Tyre Pressure Monitor Valve Stem Caps

I went out on a training ride recently with a professional instructor. I figure we have perishable skills and it's always good to check to make sure I am not just practising my own mistakes.

Anyway, he had a real focus on checking tyre pressures before each ride. I ride the Bandit every day and must admit to being an occasional checker and have found pressures quite low at times (no excuse). The instructor had tyre pressure monitor valve stem caps which show a colour. Green is normal, yellow is down by 4-5 psi and red is when the pressure is down by 10 psi. You can see at a glance.

I bought some from a guy in the USA through EBay. They are metal, well made, worked perfectly and I bought 4 at USD$2.20 each plus $2 shipping. Very reasonable, and unlike some on the market, have a square profile so they can be tightened with a spanner:

http://www.ebay.com/itm/Tire-Pressure-Monitor-Valve-Stem-Caps-ROUND-26-70psi-/290651601393?pt=LH_DefaultDomain_0&var=&hash=item8961b8e0f9#ht_1065wt_654

Will post if there's any issues, but at that price, well worth it.

kewwig wrote:
I bought some from a guy in the USA through EBay. They are metal, well made, worked perfectly and I bought 4 at USD$2.20 each plus $2 shipping. Very reasonable, and unlike some on the market, have a square profile so they can be tightened with a spanner:

http://www.ebay.com/itm/Tire-Pressure-Monitor-Valve-Stem-Caps-ROUND-26-70psi-/290651601393?pt=LH_DefaultDomain_0&var=&hash=item8961b8e0f9#ht_1065wt_654

Hi Kewwig, just had a look at the link you gave, it sent me to the round units, the better hex ones (from the same seller and same price) you recommend is:

http://www.ebay.com/itm/Tire-Pressure-Monitor-Valve-Stem-Caps-26-80psi-LQQK-/300639985918?pt=LH_DefaultDomain_0&var=&hash=item8bb4a1cff4

It looks like you nominate the rating when you buy them, not that I can see anyone wanting to put this much pressure into a standard wheel, but these hex units go all the way to 80 psi (round "only" goes to 70 psi).

I do like the simplicity of just looking at the wheels for a quick indication of pressure, would be interesting to hear how they go as far as accuracy and with a couple of kay's under their belt.

I was pondering a TPMS but the end of valve stem units are not getting a good rap and I have a phobia about putting the interrnal sensor inside the wheel, at least with a valve cap type unit you still have a standard valve to work with if something goes wrong. This looks like a very cheap alternative.

Thanks for the info.

They are certainly the right price - but only if they stay accurate after a few k's (nothing worse than a tool that doesn't do its job, no matter what the price). There is a lot of centrifigal force on the rim of a wheel. I'll be very interested to see what you reckon of them after say, 2,000kms & 5,000kms.

I got walked over to my bike for a lesson by my Dyno man Neville, of Lush Racing(who as 35years race experience). He asked, did I know there was no valve cap on the front. mmmmmmm yes, why? He asked, Do you go near 200km. mmmmmmm yes(on track), why?.........Well, At around 200km the Centrifugal force opens the valve. Shiiiiiit.

He said he only made this mistake once . He swapped valve caps on his race bike for cheap ones(pink or something) at the track just fooling around & forgot about it. Old mates rear tyre valve opened going down the main straight and he low sided at the first corner. His mate walked away and bike was fixable.

I have TPMS on the car (internal transmitters) and on the Bandit (Valve Cap transmitters).

barry mcki, the internal ones are mounted on the end of the valve stem inside the tyre but do not change the valve stems usability in any way. Should the transmitter fail, the valve stem is not affected.

The external ones I have on the Bandit work perfectly; in fact they alarmed just yesterday to advise me the front had dropped below the set cold pressure. Only issue I'm aware of with them is that they need to be fitted to rigid steel stems, not the el-cheapo flexi rubber stems most commonly seen on tubeless bike rims. They are locked in place and cannot be stolen or fall off without being unlocked.

I would recommend TPMS to anyone for bike and car.

A bit of googling found a review of these cheaper units:
"Some Consumers Report the Following After Using Tire Minder:

The air pressure of the tire was very low but the Tire Minder never changed color.
The tire service place had to replace the valve stem because the plastic part melted to the valve stem.
They were great for a while, but it can get difficult to see whether it is green, yellow, or red with brake dust and condensation inside (now this comment was a bit unfair - BM).
After a while, the threads corrode and fuse to the valve stem. Then you have to remove the tire from the rim and replace the valve stem.
If you knock the plastic cover off against a curb, the tire will deflate.
If the cap isn't tightened enough, if the o-ring fails or if the plastic cap develops a leak it will result in rapid air loss in the tire.

Tire Minder seems like a good idea although the consumer comments really make me wonder how accurate they are over the long term. I would personally stick with the old way of checking tire pressure... as long as you can remember to do it on a regular basis!"......might be giving them a miss me thinks, btw the Tire Minder company themselves recomend changing them (i.e. getting new ones) every 12 months.

Hi Al, the reports I saw about the end cap style TPMS transmitters quoted failures as the units flexed on the valve stem and hit the rim (btw this was mainly from 4WD off road users), so your steel stems would stop that problem. As for the internal tranmitters they looked like they included the valve stem, hence my concern if something went wrong would you still have a normally functioning valve. I suppose that as TPMS is manditory on all US cars now they would have sorted all the bugs out. Strange we don't hear too much about them over this side of the pond.

I've had these on since November, seem to work ok. Last week I checked the pressures with a gauge and they were both down slightly (1 or 2 psi), as expected the tyre minder was still green.
I think they are a good idea as long as you still periodically check them with a gauge.

Most of those problems listed are because people put them on and forget about them. They show green so they don't care

I'll be sticking with my pencil gauge and weekly check or a check before every "ride".
The caps sound like a good idea but I know what works for me. I'd be checking anyway out of a lack of trust

Reardo wrote:I got walked over to my bike for a lesson by my Dyno man Neville, of Lush Racing(who as 35years race experience). He asked, did I know there was no valve cap on the front. mmmmmmm yes, why? He asked, Do you go near 200km. mmmmmmm yes(on track), why?.........Well, At around 200km the Centrifugal force opens the valve. Shiiiiiit.

He said he only made this mistake once . He swapped valve caps on his race bike for cheap ones(pink or something) at the track just fooling around & forgot about it. Old mates rear tyre valve opened going down the main straight and he low sided at the first corner. His mate walked away and bike was fixable.

That's interesting. Now I want to do some calcs and work out the angular velocity and associated forces. Anyone know the spring rate of a Schroeder valve? Does make sense at high speeds tho. I have the oem TPS on my Beemer and it gives me the schits most of the time cos the rear internal sensor became intermittent about 20,000 kms ago and stopped working 9000 kms ago (we've done 60,000 km so far). Then last week it told me something briefly then went back to sleep. The most annoying bit is the big angry warning triangle that stays lit on the dash. Nothing subs for a good gauge I reckon. One of the things I like about the GSX is its honest simplicity.
Bill.

Update after a couple of months.

Checked my pressures and about 5 psi down and the caps haven't changed colour. I have never been 5 psi down and assume a slight air loss at each cap. They will show quite major loss, but aren't sensitive enough for a bike and in fact lull you into not checking the pressures enough. I have gone back to standard caps and regular checking.