What are your thoughts about external (valve cap) TPMS (tyre pressure monitoring systems) - and for tubed tyres?

Which are options are good and bad? Or are they all more or less useless for the mixed type of riding many of us do?

Checking pressure before every ride, an sometime more than once s day on 5hose long rugged days - is adviceable. I get a bit lazy sometimes...

On spoked wheels with innertubes, a puncture or a blow out can lead to losing air far more rapidly than on a tubeless. Early warning can prevent injury or bike damage. Also, an early warning can save you from having to fix a leak in a very much more iconvenient l8cation than one that is now too far behind you (where you started for the day, or a tyre repair shop that you passed...).

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There is progress to be found in some new tech... ABS, TPMS, GPS...

I travel with both bikes and cars that are 60 year old, and bikes that are brand spanking new. I don't fear new tech any more than the nostalgic old. However, if I can have the better tool for the job, I won't deny myself. I can light a fire like a caveman, but use a lighter 999 times out of a 1000 - like any wise man would. I have done trips of many thousands of kilometers on bicycle style bike seats - but prefer the ergo seats on my other rides. Each to their own I guess - but thinking that other people are doing it wrong because they improve the capabilities of their ride?

I have have been riding 30 yrs without TPMS. Stepping on the wheel, using a gauge, etc... I still want iTPMS (presupposing it is reliable). Checking tyre pressure on a heavy bike with your fingers? Yeah right! Nonsense BS!

I have had more than a few experiences where a TPMS would have saved me a lot of trouble. Only yesterday... I had just packed my car to the brim to take my family on a longer road trip. Right before leaving... I decided on an off chance to check the pressure (using a gauge and not my fingers). Only reason I did was because I had not used the car for a week, and I was killing time waiting for my family to put their shoes on. As I unscrewed the cap half a turn, it blew off from being under pressure. The valve was leaking, and must have for a while as I had lost 1 bar - though not enough to eyeball on the big wheels. The only thing preventing the air from rushing out real fast was a plastic cap, that would have shot off in the first bump I'd hit. I would most definitely have gotten a flat high up in the mountains - in the snow, in the dark, with kids... Had I not checked, and if I had TPMS, I would still have gotten an early warning and still have been ok.

It was a 30 second fix of the valve, and a quick top of with the air compressor at home. A few hours into that drive, the story would have been a lot different if I had not checked.

On another occasion, 12 hours into a high speed ride on the Autobahn, while really fatigued, I noticed I was loosing air - and just in the nick of time before things would have ended bad. That could have been and end of me, and the experience has made me far more disciplined on checking pressure - which has saved me a lot of trouble several times since.

TPMS is something I expect will become obligatory by law in not too many years - again presupposing they can be relied upon and not cause false security. It is a safety thing.

The question is rather if the valve type are any good, not if tyre pressure gadgets is a good idea or not (as long as they work).

And just so that it is known. It is very, very, very adviceable to check tyre pressure frequently and check the valve with a bit of spit. This is especially important before going on a very fast ride - and also every few hours on that ride. Also, before venturing off the beaten track (and every morning of that ride) and right after coming off the rough stuff and heading back onto the fast stuff with all the others - as well as throughout the day if your wheels are taking a beating. Also, after the bike has been standing for a while.

In fact, besides frequent brake checks, I can't think of anything more important thing to be more anal about checking than the condition of your wheels!

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How do these valve cap sensors work? Please tell me it’s not by deliberately ‘bypassing’ the actual valve to read the pressure in the tube /tyre and acting as valve and valve cap rolled into one themselves. If it is then you’re overriding a simple, time served, reliable and critical piece of safety equipment and handing the job to an unknown gadget of unknown provenance, whose only mass market testing is via Amazon star ratings and that may or may not break without warning. And you’re doing this in the expectation of greater safety? Or have I got this wrong?

My only experience of tpm systems have been the factory fit internal ones fitted to my wife’s last few (BMWGroup) cars and they have been the only things to go wrong while we’ve had those cars. On the last car we put in a warranty claim because of the tpms continuously giving us false readings and the current one still gives intermittent false readings. Not a system I have great confidence in but at least if it goes wrong it’s only an annoyance. And that’s factory fit. Excuse me if I pass on unknown Chinese valve caps where only the sticker changes between brands.

I think you have it wrong.

