Multi-speed hubs have a long, and not particularly glorious past. Just about every bicycle hub gear (and most automatic cars, trucks and trains) involves an epicyclic gear system – a set of ‘planet’ gears whirling about a central gear, called the ‘sun’ for equally obvious reasons.

This arrangement is compact, light and in its simplest form, provides direct drive, plus a gear up and a gear down, making three per epicyclic (sometimes only two gears are used). Join two or three together and you produce a ‘compound’ epicyclic, producing 5 or 7 gears, as in earlier Sturmey hubs. Feed power through one epicyclic, then through another, and the number of gears is multiplied, producing anything up to, er, nine gears – the limiting factor being the complexity of the gear shifter mechanisms. Manufacturers are increasingly choosing this more complex route, using a group of two or more epicyclic gears in all sorts of odd arrangements.Typical is Shimano’s Nexus Inter-7 (seven gears from two compound epicyclics), or the Rohloff Speedhub (14 gears from three compound epicyclics).The details are a bit of a head-scratcher, but all we end users need to know is that modern hubs give plenty of gears and a wide range.With some complicated engineering, they can also be set up to give evenly-spaced gear steps, or relatively close ratios in the middle gears, and broad steps at either end – probably a more useful arrangement. However, the more complex the gear train, the greater the internal friction.

If you want to know more about how and why hub gears do what they do, we’d recommend Tony Hadland’s excellent Sturmey Archer Story [hadland@globalnet.co.uk].

Beyond the 5-speed

Seven speed hubs began to appear in the 1990s, first from Sachs (now SRAM), then Shimano (these hubs are confusingly called Nexus), and finally Sturmey Archer, which first dipped a corporate toe into the multi-gear world with the Sprinter 7. Of the three, we much preferred the Sturmey, because it was light, cheap, simple, and user-friendly. Unfortunately, despite a lengthy gestation period, reliability problems persisted and the hub never really found its feet.

The Japanese and German hubs remain in production, but neither has really caught on in a big way, thanks to servicing complications and other flaws – odd gear ratios and unreliable shifting on the Sachs, and a rather limited gear range on the Nexus. Others have come and gone – Sachs produced a dinner-plate sized 12-speed a few years ago, but this monster was quietly forgotten, and Rohloff, a small German engineering company, build a 14-speed, but it’s a bit pricey. Most of these hubs are pretty good, but not quite up to killing off the derailleur just yet.

8-speeds

Although Sturmey held some key 8-speed patents, development work was shunted into a siding following the company’s collapse and eventual acquisition by Taiwanese company Sunrace. Consequently, Shimano was first out of the starting blocks with an 8- speed hub in 2003.

We haven’t had much experience with Shimano’s Nexus Inter-8, but it certainly looks smart and offers a wide 307% range.That’s about the same as a medium-tech 24-speed derailleur, but without the complexity of twin levers and overlapping gear ratios.The gaps between gears are all 17%, except for 1st to 2nd and 5th to 6th, which are both 22%.

Right from the beginning, Sturmey aimed for what might be termed a close-ratio six speed, plus a crawler gear for hills, and an overdrive top for long sweeping descents. And they’ve been true to their word: First to second is a 28% leap (the sort of gap you’d find on a three-speed, for example), all the intermediate gaps are 13%, and gear seven to gear eight is, once again, 28%.This is all achieved with three epicyclics, connected in increasingly complex ways as the ratios get higher.

We fitted the Sturmey RX8 to our Ezee Forza test bike. Two reasons for this – it’s the only conventional-ish ‘cumbersome’ bike at A to B Towers, and it desperately needs more gears. Like many utility machines, the Forza is fitted with the Nexus 3-speed, a user-friendly, light, reliable workhorse, but offering rather limited gear ratios of 46″, 62″ and 85″. Obviously Sturmey will want to snatch discontented 3-speed owners from Shimano, before they trade up to the Nexus 8-speed hub.

Fitting & Removal

Fitting the 8-speed is straightforward, and most of our observations would apply to any Shimano hub-geared bike. For a variety of reasons (including nervousness, it must be said), we kept the original Shimano outer cables, changing only the inner brake cable, gear cable and twistgrip. One point to watch is that the standard kit is designed for bikes with a horizontal rear drop-out. If your drop-out does anything else (ouch!), you will need an alternative fulcrum lever (that’s the bit you and I might call the cable guide).

The Forza has a Nexus roller brake at the rear, but the conversion to Sturmey drum brake went smoothly. In theory, this sort of swap is best avoided, but the ‘feel’ of these very different brake systems is not wildly different and we left the brake levers unchanged.

