Can someone explain the Physics for this...
Ross Gardner
Posts: 230
If you don't use your bike, the tyres run flat. If you use your bike regularly, the tyres keep their PSI for longer. What gives?
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Er um, so they go flat quicker if you use it?
Makes sense, as tubes/tyres are slightly porous, so more force will force out more air.
But to be sure, have you actually tested your hypothesis?I don't do smileys.
There is no secret ingredient - Kung Fu Panda
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Parktools0 -
cooldad wrote:Er um, so they go flat quicker if you use it?
Yeah I worded that wrongly. Thanks for helping me correct myself.cooldad wrote:Makes sense, as tubes/tyres are slightly porous, so more force will force out more air.
But to be sure, have you actually tested your hypothesis?
I was being lectured by someone that tyres get flat quicker if you don't use them. I was like... what?0 -
Ask them if they've ever tested their hypothesis.
Leaving a bike in a shed for a year or two doesn't count.I don't do smileys.
There is no secret ingredient - Kung Fu Panda
London Calling on Facebook
Parktools0 -
Your mate is wrong. Simple as that.0
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cooldad wrote:Ask them if they've ever tested their hypothesis.
Leaving a bike in a shed for a year or two doesn't count.
Well he's been riding seriously for twelve years, and I just recently restarted the sport last year. I could tell if he was winding me up.0 -
Ross Gardner wrote:
Well he's been riding seriously for twelve years.
Must be because he's so tired he became confusedNow where's that "Get Out of Crash Free Card"0 -
If it is kept at the back of the shed as opposed to say by the back door then it will be marginally warmer and thus the tyres will expand slightly more than those of the one left outside thus imitating the effect of lower pressure. The back door bike will be more exposed to the sun and so the tyres will be slightly hardened by polymer cross linking which would proxy a higher retained pressure.
Also, as Cougie says, the molecules in the shed tyre are described by Bose Einstein Statistics whilst those in the back door bike follow Fermi Dirac stats - surely you knew that?
Also if you had a Mammoth or other paciderm in the shed then this would press up against the tyre and force air from the valve thus reducing the pressure - surely you knew that?...take your pickelf on your holibobs....
jeez :roll:0 -
I think that's 'Pachyderm'... but surely you knew that?All the gear, no idea and loving the smell of jealousy in the morning.
Kona Process 134 viewtopic.php?f=10017&t=129946070 -
Do they really go flat quicker or is it a way of trying to convince yourself it's not really that long since you last rode your bike.0
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Veronese68 wrote:Do they really go flat quicker or is it a way of trying to convince yourself it's not really that long since you last rode your bike.
Lol!All the gear, no idea and loving the smell of jealousy in the morning.
Kona Process 134 viewtopic.php?f=10017&t=129946070 -
I have a bike permanently sat on the turbo atm
the back wheel gets a daily workout rotating around 30 miles of distance ... the front wheel get a 1/4 rotation every week or so when I remember
neither one looses pressure any quicker
does sitting on the bike but not turning the wheels constitute as using the bike .... in which case if you balance 70kg on your saddle when you park the bike, the tyres will stay up ?0 -
Surely as soon as the wheels stop turning, all the air falls to the bottom of the wheel? If the valve is at the bottom all the air will come out through it. Obvious really.0
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philcubed wrote:Surely as soon as the wheels stop turning, all the air falls to the bottom of the wheel? If the valve is at the bottom all the air will come out through it. Obvious really.
That can't be right.
Haven't you ever had a flat tyre? When you do you will notice that all the air goes to the top of the tyre, leaving only the bottom flat.“Life has been unfaithful
And it all promised so so much”
Giant Trance 2 27.5 2016 ¦ Sonder Broken Road 2021¦ Giant Revolt Advanced 2 2019 ¦ Giant Toughtroad SLR 1 2019 ¦ Giant Anthem 3 2015 ¦ Specialized Myka Comp FSR 20090 -
That is because the air is lighter than air.
Surely you knew that?...take your pickelf on your holibobs....
jeez :roll:0 -
Angus Young wrote:I think that's 'Pachyderm'... but surely you knew that?
Right - but I was making a trunk call at the time....take your pickelf on your holibobs....
jeez :roll:0 -
bompington wrote:I think you're all just ignoring the elephant in the room. The real issue is that, if you don't use the bike, the air just gets bored and wanders off to find something to do.0
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You know the stare effect, right? When you're cooking, directly observed food gets done quicker than food left without any supervision. This is a similar concept. If you're not around your bike, it's performance drops significantly and as a consequence, tires don't hold air as well as they should.0
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...I think it is tyres - but surely you knew that. Maybe you were tyred from stairing at your cooking....take your pickelf on your holibobs....
jeez :roll:0 -
I almost felt like letting you know that both tire and tyre are accepted and perfectly correct, but then I realised that there is no way someone with access to the internet doesn't know that.0
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LimitedGarry wrote:I almost felt like letting you know that both tire and tyre are accepted and perfectly correct, but then I realised that there is no way someone with access to the internet doesn't know that.
Nonsense! The word is 'tyre'.
You'll try telling us next that your bike is made of something called 'aluminum'.“Life has been unfaithful
And it all promised so so much”
Giant Trance 2 27.5 2016 ¦ Sonder Broken Road 2021¦ Giant Revolt Advanced 2 2019 ¦ Giant Toughtroad SLR 1 2019 ¦ Giant Anthem 3 2015 ¦ Specialized Myka Comp FSR 20090 -
Where are you guys from?0
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It is because the butyl in the tubes start harden when not used, causing microscopic gaps to open up thus releasing air. When the tyre is rolling and in use, the tube stays more supple.
Maybe. It's witchcraft really.0 -
JBA wrote:philcubed wrote:Surely as soon as the wheels stop turning, all the air falls to the bottom of the wheel? If the valve is at the bottom all the air will come out through it. Obvious really.
That can't be right.
Haven't you ever had a flat tyre? When you do you will notice that all the air goes to the top of the tyre, leaving only the bottom flat.FishFish wrote:That is because the air is lighter than air.
Surely you knew that?
I think we've all been a bit Newtonian about this. I didn't want to get into Quantum Physics as no-one understands it, but the air in the tyre is both lighter than, and heavier than air. It is only when the tyre is observed that this duality is resolved. Physicists know this effect as 'Schrodingers Shed'0 -
LimitedGarry wrote:I almost felt like letting you know that both tire and tyre are accepted and perfectly correct, but then I realised that there is no way someone with access to the internet doesn't know that.0