Deflating tyres for plane

jmmL

If I'm putting my bike on a plane do I need to deflate my tyres? Guy at Halfords reckons I do - LBS reckons you can get away with not doing it.

I won't have a track pump with me, and need to get away from the airport ASAP to get to first hostel in the light, don't really want to find a LBS in Milan and try to get them to pump by tyres in pidgin Italian!

d87heaven

From the BAA site

Preparing bicycles for travel:

•bicycle pedals must be removed (or fixed inwards)
•handlebars must be fixed sideways
•the bicycle must be contained in a protective case or bag
•you may wish to deflate the tyres to reduce risk of damage

Monty Dog

I would partially deflate - they at least provide some protection to the rims and lesser risk of pinch flat damage to the tyre. Aircraft holds are pressurised, but often aren't quite 1 atmosphere and therefore there is a risk that the tyre could over-inflate due to a significant pressure drop.

Mad Roadie

jmmL
I fly my bikes around a lot - yes deflate for sure.
there is also some interesting advice of CO2 gas pumps I have too if you are interested

jibberjim

Monty Dog wrote:

Aircraft holds are pressurised, but often aren't quite 1 atmosphere and therefore there is a risk that the tyre could over-inflate due to a significant pressure drop.

If your rims and tyres are rated to 120 psi, then tyres inflated to 100 psi, couldn't possibly be a problem with the drop in pressure in the hold (or even outside the hold) however if they're rated to 120, and you have them at 120 then it's a different matter.

Mad Roadie

jibberjim wrote:

Monty Dog wrote:

Aircraft holds are pressurised, but often aren't quite 1 atmosphere and therefore there is a risk that the tyre could over-inflate due to a significant pressure drop.

If your rims and tyres are rated to 120 psi, then tyres inflated to 100 psi, couldn't possibly be a problem with the drop in pressure in the hold (or even outside the hold) however if they're rated to 120, and you have them at 120 then it's a different matter.

you only inflate to pounds per square inch as a relative pressure differential between 1 atmosphere outside and the pressure inside - at 20,000 ft there is noting like 1 ATM ouside so your 120 psi at sea level would be more than double

Altitude Above Sea Level 0 feet
Absolute Atmospheric Pressure 101.33 Kpa


Altitude Above Sea Level 20,000 feet
Absolute Atmospheric Pressure 46.61 Kpa


POP!

Anonymous

Ooops, I left mine fully inflated. No problem. Will deflate slightly in future though!

jmmL

I think I'll just partially deflate. It's gonna be damn near impossible to get to 120psi with a mini pump though.

Also I'm just reading easyjet's rules on taking bikes with you and it says "No other items can be carried in the bicycle box (e.g. clothing)". Do they enforce this? I'd been planning on putting my shoes in there along with bottles, multitools and other things we might not be allowed to carry on.

Anonymous

jmmL wrote:

I think I'll just partially deflate. It's gonna be damn near impossible to get to 120psi with a mini pump though.

Also I'm just reading easyjet's rules on taking bikes with you and it says "No other items can be carried in the bicycle box (e.g. clothing)". Do they enforce this? I'd been planning on putting my shoes in there along with bottles, multitools and other things we might not be allowed to carry on.

We flew easyjt and my bike bag was freakin' CRAMMED!

Mad Roadie

NapoleonD
ditto

I put all the bike related stuff in mine

dennisn

I would venture to say that since air pressure at sea level is 14.7 PSI, that if you inflated a tire(at sea level) to 100 PSI, then shot it into space (space being at 0 PSI) that the tire pressure reading would then be 114.7 PSI. Not enough to cause bursting in a normal tire.

Gene Hunt

Not quite true DennisN, otherwise your bike pump would always read 14.7 psi when not even connected to anything! The reading on a pump gauge is relative, as the earths air pressure is pushing on the outside of the tyre. This would disapear in space, so a 100 psi tyre on earth actually has 114.7 psi's worth of air in it. Take it into space and you then have 114.7 + 14.7 = 129.6 psi which may just go pop. But then, I suppose, that doesn't account for temperature............ :?

jmmL

Apparently the hold is pressurised at about 6000 - 8000 feet. If you go to the top of a 6000' mountain, your tyres aren't just going to pop.

Good to know about stuffing the box - that's what I plan to do!

Pretre

jmmL wrote:

Good to know about stuffing the box - that's what I plan to do!

