Moulton APB Alfine 8-Speed Conversion

Moulton APB

This week I’ll be working on a Moulton APB Alfine 8 speed conversion. Read on to find out more.

Wind back to January 2022, in comes a gentleman wheeling a silver-grey Moulton with a few gear issues. This particular bike, a Moulton APB (All Purpose Bike) circa 1995 came fitted from the factory with the now super rare Sturmey Archer Sprinter-7, a seven speed gear hub. The Moulton APB was produced from 1992 until approximately 2005. I’ve had many early Brompton’s through the shop with the Sprinter 5-speed fitted but this would be the first 7-speed I’d got my hands on. The owner reported the gears were slipping so I made a start with stripping it down to see what the problem could be.

The hub was in remarkably good shape with an expected amount of wear given it’s twenty-seven year age. With two new gear ring pawls fitted and new bearings it was back together and tested. The hub worked and all seven gear engaged just fine however it seemed to be changing gear by itself. This issue was traced to a very worn and sloppy twist grip shifter and given that Sturmey Archer haven’t been manufacturing these for almost three decades, wasn’t something that could easily be obtained.

Sturmey Archer Sprinter-7

Alternative Options – Sturmey or Alfine, Nexus?

It was soon decided, the best way forward in this case was to build up a new wheel with something more modern. A standard three speed was looked at but soon dismissed as with just 177% gear range, it was way down on the Sprinter-7’s 278%. Another option was the S-RF5(W) but it seems Sturmey Archer are winding down production of this model and availability was limited. The only other model that was in current production and within specs was the rotary shifted RX-RF5 but again, nowhere in the UK seems to have one in stock.

After six month wait, I received a message in my inbox from the owner asking about the possibility of using something from the Shimano range. I had initially ruled out the Nexus/Alfine 8-speeds early on as the 135mm O.L.D. would be a tight fit on the Moulton’s 129mm dropouts, or so I thought. He was keen for me to investigate further so dropped off the bike for me to measure up again to see if it was possible. With light pressure, the dropouts could indeed be stretched to accommodate the 135mm O.L.D. of the Alfine 8. Time to go shopping.

Moulton APB Alfine conversion

Boxes Arrive

Parts arrived within a few days and the hub was soon fitted into the frame to test. With no major hurdles evident, the wheel was built up using the standard Moulton rim size of 20 inch 406 and quality stainless DT-Swiss Champion spokes, two cross pattern with no lacing. Shifter was the rapid fire type in black to match the hub shell. Gearing was going to be a Sturmey Archer FCSS1 54T crankset with a 20T rear Shimano narrow sprocket, which would produce near identical gear ratios to the old Sprinter.

The Last Ten Percent

With the wheel built up, trued and fitted into the frame, the time came to fit the cables, shifter and new grips. With this Moulton APB being the separable type, the gear cable had to be split on the downtube truss and the original barrel connector fitted. Dishing on the rear sprocket was moved inward to achieve a better chain-line and a new chain fitted. Indexing adjusted and it was out for a test ride.

My Verdict – Shimano Alfine the way to go

Right out of the gate, the bike ran perfectly. The gearing was indeed near identical to the outgoing Sprinter-7, with the added benefit of one extra speed and narrower spacing. The Alfine is smooth, silent and shifting positive. Gear one is possibly a little too low for the flat countryside of Cambridgeshire but I guess I’d be thankful of it with the bike loaded up with luggage on a hilly assent. On the flat you’d likely only be using gears four to eight. There is always the option to drop one tooth on the rear and fit a 19T but for now, it’s ready to be picked up.

Drop me an email of you have a Moulton that you think would benefit for this conversion. I’d be happy to help.

2 thoughts on “Moulton APB Alfine 8-Speed Conversion”

  1. Pingback: PW Cycles - 2022 review – PW Cycles

  2. Pingback: Moulton TSR Alfine 11 speed build – PW Cycles

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