Bicycle gears calculator More than ever people ask nowadays: "What gears to choose for my bicycle?". Old school 3×9 or more and more popular 2×10 or perhaps the newest addition by SRAM XX1 1×11, or any other options? What combination is best for hilly courses, technical courses or flat ones? Compare all the gearing options you are considering and pick the best one. Added list of wheel / tire combinations and made calculations more precise, if you find anything incorrect let me know please.