I'd be careful on this - sometimes Easyjet/Ryanair are a bit strict on their weight limits, esp. on the way out

jmmL

Perhaps I was exaggerating a touch :P

I've got a 32kg allowance, and the bike tips the scales at about 10kg, with rack and bags. I'm not going to come close to the weight limit - I was just concerned that they would make a fuss if I put my shoes and a few tools in there.

dennisn

Gene Hunt wrote:

Not quite true DennisN, otherwise your bike pump would always read 14.7 psi when not even connected to anything! The reading on a pump gauge is relative, as the earths air pressure is pushing on the outside of the tyre. This would disapear in space, so a 100 psi tyre on earth actually has 114.7 psi's worth of air in it. Take it into space and you then have 114.7 + 14.7 = 129.6 psi which may just go pop. But then, I suppose, that doesn't account for temperature............ :?

Sounds reasonable. I had to read it 3 or 4 times before it got through the cobwebs in my mind. You're saying zero on the pump gauge is in effect 14.7? :? :?

Ollieda

jmmL wrote:

Perhaps I was exaggerating a touch :P

I've got a 32kg allowance, and the bike tips the scales at about 10kg, with rack and bags. I'm not going to come close to the weight limit - I was just concerned that they would make a fuss if I put my shoes and a few tools in there.

They are probably refering to clothes as meaning your normal everyday stuff. for the purpose of this argument cycle clothing is technically sports equipment being equipment designed and used specifically for a sporting activity.

I remember comming home from China and getting stuck behind the Irish A1 GP team arguing that racesuits were sporting equipment and trying to pack them with carbon add-on bits of the car they were checking in. It didn't help that the check in lady didn't know what F1 was let alone A1!

Dess1e

Most bike tyre manufacturers test air pressures to twice that stated on the sidewall. So in a pressurised hold it shouldn't be a problem to leave them at 100psi.

I wonder if the airlines deflate and re inflate the aircraft tyres as required?

cougie

I've flown many times with the bike. I'd read the calculations that showed that yeah they will inflate slightly, but if you're not near the limits - you'll be fine. I normally run mine at 95PSI anyway so plenty spare. I do take a tiny bit out - so its probably around 80psi.

Plenty enough to protect the rim, but I'd pump them up again at the other side. You'd not want to leave them rock hard just in case the bike gets left in the sun somewhere baking hot and explodes the tube.

alfablue

It is absolutely unnecessary to deflate tyres, and I have refused to do so when asked. Commercial airline Aircraft cabins and luggage holds are pressurized at about 6900 feet - you can cycle higher than that! It is an old wives tale.

As for the 32 kilo's - when I flew Easyjet, my total allowance was 32 kilo's because I paid for a bike, but they do not allow you to put items in the bike bag. However, as they charge per item for luggage I managed to get our 4 pannier bags into one large cheap holdall, which then attracted only one charge.

pilot_pete

They won't explode. As Jmml said earlier, the hold is pressurised to the equivalent of standing on a 6-8000ft mountain. Never seen Le Tour stop half way up the Alps to remove a bit of pressure from Lance's rubbers!

Check my nick for related qualifications Gene Hunt knows what he is talking about too!

PP

andy_wrx

Re the 'nothing else in your bike bag except a bike', I expect what they're trying to avoid is you stuffing everything into your bike bag and not having any other luggage, since they charge you per bag.

In practice I've flown with Easyjet and Ryanair several times and they've never looked inside the bike bag - but what has happened each time has been different so I expect it depends on which airport, who the check-in staff are, what day it is, etc.

Sometimes they've never bothered to even look at the bike bag - it has to go through the oversize luggage desk and the guys there have weighed it, but they're not Easyjet/Ryanair they're employed by the airport and all they're interested in is that it doesn't weigh more than the 32kg single-bag limit, which is airport regulations so as not to cripple the baggage manglers.

Sometimes check-in have said that I have a normal 20kg weight allowance, but with the bike fee as well it's increased to 32kg in total, so they've weighed both bike bag and hold bag and checked they weren't more than that 32kg total, but not cared which bag weighed what, or what was in each.

I expect though that if you turned-up with a bulging bike bag and just hand luggage, they'd look in the bike bag and probably get awkward if you had all your clothes and stuff in there, avoiding having a hold bag.

Myself though, I've had my baggage go walkabout, or be left behind because there wasn't room or time to put it on the plane.
If your bike bag were left behind, you're a bit bu$$ered, either have to wait for it to turn up or maybe hire one.
But if your bike turned-up but your hold bag didn't, well I'd not want all my bike clothes, shoes, etc in my hold bag...
So personally I put my shoes, helmet, etc in my bike bag and a couple of changes of bike clothes in there too, so even if my hold luggage was delayed I'm not stuck without it.

Similarly I've hired a bike a couple of times and so have carried my shoes and a set of bike clothes in my hand luggage, just in case my main bag didn't turn up.