BTwin Self Sealing Bike Inner Tube - Presta

BTwin's 700x18/25 Self Sealing Bike Inner Tube is a narrow-section goo-filled model designed to seal tiny punctures as you ride. The butyl might not be of the same quality as household names, and arguably standard tubes fed aftermarket sealant are more dependable, but our Presta-valved example has proved a pleasant surprise.

These and the aftermarket sealants work to the same science: small quantities of liquid latex slosh around inside unnoticed, then when small sharps burrow through the tyre casing and pierce the tube, rotational pressure (or in some instances a quick tote from a pump or CO2 cartridge) forces said green fluid into the hole, sealing it shut.

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There's generally some pressure loss, which in my experience depends upon temperature and the size of the invasive particle.

The BTwin weighs a portly 181g, 60-odd heavier than some premium brands, but despite feeling a little thin, its construction is better than I've come to expect from this price point. It's slightly narrower than 25mm would suggest, and at the other extreme, there have been no problems slipping it into 19 and 20mm rim sections.

The Presta stem is positively giraffe-like, so no compatibility hassles with deep-section aero hoops – something that presumably also keeps manufacturing costs and, ultimately, retail pricing favourable. But do go carefully with the valve stem if fitting by the roadside to shallow rims and relying on a mini/midi pump.

Pressure retention seems comparable with premium brands' bog standard butyl. When checked with a high quality digital gauge, 8psi was lost over the course of 10 days (although it's worth noting that I store my bikes off the floor).

Several weeks spent charging along the lanes testing tyres of varying sophistication, and punctures remained conspicuously absent. This despite my best efforts – intentionally speeding through shards of glass, flints and organic sharps, and resisting the urge to brush tyre casings afterwards.

Eventually, it succumbed to a vicious thorn, while I was thrashing along a spooky little lane at 5am. Cutting to the chase, the magic green goo did its thing, though not without some rider input...

An initial rush of air induced that familiar split-second state of dejection, which grew worse before it got better, since the pressure was bailing pretty fast once I'd coaxed the embedded sharp free using some small cosmetic tweezers. Mercifully, hissing turned to subdued sputter as sealant plugged the wounded butyl.

In total it had lost 30psi – down to 85 and still rideable. However, experience with these in lower temperatures led me to introduce a quick blast of CO2 – not just to restore pressure but also to hasten the sealant, which seems less mobile when the mercury struggles to rise much above freezing. Credit where it's due, the hole seems genuinely plugged, retaining full pressure during the remaining 15 miles and, indeed, since.

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Decathlon also offers these in a 25/32mm width with Presta valve, and a 35/45mm Schrader valve option, as well as 26 and 29 inch sizes. I've bought some to see how they compare in mixed terrain contexts, as experience with premium brands suggests they are more prone to flats along green lane or canal path forays.

Bottom line, rather like glueless or traditional patches, choice very much boils down to faith, and I was sceptical. However, ours did what it was designed to, and I'd say they are worth a punt if you're running decent training tyres and seeking additional defence against punctures.

Verdict

Solid budget tubes that do offer some additional protection from punctures