GUP Kwiki Sealant & Inflator

GUP's Kwiki, a 'Quick-Fix Sealant & Inflator', is precisely that: a 125ml combination of latex sealant and CO2 which works to the 'spare tyre in a can' narrative, theoretically mending the puncture and re-inflating the tyre in one, rather like those kits supplied with some new cars. Performance is pretty good – to a point.

• Pros: Super-efficient and ultra-convenient in certain contexts
• Cons: Expensive, and puncture-type-dependent

It certainly seals small holes, and managed to raise a flat 700x38 tube to 90psi within 20 seconds. It's vastly superior to similar concepts I've used. However, it's not foolproof and, in common with some sealant-based products in my experience, holes around the millimetre mark are its limit.

How does it work?

Each 125ml canister has a smart head, designed for plug 'n' play convenience with Presta or Schrader valves. Butane propellant works with the CO2 component to deliver the liquid latex sealant and inflate the tyre.

To use, give the GUP a quick shake to agitate and mix the contents, pop the cap and push its yellow connector firmly onto your open valve while pressing the can to deliver. In common with many CO2 cartridges these days, the delivery is very controllable – just back off slightly and it will ease up. This greatly reduces the likelihood of over-inflating or, worse still, blowing the tube to smithereens.

As with other goo-filled products, spin the wheel to traffic that latex where it's needed. All things being equal, you are now ready to scoot off.

Real world performance

Provided you've done the preliminaries and the hole is a reasonable distance from the valve stem, happy days! The contents are pretty generous, so you're good for 90-120psi. Others I've used have managed only around 65, which is adequate for getting home on but optimal pressures are always better. In fact, there was a reasonable bit left over in the can after resuscitating the 38mm Soma.

As an experiment, I delivered the remainder into a pinch flatted but otherwise serviceable spare tube, just to see if the GUP was single use or would self-heal later down the line. Obviously, this resulted in some unwanted pressure and I needed to rotate the tube rapidly. Nonetheless, latex had been delivered and the snake-bite healed.

Several weeks and around 250 miles later, the GUP-treated butyl is serving me very reliably, and the other tube also seems to be holding up.

It's not a magic bullet for all punctures, though, and I'd caution double checking for ruinous holes/damage before use. Having swapped over to my dynamo wheel for nocturnal meandering, I discovered the front tyre (a Panaracer T-Serv Protite) as flat as the proverbial, with nothing obvious embedded in the casing.

Bike hoisted into workstand, valve open, GUP deployed as before... All was going to plan, then 15 seconds in there was an almighty sputtering from the tyre and I was engulfed in a torrent of white goo. Closer investigation revealed the butyl had perished around the valve stem.  

Conclusion

In certain contexts, the GUP is super-convenient and a godsend, but it also has some limitations and is expensive compared with alternatives: B'Twin's inflator and CO2 cartridge plus an impregnated latex tube for £12, for example, or a CO2 inflator and sealant for a couple of quid more.

Verdict

Super-convenient at certain times but not a magic bullet for all punctures, and pricey compared with alternatives