The Schwalbe tube No. 21F fits 27.5" or 27.5+" tires with a width of 54-75 mm and is typically used in mountain bikes. The Schwalbe Freeride stands out due to its large volume and low weight. Thanks to their excellent manufacturing, Schwalbe tubes have proven themselves in the market for years. They have a consistent wall thickness and are round in shape. Their precise construction makes them durable at the seams. A comparative test showed that the Schwalbe tube maintains air pressure significantly longer than other tubes, which lost almost twice as much air pressure in 30 days compared to the Schwalbe tube. A possible reason for this could be a lower butyl content in the other tubes. The exceptional quality of Schwalbe tubes comes from the uniqueness of their rubber compound. To ensure this high quality, each individual Schwalbe tube is inflated and inspected for at least 24 hours before leaving the factory.