Wheel removal is easier than the nail-breakingly frustrating Nexus system, but you still have to winkle the cable off its drum.The dear old Sturmey 7 featured a cable quick- release – a much neater solution.

Multi-gear hubs usually offer direct drive in the middle gear, but the X-RD8 provides direct drive in 1st; the gears rising thereafter to the maximum of 305% in gear 8.What this means in practice is that the wheel is spinning three times faster than the drive sprocket, so the bike only needs a tiny chainring – 33-tooth in this case.This upwardly mobile gearing would, of course, suit small-wheeled folders rather well, as would the concentric cable drum… Checkout loan zeus for more details. So will the X-RD8 fit the Brompton? Our drum brake version is too wide, but Sturmey tells us a 116mm version is set to follow next month, and this probably could be shoe-horned in.The only disadvantage is that the X-RD8 has very large input splines, so sprockets are only available with 25- or 23-teeth. If you’re floating away on a sea of confusing figures, this simply means that a small-wheeled bike will need a conventional large chainring, whereas a big-wheeler will not.

More positively, the hub is particularly light – only 340g heavier than the Sturmey 5- speed, itself a light hub, and a full 224g lighter than the chunky clunky Nexus 4-speed.

On the Road

Gear adjustment is one of the strong points of the X- RD8. Like the Sturmey 7- speed, Nexus 7 and others, the cable runs straight back to the hub, wrapping around a drum concentric with, and adjacent to, the giant drive sprocket. Adjustment is dead easy – as with the Shimano multi-speed hubs, you simply align a yellow arrow between a pair of pointers in gear four. Mind you, it needs to be easy, because with so many gears, adjustment is critical, and a turn or two on the adjuster is enough to cause knocks and bangs in certain gears. Incidentally, tolerances in the components biased the perfect adjustment point towards the forward- most pointer, rather than between the two – these few millimetres make a lot of difference. But once the cables and connectors have bedded down (and you’ve got acclimatised to being positive, but not over-positive, with the shifter) the hub settles down nicely. Like most Sturmey hubs, the X-RD8 also prefers a momentary pedal- pause between gears.

With the standard 33-tooth chainring, 25-tooth sprocket, and a typical 559mm wheel, we ended up with ratios of 34″, 44″, 49″, 56″, 63″, 72″, 81″ and 104″.That’s perfect for an electric-assist machine like the Forza, but on a conventional bike, we’d probably aim a bit lower. A smaller 30-tooth chainring would give 31″ to 95″, and so on with other chainrings, if your maths is up to it.

On the road, we couldn’t detect any roughness or noise from the hub, and gear spacing proved excellent, although under certain tailwind conditions it’s possible to find yourself ‘hunting’ awkwardly between gears 7 and 8 – quite a big leap, of course. At the other end of the scale, the big gap between 1st and 2nd is fine. Between these two extremes, gears pop up more or less wherever you need ‘em, just as they should.

Conclusion

There seems to be little to choose between the Sturmey and the Nexus. Unfortunately, Shimano got the Nexus Inter-8 out first, and with their usual marketing flair, the Japanese company has already schnozzled up most of the OEM (original equipment) business. But the Sturmey seems to have the edge in terms of weight and gear steps (the overall range is almost identical). And the 116mm version promises to fit into all sorts of places a Nexus wouldn’t go. Price is expected to be a very reasonable £144 complete with sprocket, twistgrip and other assembly parts, or £159 for the complete drum brake version.The very neat little chainwheel and crankset would add about another £8.85.

Forty years ago, Doctor Moulton demonstrated that 16-inch tyres offered lower rolling resistance than anyone thought. Controversially, he went on to prove that his own 17- inch tyre rolled as well (or even better) than its 27-inch equivalent. For many years, the ‘cooking’ Moultons were sold with smaller 16-inch tyres, or to be more precise, 16″ x 13/8″. Incidentally, there are three slightly different 16-inch formats, so its safer to use the international metric rim size: 349mm. Look on the tyre and you’ll usually see 37-349.The 37 refers to the width in millimetres (that’s the 13/8″ bit).

While sales of the Moulton were strong, these tyres became widely available, but with the decline in Moulton sales at the end of the 1960s, tyre companies lost interest, and the 349mm format began to fade away.

Fortunately, as we’ve recounted numerous times, this ‘ideal’ folding bike tyre size was saved – initially by the Bickerton (fitted only at the rear, of course), then the Micro, and from the late 1980s, the Brompton and later the Airframe. It might have been an ideal size, but by this time there was only one half-decent tyre left in mass production – the Raleigh Record.

