Can someone explain the Physics for this...

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?

Ask them if they've ever tested their hypothesis.

Leaving a bike in a shed for a year or two doesn't count.

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?

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.

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 ?

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.

Angus Young wrote:

I think that's 'Pachyderm'... but surely you knew that?

Right - but I was making a trunk call at the time.

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.

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.

Where are you guys from?

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'