If you investigate TPMS systems used on heavy transport trucks (semi-trailers), most of them use a system that is connected to the inflation valve and measures pressure at the valve, by keeping the Schrader valve depressed. There is nothing wrong with that design - but the safety and reliability of it is, of course, very much dependent on good quality components and meticulous quality control during the manufacturing process.

I use the Garmin TPMS on my motorcycle, primarily because my GPS supports display and monitoring of tire pressure via Garmin supplied pressure sensor caps that fit over top of the Schrader valves. I have complete confidence in this system - I have used it for 5 years and 60,000 miles without any problem, and it did save my bacon once when I encountered a puncture from a large nail on the highway.

Like anything else, you need to be a critical consumer when purchasing equipment, particularly safety equipment. I don't purchase anything from unknown Chinese (mainland Chinese) manufacturers. Garmin makes their TPMS sensors in Taiwan, which is a totally different environment and culture from mainland China, and I have trust in Garmin as a manufacturer.

In reply to the original poster, who asked about TPMS in general, my recommendation is to purchase a system from a manufacturer that has a reputation for quality and dependability. Personally, I like the concept of TPMS integrated with the GPS because it minimizes the number of different systems on the motorcycle, and enables the manufacturer to easily update the software that operates the TPMS. The only downside that I have encountered so far is that the little batteries that go inside the sensor have a maximum life of one year, and it can be difficult to buy them when you are on the road because they are an uncommon size. This means you need to carry a couple of fresh spares with you.

Michael

I can only speak for the manufacturer I work for but this is not the case with all systems.

An external retrofit solution puts a pipe on the valve that opens it. This volume is open to a gallery where the pressure-voltage transducer is and then continues to another schrader valve. The unit is mounted on the wheel nuts so puts minimal stress on the tyre valve. In the event of failure the original valve can close.

An external solution mounting a complete P-V wireless unit on a valve tube is adding stresses to a component not designed to ta take it. Some valve stems are in metal which helps but many are not. If the original stem fails there will be an immediate and rapid loss of air. An external unit that has to be removed to put air in is permanently holding the valve open, so air is held by something potentially tested to a manufacturers internal standard not a tyre valve international one.

Internal systems either valve or strap mounted are before the valve and do not stress the stem. These will be the standard when legislation comes in. Temperature is a more useful measure in catching a blowout than pressure and you measure this off the rim not the valve air.

Personally I'm not going to screw Chinese tat onto my valve stems when two tyres can be checked in seconds with a hand held gauge. I am motivated to do this. A truck driver with 20 to do is less motivated and car drivers are incapable, hence legislation here/coming on 3+ wheeled vehicles.

Andy

I bow to greater knowledge of the subject - I'm no expert (or even much of an interested bystander) but there's a huge consequential difference between a tpms cap failure on a 32 wheeler and on a two wheeler. Especially as a trucking co is likely to be using caps with some sort of track record (to minimise failure inconvenience if nothing else) whereas the bike aftermarket is likely to be a bit of a race to the bottom minefield - especially if all you have to guide you is marketing or word of mouth. Most of the ones I've looked at since this subject came up have been heavy on marketing 'sizzle' (bluetooth this, handlebar display that, app on your phone the other) and light on independant safety assessment of the cap itself. Maybe they are a genuine advance in road safety but they - all of them - are going to have to be at least as safe and reliable as the simple time served mechanism they're bypassing to justify their place. So far I don't see any of that.

In practice what's going to happen - if your tyre and valve are functioning as they should then very little happens - no air leaks out between checks. Add a tpms and it'll tell you - nothing, and if nothing changes it'll get ignored. If it indicates something amiss you'll check a few times and it turns out to be a sensor fault (my car experience of them) through the battery going flat or it's cheap electronics or water's got in or whatever it'll get ignored ('the damn thing's playing up again'). A gadget version of the boy who cried wolf. I might come across as some kind of mechanical luddite with this but not so - I'm usually closer to an early adopter than the opposite, but aftermarket tpms's don't form a complete risk / cost / benefit circle for me at the moment. They seem like a half developed technology.

If you read in BMW or KTM forums about issues on standard TPMS it sounds sometimes similar like a half developed technology.
Riders critisize periodic connection failures to the ECU. Some complain about variable unrealistic pressure data shown in high and low environmental temperatures.
Often these issues get more frequent when the TPMS sensor had to be replaced after 40-60.000 km. Problem with the sensor is that it is nearly impossible to replace the soldered in battery. You have to invest another 70-100€ for each sensor + installation costs.

