--- In bicyclecommuting@yahoogroups.com, "adyard" <adyard@...> wrote:
>
I ride a lightning thunderbolt. It's a short wheel base recumbent.

Internal geared hubs have a couple advantages over derailleurs, they
allow for shifting from one gear to another without requiring the
chain or the wheel to be moving (so I wouldn't have had to have been
shifting into the biggest cog as I rolled into the left turn lane),
and all the parts that need to be lubricated are covered up, inside as
it were. There are some disadvantages too or else every bike would be
so equipped. I understand that the gear to gear transfer of energy
isn't quite as efficient as the gear to chain transfer, or at least in
the case of a properly maintained chain it isn't. I tend to let some
of this maintenance slide so that may not be as big of an issue for me
as it might be for some folks. Generally speaking the internal hub is
lighter than the cassette and derailleur it would replace, I'm kinda
surprised that the weight weenies haven't gone over to 'em.

A lot of the configurations that employ an internally geared hub also
use a derailleur, like the SRAM dual-drive system. Where the geared
hub replaces the front derailleur and chain rings leaving the rear
derailleur to move the chain in and out onto different cogs of the
rear cassette. I guess if you're still gonna have a derailleur too
there isn't as much weight taken off the bike. But this German
outfit, Schlumpf, makes a crankset that has a planetary gear between
the crank arms and the chain ring. You shift it with your heel and it
has two positions, one being a 1:1 ratio and the other being either
lower or higher depending on the model that you buy, speed drive or
mountain drive.

I think it would be nice to have a bike where the chain didn't move
other than 'round and 'round, staying on the same two pulleys front
and rear the whole time. I want my chain completely covered up so
that it gets less road grime on it and doesn't leave a greasy mark on
the thigh of my britches. But I still want a wide range of effective
wheel sizes provided by different gearing options. The only thing
holding me back is the price, dang them Schlumpf boys is proud of
their stuff.