the original post: treehugger's report about a , and uses a "hydraulic drive" instead of a chain. this drive idea is generating a lot of buzz and a lot of questions.
from there, the comments led me to discover that (just like those under the hood of your car) are already in production, which don't require any grease and have a much longer lifespan than the common chain drives.
then i was led to a few pages about . from the illustrations these look like a car's transmission, with all the bits enclosed inside the rear hub of the bike. ()