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Those flares are so getting caught up in that chainset.
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I'd prefer to ride at the lower recommended PSI for TL, but with how bad the surface conditions are where I ride, it'd heavily increase the probability of needing wheel servicing.
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Originally Posted by PeteHski
(Post 23086350)
Ah I see now! JLR do have a poor reliability record, but AFAIK it doesn’t mean that all their TPMS sensors read low by exactly the same amount.
Lotus = Lots Of Trouble, Usually Serious!
Originally Posted by eduskator
(Post 23086502)
I believe LR is the most unreliable car brand on the planet. Great looking cars, but man, you buy new and get rid of this after 3-4 years of ownership. Resale value must be low too.
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Originally Posted by DangerousDanR
(Post 23086806)
If the software is off, all the sensors will be off. By the way, all of the major components that have failed on the Jag have been German. Go figure.
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Originally Posted by DangerousDanR
(Post 23086806)
If the software is off, all the sensors will be off. By the way, all of the major components that have failed on the Jag have been German. Go figure.
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Originally Posted by PeteHski
(Post 23087428)
Maybe the software is doing some temperature compensation.
It is a MEMS sensor and temperature dependence (beyond normal gas physics) is a function of how they work. The car reads low, but not very much low. Not enough discrepancy to cause trouble either way. Jaguar calls for 47 PSI in the rear, so running 45 on the TPMS set at near freezing will be okay all winter. I don't see any caveats about temperature in the JACO data. If I wanted, I could check the JACO against a calibrated sensor at work. |
Originally Posted by DangerousDanR
(Post 23087437)
I'm currently using an electronic pressure sensor in a couple of products. The one we use is cheap and it reports temperature and pressure. We do the correction in software.
It is a MEMS sensor and temperature dependence (beyond normal gas physics) is a function of how they work. The car reads low, but not very much low. Not enough discrepancy to cause trouble either way. Jaguar calls for 47 PSI in the rear, so running 45 on the TPMS set at near freezing will be okay all winter. I don't see any caveats about temperature in the JACO data. If I wanted, I could check the JACO against a calibrated sensor at work. The analogue gauges on my 2 track pumps also seem consistent. I often hear about how inaccurate they can be, but mine seem pretty good. |
I think it's beyond the capability of virtually anyone on here to determine ideal tire pressure for speed, any more accurately than +/- 5 psi. Heck, probably 10psi. Too many variables, too many unknowns, too much subjective assessment, not enough good data.
I'd go further and speculate that even with all possible simulation capability, computing power, and eliminating rider weight and road smoothness variables, it's still too hard. Not that a number couldn't be calculated, but there are still variables and lack of good data. |
Originally Posted by downtube42
(Post 23087679)
I think it's beyond the capability of virtually anyone on here to determine ideal tire pressure for speed, any more accurately than +/- 5 psi. Heck, probably 10psi. Too many variables, too many unknowns, too much subjective assessment, not enough good data.
I'd go further and speculate that even with all possible simulation capability, computing power, and eliminating rider weight and road smoothness variables, it's still too hard. Not that a number couldn't be calculated, but there are still variables and lack of good data. |
Originally Posted by downtube42
(Post 23087679)
I think it's beyond the capability of virtually anyone on here to determine ideal tire pressure for speed, any more accurately than +/- 5 psi. Heck, probably 10psi. Too many variables, too many unknowns, too much subjective assessment, not enough good data.
I'd go further and speculate that even with all possible simulation capability, computing power, and eliminating rider weight and road smoothness variables, it's still too hard. Not that a number couldn't be calculated, but there are still variables and lack of good data. Not a big deal anyways. Most cyclists only want to feel good on their bikes and they find a certain pressure that suits their needs. |
Originally Posted by Sy Reene
(Post 23083681)
If your tubeless wheels are hookless, you do indeed have to reduce your pressure by a lot to be safe per ETRTO. Make sure you also abide by the tire and rim manufacturers specifications -- ie. go with the lowest of the sources. See Silca disclaimer I pasted below
96R/85F -- that seems like a much larger difference than Silca's calculator usually returns between rear and front. Are you running different width tires in Front vs Rear? https://cimg3.ibsrv.net/gimg/bikefor...7cd5874a39.jpg That must be a new concept. |
Originally Posted by downtube42
(Post 23087679)
I think it's beyond the capability of virtually anyone on here to determine ideal tire pressure for speed, any more accurately than +/- 5 psi. Heck, probably 10psi. Too many variables, too many unknowns, too much subjective assessment, not enough good data.
I'd go further and speculate that even with all possible simulation capability, computing power, and eliminating rider weight and road smoothness variables, it's still too hard. Not that a number couldn't be calculated, but there are still variables and lack of good data. |
Originally Posted by DaveSSS
(Post 23088461)
The Zipp pressure calculator is what I've been using for the last 3 years, since going tubeless on hooked rims for a year, then on to wider hookless rims. It's simple to put in all necessary information, except for tire casing. I have to decide whether thin or standard is most appropriate for the top level hookless compatible tires like the Pirelli P-Zero tires that I use. Thinner casing, requires more pressure. I've been using something in between thin and standard. It's only a suggestion and up to the rider to decide what they prefer.
