been selling these pumps for many years, and have never heard of any issues.

Although this sounds like a stupid question, was the employee that you spoke with at your LBS familiar with the Joe Blow pumps? Even if you had a problem with yours, there are repairs kits available to replace any of the working parts.

At any rate, good luck with your new pump.
Eden2011-04-09 00:32:39 +0000 #8
Another person who thinks the advice about Topeak pumps is questionable.... We use ours to get TT tires up to 140 - and even 105lbs of me can do that....

But anyway - I think you are fine, you're just not used to road bike tires. They *should* be hard - hard enough that your thumb cannot dent them, hard enough so that your entire body weight on the bike just starts to deform them a little. It does depend on your body weight and the psi ratings of your tires and rims just how far or how low you can go - generally you'll see a range printed on the tires. If you are light the lower end of the range, heavy the upper end.



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