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-   -   The Pressure is on. (https://www.bikeforums.net/general-cycling-discussion/1157756-pressure.html)

GlennR 10-12-18 07:59 AM


Originally Posted by rumrunn6 (Post 20612668)
after confirming the gauge on my pump matches my patented pencil style gauge, I no longer use the hand held gauge at home. but I do carry it on the road but rarely use it even when fixing a flat

you carry a pump on rides?

I just save the space and carry CO2. It provides enough pressure to allow me to finish a ride.

CycleryNorth81 10-12-18 08:01 AM


Originally Posted by Litespud (Post 20612651)
As others have said, consistency is more important than accuracy. I pump my tires to 100 psi, according to the gauge on my old Silca floor pump. It is truly 100 psi? Don't know, but it works for me - not teeth-rattlingly hard, but have never had a pinch flat. If I ever replace the pump, I'll titrate the pressure again to achieve this optimal (for me) pressure. It might not be 100 psi according to the new gauge, but the actual numerical value won't matter.

If you had an accurate gauge you would know what the pressure really is and be able to duplicate/replicate the pressure easily. Accuracy enhances the consistency. :)

Phil_gretz 10-12-18 08:03 AM


Originally Posted by Nachoman (Post 20612518)
What led you to the conclusion that the Joe Blow 3 was accurate and the others were not?

That's the right question. It's a long story, but I had suspected that the wide variation among the gauges made them useless in an absolute sense. Then we took a few of the pumps up to MD, where my former college roommate has medical instrument calibration equipment in his home office/storage. We compared the measurements to his standard high-end pressure gauges. The Joe Blow was dead nuts on. Probably, this is random among the population of JB3's, but mine (for now) is the most trusted. But I run tires at lower end of pressure ranges, anyhow. I ride "light" for the most part.

rumrunn6 10-12-18 08:03 AM


Originally Posted by oldnslow2 (Post 20612682)
you carry a pump on rides? I just save the space and carry CO2. It provides enough pressure to allow me to finish a ride.

I was referring to carrying the gauge not a pump BUT I do carry a pump (& CO2). haven't used the road pump in a cpl years cuz I just use the CO2 for the last few needs. I suppose at some pint I'll stop carrying it. (fwiw - the pump I have at home is electric)

GlennR 10-12-18 08:06 AM


Originally Posted by rumrunn6 (Post 20612688)
I was referring to carrying the gauge not a pump BUT I do carry a pump (& CO2). haven't used the road pump in a cpl years cuz I just use the CO2 for the last few needs. I suppose at some pint I'll stop carrying it. (fwiw - the pump I have at home is electric)

There's not much you can do after using CO2 to increase the pressure. you can only let some out. i find a 16g CO2 give me about 85PSI which is a bit low but gets the job done.

wphamilton 10-12-18 08:27 AM

My electric pump has a pressure gauge. It could be marked in Chinese for all I care because I just fill until the needle is pointed in an approximate direction, depending on the bike.

rumrunn6 10-12-18 11:21 AM


Originally Posted by oldnslow2 (Post 20612690)
There's not much you can do after using CO2 to increase the pressure. you can only let some out. i find a 16g CO2 give me about 85PSI which is a bit low but gets the job done.

I don't carry a pump to add air after using a cartridge. sorry for any misunderstanding. I carry 20 gram cartridges cuz I've been riding 700x45mm tires & now 29x2.25" tires. it's not uncommon for me to air down for a soft section then air back up when getting onto firmer dirt. & last bike's rear wheel/tire/tube had a tendency to pinch & leak, so I would sometimes after airing down, then have to continually add CO2 until the end of the ride. that situation should be gone now that I'm on bigger tires. admittedly, I waste some of the cartridge cuz I don't use it all, then leaving it on the inflator it either leaks out or when I get home & take it off the inflator, the CO2 escapes :/

GlennR 10-12-18 11:27 AM


Originally Posted by rumrunn6 (Post 20613119)
I don't carry a pump to add air after using a cartridge. sorry for any misunderstanding. I carry 20 gram cartridges cuz I've been riding 700x45mm tires & now 29x2.25" tires. it's not uncommon for me to air down for a soft section then air back up when getting onto firmer dirt. & last bike's rear wheel/tire/tube had a tendency to pinch & leak, so I would sometimes after airing down, then have to continually add CO2 until the end of the ride. that situation should be gone now that I'm on bigger tires. admittedly, I waste some of the cartridge cuz I don't use it all, then leaving it on the inflator it either leaks out or when I get home & take it off the inflator, the CO2 escapes :/

Ah... I was thinking road bike and not off road. You certainly want to air down for better grip on the a loose surface. And then air up when getting back on tarmac.

CliffordK 10-12-18 11:50 AM


Originally Posted by noimagination (Post 20612497)
Yep, my right forefinger and thumb. I can use my left in a pinch (ha ha).

This ain't rocket science, folks.

Same here.

I let my pressures vary a bit. I start with maybe 100 or 110 lbs... and then over a month or so the pressure slowly goes down to where I feel it needs tightening a bit (probably below 80, perhaps even in the 60 range), then I pump it up again.

Pumping with both the thumb, and gauge on the pump.

bogydave 10-12-18 12:30 PM


Originally Posted by Retro Grouch (Post 20612504)
"Seems accurate".

yea
No dead weight tester, no way to calibrate it.

compared to my other gages ,
it’s closer, guessing +/- 10%.

“Assuming” car computer close:
Wife had LR tire pressure warning, said was 27 psi, my other gages read tire near 35 - 40,
this one read it at 27.

To my “squeeze test” +/- 5% :D


pvillemasher 10-12-18 01:26 PM


Originally Posted by CycleryNorth81 (Post 20612685)
If you had an accurate gauge you would know what the pressure really is and be able to duplicate/replicate the pressure easily. Accuracy enhances the consistency. :)

Accuracy means the meter returning the correct value.
Precision would be the meter returning the same value each time, whether accurate or not.
So as was said earlier in the thread, if my tires feel right at 90psi on my meter, and I use that meter to measure, then I just pump to 90psi. It could really be 100psi.

bogydave 10-12-18 01:30 PM


Originally Posted by pvillemasher (Post 20613358)
So as was said earlier in the thread, if my tires feel right at 90psi on my meter, and I use that meter to measure, then I just pump to 90psi. It could really be 100psi.

+1
:thumb:

rumrunn6 10-12-18 01:40 PM


Originally Posted by oldnslow2 (Post 20613137)
Ah... I was thinking road bike and not off road. You certainly want to air down for better grip on the a loose surface. And then air up when getting back on tarmac.

I have to admit, I carry too much stuff, or rather more than I need, so even on my road bike, I just put the same trunk (w pump & CO2) on that bike but swap appropriate tubes ...

cyccommute 10-12-18 01:50 PM


Originally Posted by CycleryNorth81 (Post 20612572)
If accuracy is not important and the gauges are in-accurate, why have gauges at all? Just pump the tire until firm.

p.s. How did you determine "None" of the gauges were accurate? You must have some reference gauge to compare the readings to.

@Nachoman beat me to the question

All measuring devices have inaccuracies. Tire gauges are no different. Generally speaking, the more you pave for a measuring device, the lower the variance. If you are paying $1 for a tire gauge, don't expect it to be accurate out to 1 pascal (0.000145 psi). If you pay $40, still don't expect it to be accurate to 1 pascal. The $40 gauge will probably be accurate to the nearest 1 pound per square inch (which is still pretty accurate). The $1 gauge is going to be accurate to the nearest 5 psi. And don't be fooled into thinking that because the gauge is "digital" that it is more accurate. It may give you tenths of a psi but that should be taken as being "accurate". That "tenths of a psi" are questionable.

Bicycle tire pressure isn't all that critical so we can live with something that isn't hyper-accurate. People go on and on about how they can tell the difference between 35 psi and 36 psi. They can't. Their gauge may tell them that there is a difference but they probably can't tell the difference in a blind test.

