SV1 12 x 1.75 - 2.50 Presta 40mm valve About Schwalbe Tubes A bicycle tube is predominantly made of Butyl rubber. Butyl is a very elastic and airtight synthetic rubber. But as with the tire, other fillers are necessary to make up the rubber compound. The quality of a tube can vary significantly depending on the rubber compound. For instance Schwalbe tubes have extremely high air retention and elasticity. This high elasticity allows a wide range of different tire sizes to be covered. There is a difference between heat moulded and autoclave tubes. Vulcanizing in a mould improves the uniformity of wall thickness, thus reducing weight and improving air retention. For this reason the autoclave tubes which can be produced easier have become less common over the past years. Schwalbe tubes have always been made using the heat moulding process. Every tube also needs a valve, which is bonded to the tube during the vulcanizing process. Why Choose Schwalbe Tubes? Besides the quality of the ingredients, the purity of the Schwalbe rubber compound is decisive for the quality of the tube. Before extrusion, the basic material is forced through a total of seven filters under enormous pressure. All tubes are inserted and inflated into a mould for the vulcanization process. Only this ensures an even wall thickness and high air retention. All tubes are inflated and stored for 24 hours to test for air retention. Afterwards, every tube is carefully checked individually by visual inspection. The Schwalbe tube has been valued by German bicycle dealers for its high reliability for many years. A tube covers many tire sizes through its high elasticity and quality. Tube no. 17 works with tyres from a width of 28 mm up to 47 mm - a great advantage for stockholding in the trade. At the same time, it is proof of the quality of the tube. All valves are nickel-plated and threaded. The valve core is always replaceable. Also, Schwalbe tubes with a classic bicycle valve can be inspected for pressure as they have a high-pressure valve core. SIZES: 47-203, 12 x 1.75 50-203, 12 x 2.00 54-203, 12 x 2.10 62-203, 12 x 2.50