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Discussion Starter · #1 · (Edited)
I just got a Topeak Smartgauge D2. If this thing is accurate, then that means the floor pump i've been using for the past ~10 years reads up to 10-15psi too high. 馃槄
The only other way I can measure pressures is with my shock pump. How accurate is a shock pump for measuring tyres? I've done some tests on both my fork and my tyres, and the Topeak and the shock pump tend to show the same pressures.
If both my shock pump and my pressure gauge is accurate then i've been living a lie for the past few years and riding tyres with about 8-9psi in them. That's just so hard to believe. 馃槄
 

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Floor pump gauges are notoriously bad. A 10+ psi error is completely possible. There was an in-depth article testing a big range of shockpumps The digital ones were good to a couple psi, the analogue were generally 5psi or better (I think). Your topeak is very highly regarded and is the go to gauge for many Pros.

So yes you probably have been squishing in more air than you thought.
 

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I know that the guage on my floor pump is high, but it is consistently high.

I get my tires to where I like the feel when riding, then I use that target number that the pump provides whenever I check my tires before a ride.

Can I provide an accurate psi number to someone taking a poll at trailhead ? No.

Can I get a consistent tire feel and not my wrecking rims? 100%.
 

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Discussion Starter · #4 ·
Floor pump gauges are notoriously bad. A 10+ psi error is completely possible. There was an in-depth article testing a big range of shockpumps The digital ones were good to a couple psi, the analogue were generally 5psi or better (I think). Your topeak is very highly regarded and is the go to gauge for many Pros.

So yes you probably have been squishing in more air than you thought.
That's great to hear, thanks for the info!

I know that the guage on my floor pump is high, but it is consistently high.

I get my tires to where I like the feel when riding, then I use that target number that the pump provides whenever I check my tires before a ride.

Can I provide an accurate psi number to someone taking a poll at trailhead ? No.

Can I get a consistent tire feel and not my wrecking rims? 100%.
Of course. I'm just shocked that for 10+ years i've based tyre "feel" off of pressures that were completely wrong.
 

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It doesn't really matter. You inflate to where your tires feel "right" then mark that pressure with any gauge. Then, you use that same gauge every time to the same marking. The gauge could use letters instead of numbers. Inflate to letter "M" every time and you'll be at the "correct" pressure.
 

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Discussion Starter · #6 ·
It doesn't really matter. You inflate to where your tires feel "right" then mark that pressure with any gauge. Then, you use that same gauge every time to the same marking. The gauge could use letters instead of numbers. Inflate to letter "M" every time and you'll be at the "correct" pressure.
Yep. Still shocked tho. 馃槄
 

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Discussion Starter · #8 · (Edited)
Yeah, my various gauges are all over the place too. There are probably some professional quality scientific gauges that are calibrated to be accurate that cost hundreds of dollars I bet.
Like you said as long as the gauge is consistent i'm all good. I can set the pressure way more consistently compared to my floor pump which likes to jump around as well.

At first I was a 100% convinced that the pressure gauge was faulty, because it showed me something like 9psi in my 2.4 front tyres, and I just got back from a ride. 馃榿
 

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I have 3 floor pumps and the issue I have is none of them is accurate or consistent at the pressures I run my MTB tires. I use either a 0-15 or 0-30 a Meiser(sp?) Accu-Gage to check my tires before every ride. Heck, one of my pumps barely even registers until it hits 20psi.
 

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Apparently these are incredibly accurate. They are $40 AUD.

 

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One problem with the shock pump gauge is that they're built to be used at higher pressures. Analog gauges are generally most accurate in the middle of their range and least accurate near the extremes. Of course the details of that depend on the quality of the gauge and the quality of the calibration. Plus the comment about the scale only being accurate to about 5psi is about right. It's simply the wrong gauge for the application. The digital ones at least avoid that particular issue. But is it even useful to do such a thing? I argue not, in most cases.

I've also found the gauges on most pumps to be the wrong gauges for mtb tire pressures, as well. Not reading a number at all until it hits 20psi is about par for the course. I use a Meiser 30psi gauge for mtb tires. It has enough sensitivity that I can be super repeatable about my mtb tire pressures, probably within 0.5psi or so. For gravel and pavement bikes, the gauges on the pumps are usually sufficient.

The only time I can see the value of an accuracy "check" of a pump gauge would be if you had multiple pumps you rotate through, and you wanted to maximize your ability to consistently set your tire pressure no matter which pump you used (such as if you use one pump at home and another that you keep in your vehicle). And you don't even need a 3rd gauge for that. All you need is to know the difference between the two for your target pressure. Me, personally, I just always use the Meiser gauge for mtb tires and ignore the gauges on my pumps, because my pumps barely register the sub-20psi pressures that my mtbs get (the needle is just starting to move, but the first number on the gauge is usually 20psi, so even though it's registering, it's not giving me anything useful).
 

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Discussion Starter · #12 ·
Since I made the post about 2 months ago, I've used the Topeak gauge before every ride. I'm fairly sure it's accurate and i've been simply running suuuper low pressures for the past few years, but the most important thing is that it's consistent. It's so much nicer to set the pressure with it compared to a pump, and the bike feels the same every ride.
 
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