What should I do?

Yesterday, I pumped my tire up to 21 psi. (what I like)

Later, I went to my friends house before we went to the skate park, and I wanted to measure my psi, the gauge said 26 psi. I figured that either the gauge was faulty, or psi gauges aren’t accurate. Do you think I should ditch the psi gauge and pump and release air to my liking?

However, I do know that on my psi reader, 21 psi is perfect.

Anyways, when I got back from the skate park, my psi gauge said about 16 psi. I cleaned my unicycle a few days ago, and I’m pretty sure the tire has no hole. Again, should I ditch the psi gauge?

My final question is…

Today at the skate park, I landed some awesome new stuff.

  1. Dropped into my first 7-foot bowl, rode away, and landed my second 3spin ever. ALL IN A ROW!
  2. Landed another 3spin.
  3. Landed a big up.

Since my psi was so low, do these^ records still count?

Ditch it… you should be able to tell by hopping what pressure you like better than a gauge imo…

Why would they not count?
Use what ever psi for what ever you want… Just remember it may be hard to change it in the middle of a competition…

That’s what I was thinking.

You still did 'em, right? :smiley:

i cant answer the last question but depending on how hot it is the air in your tyre would expand increasing the psi. And then when you got back if it was cooler the air would have reduced so that gives you your 16psi measurement

i hope this helps

EDIT: the same thing happened to me at the bucket races

I know they count, eve though the psi was low. I was worried it made it easier.

Hey, I’m just stoked. I did a 7 foot bowl today and a 3spin right after.

So what if it made it easier? Use all your recources to make stuff easier. (to an extent).

It is like saying that Loic didn’t do the first 900 and quadflip because he did it off a ledge, making it easier.

Man screw psi what ever feels good.

I love psi. Cause I know what feels good, and I measured it and its at 30psi. So now, no more guessing around with what feels, cause I know. Pump it to 30 and ride off.

It’s normal for a tire to loose a bit of pressure over a couple of days. My 20 goes down from 30 to ~25 in a week. If it does that in a day w/ same conditions (temp, left in hot/cold?) it may have a slow leak.

This hasn’t happened to me, but I think you would have had to left it in the hot sun for a hour or so, lowered back to 21, went home and left your uni in the freezing cold for 1 + hrs then measured 16. Or you used different guages and at least one of them is faulty.

Just use whatever pressure you like and always use the same guage.

I remember reading about a guy who was road-racing motorcycles. He left his guage at home, so he borrowed one. The whole day he couldn’t get the chassis set up right, w/ his regular pressures front and rear, then he checked the psi w/ a different guage and the previous guage read 2 psi too low. He raised it by the 2 psi and quickly found his ideal set-up.

If you know 21 psi is your favourite then thats fine.Stop checking the psi in the tyre every 5 seconds to see if its still the same.Only reason you should ever even check if its the same is if it feels different.Im sure youve been checking even if it feels the same…

Stop worrying about your PSI! As long as it doesn’t touch rim your fine!


I check PSI every 2 hops or every 15ft of rail, just to be safe. :wink:

I agree, but not for the reasons everyone has mentioned so far. If you want to talk about PSI, DO IT IN ONE OF THE ZILLION PSI THREADS THAT ALREADY EXISTS! They probably already say what you were going to say anyway. :slight_smile:

Having said that, what I would conclude from your original post is that:
a) Your gauge isn’t very accurate (assuming you were using the same gauge)
b) You should be able to tell the right pressure by a combination of pinching the tire and hopping around a few times. Gauges are for motorcycle racers.

I never use one for unicycles. When in doubt pump it past where you need it, then lower the pressure to taste. Even if 21 psi works for you now, that number is only right if nothing changes, including the temperature.

All of this fuss over pressure. This is over-analyzed. There are so many other factors involved, both quantitative and, more importantly, qualitative. That said, I have seen references to temperature changes and pressure changes in tires before in this forum. There are people who say that this relationship is significant and, when I quantify it to show that it isn’t significant, I’m scolded for it. Lots of folks don’t want any facts to get in the way of how they feel about something. So let’s over-analyze some more and you can scold me for trying to quantify it for you.

For a 24"x3" Gazz tire at about 2 atmospheres absolute (15 psi gauge), the pressure/temperature dependency is something like 0.07psi/F (degree F). A 10 degree F change will produce about a 0.7psi change. It takes about a 100F change in temp to change the pressure in this tire by about 7psi.

Har-per the Science Guy

Harp! Harp! Harp!
Harp! Harp! Harp!

Boyle’s law is a property of matter

HARP Harp harp Har-per the Science Guy.

John M

I need to see a video of you dropping into the 7’ bowl! :smiley: