Bike in Plane – Deflate tyres?

I know airlines ask you to do it but does anyone bother? Flying later with road bike nicely packed up ready to go. Around 80psi in the tyres (tubes).  Will my wheels explode, will we all die to death?

I haven’t been asked if I’ve done it for years, and it makes no difference.

If worried about it inflate your tyres to 100psi and then let some air out so they’re 80psi again. Technically you’ve let some air out of the tyres…

Hold is pressurised.

If the airline asks you to let the pressure out, just let the pressure out. Is it really worth ****ing around with people who can have you thrown off the plane?

The maximum pressure differential for a Boeing 737 air frame (I.E, a very typical airliner) is around 9 psi.

So if your tyres are at 80 psi on the ground, in the hold they will be under the maximum equivalent pressure differential as if they were at 89psi on the ground. And even that would be in abnormal operations.

It’s a load of bollocks and having flat tyres makes your rims vulnerable but you’ll never have a sensible conversation about it so shrug and put up with it.

I never do. I say that I have when asked.

If I was a pilot I’d probably be a bit annoyed at people (like me) ignoring guidelines.

You could imagine a situation where an MTB tyre at 35psi could exceed the stated 40psi max when in a depressurised luggage hold. Very unlikely to go pop but I imagine pilots don’t like things doing even unlikely and small bangs in the hold.

In all the many times I’ve flown with a bike, I’ve never been asked once.

The correct answer, when asked by airline staff at check in as to whether you have deflated your tyres, is “yes Sir / Madam”.

Whether you have or not (and you don’t really need to because the hold is pressurised and the difference is little more than being at the top of a high mountain pass in the Alps), the airport is not the place to get into a discussion of physics and practicality and trying-to-be-clever arguments like “does the aircraft depressurise its tyres?”.

when in a depressurised luggage hold.

Do such things exist?

@snotrag is right. That said, on the rare occasion I’ve been asked to deflate it’s not really worth arguing the toss over the physics.

It is somewhat dangerous if it’s a high volume tyre @ (say) 80PSI as there’s a lot of potential energy = explosion, which is not what you want on an aeroplane.

I always do.

Does it make any difference? I have no idea. But it takes ten seconds to do and a minute at the other end to reinflate so why not?

I haven’t deflated shocks and forks though but they’ve never asked about those (I’m quite light and run them with quite low pressures anyway.)

Do such things exist?

Well they do but you’re probably not going on your holiday on one.

soft but not flat

I can beleive some road tyre has gone pop at some point but most mtb tyres are used at about half their rated maximum.

what they really want to do is make sure your tyres have air in them and not cocaine or semtex.

TSA checked one of my wheels two weeks ago, they had let out even more air than I had done. I make life easy for them by ensuring the valve is at the top so they dont feel the need to take the wheel out. not sure what would happen if you had an insert in.

branes

Full Member

@snotrag is right. That said, on the rare occasion I’ve been asked to deflate it’s not really worth arguing the toss over the physics.

It is somewhat dangerous if it’s a high volume tyre @ (say) 80PSI as there’s a lot of potential energy = explosion, which is not what you want on an aeroplne.

I did an early morning time trail back in the day when we rode very narrow tubs and stupid high pressures – 18mm at 10 or 11bar. Typical spring day it was very chilly early but got toasty later. One competitor must have put his bike back in the car afterwards without deflating his tyres before his cuppa in the village hall. Rear wheel must have been pressed up against the rear glass of his hatchback. An almighty bag as the tub exploded along with his rear window. Messy.

To be honest though – exploding tyre in a bike bag is going to do little damage beyond the bag.

There are some funny rules though – not allowed to take co2 canisters for inflating tyres but are allowed to take the very same canisters for inflating life jackets. And a spare.

@branes I teach people who fix ’em 😉

You are quite right that there is reasoning behind it, and if that particular airline asks you, then just do it.

There are far, far more dangerous things that people do regularly that I will never condone – travelling with Lithium Ion Batteries or other Dangerous Good etc – this is very serious stuff, the implications are high, and the penalties serious.

That little board at the check in desk they ask you to read – read it. 

(I have some good stories about stuff people have tried to check onto airplanes…)

@Kramer

Do such things exist?

Yes, some aircraft are unpressurised. Not the kind you will ever be using for your holidays though.

However aircraft do occasionally suffer from decompression, through technical faults etc. This is where the ‘risk’ is.

I deflate them just enough so they fit properly in the lid of a BikeBoxAlan, which is also just enough to keep them on the bead and stop the sealant pissing out.

Since you’re running tubes I can’t see any reason why you wouldn’t.

@snotrag re. Li-ion, I’ve only just thought about my Di2 battery in the seatpost – should i be taking this out or is it okay just disconnected?

@convert

There are some funny rules though – not allowed to take co2 canisters for inflating tyres but are allowed to take the very same canisters for inflating life jackets. And a spare.

Not quite. There are limits on quantity and size.  It was simply that the life-jacket usage was a well known tpyical reason for people taking them on board, and when the regs were initially written. Amended:

https://www.icao.int/safety/DangerousGoods/Working%20Group%20of%20the%20Whole%2011/DGPWG.2011.WP.014.2.en.pdf

@Haze needs to go with you in cabin baggage, also needs to made safe ie covered terminals.

Spare batteries for portable electronic devices (including metal devices) containing lithium metal or lithium ion cells or batteries carried for personal use.

Must be individually protected so as to prevent short circuits (by placement in original retail packaging or by otherwise insulating terminals, e.g. by taping over exposed terminals or placing each battery in a separate plastic bag or protective pouch).

