"overdrive" rear hub

I commute to work on my touring bike 6 km/4 miles each way. The route to
work is slightly uphill and the route home is slightly downhill. I
would like to purchase some equipment that would give me greater (gear)
speed for the downhill trip. On my last bike I installed larger front
gears but shifting was awkward and unreliable even after much fussing
with the front deraileur. Do rear hubs with an overdrive mechanism exist?

Mel Comisarow wrote:

I commute to work on my touring bike 6 km/4 miles each way. The route to
work is slightly uphill and the route home is slightly downhill. I
would like to purchase some equipment that would give me greater (gear)
speed for the downhill trip. On my last bike I installed larger front
gears but shifting was awkward and unreliable even after much fussing
with the front deraileur. Do rear hubs with an overdrive mechanism exist?

The SRAM DualDrive [1] combines a 3-speed hub [2] with either a 7, 8 or
9-speed cassette. It was preceded by the Sachs/SRAM Spectro 3x7 hub
which combined the Sachs Torpedo hub with a 7-speed cassette, and an
even older version that used a 2-speed hub and 6-speed freewheel. The
DualDrive internals are not the same as the Torpedo, but have been
redesigned for lower friction and better shifting under load.

[1] http://www.sram.com/en/sram/comfort/dualdrive/index.php.
[2] 0.73:1 underdrive, 1:1 direct drive, and 1.36:1 overdrive.

--
Tom Sherman - Earth (Downstate Illinois, North of Forgottonia)

Sun, 20 Mar 2005 04:33:58 GMT,
,
Mel Comisarow wrote:

On my last bike I installed larger front
gears but shifting was awkward and unreliable even after much fussing
with the front deraileur. Do rear hubs with an overdrive mechanism exist?

You don't say what you're using now.
With typical touring or MTB triple chain rings and a SRAM 3 X 8 rear
hub you'd have seventy-two gears to twiddle. In "high" gear it would
give you a 36% increase over your normal top gear.
--
zk