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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.
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.
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.
Solid budget tubes that do offer some additional protection from punctures
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road.cc test report
Make and model: BTwin Self Sealing Bike Inner Tube - Presta
Size tested: 700x18/25
Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
No description from Decathlon.
It's essentially a 700x18-25 tube impregnated with a liquid latex sealant that rushes to seal small punctures before they induce a flat proper. To date, ours has behaved impeccably, but it will be interesting to see how it performs in the long term against premium brands and standard butyl filled with aftermarket sealants.
Tell us some more about the technical aspects of the product?
700x18/25 butyl tube with liquid latex sealant and extra long Presta valve.
Decathlon says: "The preventive sealant inside the inner tube automatically repairs punctures (less than 3 mm)."
Not had any problems to date, not even a puncture until very end of test period, but I do wonder how well the sealant and other components will last in the longer term. I've had premium brands go "off", sealing valve stems shut or peppering green goo over rims and flooring alike after six months.
Hefty compared with a standard butyl tube.
£3.99 is markedly cheaper than other off-the-shelf versions and arguably more convenient than adding sealant to standard butyl.
Tell us how the product performed overall when used for its designed purpose
Overall, these tubes have done exactly what I've needed from them thus far.
Tell us what you particularly liked about the product
Tell us what you particularly disliked about the product
Weight (even compared with other sealant-filled tubes).
Did you enjoy using the product? Yes
Would you consider buying the product? Possibly
Would you recommend the product to a friend? Worth a look if they didn't want to take the aftermarket sealant route and their bikes weren't on calorie controlled diets.
Use this box to explain your score
Seems on par with premium brands to date, although there's a weight penalty over traditional budget butyl.
About the tester
I usually ride: Rough stuff tourer based around 4130 Univega mountain bike frameset My best bike is: 1955 Holdsworth Road Path and several others including cross & traditional road
I've been riding for: Over 20 years I ride: Most days I would class myself as: Experienced
I regularly do the following types of riding: cyclo-cross, commuting, touring, fixed/singlespeed, mountain biking
Shaun Audane is a freelance writer/product tester with over twenty-eight years riding experience, the last twelve (120,000 miles) spent putting bikes and kit through their paces for a variety of publications. Previous generations of his family worked at manufacturing's sharp end, thus Shaun can weld, has a sound understanding of frame building practice and a preference for steel or titanium framesets.
Citing Richard Ballantine and an Au pair as his earliest cycling influences, he is presently writing a cycling book with particular focus upon women, families and disabled audiences (Having been a registered care manager and coached children at Herne Hill Velodrome in earlier careers)