# how accurate is your Topeak SmartGauge D2?



## cmart (Feb 22, 2017)

I bought a brand new SmartGauge D2 from Amazon, and compared its reading to my other pressure gauges around the house. I have two digital gauges (marketed for car tires) and two JoeBlow floor pumps with built-in analog gauges. Three of these four gauges agree with each other within a PSI or so; the fourth (the analog gauge on the more beat-up floor pump) reads a little low.

The SmartGauge D2 consistently reads about 10% lower than my three gauges which agree. 27 instead of 30 PSI, 28 instead of 31. This discrepancy holds no matter which order I use the gauges in. It doesn't matter whether I'm measuring bike or car tires.

Thinking I probably got a bad unit, I exchanged it for a new one. The replacement gauge came today, it does the exact same thing, and I don't know what to believe.

Folks out there who have the SmartGauge D2 and another gauge, can you please compare them and share your result? Thank you 

(I don't need replies just to tell me that I can find the pressure that "feels right" and the exact number on the gauge doesn't matter. I'm a nerd, I want to measure pressure accurately.)


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## dundundata (May 15, 2009)

Mine is off about 2 psi from a specialized floor pump. I think it reads low as well but haven't used it in awhile. It is consistent though.


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## Prognosticator (Feb 15, 2021)

Mine is consistently low when compared to the mechanical gauge on my shock pump. 10% is about what I am experiencing also.

The inconsistency isn't too frustrating on tires. I run them at around 18 - 22 PSI reading on the Topeak. I squeeze test the tires before riding and add pressure if needed Since tires are low pressure, I don't have to worry about losing too much air when I disengage the tire pump.

HOWEVER, the discrepancy drives me crazy when it comes to shock pressure. I will pump my shock to, say, 200 PSI reading on my shock pump, disengage the pump -- which inevitably results in some lost air -- then check with the Topeak and it will read around 180 PSI. So, I am left wondering, Did I lose 20 PSI when I disengaged the shock pump? I doubt it, but shocks are so high pressure that it's possible. It's gotten so frustrating that I am considering buying a new shock pump that releases more easily. The one I currently have screws off the valve, and I am wondering if there is a better pump/valve interface that releases from the valve more quickly and efficiently, without losing air.


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## 127.0.0.1 (Nov 19, 2013)

you don't lose pressure disengaging a shock pump, they are designed to retain air in the shock...all you hear is the air in the hose letting loose...the shock valve is already closed before that happens.

attaching the topeak to the shock, or any gauge to check it.... or attaching the pump and you see the pump gauge read pressure....that is when you lose pressure in the shock itself. and if it has a small air can like a rear shock, a little hiss means a lot of PSI

go by feel with shock and shock pumps. pump it, note what the shock pump says, go ride. note how it went. add more or less pressure and note what it says. if the shock pump is technically inaccurate it does not matter, what matters if it is _consistently_ inaccurate. that way whatever you note based on what the dial says and how it felt...use those numbers and it will be good for how you like it and able to be repeated if you use the same pump and same gauge.

trying to fight technical accuracy in PSI is kinda useless without spending thousands on scientific equipment that will be 100% accurate for lab work...and you need to have those calibrated often by other more expensive equipment. not worth it imho unless you build and design shocks yourself, or happen to work in a lab with that gear already around and won't cost you anything to use.


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## Prognosticator (Feb 15, 2021)

127.0.0.1 said:


> you don't lose pressure disengaging a shock pump, they are designed to retain air in the shock...all you hear is the air in the hose letting loose...the shock valve is already closed before that happens.
> 
> attaching the topeak to the shock, or any gauge to check it.... or attaching the pump and you see the pump gauge read pressure....that is when you lose pressure in the shock itself. and if it has a small air can like a rear shock, a little hiss means a lot of PSI


Yes, this came up when I mentioned it on a different thread. What I find concerning is that sometimes it's a quick burp of air when I disengage the pump and other times it's a longer sigh of air, and when I validate using the Topeak, there is a difference in lost pressure between the burp and sigh, with the sigh being lower pressure.


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## dundundata (May 15, 2009)

I haven't used it for shocks just tires. Figure the shock pump is accurate enough.


