Aluminum alloy 3x6/3x7 thumb shifters for 18/21-speed bikes provide precise, easy shifting across hills, flats, and mixed terrain. Designed for mountain biking, city commuting, or leisure riding, they improve control and comfort on every ride. - Easy Shifting, Smooth Ride: Seamless gear changes for 18/21 speeds, enabling precise and effortless shifting on varied terrain. - Compatibility with Your Bike: Fits handlebars with a diameter of 22.2 mm and works with mountain bikes, city bikes, leisure bikes, road bikes, and folding bikes. - Reliable Construction, Durable: Made of high-quality aluminum alloy for long-lasting performance. Includes a stainless steel inner cable (150-200 cm / 59-79 inches), wear-resistant for smooth operation over years of use. - Comfortable Design, Better Control: Ergonomically designed thumb shifter allows shifting without removing hands from the handlebars, enabling easy control and fast shifting. Use scenarios: - Mountain trails: quick, reliable shifts on steep climbs and technical sections. - City commuting: smooth, responsive gearing for urban inclines and flats. - Leisure rides: comfortable, confident shifting during road trips or mixed-terrain rides.