PSA: Check your floor pump gauge

[dubjay]

Just wanted to throw this out there so you don't experience what I did over the weekend.

During The Traverse, I had both my rear and front tires blow off the rims (Bontrager Dry X 29er & Stan's Arch). I had the tires set up tubeless, using Stan's yellow tape, 3oz of sealant and ~30psi. This was the first time it happened, and luckily I was going slow when the blowoffs occurred.

So off goes an email to Stan's come Monday morning, and one of the things they suggest is that I check the accuracy of my floor pump gauge. I have a peak hold gauge I use for the car, so off I go to the bike shop to get a presta/schraeder adapter so I could use it.

SOOO....apparently what I thought was 30psi on my floor pump gauge was in actuality...45psi - which is above what is recommended for Stan's rims (40psi I believe).

Hopefully that was the real cause, as I'm continuing to run tubeless - but moral of the story - check how accurate your floor pump gauge is.

[Winger]

....assuming the peak hold gauge is accurate.....

That's a huge difference. So....how would an average joe calibrate their pump? Maybe get a few and take an average?

[dubjay]

Originally Posted by Winger

....assuming the peak hold gauge is accurate.....

That's a huge difference. So....how would an average joe calibrate their pump? Maybe get a few and take an average?

The peak hold gauge I have reads the same PSI as the tire inflation monitor on my car, so I'm going to assume it's accurate for now, but you do bring up a good question.

I'm wondering if maybe some of those digital gauges might be more accurate?

[2wheel_lee]

Bike pump gauges are notoriously inaccurate. But even better quality gauges aren't always sureproof. Unknowingly, I was using an Accugauge for my dirtbike that went way off at some time or another.

Gauge accuracy doesn't matter if you only use the same gauge/pump. It's only a number of reference.

Ideally, you should learn how to feel your tires with your hands/thumb/fingers. I know how I want my tires to feel for given conditions better than I know a PSI number. This will prevent problems of using other pumps/gauges. It also makes it easier to set the correct PSI when doing a trailside flat repair or pressure change.

Kind of funny, when I recently started riding BMX again, I was wondering what pressure I wanted to run. I was trying to remember what I ran 20+ years ago, then I remembered that I never set the pressure based on a number, but only by feel.

[KeepsWhatHappens]

To be sure get a separate gauge to check your pressure. Tubeless IS the WAY to go!!

[Devoid169]

Lee -
We seem to have lived in parallel bmx universes way back. I've always gone by 'feel' as well. I only look at my gauge to get me in the ball park. Then its all in the pinch....

[RustyIron]

Right on. I had a fancy digital gauge that I used exclusively, until one day I noticed the tires feeling unusually firm. A quick check with another gauge confirmed that the digital unit had gone bonkers.

Now I have a nice dial-type gauge. They may have more components to introduce inaccuracy, but it's unlikely that one will go completely nuts without showing other signs of failure.

[OldDogDan]

Yeah, I pump up by floor pump gauge, then check by feel. I can usually tell within a few psi by feel (as can most but not all of my friends). Also, to check by feel, after squeezin' em, I lean all my weight on first the front, then the back, and eyeball the amount of "squish". Once you learn the feel of what you like to ride on, the gauge pressure is more relative than absolute if ya know what I mean.

(RustyIron, I like the "Master Cylinder"! might be giving away your age there!)