BMW and KTM plug in Schrader Motorcycle TPMS.
https://www.schradertpms.com/en-gb/o...otorcycle-tpms

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Problems with not reading are down to the signal strength limits set by the EU. They are the same as alarm remote controls but don't take into account data has to be in complete chains not just on/off and that radio waves dislike metal cages.

Taking temperature into account is why you want an internal sensor and properly developed software, not some students project with an industrial P-V and the Bluetooth on his phone.

Sensor batteries get run down by endlessly trying to connect to a system that's just out of range, just like your phone trying to connect to duff wi-fi. Ultimately, assuming they cannot have a more powerful signal they'll mount receivers inside the mudguard to pick up sensors built into the tyre.

Andy

Pressure changes with altitude and temperature changes - which is not a fault with the TPMS. Riding will increase tyre temp. Higher speeds, tougher terrain, thicker innertubes, higher outside temp, will all make the tyres run hot - and pressure increase. The constant changes of pressure is not a fault with the TPMS (presupposing it is a reliable device).

My main reason for retrofitting a TPMS would not be to have a correct ambient reading, or have a temp sensor try to calculate it. My main reason would be to have an early warning system for loosing pressure - mostly while in the go. I would still probably be checking the pressure with a gauge sllmost as regularly as I do today, and less frequent as my confidence in the system grew.

The valve cap version would take seconds to retrofit, but are there any good ones that are compatible with innertubes? Do they pose a safety issue in themselves? I have no clue. When it comes to the valve type, I've read somewhere that the simpler varieties with a small handlebar display (of a recognized brand) is preferable to more advanced variety with larger displays, temp sensors, etc - claiming longer battery life, better reliability, etc. Wether that is good advice - I don't know - this tech is new to me.

As I change tyres frequently, I'm not too worried about the inconveniences of having to replace a battery inside the tyre - but the valve cap solution is such a smooth install... but only if it doesn't lead to a rapid loss of air 7n itself. Now, I hardly ever go above 140 km/h on an adventure bike. So, is the potential stress 8n the valve stem really an issue - or just anoter SoMe echo chamber "fact"? Again - I have no clue. I would however assume that if there was a real and significant risk of a technology such as this and which has been arround for s few years - that legislation would be out in place to sell or market them for such risky applications. Or am I just being naive?
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Cholo - I apologize for the insulting connotation of my response to your comment. It's just that your response could come across as something that advocates KTT - which to me falls in the same category as riding without gear, eye protection, open faced helmet, hiking boots, etc - all topics I am bit overly sensitive about. Sure, it is a personal choice - but one that comes at a risk.

I still don't for one second believe that one can eyeball pressure (except when close to flat), or even read it with any degree of accuracy by kicking, stepping or squeezing the tyre. Sure you can when you are dealing with a tyre that is flat or close to flat, but can you recognize 1/4 bar change? I sure can't - and I am no beginner. Even if I had hydraulic strength in my fingers, I don't think I could - and it is not for lack of trying. On a side stand, center stand, balancee, loaded or unloaded - I can't.

With the potential dangers involved in not being on top of one's wheel condition at all time - taking frequent and methodical measurements with a calibrated quality instrument is the only sound practice in my opinion. I still step on my tyres when I can't be bothered to take out the gauge - between the frequent gaugings.

As for making fun of riders that have crash bars, etc - I can think of many reasons where having many of the items you mention is more adviceable than not having then. That much said, I agree that for some applications, some people go a bit too far for their own good. This TPMS might very well be such a case for me - that is why I want to discuss it. For most of us, funds is a limited resource. For many of us, every item added comes at the expense of exponential amount of clutter in our life, more weight, more space consuned, more worries, and can over sll require more attention and concern than what it was intended to leviate, etc. Having one turn by turn GPS and a second with a route - I see it has its place. A GPS to replace your phone which doesn't stand up to heat - I get it. Still, one ought to be critical about these things - so at some level I agree with you... but definitely not on tyre pressure.

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These sensors have a gravitation switch which is activating the electrical flow when the wheel starts spinning with 15-20km/h.

The sensor itself has no paired or bilateral confirmed wireless connection to the 433mhz receiver. It is just sending the data in fixed chronological intervals. All modern sensors send data of id, pressure and temperature but not every receiver shows temperature.

