Anura IGH - Smooth Changing Gearing
The Anura offers a choice of gearing systems. The Anura RL has the conventional 27 speed derailleur system with a triple chainring and crankset, and nine speed rear cassette. However, the Anura IGH offers the increasingly popular Nu Vinci infinitely variable ratio hub. This has a number of advantages over the old chain derailing systems. It has a gear range of 380%, from 0.5 in bottom to 1.9 in top. There is no clunk or jerk as the gears are changed, there is just a very smooth change in gear ratio as you twist the shifter, from low to high or from high to low.
As there are no steps in the system, there is no such thing as having one gear too low and the next too high, you can choose the ratio which is exactly right for whatever you are doing. Plus, without any internal gears nor ratchets, the hub is completely silent. At the front of the IGH is a ATS Speed Drive - a two speed bottom bracket, which increase the gear range to 627%. If need be, this can be replaced with a Mountain Drive, giving a gear range of 950%. Yet another advantage of the Nu Vinci system is that you change through over 50% of the range while stationary. So if you have to stop suddenly and do not have time to change down, you are able to change down far enough to take off OK while stopped.