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## 127.0.0.1 (Nov 19, 2013)

that may be an issue with the pump gasket or oring...somehow. 
try lubing it a little bit with shock oil but just a tiny wipe with a q-tip

the chuck has a long nose and stops depressing the valve well 
before the pump chuck gasket lets go of the seal. replace the seal ?


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## NJPhil (Oct 15, 2007)

Mine reads low also compared to other gauges I have available to me. This is not an issue for tires as long as it is consistent, but was worrisome for use on my fork and rear shock. I only depend on the shock pump gauge and sag now for suspension setup.


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## A. Rider (Jul 25, 2017)

My digital Topeak D2 SmartGauge also consistently reads right about 10% lower than my analog Meiser Accu-Gage. I'm glad I saw the other responses in this thread because I've always wondered if the Topeak gauge was reading low.

I actually hate using the Topeak gauge. You have to push it dead straight onto the valve or you get inconsistent readings. I end up having to check and recheck the result like half a dozen times or more just to end up believing what the correct reading is.

My Meiser Accu-Gage however reads consistently the same every. damn. time., without ever worrying about having seated it properly onto the valve stem.


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## cmart (Feb 22, 2017)

Three clear confirmations (@Prognosticator, @NJPhil, @A. Rider) and zero clear dissents! Still a tiny sample size, but this sounds like a possible systemic issue with the SmartGauge D2.

Is there a better presta-valved digital gauge out there? The Meiser Accu-Gage sounds great for measuring pressure but too heavy and fragile to carry on a ride.


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## Ratt (Dec 22, 2003)

Another vote for 2 - 3 psi low. My 2 floor pumps will say 25 psi and the Topeak will read 22. At least these things are consistent.

My eyes are going bad and I find the topeak easier to read than my old analog and cheapo digital gauges. So keeping it and just knowing I need to +2 to whatever its saying.


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## MSU Alum (Aug 8, 2009)

I just always use the same gauge.


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## shakazulu12 (Jul 14, 2015)

Same ten percent versus my Meiser’s as well. Now that doesn’t mean one is more right than the other. But they always read ten percent off. That said, after three Topeak’s going dead in four months, I just use the Meiser units now. Don’t have to fiddle as much to get a correct reading and I don’t know wtf im
Doing that kills the Topeaks, but they don’t last long if I ride with them in my pack.


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## Cleared2land (Aug 31, 2012)

I don't concern my self too much with accuracy. I want consistency. I use the same gauge.


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## customfab (Jun 8, 2008)

If accuracy is what you're after, get a certified gauge. Keep in mind that pressure gauges are similar to torque wrenches in that they usually only meet their claimed accuracy in the upper XX percentage of their range.

McMaster has a pretty wide range of gauges and you can probably find one that you could replace a stock gauge with.


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## ToddWadd (Dec 11, 2020)

Recieved as Xmas gift that I asked for, checked shock w my Specialized Shock Pump showing 170 put the Topeak on and it blew the screw top off and a few pieces strewn on my floor. Amazon replaced very quickly, so I used new one on tires and it was showing 2-3 lbs low compared to my floor pump w gauge. Checked Shock w Shock Pump again at 170 and the D2 wouldn’t read over 100 took it to my LBS and let them play w it ( maybe it was me doing something wrong) same results it was way off on the Shock by like 60-70lbs. I got it to read 110 on my wife’s bike that was set to 130 w Pump. But it’s not working properly so I guess it’ll be returned. Too bad was hoping it would be handy to travel with, but think it’s too wide of range to measure anything close to accurate. Will stick to Shock Pump and Auto gauges for tires. Anyone had decent readings off their shocks with the D2?


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## A. Rider (Jul 25, 2017)

ToddWadd said:


> Recieved as Xmas gift that I asked for, checked shock w my Specialized Shock Pump showing 170 put the Topeak on and it blew the screw top off and a few pieces strewn on my floor. Amazon replaced very quickly, so I used new one on tires and it was showing 2-3 lbs low compared to my floor pump w gauge. Checked Shock w Shock Pump again at 170 and the D2 wouldn’t read over 100 took it to my LBS and let them play w it ( maybe it was me doing something wrong) same results it was way off on the Shock by like 60-70lbs. I got it to read 110 on my wife’s bike that was set to 130 w Pump. But it’s not working properly so I guess it’ll be returned. Too bad was hoping it would be handy to travel with, but think it’s too wide of range to measure anything close to accurate. Will stick to Shock Pump and Auto gauges for tires. Anyone had decent readings off their shocks with the D2?


