Originally Posted by
fooferdoggie
with long wheel recumbents and long chains why not use this method instead of having to retake the bottom bracket? it would be far easier to deal with and easier to fix or take off a chain.
As someone who had built a few recumbents and ridden a lot more, many of them have absolutely appalling chain management.
Other than old or really cheap frames, tandems tend not to have them for the same reason fixed gear bikes don’t. The lower chain portion can end up in tension, which tends to be hard on the idlers. Most also want the chain length to be fixed, IE no rear derailer type idlers. Without the fixed length chain the sync between captain and stoker floats a bit and the top can lose tension.
Finally, a half decently made eccentric is more secure and less easily damaged than an idler.
Don’t get me started on plastic tubes being used as chain guides.