How accurate are pump pressure gauges?
I tested three of my pumps, two floor and one handheld, against the Outrider TL Pro to see how accurate they really are.
From left to right, I have the JoeBlow floor pump which I use as my daily inflator, next to it is a Toolitin pump I picked up from Walmart a while back after loosing my pump in a move. Lastly is the Schwinn handheld pump, the only handheld I have with a pressure gauge. It's meant for Shrader valves, but a Shrader to Presta adapter will make it work.
I then installed an Outrider TL Pro in my road bike and paired it to my phone. The TL Pro has an accuracy of +-0.5% which will be used as a reference for these tests.
Procedure:
1) Start a 0 PSI (0 Bar)
2) Attach the pump and add 10 PSI (0.69 Bar)
3) Record the Outrider TL Pro's reported pressure and the pumps pressure
4) Repeat steps 2-3 for pressures from 15psi (1.03 Bar) to 75psi (5.17 Bar)
Results:
Toolitin Floor Pump
| Outrider Pressure (psi) | Toolitin Floor Pump (psi) | Error (%) |
|---|---|---|
| 75.4 | 92 | 22.02 |
| 65.4 | 81 | 23.85 |
| 54.8 | 71 | 29.56 |
| 44.7 | 60 | 34.23 |
| 35.1 | 50 | 42.45 |
| 25.0 | 39 | 56.00 |
| 14.9 | 24 | 61.07 |
| Average Error | — | 38.45 |
JoeBlow Floor Pump
| Outrider Pressure (psi) | JoeBlow Floor Pump (psi) | Error (%) |
|---|---|---|
| 75.7 | 73 | 3.57 |
| 65.4 | 64 | 2.14 |
| 55.1 | 54 | 2.00 |
| 43.1 | 42 | 2.55 |
| 35.2 | 34 | 3.41 |
| 25.1 | 22 | 12.35 |
| 15.0 | 13 | 13.33 |
| Average Error | — | 5.62 |
Schwalbe Handheld Pump
| Outrider Pressure (psi) | Schwalbe Handheld Pump (psi) | Error (%) |
|---|---|---|
| 74.4 | 79 | 6.18 |
| 65.6 | 71 | 8.23 |
| 55.8 | 53 | 5.02 |
| 44.9 | 40 | 10.91 |
| 35.3 | 37 | 4.82 |
| 25.8 | 29 | 12.40 |
| 15.2 | 20 | 31.58 |
| Average Error | — | 11.31 |
The Toolitin pump was the cheapest, and also the worst with an average error of 38.45% and max error as high as 61%! In second was the Schwalbe handheld pump with an average error of 11.35% and peak error of 31.58% at 15psi. While I would never use this to setup my bike, it has its use in a trail emergency. The JoeBlow was the most accurate with an average error of 5.62% and maximum error of 13.33%. The Toolitin and Schwalbe pumps tended to overshoot most measurements, while the JoeBlow was consistently under.
An interesting observation was that at lower pressures, there was a clear trend of higher inaccuracy. This likely comes from the fact that friction inside the gauge mechanism stays roughly constant, while the force moving the needle becomes very small at low pressures. With less force to overcome that friction, the reading becomes less reliable
In addition, these gauges are designed to cover well over 100 psi, so the low pressure end of the scale is compressed into a very small portion of the dial. That makes each tick mark represent a larger percent of the total pressure, and small reading errors or simple human interpretation show up as larger inaccuracies.
Conclusion:
Overall, it was interesting to see how much the pump gauges varied. Across all three pumps, accuracy ranged from 38.45 percent error at the worst to 5.62 percent at the best. Most pump manufacturers never publish accuracy specs, so it is hard to know which pumps readings you can rely on.
If you are interested in a consistent and highly accurate tire pressure setup, you should check out the Outrider TL Pro here. Please comment and share if you found this interesting! And if you enjoyed this comparison, please share it with others and follow us on social at @outrider_components. We’ll be posting more tests soon, including a deeper look at the precision of these gauges.