There are several guides setting out details of maintenance on Sturmey-Archer hubs, and of course there is much useful information to be found in Tony Hadland’s “The Sturmey-Archer Story” [and in Hilary Stone’s Masterclass on APB hub gears published in issue 52 of The Moultoneer – AssEd]. However, when I think back to my early fumble-fingered attempts, I expect there are many people who, like me, can’t relate instructions to the greasy bits, so from the position of the idiot that I was, here’s the Idiot’s Guide to S-A 4-speed adjustment.
I don’t intend to discuss the hub internals – this is best left to experts, and very few 4-speed hubs that you’ll ‘adopt’ with your rescued Moulton will actually be faulty. The problems usually stem from poor adjustment, which on the FW 4-speed is a very delicate setting. The most general rule of thumb is that the gear cable should be very tight in 1st gear, with the trigger hard to engage into the 1st position. In 4th gear, the cable should be slack. A measurement is possible by watching the central spindle or “indicator rod” that runs through the hub axle. Look into the “window” of the nearside rear wheel nut. When in 2nd gear, the rod end should be flush with the wheel axle; when in 3rd, the rod end appears in the centre of the wheel nut window.
4-speed hubs were fitted to the majority of production Moultons. Between 1963 and 1969, when the 4-speed was discontinued, it appeared on Deluxes, later Standards, Speeds, Majors, Major Deluxes and Super 4s. I believe that ill-adjusted 4-speeds may have been responsible for the early demise of many a Moulton. Here’s a handlebar-to-hub checklist to remedy some problems.
Ensure that the stiff wire spring is intact and pressing down on top of the trigger. This keeps the trigger engaged in its gear settings and retains cable tension. Triggers can become rusty and stick. Some ordinary light oil often eases this. It’s best to remove the cable before cleaning, oiling and testing the trigger in its 4 settings. Treat your trigger with reverence: they have been obsolete since 1969 and few replacements remain.
Sometimes trigger casings become distorted. If it has become pinched, maybe in an accident, the trigger will stick. Prise the sides open slightly by gently wedging a screwdriver into the slot. If the sides are too open, the trigger will rattle. Gently close the gap, using a Mole grip.
It is all-important to mount the trigger carefully on the “brow” of the all-rounder style handlebars, so that you can engage 1st gear without bar profile or brake lever hood snagging its lowest setting. This is a common, simple oversight, as 1st position is actually lower on the trigger than the marking for 1st is printed.
Presuming the cable is back in place, with the trigger working, you may find you can engage all gears going from 4 to 1, tightening the cable, but cannot catch them all when moving through 1 to 4. This can be because the cable is sticking and the return spring in the hub can’t pull the tired, kinked or rusty cable smoothly back. Remove the inner from the outer cable and examine it. If the outer is rusty or the plastic coating is cracked, replace it. Otherwise, clean the inner and lightly re-grease it or coat with a little oil. Test it by running the inner cable through the outer to check that no resistance is felt. If all is well, re-assemble, or if not, buy a new cable. The difference when you buy a new cable is that it will seem shorter, but it will have a separate toggle adjuster barrel for you to fit on, so you can make it as long as possible – and just long enough to fit.
You have now either fitted your new or restored cable, threading it first into the trigger. To do this, the inner cable passes into a hole on the trigger casing side, then up, under the sprung plate (it helps to lift this with a very small screwdriver while the cable end comes through) and you then bed it into the trigger’s internal groove. The cable outer should be routed away from the trigger to run along the nearside of the frame, resting over the bottom bracket before crossing under the frame to meet the cable stop clamp on the offside rear fork blade. Generally this should be positioned under the rear brake cable bolt. You now have to attach it to the hub/toggle chain and adjust it.
There are two possible places for adjustment:
The distance between the cable stop and hub is critical, and it may take several attempts to achieve all four gears. Remember, a general test at the trigger is: 1st gear very tight, 4th gear slack. Gears 1 and 2 will run silently in the rotating hub, whereas 3 and 4 tick. At first you may find the pedals spin without engaging certain gears, or you produce dramatic sounds akin to the crunching of a car gearbox. With careful barrel adjustment and/or moving the cable stop, you should eventually achieve all 4 gears.
Apart from sticky cables, slow cable return may be due to a weak return spring in the hub or a worn toggle chain. The springs can be replaced at cycle shops – so can the toggle chain! Most shops will inform you that the 4-speed rod and chain are obsolete: true, but they can remove your worn or broken chain and re-rivet one from a new, readily available, 3-speed. They can carefully pinch one of the little riveted chain links, replace the chain and re-rivet by splaying out a rivet head with a small punch.
Under no circumstances should you throw out old toggles and indicator rods. These really are an endangered species. They are made up of two finely threaded rods that screw into each other. If the male or female thread is ruined, the unit is useless. If handled carefully, it can be unscrewed and removed for cleaning. Insert a small screwdriver into the nearside of the hub, turning the toggle chain end in the opposite direction till both ends separate and can be pulled from the hub. Clean all grittiness from the rods and from the internal spindle, using cotton wool buds. Then oil the rods, pressing both ends back into the hub spindle towards each other whilst re-screwing them together firmly, but not over tightly, as they can snap.
It is important to store all 4-speed Moultons in 4th gear to de-stress cables while at rest, and expect new cables to stretch slightly.
I usually put a drop or two of light oil into the trigger twice a year. The cables are lightly brushed with grease and their ends are touched with oil at general services, when the toggle chain is also oiled. In daily use, the hubs receive a dozen drops of oil monthly.
PS: Should any Moultoneers have converted their bikes from 4-speeds to other methods of gearing, Moulton Preservation would be most grateful for rare components like indicator rods to help other owners to stay roadworthy.