power when suns #3 and #4 are disengaged from the center axle and will overrun when one of the sun gears is locked and power is transmitted to the ring gear by the planets. In other words, ring gear 2 can either rotate at the same speed as the shared planet carrier or at a higher speed. Clutch #3 couples the reduction stage sun gear to its ring carrier (direct drive), clutch #4 locks the reduction stage ring gear to the stationary axle. Freewheeling is achieved by allowing ring gear 3 to freewheel in a forward direction. It will thus either freewheel relative to the axle when final reduction is enabled, or to the sun gear when final reduction is in direct drive. In other words, when the final reduction stage is in direct drive, the freewheeling contribution will put the planetary system into reverse overdrive with the planet carrier now the input and the ring gear the output that has no load. The IGR (inner gear ratio), hub revolutions per sprocket revolution of the Speedhub, lies between 0.279 and 1.467 depending on the gear chosen. Gear 11 has a ratio of 1.0. The Speedhub has a 526% range between the highest and lowest gear. The range of gears in detail is: The overall average loss of the gears is about 1 %–5 %, comparable to a derailleur. Mounting The Speedhub is provided with a twist shifter for shift operation, with one cable pulling in each direction. The indexing mechanism is part of the hub. As with all hub gears, there is a torque reaction that must be countered if the internals are not to rotate, and this is routed to the bicycle’s frame by means of specially designed wheel dropout slots (OEM versions), or a torque bar bolted to the frame (EX) or the disc brake mount (DB). The hub contains 25 ml of oil which should be replaced once a year or after 5,000 km (manufacturer advice). Overfilling can lead to leaks, as can laying the hub/cycle on its side in some low-pressure aircraft holds. The sprocket on the hub is made for standard-pitch derailleur-type bicycle chains 1/2″ × 3/32″ (ISO 082) and is offered with different numbers of teeth, like 13/15/16/17. The 15-, 16-, and 17-tooth sprockets are reversible, offering double sprocket life once the sprocket is worn out in one direction. The 13-tooth sprocket is non-reversible