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Originally Posted by DaveSSS
(Post 23088461)
The Zipp pressure calculator is what I've been using for the last 3 years, since going tubeless on hooked rims for a year, then on to wider hookless rims. It's simple to put in all necessary information, except for tire casing... .
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Originally Posted by Sy Reene
(Post 23088472)
..and road condition and tire's inflated width. And it lets you choose rim type, but not tire type but I guess we'll assume nobody uses tubed tires on a tubeless rim :-)
I like the silca one but how does one know what speed to put in? what is a fast group ride or moderate group ride? ultimately I end up going with the firm setting from the Rene Herse calculator which is quite a bit higher than either of the other two... |
Originally Posted by Sy Reene
(Post 23088472)
..and road condition and tire's inflated width. And it lets you choose rim type, but not tire type but I guess we'll assume nobody uses tubed tires on a tubeless rim :-)
It would be strange to buy expensive tubeless tires and use tubes in them. The recommended pressure for tubeless might result in pinch flats with tubes. I carry a spare tube, since it might be needed with a damaged tire, but I wouldn't use tubes in them. |
Originally Posted by Alan K
(Post 23087872)
Fastest possible pressure!
That must be a new concept. |
Like many I have been on this slow increase in tire width and slow decrease in pressure. Currently I am running 30mm (31mm actual) GP5000 S TR tubeless at around 50-55psi for my 170lb me+bike weight. In the summer I will bump that up ~5psi. The Silca calculator says 65psi for me.
When I first got the 30mm tires I was running 70psi which probably gives optimal speed on reasonably smooth pavement, but the handling is so much better at lower pressures, both for smoothness of the ride and for grip when you need it. Especially in winter I really appreciate the lower pressure as the roads are wet much more often and the grip can be minimal at times. |
Originally Posted by scottfsmith
(Post 23089477)
Like many I have been on this slow increase in tire width and slow decrease in pressure. Currently I am running 30mm (31mm actual) GP5000 S TR tubeless at around 50-55psi for my 170lb me+bike weight. In the summer I will bump that up ~5psi. The Silca calculator says 65psi for me.
When I first got the 30mm tires I was running 70psi which probably gives optimal speed on reasonably smooth pavement, but the handling is so much better at lower pressures, both for smoothness of the ride and for grip when you need it. Especially in winter I really appreciate the lower pressure as the roads are wet much more often and the grip can be minimal at times. |
Originally Posted by downtube42
(Post 23087679)
I think it's beyond the capability of virtually anyone on here to determine ideal tire pressure for speed, any more accurately than +/- 5 psi.
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Originally Posted by tomato coupe
(Post 23089402)
What term do you prefer for the pressure that minimizes resistance?
But don’t worry, I fully understand bastardization of language. 😉 |
Originally Posted by DangerousDanR
(Post 23086127)
Do I really have to explain? OK. Let me try...
In the Beatles movie "Help" there is a scene where the "baddie" points a pistol at Mr. Starkey. He in turn sticks his finger in the barrel and says, "It's British you know...won't work." Like the old joke about warm beer and Lucas refrigerators. I have owned three British motor vehicles: a Norton Commando (with a Boyer-Bransden ignition that would stop working when the temperature was above 90F), a Series II land Rover, and my current Jaguar XE. All three of them have been absolute hoots to drive in their preferred environment. Not a one of them was what you might call reliable. I have also tried to buy two Lotus automobiles, but the deals fell through. He should have realized when Ford ownership actually improved the quality of Jaguar. Now it’s ownered by Tata (an Indian company known for its unsafe and unreliable crap vehicles) but the guy keeps going back to it. 🤪 |
Originally Posted by PeteHski
(Post 23087653)
A couple of days ago I topped up tyre pressures on our 2 cars using a cheap portable compressor with a built-in digital gauge. I set all 8 tyres to 40 psi on the gauge and all 8 TPMS sensors reported 40 psi. I was actually quite surprised none of them read slightly different! But now when I think back to other cars I’ve owned, I can’t actually remember a TPMS sensor reading low/high relative to my Topeak digital gauge.
The analogue gauges on my 2 track pumps also seem consistent. I often hear about how inaccurate they can be, but mine seem pretty good. I added air to four tires of my car (excluding the spare), each of the four tires were off by 1-3 PSI. An external high quality digital meter was used fill exactly 36PSI. The gauge in the reported inconsistently lower numbers. I’m not sure if individual pressure sensors can be recalibrated, As for bicycles tire pressure, I have always liked to use a few PSI lower pressure than the maximum. On 25mm I usually use around 70-75 PSI. |
Originally Posted by Alan K
(Post 23090062)
40 PSI? A lucky coinkidink!
I added air to four tires of my car (excluding the spare), each of the four tires were off by 1-3 PSI. An external high quality digital meter was used fill exactly 36PSI. The gauge in the reported inconsistently lower numbers. I’m not sure if individual pressure sensors can be recalibrated, It also helps my “luck” in that my compressor actually targets 0.5 psi higher than the nominal setting. So it sets my tyres pressures to an indicated 40.5 psi. Which means that the TPMS sensors are less likely to read 39 or 41 psi because they don’t round their readings up or down. So 40.1 and 40.9 both display as 40. |
Originally Posted by WaveyGravey
(Post 23085859)
I ride Gatorskin 700x25 at 100 PSI. I weigh about 160 pounds.
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