"Gear range" is a comparison of the lowest gear to the highest gear. It is shown as a percent. For example a Rohloff Internal hub has a gear range of 526%. Typically with deraileur systems, the high gear is about 400% higher than then low gear. If the low gear was a ratio of 1 to 1 and the highest gear was a cog ratio of 4 to 1, the range would be 400%. This is a very common statistic quoted for internal hubs.