In 1996, with the arrival of the race-bred Primo Comet, 349mm tyres were back at the cutting edge.The better tyres helped to sell bikes, and more bikes brought better tyres…There are now four main choices, and a number of interesting developments on the horizon.

Most of these tyres are available with or without a tough kevlar under-layer to resist punctures. Kevlar increases rolling resistance, but we’re not convinced it reduced punctures.The results of our small reader’s survey (sent out with December 2003 renewals) seems to confirm this.

Raleigh Record (37-349mm)

Are we serious? Well, they’re cheap, but thereafter it’s all negatives: the Record is heavier than the new breed, it punctures more frequently, rolls less well and is more difficult to remove from the rim. For very mean people who don’t mind mending a few punctures, a pair of Records will last 3,000-4,000 miles. But life’s too short, surely?

Points to watch: Prone to punctures, particularly when badly worn, but may outlive you.
Weight: 338g
Puncture resistance: Mediocre
Rolling resistance: Poor
Price: £5
Outlets: Less glamourous cycle shops

Primo Comet (37-349mm)

The story has it that American recumbent manufacturer Vision developed a small race- bred tyre, and licensed the technology to Cheng Shin in Taiwan, who succeeded in producing an everyday racing tyre for an everyday road price.The magic ingredients were a near-slick tread, and strong, but paper-thin reinforced sidewalls that rolled and flexed much better than the conventional kind, yet lasted almost as long.What also impressed about the Primo was its strikingly low weight of 201g a tyre – a saving of no less than 137g over a Raleigh Record. As if by magic, small wheeled bikes started to go much, much faster, and weigh less too. Strangely enough, considering the Primo’s light, supple construction, the tyres proved to be relatively puncture-proof, and (on tarmac, at least) the lack of tread has no negative effects. Needless to say, this is not a tyre for muddy or loose surfaces, and the sidewalls will be damaged if used with a dynamo, but the Primo remains a firm favourite with some.They’re surprisingly hard wearing too. With care (ie, no dynamo and no riding whilst flat), a Primo should last up to 3,000 miles and puncture around every 1,000. Eventually, the sidewalls become a bit frail, and cuts in the tread harbour glass and flint shards, causing more regular punctures.

Early Primo tyres had natural brown sidewalls that soon looked shabby, but later examples were all-black, and some have reflective sidewalls too.There’s a kevlar option, but we’ve seen no evidence that it’s worth paying extra for.

Points to watch: Rolling resistance is so low that you may not notice a puncture before the rim hits the ground. And avoid the ultra-light 19mm (19-349) Primo unless you’re building a one-race special. Although light and free-running, it is unsuitable for road use and can fail rapidly.
Weight: 201g
Puncture resistance: Good
Rolling resistance: Excellent
Price: £15
Outlets: Rarer now, but try Avon Valley Cyclery or St John Street Cycles (see ads in back pages).

Brompton (yellow flash) (37-349mm)

By the late 1990s so many Brompton customers were fitting their own Primo tyres that Brompton decided to develop a road version for themselves. After a number of experiments, the now familiar ‘snakeskin’ tread pattern first appeared in early 2000 and was soon standard on all Brompton models, apart from the lowly C3.

With thin supple Primo-style sidewalls, and a tougher, but equally flexible (possibly more flexible) tread, the tyre was expected to have slightly inferior rolling performance to its racing forebear, but our tests found little difference, and engineers at Greenspeed (see graph) have actually recorded a modest improvement.This may be down to the rubber compound chosen – the Brompton tyre is quite hard, making it relatively puncture resistant and very long lasting. According to our reader’s survey, Brompton tyres have a life of 1,000 to 8,000 miles, with a mean figure of about 4,000 miles; something we’d agree with from experience. Puncture resistance seems to vary a great deal, but the mean figure is 1,060 miles – far in excess of any other tyre. Indeed, almost half our respondents had never experienced a puncture.The downside appears to be a lack of grip in the wet, particularly when running obliquely to white lines and low kerbs. The evidence for this is quite patchy, but sufficiently widespread to cause concern.

If the standard Brompton tyre is so good, surely the ‘green flash’ kevlar-lined version is even better? We don’t think it is. Our reader’s sample was small, but together with the evidence we’ve seen over the years, it suggests the kevlar tyre has a shorter life and is actually more vulnerable to punctures.

Points to watch: May lack grip in wet weather, particularly when new. Either ‘run in’ with care for a few weeks, or try buffing the tread with sandpaper before use!
Weight: 248g
Puncture resistance: Excellent
Rolling resistance: Excellent
Typical Price: £9.99 (kevlar ‘green flash’ tyre, about £16.25)
Stockists: All Brompton dealers

Schwalbe Marathon (37-349mm)

The Marathon is a newish tyre, allegedly developed from the long-established Swallow, which sold here back in the days when the Brits were a bit suspicious of the Germans and preferred to buy products with British-sounding names. Still, we’re all friends now, eh?

