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I've just purchased a Topeak smarthead gauge as my portable ride doesn't have one built in. I was surprised to find a considerable 5-6 psi difference between what my JoeBlow says (30psi) and the smart gauge stated (24psi).
It the track pump that inaccurate?.. Or is there an issue with the smarthead gauge? Ive checked various bikes in our stable to achieve the same difference each time
One of them is wrong, possibly both, you'd need to borrow a third guage and hopefully confirm which is which...or you may get a third different reading!
I suppose the easiest workaround is to know what pressures work for you with one guage, and compensate for the 6psi difference when using the other.
Doesn't the smart gauge take a bit of air out of the tyre to work ie give you a reading?
I had an old Blackburn (TP5) pump and later bought a Topeak gauge.
I noticed that the Blackburn was allowing a lot of air to escape from the valve while removing the pump. For example, if I pumped the tyres up to 100psi, perhaps 10psi (it may have been more than that) would escape when removing the pump head, then the Topeak gauge would only read 90psi. I used to pump up the tyres a fair bit beyond the required pressure, then use the 'bleed' facility of the Topeak to bring them down to the required pressure.
I've since bought a new Blackburn pump, and that corresponds exactly to the Topeak gauge.
My track pump reads 60psi, a gauge 22psi, I go off feel anyway rather than a figure.
I'd trust the Topeak gauge over a pump gauge.
The Topeak smarthead is only supposed to loose 1psi per use.
Just worth pointing out that my track pump is also Topeak Joe Blow.
To be honest you can't trust either reading with so much discrepancy..
Go by feel, if 30psi works for you with one guage and the other is consistently 6psi down, then pump to 36 when using that pump.
The actual accurate PSI is not so relevant, as people have preferences to grip /feel /terrain/even brand of tyre , it would be silly to say every one should run 30psi precisely.