- Joined
- Nov 10, 2007
- Messages
- 1,615
- Age
- 61
- Location
- Vancouver, British Columbia, Canada
- Bike
- 1&2&3-2005 ST1300ABS
- 2024 Miles
- 002662
- STOC #
- 8562
AV8R, Looks great, numbers look good too.
Max Min tire pressure settings in TPMS App
- Thread starter AV8R
- Start date
OP
OP
Day 2...
- I see that the tire pressure numbers decreasing (for brand new tires). I assume thats due to the 3-5 *F lower ambient temps).
- What are the blue numbers above the big black ones?
- I see that the tire pressure numbers decreasing (for brand new tires). I assume thats due to the 3-5 *F lower ambient temps).
- What are the blue numbers above the big black ones?
From Fobo user manual
14 Reference pressure at 20 deg C:
Reference pressure is a temperature-compensated tire pressure referenced back to a
standard temperature of 20 degree Celsius. This is useful and serves as a guide for
the user to decide on the approximate amount of air needed to inflate the tire during
hot season or immediately after a long drive.
The reference pressure reading is located above/below the actual pressure reading
in blue with smaller font size. The user has an option to show / hide the reference
pressure reading for individual profile by going to the “settings” at top right corner
Sent from my SM-N960U using Tapatalk
14 Reference pressure at 20 deg C:
Reference pressure is a temperature-compensated tire pressure referenced back to a
standard temperature of 20 degree Celsius. This is useful and serves as a guide for
the user to decide on the approximate amount of air needed to inflate the tire during
hot season or immediately after a long drive.
The reference pressure reading is located above/below the actual pressure reading
in blue with smaller font size. The user has an option to show / hide the reference
pressure reading for individual profile by going to the “settings” at top right corner
Sent from my SM-N960U using Tapatalk
Somebody told me that they no longer teach logarithms in school now - its all done w/ calculators. Wonder what else is obsolete. (Besides paper in all those paperless offices.....)
OP
OP
Paper textbooks is the biggest, but slide rules are gone too
Seriously, truth is gone...
- Fuzzy math, common core
- Revisionist history, Constitution and Founding fathers replaced with social issues
- Fake science, replaced with faith systems (beliefs not facts) including Evolution, Gia and global Armageddonism
- Ethics both Classical and American, replaced with PC agendas, like pressuring kids to Marxist views.
I know this as having kids in grade school and college
Last edited:
OP
OP
And innocence is gone
OP
OP
Thank you for the manual reference. Missed it in my scan through the PDF manual. I’m old fashioned and do better with paper books. Anywho....
The manual says:
“This is useful and serves as a guide for the user to decide on the approximate amount of air needed to inflate the tire during hot season or immediately after a long drive.”
So 20°C is equal to 68°F (The conversion formula is °F = (9/5 °C)+ 32), how do I make use of this reference exactly (keepin in mind the ambient here is 80-90 *F). What’s the math?
That's the cosmic question of the day!
I just answered the easy question because I had some down time to look.
Sent from my SM-N960U using Tapatalk
the math was the previously mentioned pV=nRT, where the pressure is in absolute units, not gauge, and the temperature is also in absolute units, as in °K or °R. However, since your display is showing the temperature as 68°F (I assume that's the temp inside the tire?), which as you say is equal to 20°C, the two values should be the same if the blue font figure is actually the value described in the manual. Its anybody's guess as to why the blue value isn't what its described to be in the manual.
OP
OP
Being the FoBo device is externally mounted on the valve stem, the temperatures are likely ambient and not internal to the tire. Why there’s 2 degree difference between the front and back tire of a garaged bike that hasn’t been ridden in days, I could only guess. Maybe that’s the error precision of the device, +/- 2 *F
That’s my story and imma gunna stick to it.
Still, I’m not sure the smaller blue numbers are of much use. I think I read they can be hidden.
That’s my story and imma gunna stick to it.
Still, I’m not sure the smaller blue numbers are of much use. I think I read they can be hidden.
You may be onto something there. Note also that the first shot shows the rear as 2 degrees warmer than the front; in the second shot it's the other way 'round.
I keep the "reference pressure" hidden on mine- I see no value in knowing what the pressure *would be* at some other temperature. What matters to me is what the pressure *is*, at the time and place I am likely to ride.
I suspect since its also measuring the air pressure the temp sensor is trying to sense the temp of the air inside the tire as well, but not sure how accurate it will be able to measure that from the valve stem. Also noticed that the two blue numbers are pretty far apart, and since the temp of the two tires is within 1°C and the pressures are identical they should be very close if they're really some temp-adjusted calculation. I'd hide those numbers, whatever it is they are trying to achieve, they don't seem to be successful at it.Being the FoBo device is externally mounted on the valve stem, the temperatures are likely ambient and not internal to the tire. Why there’s 2 degree difference between the front and back tire of a garaged bike that hasn’t been ridden in days, I could only guess. Maybe that’s the error precision of the device, +/- 2 *F
That’s my story and imma gunna stick to it.
Still, I’m not sure the smaller blue numbers are of much use. I think I read they can be hidden.
You are correct - but to split the hair even further, the pV=nRT relationship is only accurate for ideal gasses - which air is certainly not...hence the term "about the same"...
At the temperature/pressure points typical for tires, air behaves about 99.9% like an ideal gas, so for the sake of this discussion we can call it ideal. I agree with your comment that the pressure would change at "about the same" rate as the temperature, I never said otherwise. My earlier comment was in regards to what pressure do you use in the calculation to adjust for temperature changes. In your example you had used gauge pressure for the calculation, but the formula is based on absolute pressure, I was simply pointing out that one difference.
OP
OP
Measured after a 4 hour ride in 88*F sun.
OP
OP
The stem turned about 5-10* with the sideways mounted Fobo
Should i be concerned? No leakage and pressures are normal.
Should i be concerned? No leakage and pressures are normal.
OP
OP
Rut-roh!!!
The front Fobo sensor barely didnt clear something and slowly wasnunscrewing itself to the point where it released air. Fortunately it was fine until I was at my destination. Good ole portable air pump saved the day
The front Fobo sensor barely didnt clear something and slowly wasnunscrewing itself to the point where it released air. Fortunately it was fine until I was at my destination. Good ole portable air pump saved the day
Do they not have lock nuts behind the sensors?
Yes Fobo does send them with lock washers. My cheap off brand set does too.
Sent from my SM-N960U using Tapatalk