Bikes fitted with hub-driven gears are becoming increasing popular. They provide for many miles of maintenance-free biking plus the shifting is smooth and silent. The use of internal hub gear systems allow cyclists to conveniently shift their gears while stationary.
A good example would be dropping to a lighter set of gears while waiting at the traffic junction. Urban or touring bikes are being fitted with internal hub gear systems like the SRAM Dual-Drive or the Sturmey Archer CS-RF3 system.
|SRAM Dual-Drive 27||Sturmey Archer CS-RF3|
|2. Easy indexing of 3-speed hub gear||2. Harder to index|
|3. SRAM DD27 only weighs only 970g (freewheel)||3. CS-RF3 (27 speed) weighs in at 1090g (freewheel)|
| 4. Better gear ratio; Overall gear range of 186%:Gear 1 : 73%
Gear 2: 100%
Gear 3: 136%
| 4. Overall gear range of 170%
Gear 1 : 75%Gear 2: 100%
|5. Shifting mechanisms are enclosed||5. Shifting cables are exposed|
|6. Click-box shifting cable is easily removed||6. Cable removal poses some challenge|
|7. Has been deployed for many years without issues of gear slippage||7. Had an old batch of gear slipping issues|
In addition, the SRAM Dualdrive system actually weighs in lighter (250g less) than a standard derailleur drive train system. Based on the feedback of various customers, overall the SRAM Dualdrive system seems to be the more reliable and lighter hub gear system you would want to use on your bike.