The screw which holds the selector-key spring in place needs to be secured with threadlock compound, or it may come out of the axle. The sun-gear selector key inside the hub can wear, also leading to trouble with shifting. The newer version with a spot on the bezel has reduced backlash. The SL-S50 shifter for the (W) hubs (black bezel) can overshift on downshifts and stick between gears, and wears, leading to slippage in 2nd and 4th gears. That is desirable so that the step from the fourth gear to the top gear is not too large, but it reduces the step at the lower end of the range, not so desirable. The outer steps are narrower than the inner ones. The steps between the three middle gears of the (W) hubs are the same as for Sturmey-Archer three-speed hubs. Sturmey-Archer's previous 5-speed hubs, with model names ending in (W) for "wide", use the common 3-lug sprocket, shift with a pullchain and have a wider range, as follows: Ratio Note: the rotary-shifting 5-speed hubs take a sprocket with 6 lugs and a 50mm center hole, not the same as for most other internal-gear hubs. Product page for the current 5-speed hubs:
CRX 4 OR 5 SPEED SHIFTER SERIES
Sturmey-Archer introduced a new series of rotary-shifting 5-speed hubs as of late 2013 overall range 244%. The 4-speed hubs use common 3-lug sprockets. Product page for the 4-speed hubs.Īs the lowest ratio is 1:1, these hubs are especially suitable for small-wheel bicycles. These hubs are not yet widely available in the USA. Sturmey-Archer introduced a series of 4-speed hubs in 2015. There is more detailed information on sprockets and on setting the gear range on another page.Ĭurrent and recent Sturmey-Archer 4- and 5-speed hubs If the terrain is all up and down, you might want to set the gear range lower. you might want to set the gear range a bit higher, as the steps between gears are smaller. These hubs work best if the second-highest gear is the level-ground gear, around 70 gear inches (5.2 gain ratio, 5.5 meters development) The top gear is used for downhill and downwind riding. The older hubs also have a "neutral" between direct drive and the higher gears. A sluggish or misadjusted shifter cable can allow the hub to freewheel or lurch forward. These hubs have a "neutral" position when shifting the sun gears, because engaging two sun gears at a time would cause the hub to lock up. These hubs have a middle, direct drive ratio, and a choice of wider or narrower ranges depending on which sun gear is locked to the axle.
The large end of the planet gears engages the small sun gear, and the small end of the planet gears (middle section on the 7-speeds) engages another, larger sun gear and the gear ring. The planet gears are stepped gears (two or three gears of different sizes, side by side, in a single piece so they all turn at the same rate). They have two or three sun gears, and only one of them is locked to the axle at any time.
Except for a 4-speed new as of 2015 and about which no information is as yet available, Sturmey-Archer 4-, 5- and 7-speed hubs all are of a similar basic design using compound planetary gearing.
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