If you think about it, the quality of a child’s bike is really important. If a child grows up with a heavy, impractical bicycle, he or she starts life with the impression that bicycles are heavy impractical machines.The evidence from the current generation is that apart from dabbling with BMX, the vast majority stop riding bicycles just as soon as they can, and most never return. Rather disturbingly, there’s growing evidence that many in Alexander’s generation will never learn to ride at all.

When Alexander was old enough for a ‘proper’ bike we chose a German-made Puky. Children’s bikes with dynamo lights, a rack and mudguards are common on the Continent, but only the Puky is easily obtainable here, thanks to importer Amba Marketing. By the spring of 2005, our 18-inch wheel example (see A to B 41) had given great service for 18 months and 400 miles, but at six, the boy was growing rapidly, and trying longer rides.The time had come for an upgrade, but not yet to a bigger bike.

Theory

…any competent cycle engineering should be able to upgrade…to hub gear operation…

How would we define the perfect bike for a small child? For obvious reasons, it needs to be reasonably fashionable. If everyone else is riding Death-Squad BMX UXB MTBs, with unobtainium gussets and nobble-tooth mud pluggers, pushing the sensible, weedy option can be hard work.The bike also needs to be suitable for road use in all weathers, plus some modest off-roading, and come equipped with user-friendly hub gears, brakes, mudguards and lights. Quite a tall order, really.

Puky sell a range of fully-equipped 20-inch bikes, and a few 18-inch bikes, but none of the smaller machines have gears.The answer was to upgrade what we had, adding a Sturmey Archer S-RC3 hub to Alexander’s Puky 18-1B, producing, one assumes, an 18-3B. The beauty of using this rare hub is that it also comes with a back-pedal operated ‘coaster’ brake. Fitting something like this might sound complicated, but any competent cycle engineer should be able to upgrade a single-speed or derailleur-geared bike to hub gear operation.

Three-speed hubs used to be almost universal in Britain, but the arrival of cheap, sexy-looking derailleurs changed all that, and enclosed hub gears are now generally confined to roadsters and small-wheeled bikes. As we point out on a regular basis, this is most unfortunate. Few adults understand the principles of riding with close-ratio derailleur gears and for children, three gears are more than enough to think about.

Hub gears can be changed whilst stationary, making them ideal in traffic (or for those of a forgetful disposition at any time) and although the number of gears might sound modest in this number/size obsessed age, even the most basic hub provides a decent gear range. The range – for those who aren’t quite sure – is the difference between top and bottom gear. A wide range of gears enables the bike to nip along under a wide range of circumstances.

With Alexander’s friends acquiring MTBs with five or six derailleur gears, we found ourselves trying to explain that a SRAM, Nexus or Sturmey three-speed offers a gear range of around 180%, which is about the same as a cheap six-speed derailleur.There’s a widespread belief that hubs are less efficient, but a three-speed should return efficiency of 94-95%, a figure that a cheap derailleur would be pushed to achieve after a few weeks’ youthful abuse. It also comes with bullet-proof indexing and is almost immune from throwing its chain off.

Coaster brakes have never really caught on here, but having seen a child grow up using one, we’re converts, and most parents on the Continent would probably agree.When you’re learning to make hand signals and keeping an eye open for traffic, there’s a lot to be said for controlling the primary The coaster hub looks brake with your feet. For as if it was made for dad, there are 33% fewer the bike. Note the ‘extra’ cables to adjust and spoke holes and rather lubricate.We hope you’re avant–garde spoke pattern convinced.

Practice

We won’t bore you with the fitting process – if you know what you’re doing, it’s easy, and if you don’t, we’d recommend visiting a good bike shop. Most of the shops that advertise in A to B can carry out this sort of work, but as usual, the real experts are Bicycle Workshop in Birdy rim will fit the larger 355m (18- West London, who regularly upgrade children’s bikes (and adult cruiser bikes) to this sort of spec. If doing the work yourself, the hub costs £65 with a lever changer, plus £8 for the twistgrip. Expect to add around £35 if the shop does the work for you.

The new hub weighs 400g, so with cables and twistgrip, the weight penalty for upgrading from a single-speed has been about 1kg. Starting with a derailleur, you’ll be removing sprockets, cables, a brake lever and a brake caliper, so the weight will be about the same. Gearing depends on circumstances – we fitted an 18-tooth rear sprocket, giving gears of 26″, 35″ and 47″. Broadly speaking, that’s one gear for the flat, and two hill- climbing options. Bottom gear will tackle 12.5% (1:8), taking care of most of the local hills.

Is the boy pleased with his gears? What boy wouldn’t be pleased with a TSS32 shifter, shiny S-RC3 hub, 178% range, 18-tooth sprocket and a host of other part numbers? At six, life is all about numbers. For Alexander, the back pedal brake is familiar territory of course, but the gears took a few days to get used to. Cycling mileage has since rocketed to about 60 miles a month, and the unusual machine, with its novel lights, rack and gears, seems to be much admired.

You can’t win of course. Alexander knows a thing or two about hubs, and he’s already applying subtle pressure for a five-speed. Sturmey doesn’t make a coaster five-speed, but the indestructible SRAM P5 is available in coaster form…The perfect 20-inch bike?

ENGINEERING NOTES

The Sturmey S-RC3, like most hubs, comes drilled for 36-spokes, but children’s rims – including our rare-in- the-UK 355mm rim – are usually drilled for 20. Its unusual to find 305mm (16-inch) rims drilled for 36-spokes, but a inch) bikes. In the largest 20 and 24-inch sizes, there are plenty of rims and tyres to choose from.To make life difficult, we decided to re-drill the old rim to take 18 spokes, lacing the wheel using alternate spoke holes, braced with a single 13G spoke to prevent the wheel ‘winding up’ under braking.This arrangement would be too frail for an adult bicycle, but for a child weighing 22kg, a new rim and 36-spokes aren’t really necessary. On our single-speed bike, we also needed to stretch the rear drop-outs slightly, but it’s more likely that adjustment would be needed in the other direction on a derailleur bike.