Need some help concerning the Tyre Pressure
 

Hey people,

I want to start off with mentioning that I searched the forums but couldn't find anything suitable that answered my questions/thoughts.

Last year I bought a Felt S22 (Triathlon/TT bike) mainly for future Iron Man distance triathlons and to train myself in/getting used to stay in an aero position for 180km. I took some rides with it in the fall never really thinking about the tyre pressure, which I actually never have done with my road bikes... I have always pumped them til' I feel they are really hard.

But today that changed, I ordered a digital gauge last week that I received today so felt on the tyres and inflated them til' they were hard as usual(meaning each pump = pretty tough). Took my gauge, checked the pressure which gave me 54.3psi on the front and 55.9psi on the rear. Knowing the tyres I use (vittoria Zaffiro) say the min. pressure should be 100psi and never over 140psi (must be hell of a bumpy ride with 140 on mediocre roads?). At this moment my jaws hit the ground, the tyres are hard, I doubled checked the pressure a gazillion times.

I mean it feels like each time I press the pump to inflate I'm waiting to become deaf out of a mad tyre explosion (at 55psi :lol:). So am I just a rookie with the topic 'tyre pressure' that have been riding on a bogus pressure for a while?

The digital gauge I use is:
http://www.chainreactioncycles.com/M...?ModelID=51403
The readings are nearly perfect each time meaning the difference is at most +/-0.2psi

Waiting for replies!
Thanks in advance.

What kind of pump are you using? Some of the small frame pumps can get pretty difficult to pump. A floor pump with built in gauge works better.

I have something like this:

http://img.shoppingnexus.com/product...-pump-5610.jpg

It is much easier to pump than my small pump and the built in gauge makes it a breeze to get the right pressure.

As far as the "feel" goes, I checked my wife's hybrid today and it felt pretty hard, but when I put the pump to it it measured only 35psi and I pumped it to the 85psi recommended pressure.

It's possible your gauge is bad but I'd be more apt to assume that if it was a gauge on a pump. If you are pumping with a poor pump or a mtn bike pump it's not odd that it's hard to get up to pressure. 100psi is indeed pretty hard. odds are you have been riding at a low pressure.

How much do you weigh? I weigh 175 and at 55psi my tires would visibly deform when I am on my bike.

Don't judge inflation by feeling the tire. Deflection of the tire while loaded is a good check for a drastically broken gauge but in general....just use the gauge.

Toss the guage. I tried two of the digital type for my car tires.
They never came close to being accurate.

I guess the fault is within me using a frame pump and never having experienced how high the pressure really is and should be. My weight is about 160 in pounds and just checked, they deform a little at the measured 55psi. I think it's time to get a floorpump, the frame pump seems to only do good if there's a puncture case while I'm on the road..

So I suppose I've been riding at a low pressure, now I've learnt a lesson :rolleyes:

Thanks for the help everyone!

I have the same pump surprisingly good for 20$ at wally world

don't floor pumps come wth guages generally? i always let out a bit of air and then pump up to desired pressure.

Do NOT mindlessly pump to the "recommended" pressures on tire sidewall. It may be ok for vehicles but on bikes where total weight is usually largely dependent on YOUR weight, pump according to that. I'm 140 lbs and have it at 70/60 psi rear/front, and it's oh so comfortable on rough roads. There was an article that mentioned your tire should deform about 15% of it's height when on the rim and should serve as a good starting point.

Scroll down to the chart:

http://janheine.wordpress.com/2010/1...-and-pressure/

Keep in mind that the weight referred to is per tire, not your total body weight.

edit: oh yeah and check your gauge because you would definitely notice 50 psi in 23 mm tires.