No. Just return it while you still have the chance. I also got one as a Christmas gift a couple years ago and I never use anymore, shortly after realizing it's so damn inconsistent.


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## chadbrochills (Aug 9, 2018)

My D2 is being a pain in the ass, sometimes it turns on, sometimes it doesn't. Brand new battery and all. As others have said, it reads about 2-3psi lower than my floor pumps (one's digital, other is analog) as well as my digital shock pump. 

Anyone find a better digital gauge?


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## dundundata (May 15, 2009)

it's called the d2 because your pressure reading will be down 2psi. see it's actually a feature.


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## Cleared2land (Aug 31, 2012)

^^^ Good one


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## cmart (Feb 22, 2017)

chadbrochills said:


> Anyone find a better digital gauge?


For real! I would pay $100 right now for a gauge that is:


Accurate to the PSI in the range of 0-50 PSI (to cover MTB and gravel)
Presta head (schrader optional) that seals at least as well as the D2
More scratch-resistant display than the D2, if it ends up next to a metal tool in your pack, or dropped on the ground. (whatever display glass Android phones have had for the past decade)
At least as durable as the D2 in all other aspects (no bourdon tubes)
No larger than the D2 and not a lot heavier
multi-year warranty and non-terrible customer service

Who wants to fill this gap in the market? Silca? Lezyne? Fabric? Fumpa?

(I see Lezyne has this gauge, anyone tried it? Also, Fumpa has this gauge, sold out with no one else selling it.)


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## mtbyb (Dec 26, 2020)

cmart said:


> I bought a brand new SmartGauge D2 from Amazon, and compared its reading to my other pressure gauges around the house. I have two digital gauges (marketed for car tires) and two JoeBlow floor pumps with built-in analog gauges. Three of these four gauges agree with each other within a PSI or so; the fourth (the analog gauge on the more beat-up floor pump) reads a little low.
> 
> The SmartGauge D2 consistently reads about 10% lower than my three gauges which agree. 27 instead of 30 PSI, 28 instead of 31. This discrepancy holds no matter which order I use the gauges in. It doesn't matter whether I'm measuring bike or car tires.
> 
> ...


mine always read 2 psi less than my digital crank brother floor pump


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## mtbyb (Dec 26, 2020)

dundundata said:


> it's called the d2 because your pressure reading will be down 2psi. see it's actually a feature.


what do you mean exactly?


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## dundundata (May 15, 2009)

mtbyb said:


> what do you mean exactly?


it was a failed attempt at humour, my humblest apologies.


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## Cleared2land (Aug 31, 2012)

It wasn't failed humor. I got it and thought it was pretty funny.


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## SickEdit (Apr 4, 2019)

I just found this thread and wanted to share the same experience. My d2 reads 0.2 bar or 3 psi too low. I don't know if it's a static offset or percentage wise, since i only use it for tires in the (then corrected) 1.4-1.8 bar (21-25 psi) range.


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## Cleared2land (Aug 31, 2012)

I just need a consistently reading gauge for bike tires. Pressure accuracy is just icing on the cake.


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## cmart (Feb 22, 2017)

Sounds like we're up to about 9 confirmations and still no clear dissents. Today, I emailed Topeak to show them this thread. I'll share the response that I get, but it would be even cooler if someone from Topeak joins the conversation here.


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## chadbrochills (Aug 9, 2018)

I got fed up with my D2 and hulk smashed it on the driveway. Inconsistent readings, when it would even turn on at all. Just using my digital floor pump now until I find something to replace that POS lol.


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## jab253 (May 8, 2017)

With respect to the OP and having purchased from Amazon...I got one from Amazon in January. I found the readings to seem a bit inconsistent when compared to other gauges. I got an email from Amazon a couple months later stating that the item I purchased was believed to be counterfeit and that my money would be refunded.


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## kapusta (Jan 17, 2004)

Mine reads a couple psi higher than my Meiser Gauge. But I have found Meiser Acu-Gauges to be all over the map and not nearly as accurate as common wisdom has them to be.


