_ wrote:

Efficiency, beloved by racers and marketing droids, will be a big issue.
Bigger than it should be, probably; and murkier, certainly.

My recollection is that previous versions of belt drives were estimated to
be less efficient that a well-lubricated new roller chain.

But a lot of the point of this new one is it's meant to be just as
efficient as a chain.

Belts do not
lend themselves well to derailleur gear systems, and that would add the
typical lower efficiency of hub gearing.

It is typical, but it's also changing. Hubs have come on a long way in
recent years while derailleurs haven't really changed /that/ much. if
they continue to improve (particularly the likes of the NuVinci CVT hub,
which just needs to get lighter AFAICT) this may start to be less of an
issue.

Cleanliness is a possible advantage - but if you are going to have a hub
gear, you might as well have a chaincase; which would probably also remove
or reverse any durability advantage.

I don't think so. An enclosed chain still needs lubrication, while a
drive belt doesn't.

It does have some clear advantages... as long as you don't particularly
need derailleurs for your particular application (and "need" can be
factored in as cost: they're popular at the low end in part because
they're not very sophisticated and thus cheap).

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/