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internal tire pressure sensor on a road bike

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BradC:

--- Quote from: mendip_discovery on August 24, 2023, 03:22:35 pm ---Could you measure the RPM of each wheel and compare the two and use that to inform you of a loss in pressure.
--- End quote ---

I did that in my old Volvo. I used the ABS reluctors on each wheel to get a precise rotational velocity for each wheel. It requires an awful lot of averaging to make it viable and even then it wasn't great. Any time I wasn't driving in a dead straight line it was almost impossible to reconcile.

With the addition of a GPS receiver for self calibration it made an incredibly accurate and precise speedometer. In all honesty it was a good exercise in "seemed like a good idea at the time.

Zero999:

--- Quote from: tszaboo on August 25, 2023, 02:21:27 pm ---
--- Quote from: Zero999 on August 24, 2023, 08:09:29 pm ---
--- Quote from: DiTBho on August 24, 2023, 12:07:15 pm ---
--- Quote from: mikeselectricstuff on August 24, 2023, 10:10:53 am ---Have you looked at automotive TPMS modules ?

--- End quote ---

thanks, good keyword to Google for  :D

--- End quote ---
Road bike tyres need to several times the pressure as car tyres.

--- End quote ---
I heard 4 BAR, that's what I use. A cyclist friend of mine said, you pump the tire until it blows up in your face and then you use the tire with just a little bit less pressure.
My car manual said 2.5 BAR.

--- End quote ---
It depends on the size of the tyre. Larger tyres generally need a lower pressure than smaller ones. A road bike with thin tyres will need a much higher pressure than an off road bike with much larger tyres.

tom66:

--- Quote from: BradC on August 25, 2023, 03:14:45 pm ---
--- Quote from: mendip_discovery on August 24, 2023, 03:22:35 pm ---Could you measure the RPM of each wheel and compare the two and use that to inform you of a loss in pressure.
--- End quote ---

I did that in my old Volvo. I used the ABS reluctors on each wheel to get a precise rotational velocity for each wheel. It requires an awful lot of averaging to make it viable and even then it wasn't great. Any time I wasn't driving in a dead straight line it was almost impossible to reconcile.

With the addition of a GPS receiver for self calibration it made an incredibly accurate and precise speedometer. In all honesty it was a good exercise in "seemed like a good idea at the time.

--- End quote ---

This is how tyre pressure monitoring works in most European cars nowadays, with the exception of BMW and Mercedes who often fit run flats to their cars and so need to warn quicker of lower pressure due to the damage of running such a tyre low at high speeds.  I believe it's now a requirement for cars to include this function, even the basic Peugeot 108 I had for a couple of days had this function.  Since these cars already have ABS, it's almost free to include - just some software and an indicator light to flash the tyre icon on the dash.

The system is quite reliable.  In my past two cars,  it has detected punctures quickly enough.  Once, it was fooled by a particularly poor road surface (warning briefly of a possible loss of pressure, but removing the warning after 10 minutes.)  The system does require you to 'calibrate' it from time to time, if it does detect a low tyre, you reinflate all tyres to the correct level then press 'SET'.  I would guess even perfectly balanced tyres have some variation in road speed despite best efforts so a calibration allows this factor to be compensated for.

tridac:
One way might be to put a height sensor on the wheel bearing end of each suspension arm or fork, as the ride height will be lower if the tyre pressure is down. Obviously some noise filtering needed, but could be cheaper and less complex than measuring tyre pressure. Ultrasonic pulse rangefinder tech perhaps ?...

joeqsmith:
Looks like there was a kickstart for one.   The comments are worth reading to get some different perspectives.

https://hackaday.com/2020/12/06/no-battery-pressure-sensors-for-bike-tyres/

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