Sturmey Archer ASC 3-speed fixed-wheel hub gear
Posted: Wednesday 12th August 2020
Hub gears have been making a bit of a comeback in recent years – with the launch of seven and eight-speed gears from Sturmey Archer and Shimano and the 14-speed Rohloff. Arguably the greatest hub gear has to be the Sturmey Archer AW was made almost unchanged nearly sixty years and is still in production, in albeit much modified form. However in the minds of classic lightweight cycle enthusiasts the most desirable gear is the ASC 3-speed fixed wheel hub gear. This gear seemed to offer the best of both worlds at the time it was launched in the late 1940s. Many riders were still wedded to riding a fixed -wheel for both time trials and club riding and for those who lived in areas not so flat the ASC looked like the perfect solution. Fixed wheel riding offers a sensation for the rider of being much more at one with the bike and I’m sure that this was a major factor in rider’s love of the fixed wheel. For club riding the fixed wheel also offered the benefit of easy control when in a group.
The demand for a variable speed fixed wheel gear was first made in the late 1920s in Cycling magazine. Back in the Edwardian era there were fixed wheel hub gears – both Armstrong Triplex and Eadie had offered fixed wheel versions but the freewheel versions were then much more popular. In the 1920s the use of the fixed wheel had become the norm amongst club riders and for competitive sport in Britain. Commonly, riders had two fixed sprockets, one on either side of the rear hub, the gear ratios being changed by turning the wheel around.
Sturmey Archer responded to the demand by introducing in the Summer of 1933 what I regard as one of their nicest gears ever made, the TF 2-speed (see image left). It offered a simple drop of 25% from top gear which was direct drive and was beautifully simple inside with the change of gear being made by a sliding sun pinion. If the rider decided that they wanted a freewheel, perhaps for touring, a special freewheel could simply be slid on the splines of the driver in place of the fixed sprocket. It weighed just 250g more than most rear hubs. This gear was really quite popular and they were used until they wore out! The drop of 25% made it an ideal gear for use in hilly areas enabling hills to be climbed much more easily. And most TFs have almost no backlash retaining that feeling of being at one with the bike. It offered the advantages of a fixed wheel with two sprockets but removed the need for the wheel to be turned around. These hubs also saw the the first use of sprockets which drove the hub driver through 12 splines and held in place with a simple lockring. Quick release cable connections and wingnuts meant wheel removal could be very fast.
The 25% drop in ratio was however less than ideal for racing (time trialling) – the drop was too large. So in August 1936 Sturmey brought out the TC medium ratio 2-speed gear with a 13.46% reduction for low gear. The innards were a lot more complex than the TF with compound planet pinions like the KS, KSW and AM 3-speed geards – this resulted in more backlash. These did not prove to be very popular.
Fast forward to 1945 and Sturmey Archer announce the ASC gear with three fixed wheel ratios in 15th August’s edition of Cycling. Top gear was direct drive with reductions of 10% and 25% for the other two gears. Apparently early production was reserved for export – I do wonder whether any were actually made as I have never heard of any steel shelled ASC gears and the aluminium shells were not introduced until 1948. Finally in November 1948 the ASC was launched in the UK. It was fitted as standard with wingnuts (the ones shown in the picture are GB aftermarket wingnuts, not the Sturmey ones) and quick-release cable fittings and used a special 3-speed trigger. But backlash in the hub was much more than with the TF and a little of the oneness with bike gained with a fixed wheel was lost. Although the ASC should have sold in large numbers to club riders I think sales were disappointing for Sturmey Archer. In the 1980s quite reasonable numbers of new old stock ones could be found in bike shops – popular items are rarely found NOS. These days most have been snapped up by enthusiasts who want to experience a fixed wheel variable speed gear.
The ASC was nearly not the last fixed wheel gear they made – in May 1951 Bicycle magazine carried a letter from Sturmey Archer announcing that they were working on an ultra-close ratio fixed wheel hub gear. But the times of most clubmen riding wheel were nearly over – even time triallists were turning to freewheels and derailleurs and the rise of road racing also signalled the demise of the widespread use of the fixed wheel. By 1956 the ASC had been dropped from the Sturmey’s range of hub gears.
The definitive source for anything related to hub gears and a truly fascinating read is Tony Hadland’s The Sturmey Archer Story at £14. it is available from Janet Read, 19 Redbridge, Stantonbury, Milton Keynes, MK14 6BD
- Always make certain a Sturmey-Archer hub is well lubed with a good quality medium weight oil – car multigrade engine oil is fine.
- Always make certain the hub is adjusted so no slipping occurs.
- If you do not have the correct ASC trigger use a standard 4-speed trigger using positions 1, 2 and 4.
- When buying a secondhand hub the condition of the bearing surface in the LH bearing cup is all important.
- Apart from the hub shell there are only three specific ASC parts – the others are common to other Sturmey hubs and replacements are available.
- Hilary recommends the use of track nuts rather than wing nuts on the ASC gear as the wing nuts can be prone to stripping the threads on this gear.