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# Bicycle puncture locator

Use gas to detect puncture.
 (+1) [vote for, against]

Punctures are hard to find so fill the inner tube with a vividly coloured gas and you will quickly see where it is escaping from. The gas could come in carbon dioxide style cylinders. Or it could be a really smelly gas and you could sniff out the leak. Or it could be a flammable gas and you could find it using a naked flame.
 — Rusto, Jun 24 2019

Phosphine https://en.wikipedia.org/wiki/Phosphine
Pyrophoric; ignites spontaneously. [8th of 7, Jun 24 2019]

I suppose ideally a really smelly, vividly coloured and flammable gas.
 — Rusto, Jun 24 2019

 — 8th of 7, Jun 24 2019

Just look for the hole; the puncture will be nearby.
 — MaxwellBuchanan, Jun 24 2019

 Hmmmm.

 To a certain extent, a torus such as an inner tube is topologically similar to a sphere, in that they both have a single surface without edges.

 This opens up the possibility of finding the hole mathematically.

 First, map the n-manifold which is the innertube (torus) to a corresponding sphere. Then reduce the sphere to a point. Et viola ! That point must contain the puncture.

Repairing the puncture is then trivial, so we leave it as an exercise for the reader.
 — 8th of 7, Jun 24 2019

But if there's a puncture, it's no longer a torus. Which, in any case, is not topologically equivalent to a sphere.
 — MaxwellBuchanan, Jun 24 2019

Precisely. All that's needed is to map the location of the discontinuity.
 — 8th of 7, Jun 24 2019

Alternatively make ordinary atmosphere visible by placing the inner tube in a clear fluid so you can see the bubbles it makes as it escapes through the puncture, H2O is fairly common & readily available, maybe that would suffice?
 — Skewed, Jun 24 2019

No - insufficiently volatile/reactive/flammable.
 — 8th of 7, Jun 24 2019

I was worried that might be a bit of a problem.. how about if we add some powdered magnesium to it?
 — Skewed, Jun 24 2019

 If you use a powdered potassium inside the tube and fill the tire with a pure nitrogen gas, then you'd know about a leak because the potassium would ignite as soon as it made contact with the air.

Also, changing the tire would be much easier as the old leaky one would likely burn itself off the wheel.

A physical action of [8th]'s mathematics would be to make an origami of the inner tube, making fold steps that reduce the warped ?sphere? until gas doesn't remain, isolating the spatial wormhole.
 — wjt, Jun 25 2019

Surely the problem here is that the medium used to fill the tyres is of the same phase as that which the bicycle is moving through. Thus, I suggest the use of different phases - by having the tyres filled with a pressurised liquid when cycling along the road, or by filling the tyres with air but only cycling underwater. Either of these would make puncture detection a trivial task.
 — hippo, Jun 25 2019

 Argon 39 and Argon 42 look promising with big half lives, beta radiation, and the added bonus of Potassium or ultimately Calcium as the decay product.

 A Geiger counter will find the leak and, of course, a ready supply of the correct Argon would be required to get you on your way, since the use of air might cause a problem with any Potassium unless it's reacted with the tyres already.

I can't see any problems whatsoever with this.
 — DenholmRicshaw, Jun 25 2019

Sheer genius. The Argon will be unreactive with its decay product.
 — 8th of 7, Jun 25 2019

 Beta will get through tyres quite easily. What you need is a combination of a beta emitter and a label that says "Don't worry."

You could go with alpha, but I seem to recall that alpha detectors are more expensive and/or less sensitive, and you'd have to scan the whole surface of the tube quite carefully to pick it up.
 — MaxwellBuchanan, Jun 25 2019

 I couldn't find a suitable gas that emitted alpha particles. My search was extensive, and lasted a good five minutes.

 How about we have an optional upgrade to the tyres to include something to block the beta particles in exchange for the "Don't Worry" label?

Those cunning nuclear science boffins have a scintillating idea for something that glows when irradiated, but they won't tell me what it is.
 — DenholmRicshaw, Jun 25 2019

 // I couldn't find a suitable gas that emitted alpha particles //

Radon. Coat the inner wall if the tube with thorium isotopes ;the primary decay product is 222Rn, with a half-life of 96 hours and a copious alpha emitter.
 — 8th of 7, Jun 25 2019

This definitely opens the door for some up market spoke beads or some scintillating treads for the cruiser.
 — wjt, Jun 26 2019

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