Stupid question regarding tire pressure
 

I was hoping someone could give me a quick response. I recently bought a Tekton tire gauge, which is used primarily for cars but was considerably cheaper than the gauges for bicycles. (Everything for cycling is twice as expensive for some reason..)

It only has a schrader valve which is the only downside. Anyway- to my question. I've been inflating my tires based only on how difficult it is to push down on the tire. When I get little resistance I consider that close to the maximum pressure the tire can handle.

Well as it turns out, repeatedly checking the pressure with the gauge showed that assessment to be way off. What I was considering enough tire pressure is measuring 35 PSI??

I'm using Schwalbe Winter Marathon tires which actually can't handle a lot of pressure, they run at 85 PSI max.

I'm having a difficult time pumping air into them around 35 PSI with my hand pump.

IS THIS NORMAL? I would hate to blow up my inner tube because the gauge was wrong!

I have noticed that when I get on the bike, the tire does sag quite a bit. And I have noticed that it seems it takes a great deal of effort to pedal around, and the bike slows quickly while coasting. This seems to corroborate the tire gauge's readings, that the tire is woefully underinflated.. Which would mean for at least 2 years I have been biking on tires at half the pressure they needed to be. :eek:

How much did you pay for your floor pump?

I can barely push air into the tire, and the gauge still only reads 35 PSI. Is it normal for it to be this difficult to pump the tire up beyond 35 PSI with a small hand pump?

I don't have a floor pump. Do I need one to get beyond 35 PSI in the tire?

Sometimes it's hard to find but usually the tire has max pressure labelled somewhere.

To answer you question 35psi seems to low. My MTN bike tires say 65psi and my hybrid tires say 75psi.

Buy a cheap floor pump at one of the big box stores.

I use one of these.

Serfas FP-200 Floor Pump

You really need a floor pump with a gauge. You won't be sorry. Your local shop will probably let you try some out so you can see for yourself.

No, a decent mini hand pump should be able to do about 90 psi with no problem, 100+ for a frame-sized pump. If you have something intended for basketballs you'll never get high enough for any bike tire.

I'm surprised a gauge intended for auto tires even goes much past 40psig

+everything.

Eventually, if you can keep it on the valve, and you don't mind the carpal tunnel

Just to see if I understand, are you trying to measure Presta tubes with a Schrader gauge and P to S adapter? If so, you might not get a meaningful reading at all.

I'm with the others, on getting a floor pump with built-in gauge.

Knowing that my tires are at the desired pressure, I make a mental note of how much they pooch out under my weight, in case I have to re-inflate them while on the road.

Amusing story: Back when I was in college, I had this ancient pump with a huge bore. I figured out how many PSI I'd get from my full weight on the pump handle, and it was roughly the correct amount. So I just pumped until the piston would support my weight.

Yeah I thought that too about the tire gauge when I bought it. But it is rated up to 100 PSI.

The hand pump I have has a little fold out stand so that it sort of emulates the floor pump action. It's designed to fit on the bike frame too.

From what I understand it was possible to pump the tires up to full pressure with it, so I never bothered to spend money on a floor pump. Since the only difference was time and effort saved. Most of the time that I need air in the tires is when I'm outside, like with large differences of temperature (Winter time) or having to inflate a spare tube.

I guess I will try resetting the gauge by taking the batteries out. Thanks everyone for the info.!

Actually as of last night I now have one presta tube and one schrader. I had a flat tire and had to replace it with a Slime tube which turned out to be a presta valve, even though I'm pretty sure I had confirmed it was labeled as schrader when I bought it. (The box disintegrated quickly in my backpack so I can't confirm) I realize I can't take the pressure on the presta so I was just checking my front tire which is a schrader.

Ok. I'm not sure what I did differently, but it's working properly now. I just got a reading of 40 PSI, and 50 PSI. At this rate it's going to take nearly 10 times more strokes to pump my tires to full pressure, than what I have previously been doing. So at least I've learned something from this.. my tire pressure HAS been woefully low. I'm actually looking forward to riding now as I'm sure I'll be so much faster. Especially since I've been "training" with slow sluggish low pressure tires! :lol:

I'll keep that pump in mind, but it will be awhile before I have any spare money to spend. And yes it does suck using the emergency hand pump. I had no idea it takes this long to properly inflate my tires. Or the fact that I've been riding around on "flat" tires. :lol: It finally explains why my bike is constantly slowing down whenever I am coasting, even downhill. It was driving me crazy as I couldn't figure out why.

I use a ~$25 electric pump that hooks up to my car's cigarette lighter outlet - works fine to pump up my tire to 90 psi. I lose a little air because the head isn't quick release .. but even my $15 foot pump from Target pumps up the tire to about 80 psi with ease.

If you are running fatter tires (i.e., don't need to fill often), you can try using the gas station pumps - though I don't know how high they go, never used one.

If it's not a bad valve on the tube then I recommend the fuji floor pump. I have used it to inflate car 3 tires and it maxes at 260 psi on the gauge. Motor vehicle tire pressure gauges, the kind that pop out especially, are no good for bicycles. You need a pump with a gauge, a digital gauge, or a stand-alone analogue gauge.

FUJI COMPRESSOR PRO FLOOR PUMP - WHT

- Andy