This gauge, by the way, is a pretty good one. It doesn't weigh much, is easy to use, accurate enough and it doesn't require a battery to run it. It's as accurate as the $40 battery powered one.

fietsbob 10-12-18 01:59 PM

Largely No, but I own a Meiser tire gauge.. for when I must.

cyccommute 10-12-18 02:01 PM


Originally Posted by oldnslow2 (Post 20612682)
you carry a pump on rides?

I just save the space and carry CO2. It provides enough pressure to allow me to finish a ride.

A CO2 cartridge will only let you finish a ride if you need it once. A pump will actually let you finish the ride if you need it many more time. These folks, for example,

https://farm2.staticflickr.com/1931/...0009b90d_k.jpgDSCN0045 by Stuart Black, on Flickr

were using my pump to get them about 1/4 mile at a time after the 20th flat for the person in front and the 6th flat (with tubeless) for the persons behind. They had just finished pumping up the tire at the top of the hill and had to refill when they got to me. I'd run out of patches at that point...and I usually carry about 20 at a time.

bogydave 10-12-18 02:02 PM

If accuracy very important to you...
Use this NIST gage as a standard to test/ adjust yours

NIST Traceable Pressure Gauges from Davis Instruments

send in annually to get it certified :)

Ogsarg 10-12-18 02:43 PM

I carry one of these in my road bike saddlebag since my mini pump has no gauge. It's small and light and fairly accurate. At home, I have a floor pump with gauge.

Eyezoff gauge

Sy Reene 10-12-18 02:48 PM


Originally Posted by cyccommute (Post 20613423)
were using my pump to get them about 1/4 mile at a time after the 20th flat for the person in front and the 6th flat (with tubeless) for the persons behind. They had just finished pumping up the tire at the top of the hill and had to refill when they got to me. I'd run out of patches at that point...and I usually carry about 20 at a time.

Sounds like a real hoot. Quicker and less hassle to hike the route it sounds like..

rgconner 10-12-18 02:56 PM


Originally Posted by cyccommute (Post 20613423)

were using my pump to get them about 1/4 mile at a time after the 20th flat for the person in front and the 6th flat (with tubeless) for the persons behind. They had just finished pumping up the tire at the top of the hill and had to refill when they got to me. I'd run out of patches at that point...and I usually carry about 20 at a time.

"Nobody told me it was 'Gunsday'!"

"Bro, every day is 'Gunsday'."

cyccommute 10-13-18 08:12 AM


Originally Posted by Sy Reene (Post 20613484)
Sounds like a real hoot. Quicker and less hassle to hike the route it sounds like..

If it were only a mile or so but we were 8 miles from the trial head. We had to stop frequently but between stops we moved much faster than walking.

eepok 10-15-18 12:16 PM


Originally Posted by CycleryNorth81 (Post 20612126)
Do you use an external pressure gauge for your tires? If you do, what do you use and what brand?

Just the gauge on my pumps. Almost every floor pump has one and I carry a Topeak Road Morph G wherever I go.

Ungaro 10-15-18 01:03 PM

Here's what I use. Accurate to within 3%: Silca Pista

Rootman 10-15-18 04:31 PM

I use what's on the pump or my compressor. As stated it does not make a whole lot of difference. Since bike tires are thin and small the pressure will change with temps and time more than a cars will.

Most gauges I've tried have been fairly accurate. I carry a fairly large foot pump in my rack bag because I have larger tires, and a bad track record with flats. Once I was on my only spare tube of a ride and had to stop 6 times to air up. The patch wouldn't seal on the first tube, a failure around the valve stem. My wife is not very good at navigating so I carry a bunch of stuff, tools, pump, tube, etc. to help make sure I can return home. A hand pump just takes too long so I got the smallest foot pump I could find. And as long as the gauge is fairly accurate it's close enough for me.

CycleryNorth81 10-15-18 05:36 PM


Originally Posted by Ungaro (Post 20617552)
Here's what I use. Accurate to within 3%: Silca Pista

That pump is gorgeous!! :love::love::love:

https://cimg9.ibsrv.net/gimg/bikefor...09bc0c2423.jpg


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