The 433mhz receiver is often hardware connected to the ecu and it only reads this data. There is no principle of trying to connect existing and necessary. If the signal cannot be received, you don`t see data. Therefor no complex software is needed because sensors talk in general trough simple commands.

This principle is also used by the TPM Systems with the caps(e.g.FOBO). The only thing which has to be fixed up in front for reading data is to tell the ecu or a seperate receiver(external display or smartphone) or a garmin trough an identification process which sensors is where.

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While riding, I think it only works with tubeless. Think about Formular one or Rallye technic. They all use tubeless to receive exact data of the pressure and temperture sensor. Either you messure inside the tyre or you messure on the valve of a tube.

The advantage of tubeless is that you get exact temperature and pressure data out of the inner volume of tyre. Means if the data reading device is programmed correctly and detects failing pressure and rising temperature togehter than you should get immediatly a warning signal.

The problem with this valve cap is that it only shows pressure. Temperature detecting isn`t given. Due to weight of the caps and the law of rotating mass it is maybe necessary to counterbalanced the wheels. Also the valve stem or the part where it connects into the tube can be damaged too through this.

The display must be easily readable. It is equal if it is an external display on the bar or if it is done by your smartphone.
The critical thing is: How does the programming behind both devices interpret the data send by sensors? Equal if you use an external display or a garmin or a smartphone as a control device, a nice warning sign and a sound signal must be given to touch your attention.

From 2026 on all new motorcycles faster than 50km/h must be equipped with TPMS in the EU. Afaik you can still buy motorcycles with a valved bases TPMS since 2012.

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I think this review is quite informative. Here are a couple of bits of info I found interesting:

• $130
• Regular watch type batteries
• Valve caps weight less than 0,3 ounces and don't require rebalancing of the wheel
• Failure of non-metal valve stems is rare, though most innertubes comes with metal ones
• Compatible with innertubes
• Designed specifically for the adv motorcycle market

I wish the display was battery powered.

The reason I want a separate display and not have the kind where I have to rely on my phone:

• I don't always ride with my phone watched to the bike
• I couldn't be bothered to launch and check an app all the time. Even if alarms were running in the background, pairing still ought to be checked
• My phone is only attached to the bike when I am to use it for something particular, like navigation

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Having the app bleeping away at 3.00am to tell you your tyre pressures are down 1 psi might be another reason.

Just a couple of additional bits of information, this from my own experience using the Garmin TPMS, which displays the pressure on the GPS:

1) Garmin recommends using a metal valve stem, not a rubber valve stem, if you install the sensors that go on the end of the valve stem. This makes sense, because the (small) weight of the sensor will cause a rubber valve stem to flex fore and aft with acceleration & deceleration. That's not a concern with a metal valve stem. I have found via experimentation (using a dynamic wheel balancer) that the presence of the sensor does not seem to affect wheel balance - but having said that, when I change tires, I get them balanced with the sensor in place on the stem.

2) Tire temperature, and the pressure rise that comes with increasing tire temperature, is not a concern for riders. The only two things that matter to us are: a) the tire is at the correct pressure setting in the morning, before you start riding, when the wheel & tire are at ambient temperature, and; b) knowing that we will get a prompt notification if the tire pressure drops below the correct pressure setting when we are riding.

The Garmin system will notify the rider if the tire pressure drops (at any time) below a lower threshold that the rider can set. On my motorcycle, the recommended pressure is 42 PSI (2.9 bar), so I set the warning threshold to 40 PSI. The 2 PSI gap eliminates nuisance warnings first thing in the morning on colder than normal days.

3) The Garmin sensors only operate when the wheel is rotating - this is to prevent battery drain. I assume there must be some kind of centrifugal sensor that detects wheel rotation. Despite that, batteries don't last more than a year (as I noted earlier), and I have learned that it is prudent to carry two spare batteries. They are tiny, about the diameter of a coffee bean and only 3 mm thick.

Having to change the batteries once a year, or even twice, doesn’t sound bad to me - I would do it with regular service or changing the rubber.

As for the cost, even if I had to replace the entire system after 20k, yet alone only the sensors at 60k as was mentioned earlier, that sounds more than ok to me.

My last leak was due to the needle inside that valve having unscrewed itself - with only the plastic cap preventing it all from gushing out. My main concern with going for a valve cap system is wether or not it increases the risk of a leak at the valve or not. How does this work?

From what I have read so far, I am leaning heavily towards getting a set.

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