Comparative test: Sturmey Archer S2 Duomatic versus SRAM Automatix

If you’re finding the gearing range of your single-speed a bit limiting, there are a couple of options. But which works best in the real world? Iain Treloar tests and reports back. 

Anyone riding a single-speed is likely to have, at some point, encountered the point where an extra gear would be really nice. Usually, however, dedicated single-speed frames don’t have the necessary lugs for cable routing, making the fitting of a shifter-activated internally-geared hub an ugly, cable-tie-heavy exercise.

There are, however, two models on the market that give you the convenience of a geared hub without the faff of fitting a shifter. These are the Sturmey Archer S2 Duomatic, and the SRAM Automatix. Both of these fill a similar niche, as they’re two-speed internal hubs without any shifter at the handlebar. However, their real-world function is quite different. Having spent quite a bit of time on both systems, this comparison is designed to help guide your choice.

Both hubs are clean in appearance, cost a similar amount, and fit on the bike in the same way.

SRAM Automatix

The SRAM Automatix (distributed in Australia by Monza Imports, for roller [$129.95] or coaster brakes [$279]) is a smooth, quiet and clever automatic hub gear. In theory, this seems like the perfect gearing solution for those used to a single-speed. However the shift point of the hub comes far too early (around 18km/h) and a flat cruising speed puts you at a low cadence that soon feels like a real slog. The fact that it’s an automatic shift at first seems like a plus, but the lack of autonomy becomes a bit grating. The hub, of course, can’t know whether you’re battling a headwind, wanting an easy spin home after a tough day, or if your legs are about to conk out. Rather than easing your worries, you end up anticipating the shift point with a certain dread, because most of the time it doesn’t bring relief but more effort. Of further frustration is the fact that only the up-shift is automatic—to make it shift down again, you need to stop pedaling momentarily, which means you’re losing speed and momentum halfway up a hill. Although you can’t change the shift point of the hub gears, you can change the cadence needed to push them with a smaller chainring. Although the quality of the system is high, my real-world experience with the SRAM Automatix left much to be desired—it’s just a little too clever for its own good and, if you’re anything but the most passive rider, soon becomes annoying.   The fact that there’s no rim-brake version brought into Australia means that, although you can get rid of your rear brake caliper, you’re left with the compromised braking performance and action of a coaster brake.

Sturmey Archer S2 Duomatic

The Sturmey Archer S2 Duomatic is activated by a backwards kick, which requires a bit of practice to find. It’s a fairly subtle motion, with a defined click to let you know that you’ve reached your shift-point. The auditory signal is the best pointer to use, as there’s little indication through the drivetrain. There are some pros and cons to this set-up; it brings back the autonomy that the SRAM Automatic removes, but complicates low-speed manoeuvres. It’s only when your attention is drawn to it that you realise just how often you back-pedal in the course of your urban riding—positioning your pedals for corners or red-lights, or getting your feet into cages (if you ride with them)—and the Duomatic forces a rethink of each of these motions, lest you trigger a shift that puts you in the high gear when you really want the low one. However, when you actually have a stretch of open road ahead of you, I far preferred the Duomatic to the Automatix. The low gear was suitable on a 44/17t ratio for most pottering about the hilly streets of my area, or when carrying a load of shopping; the high gear offered a suitable alternative for dropping the hammer or downhill. The cog at the back is for a 1/8” chain, not a 3/32” (which I had on my bike) so factor in the expense of a chain if you’re in the same boat. The Duomatic hub is available for coaster brake, freewheel (rim brake) or 6-bolt disc, retailing for around the $170–$180 mark (distributed in Australia by Bicycle Parts Wholesale). Factoring in the cost of a wheelbuild, the cheap and cheerful option is to buy a complete wheel from Cell ($169, feature image) with a heavy but solid deepish profile rim available in a number of different colours. Cell use the non-coaster (i.e. rim brake) variant of the hub, which positions it as a convenient aftermarket upgrade for most single-speed users. The braking on the Cell rim lacks a little bite, but the value for money of the complete setup is undeniable and makes for a really easy and affordable swap-over.

Conclusion

In all, the decision as to which one is best for you will come down to what sort of rider you are. The SRAM Automatix is a smoother, more polished system, but it’s almost too clever for its own good and if you’re used to having a degree of control over your own cadence, you’ll find its independent nature very annoying. Sturmey Archer’s hub is a little more old-school in its look and feel, and the shifting isn’t 100% predictable/repeatable, even with practice. However, at least you’ve got some control over the fact that it’s shifting. In essence, the Automatix demands less of you as a rider but takes more; the Duomatic is the exact opposite.

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