Bicycles on Planes - Stupid Question of Week

[A Squared]

If a 7psi pressure differential is enough to split open a Comet (even with the metal fatigue) then might it not also do the same to a bicycle tire?

No, very unlikely. Not saying it can't happen, but a bicycle tire is a little different than an airplane fuselage. A bicycle tire is tough and resiliant and a 7 psi change in pressure is *very* small compared to the ultimate load. When I was a kid, my friends and I took our bikes down the the local filling station and filled the tires to 120 psi, mostly because we didn't know any better. If I recall correctly, those tires were supposed to have 30 psi, so that was a 300 % overload. They didn't burst, although I wouldn't recommend trying this. Even a relatively low pressure mountain bike tire is intended to normally hold 40-50 psi, plus being continuously hammered on rocks. They can probably hold twice that pressure pretty easily. Many road bike tires are designed to run at 120 psi or even more. A change in pressure differential of 7 psi, is just small potatos for a bike tire. That small a pressure increase may happen merely by hitting a stone while riding, and certainly over inflating a tire by 7 psi is pretty common. It's equivelant to the difference between 40 psi and 47 psi on a mountain bike. trust me, a mountain bike tire is nowhere near bursting at 47 psi.

An airplane fuselage is a different story, entirely. 7 psi is the entire normal load. The margins are much thinner. I don't know what specs the Comet was certificated under, but Part 25 only requires aircraft to be designed for 1.67 times the max relief valve setting. There may be some other factors which are applied to this, I don't know, but all in all, it's a fairly low pressure assembly. It's quite possible that a correctly designed and manufactured fuselage would rupture at 15 psi. for sure, it would rupture long bfore the pressure got to 30 psi, so 7 psi is a much rgreater portion of hte ultimate strength of the fuselage than it is a bicycle tire. And remember, that the COmet fuselage wasn't a new structure in good condition, it was already compomised by a developing fatigure crack.

 

[Swass]

Also, don't put a gas station airhose up your butt to get high, you might explode like a Comet.

 

[CrimsonEclipse]

If a 7psi pressure differential is enough to split open a Comet (even with the metal fatigue) then might it not also do the same to a bicycle tire?

You're kinda comparing apples to oranges.
The comet was due to metal fatigue and square windows.
The square windows created a stress point (or focus) on the corners
which allowed cracks to form over time. The multiple cycles weakened
the metal by work hardening the material. Also the airframe wasn't
designed with damage control (crack propagation prevention) in mind.

Apples to apples.
Pump your tire to the normal pressure. For instance 30 PSI.
Now increase the pressure by 15PSI (if you can read 14.7 on your
floor pump, more power to ya!). Did the tire ASSPLODE?

If no: Put it in the airplane and don't worry about it.
If yes: quit buying tires at Walmart.

Remember, to OUTTER SPACE, it's only 14.7 PSI.

...and then there's this new trend of putting Nitrogen in auto and
bicycle tires....don't even get me started....

CE

 

[Goose Egg]

Frankly, anyone who feels they have to call a folding bike "gay", almost certainly has some maturity issues, at the very least.

Yeah, I get that a lot.

-Goose

 

[Goose Egg]

A more universal question, what is everyone out there riding?

Specialized Hard Rock FSA1 Comp c. 1999 - Cheap bike but love it to pieces. May be bumping up the componentry to LX. Well overdue for new pedals. I doubt I'll every own any mountain bike other than Specialized.

Cannondale R800 c. 1997 (so we're talking CAAD3), 105 everything except a Dura-ace shifter aftermarket. Good ride.


-Goose

 

[Caveman]

Ellsworth Joker X/C (all XT)
Litespeed Solano (all DuraAce)
Surly Crosscheck (singlespeed)

Bought all 3 framesets and spec built them myself. Just finished a road ride and I'm reading this thread all doped up on endorphines (sp?). Best high there is IMO.

 

[Goose Egg]

Is wierd that I still prefer hardtails and v-brakes on an MTB?

-Goose

 

[Caveman]

Hardtails? No that's not weird. I tend to agree with you. Disc brakes are another thing. I'm never going back to V-brakes in the dirt.

 

[Goose Egg]

Disc brakes are another thing. I'm never going back to V-brakes in the dirt.

Yeah, probably shouldn't knock 'em 'till I've tried 'em.

-Goose

 

[seethru]

I bought a Sherpa MTB (not even sure if they make 'em anymore) about 10 years ago. It mostly sat in my garage until a couple of months ago when I started riding with some partners.

I'm very delighted with the low impact cardio, and now I wish I had picked it up sooner. I've been slowly upgrading components and use the bike strictly for roads, although eventually I would like to try out some trails some time.