Member Contributer MadScientist Posted October 27, 2015 Member Contributer Share Posted October 27, 2015 Dae's Post in the Angel GT mileage thread shows a very cool TPMS that I want to have on my bikes. Rather than necromance this thread from 2008 or this one from 2011, I thought I would start us off fresh. So, who out there is, or was, running a TPMS on any of their bikes? How do you like it? Is it precise? I don't really care exactly how accurate it is, as long as the inaccuracy is predictable. If you are using an external type, how heavy are the transmitter caps and will they interfere with anything if mounted on a 90 degree valve stem. I don't expect a whole lot of responses, but please don't recommend hand held tire pressure gauges. Since most of my bikes are driven daily, the prospect of getting the pressure gauge out, moving the bike so the stems are accessible, measuring, and washing the brake dust/road grime/chain lube off of my hands is unattractive. $100-200 for a TPMS would be worth it to me for the time spent and also provide a warning system for slower leaks while on long ride. advrider alerted me to the existence of the FOBO bluetooth/smartphone TPMS. This is now a frontrunner, assuming it fits my 90 degree valve stems. Riders say the sensors weigh about 10g and they are 26mm diameter ~19mm tall. I've emailed FOBO for more info, but if anyone is using this, feel free to chime in. Upon doing some calculations: (Rear Wheel) The radius from wheel center to cap is ~190 mm The rotational speed of the wheel is ~ 980 RPM at 70 mph With a 10g weight, gives a centripetal force of about 20 N (~4.5 lbs-force). This is ideal and neglects gravity (frictionless with horizontal axis). In reality, the centripetal force is cyclic and changes when Earth's gravity pulls with or against the centripetal force. I didn't measure the front wheel, but it looks like the radius will be larger, so the force greater. All that crap aside, I think this may require re-balancing. Anyone out there re-balance? I did neglect the weight of the original valve cap, which makes this a bit worse. Even so, the cap/sensor now applies this as shear force to the end of the valve stem. I'm now thinking that 90 degree valve stems might be a poor choice for mounting the sensors. Quote Link to comment Share on other sites More sharing options...
Member Contributer FJ12Ryder Posted October 27, 2015 Member Contributer Share Posted October 27, 2015 I don't know that I would put them on the angled valve stems, just to be on the safe side. I don't think it would be much of an issue, but why take a chance. I also wouldn't put them on rubber valve stems, too much chance for flex failure. I have a TPMS on my triple axle toyhauler and they are mounted on steel stems. They weigh more than these do, but I'd err on the side of safety. There have been reports on the RV forums I frequent of valve stem failure after mounting a TPMS sensor on a rubber valve stem. Could be old worn out valve stems, but i don't know. On one hand I think it's kind of silly, but OTOH it does have a certain practicality in that there would no reason to ever not know the tire pressure before starting out on a ride. I don't check pressures before every ride and this would remove the need to do so manually. I don't own a smart phone, but I might actually think about it if I did. The price is really reasonable too. Quote Link to comment Share on other sites More sharing options...
Member Contributer MadScientist Posted October 27, 2015 Author Member Contributer Share Posted October 27, 2015 FJ12 - What brand do you have on the trailer? Sounds like they are external mount. Have you ever checked their accuracy? Quote Link to comment Share on other sites More sharing options...
Member Contributer FJ12Ryder Posted October 27, 2015 Member Contributer Share Posted October 27, 2015 I have the TST system and yes, they are external mount. I've only checked their accuracy relative to the gauges I use at home, and they are within a couple psi at 105 psi. I had a couple of OEM trailer tires rapidly depressurize and totally spoiled my day. I don't really think the alarm for low pressure on the motorcycle unit is all that relevant since by the time the tire is going down you've probably already realized it. But it would be nice to now what the pressure is at the beginning of a ride, and then at stops. I think it has it's place and the price is right. Quote Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted October 30, 2015 Member Contributer Share Posted October 30, 2015 I have the Garmin ones; they work through my Zumo 590. I have them mounted on Bridgeport aluminum 90-degree valve stems. They work, but the Zumo has trouble keeping in radio contact with them, so I frequently get "sensor not connected" error messages, which is an annoyance. But most of the time they do work, and I suppose they are accurate (when they're connected!) One thing I like about TPMS is that you usually get an alarm or warning when the pressure goes below a certain point, which you can choose separately for each tire. Ciao, Quote Link to comment Share on other sites More sharing options...
enzed_viffer Posted October 30, 2015 Share Posted October 30, 2015 Is a TPMS really necessary? I've got one on my car (came with it), but on my bike I can feel a 1 or 2 PSI drop in pressure pretty readily. Over 42-odd (and sometimes VERY odd) years of motorcycling, I've had only 4 punctures, all in the back tyre, and 3 of them in newish tyres. Luckily (?) they were all screws or nails, and plugged OK, so I still got the full life from the tyres. Had none for years (ever since I stopped riding in places I shouldn't, like the edges or middle of roads, where all the crap gets swished by traffic. Quote Link to comment Share on other sites More sharing options...
Member Contributer FJ12Ryder Posted October 30, 2015 Member Contributer Share Posted October 30, 2015 I would say not necessary, but could be handy. I like the idea of knowing what the pressure is before taking off on a ride without manually checking the tahrs. I couldn't tell if I were a couple psi low, but I could tell if the tire was pretty low. I've only been riding for 50 years though. LOL Quote Link to comment Share on other sites More sharing options...
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