EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: DiTBho on August 24, 2023, 10:06:05 am
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How would you build an internal tire pressure sensor on a road bike?
it must be
- internal tire
- digital out
- able to measure { 5 .. 8 } BAR pressure
- installed inside the rim, under the inner tube
- or on the valve that is used to inflate the inner tube. In this case, it will be installed on a spoke?
- avoid Wifi, if it's possible
first problem is: how to communicate the data if the sensor is inside the wheel and this rotates on a hub?
how to decouple the wheel and hub by sending the data to the computer that I will install on the bike frame, approximately where the water bottle is mounted.
Mumble ... :-//
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Have you looked at automotive TPMS modules ?
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Have you looked at automotive TPMS modules ?
thanks, good keyword to Google for :D
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I've always found bike tire pressure to be pretty obvious to the rider, you can feel when you have too much or too little. Maybe it's different when the bike is heavier, carrying a motor and battery?
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If your valves are compatible with car tyres, theer are also external TPMS sytems that have a sensor in the cap
e.g. https://www.aliexpress.com/item/4000723547368.html (https://www.aliexpress.com/item/4000723547368.html)
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I just went through changing out the TPMS sensors on my ancient Civic. The sensors were behind the valve, battery powered, and used WIFI. I believe later cars use something like a Hall sensor on each wheel to sense rotation speed. The speeds of the four wheels are compared over a period of time, and if one is spinning faster than the others, its pressure is assumed to be lower. Perhaps something like that would work for a bike, but you would be dealing with very small differences.
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Could you measure the RPM of each wheel and compare the two and use that to inform you of a loss in pressure.
I remember Jean Louis Schlesser had a tyre pressure setup that allowed for adjustment while driving. I think it pumped air through the hub.
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On my bike, I just use my thumb. Takes a little practice, then you've got the feel.
Always on hand. :-DD
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Could you measure the RPM of each wheel and compare the two and use that to inform you of a loss in pressure.
yup! the bicycle computer module I am designing already has two RPM sensors, one on each wheel, so it's feasable at zero cost :o :o :o
I will do the test on a Lemond Croix De Fer Road bicycle
(
I just have to be careful and not get distracted while I'm fiddling with the electronics
or else someone might steal it
)
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Looks like they sell products for this. Maybe something you could just buy. My experience with a road bike has been if the tire pressure drops, its a flat. I don't need a sensor. Better to carry tools, patch kit, spare tube..... I should bust out my old bike. Maybe I could make it more than a mile before passing out. :-DD
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https://www.dcrainmaker.com/2018/04/hands-on-quarq-tirewiz-cycling-pressure-sensor.html (https://www.dcrainmaker.com/2018/04/hands-on-quarq-tirewiz-cycling-pressure-sensor.html)
Better, control the pressure:
https://newatlas.com/bicycles/scope-atmoz-bicycle-tire-pressure/ (https://newatlas.com/bicycles/scope-atmoz-bicycle-tire-pressure/)
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Always on hand. :-DD
until you need to detach them to leave them installed on the tire. :P
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Have you looked at automotive TPMS modules ?
thanks, good keyword to Google for :D
Road bike tyres need to several times the pressure as car tyres.
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I was thinking you could sandwich a strain gauge between the rim and tube. Small coil and some electronics. Power it from a magnet mounted to the chassis. Google search someone actually tried something similar.
https://gigazine.net/gsc_news/en/20130110-btps/
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I was thinking you could sandwich a strain gauge between the rim and tube. Small coil and some electronics. Power it from a magnet mounted to the chassis. Google search someone actually tried something similar.
https://gigazine.net/gsc_news/en/20130110-btps/
that's super interesting! thanks :D
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For live monitoring you are probably best off with that sram unit.
There are some non-live sensors as well, similar to the one joeqsmith linked above using NFC:
https://www.bikeradar.com/news/tubolito-tubo-mtb-p-sens-inner-tube/ (https://www.bikeradar.com/news/tubolito-tubo-mtb-p-sens-inner-tube/)
https://bikerumor.com/exclusive-rover-psicle-wireless-tire-pressure-monitor-is-accurate-tubeless-battery-free/ (https://bikerumor.com/exclusive-rover-psicle-wireless-tire-pressure-monitor-is-accurate-tubeless-battery-free/)
Are you using TPU? https://www.bicyclerollingresistance.com/specials/tpu-inner-tubes (https://www.bicyclerollingresistance.com/specials/tpu-inner-tubes)
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For live monitoring you are probably best off with that sram unit.
There are some non-live sensors as well, similar to the one joeqsmith linked above using NFC:
p-sens-inner-tube/ (https://www.bikeradar.com/news/tubolito-tubo-mtb-p-sens-inner-tube/)
wireless-tire-pressure-monitor (https://bikerumor.com/exclusive-rover-psicle-wireless-tire-pressure-monitor-is-accurate-tubeless-battery-free/)
Are you using TPU? tpu-inner-tubes (https://www.bicyclerollingresistance.com/specials/tpu-inner-tubes)
thanks for this info!
my 28" wheels are not tubeless as rims are not compatible with this technology, instead they use old school inner tubes (so, they are not TPU), but able to go up to 8 BAR of pressure!