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## Cleared2land (Aug 31, 2012)

My experience is same manufactured gauges are inconsistent at best. 
I stick with one gauge and I'm not too concerned with accuracy, just consistency.


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## Cleaner (Mar 23, 2004)

Is this a concern in the context of filling a bike tire? IMO it is not. If the reading is repeatable within a reasonable tolerance (+-10 % of rated working range) then it is fit for purpose. As others have stated if it reads consistently at the pressures you measure then you are good to go on your tires.

This reporting of correlation of measures is not relevant unless you bought a calibrated gauge with certification documents. You should have no expectation that the gauge is repeatable or accurate in its readings.

Unless you have a calibration reference and the ability to measure the performance forget about this correlation between all pumps/gauges you are checking.

There is a reason that a calibrated pressure gauge is much more expensive.


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## Lovespicyfood (Aug 4, 2012)

Glad to see this thread, a D2 was on my to buy list but not anymore. My 0-30 Accu-Gauge is ANSI B40.1 Grade B which means it should be accurate to 2-3% which equates to .6-.9lbs.


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## alexdi (Jun 25, 2016)

My D2 says my 29/2.6 tires are 17 PSI and 12 PSI respectively when set correctly for me at 180 lbs. My floor pumps (Specialized, Bontrager, both rated to 160 PSI) say more like 25 PSI and 20 PSI. I suspect the correct value is more toward the higher side, but the D2 is consistent and easy to use, so I don't really care.


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## Hpirx (Jan 15, 2009)

I had the Topeak tested at a car track meet by the Bridgestone Tire rep. They were pretty impressed by it’s accuracy. I have several for car and bike use. I’ve found it’s pretty accurate for my Fatbike tires in the less than 10 psi range, compared to the analog gauge. I’d be leery using it for shocks and such.


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## canuck_tacoma (May 1, 2011)

Yeah, I have two. Bought a year or so apart. They both read the same. I’d trust the Topeak over my floor pump gauge.


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## cacatous (Dec 1, 2013)

Mine is a piece of crap and has died twice. I sent it back because it was dead. The LBS claimed the battery was flat - after 10 readings? Nah.

It died again after they claimed they'd changed the battery. It went in the bin after that. AU$50 down the drain.


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## dundundata (May 15, 2009)

I'm still using mine, I don't use it that often and keep the battery removed.


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## ToddWadd (Dec 11, 2020)

Xmas gift 2021 never worked well and stopped working after a couple weeks, replaced and same spotty performance so I never trusted it. Checked against my analog handhelds I keep in my cars which were spot on with each other but differ brands. D2 was 5-7lbs off I don’t even feel right giving it away. I’ve got an AWD sports car that I’m very particular about tire pressure with, and her suv a Jeep GC has pressure sensors to check against their readings also, so I gave this tool a lot of opportunities to show me it was accurate and it was never close. Love the idea and size, and hate to rag on a product but no love here.


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## Tallboy723 (4 mo ago)

ToddWadd said:


> Recieved as Xmas gift that I asked for, checked shock w my Specialized Shock Pump showing 170 put the Topeak on and it blew the screw top off and a few pieces strewn on my floor. Amazon replaced very quickly, so I used new one on tires and it was showing 2-3 lbs low compared to my floor pump w gauge. Checked Shock w Shock Pump again at 170 and the D2 wouldn’t read over 100 took it to my LBS and let them play w it ( maybe it was me doing something wrong) same results it was way off on the Shock by like 60-70lbs. I got it to read 110 on my wife’s bike that was set to 130 w Pump. But it’s not working properly so I guess it’ll be returned. Too bad was hoping it would be handy to travel with, but think it’s too wide of range to measure anything close to accurate. Will stick to Shock Pump and Auto gauges for tires. Anyone had decent readings off their shocks with the D2?


I can’t get mine to work on my fox shock. It always reads 111psi. When it’s around 200psi. I have to use my pump analog gauge. The toepeak works great for tires. Never got around to sending it back, but it doesn’t show above 111 psi on the shock.


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## cacatous (Dec 1, 2013)

I just give my tyres a squeeze and get on with my ride. I've come to the realisation that I'm not a pro athlete where these things probably matter more.


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