URGENT! Flying with Brompton in the hold - deflate tyres?

[Fab Foodie]

Hi
I might fly with my Brompton tomorrow and I suddenly wondered if I need to deflate the tyres (they're a fag to pump with the little pump) .... I think not, but better check!
Cheers
FF

[LittleWheelsandBig]

I never do with my Brompton or any of my other bikes. Many airlines no longer require deflated tyres.

[Kim]

The physics answer is 'no': Atmospheric pressure is all of about 14-15PSI, so unless they're already seriously overinflated, you could reasonably expect to expose the tyres to hard vacuum without anything untoward happening.

The practical answer is that it's extremely unlikely that everyone who will handle the bike from check-in to collection will have a working knowledge of the relevant physics.  So prepare for them to either ask you to deflate the tyres, or for them to be deflated on arrival.

[LittleWheelsandBig]

Deflation in transit is very rare (once in over 20 years of flying with bikes). As I noted, many airlines no longer require tyre deflation, British Airways for one.

[Veloman]

Aircraft holds are pressurised same as cabin pressure.  No need to deflate.

[David Martin]

I had it happen a while back. Kim, as ever, has the physics spot on. Unfortunately too many are scientifically illiterate.

[Kim]

Presumably CO₂ cartridges are verboten on planes for much the same reason...

[hellymedic]

Presumably CO₂ cartridges are verboten on planes for much the same reason...

Yup!

[andrewc]

I've flown with a bike multiple times & have always been asked at check in if my tyres were deflated, even on BA.   I usually let enough out so they are soft to the touch but don't need to be pumped up from flat.

[Kim]

Probably worth bringing a decent pump, then.

[LittleWheelsandBig]

My reply is always "Yes, my tyres are fine."

[Fab Foodie]

Thanks, It's in a Bike Pod 'Suitcase' so I was going to check it as normal hold luggage, am assuming that's OK (am on BA).
Do I need to put it via the 'special handling' bit like Skis and surfboards?

[Veloman]

Do I need to put it via the 'special handling' bit like Skis and surfboards?

Depends on policy of carrier.

I know someone who took an Airnimal to Mallorca in a normal suitcase as hold luggage, but because it was a bike they said it must go as a bicycle, even though it was not oversize!

Suggest you phone and check as website may not consider a bicycle in luggage suitable as hold luggage.

[mark]

Presumably CO₂ cartridges are verboten on planes for much the same reason...

Actually I was allowed to bring a fistful of CO2 cartridges the last time I took a bicycle on a British Airways flight (and yes, they knew I had them). On that journey BA staff in Denver required me to deflate the tires, while BA staff in Gatwick, Pisa and Heathrow took a few minutes to check the rules and let me leave the tires inflated.

Regardless of what position they've taken on inflated/deflated tires, BA staff have always taken good care of my bicycle.

The BA website spells out their bicycle policies much more clearly than many airlines, and their bicycle policies are more reasonable than most airlines, IME.

[Ubert767]

Whilst agreeing with comments about there being no need to deflate tyres in theory, my advise is to do so, following my experience when flying from Bournemouth to Pisa. The check-in staff accepted my bike in a CTC plastic bag with tyres fully inflated.  Upon collection at Pisa I found  very neat puncture slits (screwdriver or pen knife sized) in each tyre side wall. I assume that some kind baggage handler at Bournemouth Airport isn't a keen cyclist !!!!
I hold baggage handlers in as much esteem as politicians, bankers, estate agents and Mr. Clarkson.

[Fab Foodie]

Well it's in the hold and we're about to go for lift off ....

[Jurek]

Well it's in the hold and we're about to go for lift off ....

Errr..... Shouldn't that be take off?
Or have you opted for a different sort of craft? 

[Kim]

Is this my fault for mentioning hard vacuum?

Thinking about it, a Brompton ought to be a fair bit quicker on the moon, as the abysmal aerodynamics won't be an issue.  Not sure how well the 16" wheels cope with impact craters and lunar regolith, but it can't be worse than the average Sustrans path...

[Fab Foodie]

Well it's in the hold and we're about to go for lift off ....

Errr..... Shouldn't that be take off?
Or have you opted for a different sort of craft? 

Ha!  Well we definitely lifted off the ground    Later I deplaned ....

The case at least has arrived in one piece .... I've not opened it up yet on account of arriving fairly late at the hotel where the food is quite exceptional ... so I've hit the Stube and the restaurant pronto.  One of the best restaurants I've ever eaten in in fact .... 

[rogerzilla]

Is this my fault for mentioning hard vacuum?

Thinking about it, a Brompton ought to be a fair bit quicker on the moon, as the abysmal aerodynamics won't be an issue.  Not sure how well the 16" wheels cope with impact craters and lunar regolith, but it can't be worse than the average Sustrans path...

I suspect the reduced weight of the rider will give rather soft rear suspension.  The impact will be the same when you hit one of those big lumps of green cheese and the bike bucks under you (your mass doesn't change), but there won't be enough pre-load.  The bike might even chatter a bit as the rear triangle loses contact with the main frame.

On the bright side, carrying it up escalators should be a breeze and the step-through frame avoids the embarrassment of trying to get your leg over in a spacesuit.

[Fab Foodie]

30 miles loop along the Rhine this evening ... and a 16 miler yesterday.  What a fab thing a Brompton is.  Don't know where I'm taking her next week yet though ....

[Arellcat]

The physics answer is 'no': Atmospheric pressure is all of about 14-15PSI, so unless they're already seriously overinflated, you could reasonably expect to expose the tyres to hard vacuum without anything untoward happening.

Does the airline insist on deflating the aircraft's tyres, too? 

I think that's something for the Mythbusters to demonstrate.

[Veloman]

Does the airline insist on deflating the aircraft's tyres, too? 

No, because they're 'soft' anyway.  They do calculate the maximum pressure at sea level to prevent explosions when cruising at 30000ft.  And if you really want some technical investigation of what challenges can arise, then how about the tyres on an aircraft that cruises at 70000ft such as the U-2.

I think the original question asked about 'hard' tyres and whether they required deflating to become 'soft' tyres.

I recall a fun day in Mallorca listening to quite a few inner tubes exploding in Muro while having coffee as the riders had left their 140psi inflated tyres in the sun.  Same principle, air can expand at an alarming rate, be it in heat or relative vacuum.

[Vince]

Presumably CO₂ cartridges are verboten on planes for much the same reason...

Yup!

Except there is one under every seat.
Probably special aircraft quality ones

[Auntie Helen]

Which bit of the Rhine are you on FF? Anywhere near me?