TPU inner tubes look *very* interesting as advertised as made for speed and designed to offer the lowest rolling resistance possible.
The final bicycle will reach ~35Km/h on average on the road, with peaks of 50km/h!!!
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That TPU link was very interesting. Not that they make lighter tubes but that there is a concern over a few grams here and there. :-DD
35Km/h is moving. I remember when I started riding above 10MPH. We lived in the hills. I would ride about 20-30 miles after work. Once we moved, it was all flat. My average speeds were 18MPH. I missed the hills, got bored and packed up the bike. Now I'm an old fat man with an old heavy bike.
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Have you looked at automotive TPMS modules ?
thanks, good keyword to Google for :D
Road bike tyres need to several times the pressure as car tyres.
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.
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a few grams here and there
how to save 200g from the inner tube with a lighter component, plus 400g off by removing the rear brake, so you can add +1200g on the wheel for the gearhub.
makes sense ;D ;D
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a few grams here and there
how to save 200g from the inner tube with a lighter component, plus 400g off by removing the rear brake, so you can add +1200g on the wheel for the gearhub.
makes sense ;D ;D
I could eat rice for a week :-DD That or just get back on the old bike. My bikes added weight = better workout = more weight loss. :-DD
I was running about 120PSI (8.3bar) in my road bicycle.
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Could you measure the RPM of each wheel and compare the two and use that to inform you of a loss in pressure.
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.
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Have you looked at automotive TPMS modules ?
thanks, good keyword to Google for :D
Road bike tyres need to several times the pressure as car tyres.
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.
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.
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Could you measure the RPM of each wheel and compare the two and use that to inform you of a loss in pressure.
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.
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.
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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 ?...
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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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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.
Sorry, but no. The majority of cars with TPMS have sensors *inside* the wheel on the back of the valve and communicate with the vehicle using an unlicensed band (like in Aus they're commonly 433MHz).
Here's the specific unit for a Pug 108.
https://luxurywheel.com.au/shop/automate-oe-tyre-pressure-monitoring-sensors-tpms-peugeot-108-06-2014-12-2020-oe-part-no-4260702031-4260742020/ (https://luxurywheel.com.au/shop/automate-oe-tyre-pressure-monitoring-sensors-tpms-peugeot-108-06-2014-12-2020-oe-part-no-4260702031-4260742020/)
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Have you looked at automotive TPMS modules ?
thanks, good keyword to Google for :D
Road bike tyres need to several times the pressure as car tyres.
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.
100psi+ (~7 bar) is not uncommon for bus and truck tires, and there are TPMS available for those too; also the fact that hitting even a small bump at speed will cause a sudden spike in pressure that could be much higher than normal suggests that they are designed to handle far higher pressures than the tires themselves can survive.
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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.
Sorry, but no. The majority of cars with TPMS have sensors *inside* the wheel on the back of the valve and communicate with the vehicle using an unlicensed band (like in Aus they're commonly 433MHz).
Here's the specific unit for a Pug 108.
https://luxurywheel.com.au/shop/automate-oe-tyre-pressure-monitoring-sensors-tpms-peugeot-108-06-2014-12-2020-oe-part-no-4260702031-4260742020/ (https://luxurywheel.com.au/shop/automate-oe-tyre-pressure-monitoring-sensors-tpms-peugeot-108-06-2014-12-2020-oe-part-no-4260702031-4260742020/)
Hate to correct you but according to Wikipedia (https://en.wikipedia.org/wiki/Tire-pressure_monitoring_system?useskin=vector) that isn't (rather, won't be) the case:
Since factory installation of TPMS became mandatory in November 2014 for all new passenger vehicles in the EU, various iTPMS have been type-approved according to UN Regulation R64. Examples for this are most of the VW group models, but also numerous Honda, Volvo, Opel, Ford, Mazda, PSA, FIAT and Renault models. iTPMS are quickly gaining market shares in the EU and are expected to become the dominating TPMS technology in the near future.
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[attach=2]Took a couple of photos of the front and rear. I would guess the bike is about 25 years old now. Never put a lot of miles on it. Maybe 4-5000 before it became wall art.
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Looks like the photo upload is broke again so you got to see my scope instead of the front wheel. I uploaded again and it seems to have corrected the linkage.
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I would guess the bike is about 25 years old now. Never put a lot of miles on it. Maybe 4-5000 before it became wall art.
Well, I bought a Speedwell Titalite made in 1985, pioner titanium frame with a lot of miles on its wheels and frame, so many miles that wheels arrived with dead rims and the fork is broken in several points, but this didn't stop me from looking for a new steal handworked novaCrMo(450g) fork and from rebuilding two 6-speed 28"/23 wheels with a 90s freewheel cassette that accepts up to six 8sp sprockets for a total 120mm Over Lock Nut, paired with a modified 7/8sp Rally3G derailleur and 8sp ErgoPower.
Masonry Steampunk art? no doubt about, but also a bloody killing machine to mock every modern carbon frame riders :o :o :o
... and I have a similar evil plan for my steel-frame 90s bicycle, so ... be very careful :D