Each spare battery must not exceed the following:

lithium metal or lithium alloy batteries, a lithium content of not more than 2 grams;
or
lithium ion batteries, a watt-hour rating of not more than 100 Wh.
Batteries and cells must be of a type which meets the requirements of each test in the UN Manual of Tests and Criteria, Part III, subsection 38.3. It may be necessary to contact the manufacturer to confirm that they have complied with the requirements.

Source:

https://www.caa.co.uk/passengers-and-public/before-you-fly/baggage/items-that-are-allowed-in-baggage

My motivation for not deflating is that I am only taking a mini handpump and I have a habit of snapping valves so i would prefer to avoid having to pump them up again if possible.

@snotrag re. Li-ion, I’ve only just thought about my Di2 battery in the seatpost – should i be taking this out or is it okay just disconnected?

I would go with what @snotrag says on the basis that he knows this stuff but realistically, I’ve flown with Di2 several times (and been in groups where others have Di2) and no-one has ever said anything – certainly no-one has ever been asked to disconnect or remove anything.

My motivation for not deflating is that I am only taking a mini handpump and I have a habit of snapping valves so i would prefer to avoid having to pump them up again if possible.

1. Buy a decent pump.

2. Learn how to use your pump so you don’t snap valves. Use your left hand to hold the valve end of the pump and the rim so that the force of the pumping isn’t taken by the valve. I have never snapped a valve in 25 years of riding. Or just buy a pump with a hose to connect to the valve.

Look out for snake bites!

I flew with it in March but genuinely never thought about the battery, had eTap on previous flights and always kept the batteries in my luggage (they’d flatten anyway left connected on the bike).

Easy enough, pop the saddle and post in hand luggage with the cable taped.

@crazy-legs I’m not trying to single you out however this exactly highlights the issue –

 I’ve flown with Di2 several times (and been in groups where others have Di2) and no-one has ever said anything – certainly no-one has ever been asked to disconnect or remove anything.

I 100% assure you that you HAVE been asked evey time you checked in. Whether in person, or when you did an online check in or bag drop – did you read the text, or just click ‘accept’ ?

(Please, not placing blame on you… this is just a perfect example)

From a 10 second google:

Ask if they deflate the aircraft’s tyres when the landing gear is retracted!

They dont. So its a good job the tyres stay outside the pressurised structure of the airplane even when retracted, so that when they pop (and they do, sometimes) they dont damage its integrity 😉

Ask if they deflate the aircraft’s tyres when the landing gear is retracted!

Here’s the thing with the people who check you in for your flight, they aren’t technical specialists, they have to deal with hundreds of grumpy travelers every day. They don’t care about the aircraft’s tyres, they just care about doing their job, getting paid, and then going home at the end of their shift. If you try to argue about whether you should have to follow instructions, you’re just going to piss them off and potentially get booted from your flight. Just let the tyres down, pump them up again at the other end, and enjoy your holiday.

^ correct answer.

Anyone is welcome to feel ‘correct’ as you sit in the terminal and the plane trundles off without you as your bags have been unloaded.

I do the front, otherwise I can’t get the wheel fully in and the bag zipped up.

Snotrag, mentions of batteries in those graphics specifies loose batteries. I’d interpret a Di2 battery inserted into the bike as OK from that. It’s quite awkward then that apparently all batteries are forbidden FROM TUi hand luggage too!

I’d let them down to ~10psi just so the tyres hold shape/hook into the bead but if checked are squishy to the touch.

But also why not just bung a larger frame or track pump in the bike box, rather than expect to use CO2 or a mini pump at the other end?

On the way back from Madeira last week, I took enough out of the tyres so that were pretty flabby. When I go home and got the bike out the bag, some-one had clearly let out the rest of the air out. Then, just for giggles they put the wheels back in so the disc were outer most, which was nice of them

In May, the guy at oversized bags at T3 Heathrow asked about my tyres and actually checked by giving them a squish. Thankfully, I’m a virtuous bar-steward and had deflated them to the point that they could be heavily depressed with a thumb.

He seemed pleasantly surprised, suggesting it’s not that common or, more probably, that I resemble some kind of valve-challenged f**kwit, incapable of letting air out of a bike tyre.

I’ve never bothered.

1 bar = 14ish psi.

1 bar = atmospheric pressure at sea level.

So if you pump your tyre up to 80psi at sea level, that’s the pressure difference between the air in the tyre and the 1 bar (14psi) of air pressure outside the tyre.

If you then seal it in a complete vacuum, (reducing the outside pressure from 1 bar to 0bar) the pressure difference rises to 94psi.

The air pressure in the hold will be higher pressure than a complete vacuum. So it doesn’t really matter.

But also, see thols post “Here’s the thing…”

I partially deflate mine. I Ican truthfully answer they are deflated if asked. Pumping them back up from 39psi to 60 on arrival is fairly trivial compared to all the other reassembly In need to do after fitting an XL tourer and racks etc into the box.

Leaving UK nobody has asked to check.

Am looking on my phone, so may have missed something, but all of the evidence up there for why a Di2 battery shouldn’t be in hold baggage seems to specifically relate to ‘spare’ or ‘loose’ batteries. My Di2 battery is bolted inside the downtube, so I would assume that this would be fine. I do let air out of tyres when flying, and always carry spare batteries or small battery-containing things in hand baggage, but I genuinely wouldn’t interpret a fixed Di2 battery to be a problem.