Sturmey Archer S2C Duomatic Kick Shift Hub Specs and Info

Marco first let us know about Sturmey’s new 2 speed kickback hub here. Let’s look into the S2C further, which has been available since later this summer.

There are actually two variations of Sturmey’s new kick shift hubs, the S2 and the S2C. The S2 is a dual shifter without the break and the S2C includes a coaster brake mechanism. The S2 is not currently available but the S2C is.

The S2:

And the S2C:

Here are the basic specs from the Sturmey Archer site:

Specs for 162mm Axle

• Hub Shell Material – 6061 Aluminum
• Axle Diameter – 13/32” Slotted
• Axle Length – 162mm
• Over Locknut Dimension – 116mm
• Right Axle Protrusion Length – 23mm
• Left Axle Protrusion Length – 23mm
• Spoke Holes – 36
• Pitch Circle Diameter – 67mm
• Flange Width – 53mm
• Spoke Compatibility – 13g or 14g
• Sprocket Teeth – 13T through 22T
• Chain Line: 1/8” Flat 43mm
• Chain Line: 1/8” Dished 41.2mm, 44.8mm
• Chain Line: 3/32” Flat 42.6mm, 43.4mm

• Chain Line: 3/32” Dished 41.1mm, 44.9mm
• Weight – 1400g

Gear Ratio

• Overall Range – 138%
• Gear 1 – 100% Direct Drive
• Gear 2 – 138% (+)38% (Gear 1 + 38%)

Gear Changing With the S2 and S2C

Gear switching on the S2 and S2C is accomplished by back pedaling slightly. On the coaster brake version, the S2C, a more deliberate and powerful back pedaling will result in the coaster brake being engaged.

S2 and S2C Installation

Download S2C Manual and Instructions PDF

Below is a video of the S2C Setup in Moulton Bike. It shows the kick back action and coaster braking.

More to come!


  1. Thank you for enlightening me on this revamp of a great old idea !! the 2 speed kickback hub. John

  2. I’ve been using a Duomatic for around 4 years now – first a 28 hole one I got off eBay, then a 36 hole I got from Marco. I love them.

    I would be very interested in a comparison between the Torpedo Duomatic and the new SC2. Can anyone provide one?

    SO far, the only thing I don’t like about the SC2 is the brake arm. I much prefer the silver of the Torpedo.

  3. The SC has been produced before 1966-1970; then it had a steel case and the second gear was direct drive 71-100%; no coasterbrake. See my post at Velobase.

  4. JT

    Just wondering, for the S2C, backpedalling hard results in a braking effect since it has a coaster brake. What about for the S2? After the kickback gear shift happens, does it continue backpedalling?

    • Dave

      Yes, it continues to freewheel. You hardly notice any difference between it and a plain single speed freewheel until you begin pedaling forward again.

  5. Another video of the hub in action:

  6. Great site!

    You also might want to take a look at Dualspeed at

    Enjoy, Ingo.

  7. I have the S2 version of this hub (freewheel). In your opinion, what would happen if I only ran one of the lock-washers on the axle? I would leave the DS lock washer in place. I am asking because I am trying to increase the overall hub dropout dimension from the stock 120mm and removal of this washer on the DS would be a big help. Thanks.

  8. MN

    I have one of these on my moulton and it leaks, jumps, cracks and annoying to drive because you basically always break when you just want to change the gear.

    • h. honnest

      You don’t need to break in order to shift! Just pedalling back a very little makes it shift already

      By the way, I realy love the S2C. Two gears, but no maintenance needed at all. Even if the bike is outside all year long in the humid conditions we have here in Holland.

      The only drawback is that there is no sprocket that suits for a 28 x 1,5 inch size wheel (old fashioned Dutch bikes have comfortable, but rather large wheels)… The largest available sprocket – 24 teeth – is too small to comfortably cycle this wheel size.

  1. 1 For Sale: Sturmey archer s2c and s2 duoamatic hubs - wheels sets - London Fixed-gear and Single-speed

    […] indicate size of chainstay for clip on end of coater arm) S2 (no coaster brake) silver only…ey-archer-s2c/ front hubs: sturmey archer bacon slicer large flange , cartridge bearings track hub (just like […]

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