This is the only modern 16-inch tyre relying on ‘old-fashioned’ tyre construction, but the Marathon incorporates plenty of clever technology, including rubber with a high silica content to improve grip and a kevlar belt for puncture resistance.

The general consensus is that the Schwalbe is relatively puncture-proof compared to the lighter tyres, but our reader’s experiences seem to tell a different story.Your figures suggest average tyre life in the region of 2,300 miles, and punctures every 860 miles.There are many reasons why our results might not be scientific – for example, a tougher looking tyre is more likely to be fitted to a hard-ridden machine – but the evidence appears to suggest that they have a shorter service life and more punctures than their lighter (and cheaper) cousins.They can also be a tight fit on the rim, making punctures even more annoying. And according to the Greenspeed data (see graph), rolling resistance is rather higher – the Schwalbe absorbing as much as ten watts more per tyre than the Brompton. At18mph (the speed at which the tyres were tested) that relates to around 16% extra effort.Whatever the truth (and Greenspeed believes its test methods may exaggerate the differential) the Marathon is a safe, grippy tyre that looks effective, and it has rightly settled down as a popular option. For tough conditions and off-road use, it is probably the best choice.

The seriously puncture-proof Marathon Plus should also be available in this size soon, but Bohle UK was unable to confirm a date.

Points to watch: Vice-free, but stodgy performer
Weight: 340g
Puncture resistance: Good
Rolling resistance: Fair
Typical Price: £15
Stockists: Most small-wheeled bike dealers (see advertisements)

Schwalbe Stelvio (28-349mm)

The Stelvio is considerably narrower than the 37mm tyres, but as it retains the same ‘aspect ratio’ (ie, ratio of width to height), it also has a smaller overall diameter.The tyre will stretch to fit the 20mm rims fitted to the Brompton and most other 16-inch bikes these days, but the reduced tyre diameter means you’ll have to recalibrate your speedometer, and accept slightly lower gearing.

The tyres feature just about every technology going – the sidewalls are paper thin, Primo- style, the centre of the tread is a slick, low-friction rubber, and the shoulders a grippy silica mix. Overall weight is marginally the lightest on the market at 196g.

Are they worth the money and the trouble? Being such a small tyre, the Stelvio is vulnerable to incorrect tyre pressures – Schwalbe recommends 85psi – 120psi, figures that most tyre pumps simply can’t reach. If run at too low a pressure, the tubes are liable to suffer from pinch punctures on bumps. Punctures do seem to be a problem generally, but there simply isn’t enough evidence to say for sure.

On a Brompton or Micro, the Stelvio serves only to give a spine-jarring ride and over-light steering for no detectable benefit, but this light, fast 120psi tyre might make sense on a fully-suspended bike such as the Moulton – preferably with the correct narrow rims. Provided you look after the tyres, and fit them to the right sort of machine, they may be the fastest 16-inch option.

Points to watch: Some potential for faster machines
Weight: 196g (you can save a further 9g per tyre by fitting Schwalbe 32mm inner tubes)
Puncture resistance: Poor
Rolling resistance: Excellent
Price: £13.50 (including UK postage)
Stockist: Westcountry Recumbents [rob@wrhpv.com]

Conclusion

If weight really matters, the Primo still has much to offer, although you’d be well advised to stock up while they’re still widely available. For racing, it’s probably fair to say that the Schwalbe Stelvio is the best, although we’d hesitate to recommend it for road use.The overall winner, in terms of value for money, life, puncture resistance and rolling resistance, just has to be the standard Brompton tyre.The only question mark seems to be wet weather grip – in all other respects, this is a remarkable tyre.

Incidentally, the tyres tested above are rated at all sorts of pressures, but please ignore such phrases as ‘inflate to 100psi’ (Brompton, in this example).Whatever the graph might seem to indicate, these figures are maximum pressures, and will only give the results indicated on a perfectly smooth surface. For most riders, on typical road surfaces, a lower pressure will give both lower rolling resistance and greater comfort.

A good general guide is to sit on the bike and adjust the tyre pressures front and rear until the tyre just begins to bulge out above the road contact patch.That pressure (always higher for the rear tyre, of course) might be 100psi, 80, 60 or even less, but it will be close to ideal for you, your bicycle and your tyres. On the road, high frequency vibration means too much pressure, and a ‘wallowing’ ride, too little. If this all sounds like hard work, aim for about 65psi front and 75psi at the rear.