Gallery of Duomatic models
From left to right: The Fichtel & Sachs Torpedo Duomatic model 102, the 101 (without coaster brake), the R2110 and the A2110 (automatic gear shift version of the R2110). This page also covers the later SRAM Automatix that is mechanically similar to the A2110.
- Model 102 was produced from 1964 to 1973. Early production units have "Torpedo" engraved or stamped on the hub shell using a cursive font, later production switched to block letters.
- Model 101 was produced from 1964 to 1970. A limited number was produced compared to the 102, so very few exists today.
- Model R2110 was produced from 1973 to 1984.
- Model A2110 was produced from 1974 to 1984. A limited number was produced compared to the R2110, so few exists today.
- SRAM Automatix was produced from 2011 to 2017. Four versions existed: With coaster brake, roller brake, disc brake (alu hub shell, 32H) and without a brake.
Torpedo Duomatic 102This example produced in 1965 (Year code "H"), 36 holes, long axle version:
Torpedo Duomatic 101This example produced in 1968 (Year code "L"), no coaster brake, 36 holes, long axle version:
Mostly disassembled (see the Duomatic rebuild page for full disassembly photos, planet carrier sub-assembly and shifter sub-assembly is the same as the 102):
Note: Even though there is no coaster brake, there is a hard stop on the backpedal stroke after the shift point, so you cannot rotate the crank backwards to reposition your pedals while waiting at a red light.
Torpedo Duomatic R2110This example produced in 1980 (Year code "Y"), 28 holes, long axle version:
As it can be seen on the disassembly photos, the R2110 version of the Duomatic hub only shares a few components with the previous model 102. Many components were simplified, probably to require fewer machining operations to manufacture the parts.
Torpedo Automatic A2110This example produced in 1981 (Year code "Z"), 36 holes, short axle, blue banderole version (meant for 26-28 inch wheels, shifts earlier than the red version):
Almost completely disassembled (centrifugal clutch sub-assembly kept together, as well as the brake reaction arm and left bearing cone):
SRAM AutomatixThis example with coaster brake has 36 holes, shifts earlier than the 28H version. Same mechanical principle as the older A2110 and a few parts are even compatible:
Almost completely disassembled (centrifugal clutch sub-assembly kept together):
The type and thickness of the hub shell surface galvanization used on the three steel versions of the Automatix hubs is unfortunately not great compared to the older Duomatics, so they will get tarnished on the outside as shown on the photos if used in Scandinavian winter weather. But the internal mechanism is of good quality.
The heart of the Automatix (like the Automatic A2110) is the centrifugal clutch unit:
Two flyweights are mechanically linked to each other and held back by a tiny torsional spring. This spring controls the shifting point of the hub. The general consensus among bicycle enthusiasts who care about pedalling cadence is that the hub shifts into second gear too early. The spring can be modified to change the rotational speed of which the hub shifts.
Since SRAM stopped production of internally geared hubs and related parts in 2017, there are no spare parts available for the hub, but some parts from earlier Sachs/SRAM models are compatible, like the planet gears, the left ball ring, the smaller driver ball ring, and the fixed bearing cone on the axle from three-speed hubs, like this one from a SRAM T3 (plus some spacers/washers to take up the difference in length):
Page last updated 2023-04-16 17:48. Some rights reserved (CC by 3.0)