Originally Posted by Jipe

I said that the BWR that has bigger reduction/multiplication ratio is worse than the Sturmey 3 which is similar to the BSR. Its an inherent feature of planetary design that, everything else remaining the same, increasing the ratio reduces the efficiency.

Its exactly the same for the 2s Schlumpf: MD and HSD with a 2.5 ratio have a worse efficiency than SD with 1.65 ratio (for their 2.5:1 an 1:2.5 vs. 1:1.65 ratio, not for their 1:1 ratio of course).

For the Brompton, anybody who had the opportunity to compare the ride on a 2s or 4s with the ride on a 3s BSR and 6s BWR knows that the latest are less efficient.