I’ve renounced chains on bikes now that I’ve fallen in love with the chainless bicycle. I’ve been riding a chainless for about 5 years now. Drive shafts for bikes were invented at least a hundred years ago; what’s new is their new low cost, clever shifting, and improved efficiency. Since there is no chain, contemporary chainless bikes use a hub transmission on the back wheel instead of a stack of different gears to “shift gears”.
A good ol’ standard bike chain can be more energy efficient if — big if — it is kept well-lubricated, aligned precisely, and fine-tuned with constant attention. Mine never was. But a modern sealed drive shaft beats the efficiency of the average neglected crusty chain (like mine). Getting rid of a chain removes the least stable part of a bike, the item most likely to need adjustment or fail, and the dirtiest component. Shifting is a breeze on these drive shafts; just click into discrete gears. I don’t mind tossing the bike into a car (no grease) and I can ride with long pants (no pinched trousers). Removing a rear wheel for repair or a flat *is* more of hassle with a drive shaft, but not unduly so.
There are some high-end custom versions of the chainless bike, but they all use either of two drive shafts. The bike I bought is a slightly clunky Taiwan-made $300 weekend bike outfitted with a Sussex drive shaft — the most popular type. It connects to a Shimano Nexus non-cog gear hub. I got a 7-speed version. Mine is not a high-performance bike, but it has gotten me everywhere I’ve wanted to go — without the hassles of a chain. This bike is no longer manufactured, but the Dekra Chainless is very similar, although it uses a different brand drive shaft (which I have not used).
Dynamic Chainless Bikes (which now owns Sussex) produces more sophisicated, higher quality, and more expensive ($600 plus) chainless bikes. These slick bikes have a lighter second generation Sussex dive shaft, an 8-speed hub, and better components. Dynamic makes chainless mountain bikes, which other Cool Tool readers have recommended, and I am tempted to try.