Old mechanism (front) and new (behind). They are effectively identical, except for the longer axle on the new item. Note the old and new locknuts.
Once upon a time the finest hub gears in the world were churned out from a factory in Nottingham, many finding homes in the Raleigh bicycles made just across the Triumph Road.The sad demise of Sturmey Archer in the autumn of 2000 is a subject we’ve returned to many times. For A to B newbies, this healthy company was brought down by a combination of corporate greed and downright stupidity, resulting in Sturmey being handed to a bunch of asset-strippers, who bled the company dry in a few weeks and chucked out a life-less corpse, the remnants being shipped to Taiwan by Sunrace.
One of the biggest potential losers was Brompton, a company with a full order-book for a folding bike designed specifically for the Sturmey 3 and 5-speed hub gears. In the final weeks, some hastily arranged heavy transport brought a reasonable stock of hubs down to London, giving a breathing space for the bikes to be adapted to accept the German/US SRAM hubs.
The excellent 3-speed SRAM worked well, but the 5-speed was much too wide for the bike. Brompton was forced to become a 3-speed manufacturer for a while, until its own 2-speed derailleur entered production in May 2002 and was fitted alongside the SRAM to produce the elegant 2×3-speed L6 and T6 Bromptons.
…the Sturmey 5-speed wasn’t the most reliable of hub gears.. thanks primarily to poor adjustment…
Meanwhile, Sturmey 5-speed spares were running low – a potential problem for the estimated 20,000 5-speed Bromptons, and countless Moultons, Bickertons and Micros in regular use worldwide. Most bikes could be adapted to take a SRAM 5- speed hub, but the Brompton could not. Conversion to 2×3 spec is not viable either, because the parts alone (3- speed SRAM and wheel, rear frame, cables, changer and 2-speed derailleur kit) cost more than the bike is worth.
In early 2001, Sunrace put the Sturmey 3-speed back into production in Taiwan, and things began to look a little brighter. In late 2002 the 5-speed hub returned too, and although very different on the outside, it was almost identical internally to the ‘ball- locking’ hubs fitted to the Brompton in the last year or so of UK production. Not quite identical, but we’ll come to that.
Can this hub – produced three years later, and 10,000 miles from Nottingham – really be fitted to an elderly 5-speed Brompton? It turns out that it can, and for a reasonable cost, new Sunrace-Sturmey ‘internals’ could revitalise your old folder.
It has to be said that the Sturmey 5-speed was not the most reliable of hubs – a fair number of machines losing one or more gears, thanks primarily to poor adjustment, made worse by a rather woolly gear-shift action. Broken axles were relatively common too.
The ‘ball locking’ mechanism was introduced to hold the hub more positively in gear. Ironically, it came into production just a year or so before the company was dragged under, but the tooling and expertise were kept together, and when production restarted in Taiwan, it was natural that the latest system would be used.
Buying the Bits
All the grime will have to be removed. Carefully check the parts for wear - this sprocket is marginal. The thin lock washer and locknut will be re-used
We’re going to describe the process of swapping old-style Sturmey hub internals for Sunrace-Sturmey parts. For the mechanically-minded, it’s all quite straightforward, and the only specialist tool required is a 16mm cone adjusting spanner. If you’re unsure about mechanical bits, contact Sturmey and Brompton specialist, Bicycle Workshop in west London (tel: 0207 229 4850).
Step one is to buy the necessary bits, and once again, unless your local cycle shop is particularly keen and knowledgeable, we recommend Bicycle Workshop.The hub gear internals will cost £70, and the indicator chain £4.50, plus postage, together with a labour cost of about £15 if the shop does the work for you.
Other parts may be needed though. Carefully inspect the inner and outer gear cables, gear shifter and Brompton cable guide. If the action of any parts is sticky or rough, replace ‘em! The same applies to the sprocket and chain. If they were fitted more than a thousand miles ago (always replace these parts together), you will also need a new 13 or 14-tooth sprocket and chain from a Brompton dealer.The new nickel-plated chain works perfectly well, but it must be 1/8″ and not the 3/32″ derailleur-type chain, fitted to the new 6-speed bikes.
Getting Started
Removing the right-hand bearing cone. The next step is to unscrew the internals from the other end
You’ll need to remove the rear wheel, and as we delight in saying, if that proves tricky, this might be the stage to hand over to an expert.With the wheel off, thoroughly wire brush both the sprocket assembly and associated (right-hand) cone and locknuts. Repeat this operation for the opposite, left-hand bits and pieces too. It’s essential that grit doesn’t find its way into the hub, and you’ll be re-using these locknuts.
Screw the new internal assembly into the shell and tighten. Note the old locknut and lock washer.
When the hub is reasonably clean, mount the wheel in a vice and remove the sprocket assembly, right-hand locknut and thin lock washer, putting the parts carefully aside in the order in which they were removed. Remount the wheel in the vice and remove the left-hand locknut and bearing cone.
You’re now ready to spin the internals out of the hub shell. If you don’t have the special ‘C’ spanner, and a hammer and punch fails to shift the ring, clamp the assembly in a vice and spin the wheel anti-clockwise.
Final adjustment to the left-hand bearing using the cone spanner
With the old internals removed, carefully inspect the inside of the shell for foreign bodies, rust or signs of water damage. If all’s well the new unit can be screwed straight in and tightened with a hammer and punch. If not, the shell will have to be carefully degreased, cleaned and regreased – tedious, but very necessary.
You will now be in a position to screw on the left-hand bearing cone and the old thinner locknut. On the right (sprocket) side, carefully hold the bearing cone and spin off the right-hand locknut without disturbing the cone. If the adjustment is upset, the cone should be hand-tightened and backed off half a turn before being locked in place. Finally, put back the dust shield, spacer and sprocket, checking sure that the circlip beds down correctly in its slot.
…the most common cause of failure is misassembly following roadside repairs…
With the axle back in the vice, it’s time to adjust the bearings.The sprocket is an important part of the adjustment process, because the left cone should be tightened until (quoting Sturmey) there is ‘minimum’ free play at the wheel rim, but noticeable play at the sprocket, with no tightness or roughness. Lateral rocking of the sprocket looks alarming, but it’s quite normal.When satisfied with the adjustment, hold the cone nut steady and tighten the locknut. Don’t spend hours fiddling – it will need checking after a few weeks riding anyway.
The hub should now look exactly the same as the old one, but with a longer axle stub on the left-hand side.Again, this looks alarming, but it has no harmful effect. If you really want to, you can angle-grind this (very hard) axle back, but we wouldn’t recommend it.
Sturmey produced a special short axle hub for the Brompton, but the difference is merely cosmetic.The only other Brompton-specific parts are the thinner locknuts and right-hand washer that just enable the 5-speed hub to squeeze into the Brompton’s narrow frame drop-out.
Assembly details. Note that the gear selector guide is followed by the lock washer and nut. The gear selector guide must point directly at the cable guide roller on the rear frame
It’s now time to refit the wheel to the bike, taking great care that the stepped anti- rotation washers sit comfortably in the drop-outs, and that the gear selector guide support (the washer with a funny bent bit sticking out), is followed by the lock washer and hub nut.The most common cause of 5-speed failures is misassembly following a roadside puncture repair, so do take care to get it right, or you could damage £75 worth of shiny new bits.The tab on the guide support is easily bent – it should stand at 90 degrees to the washer face – and the tab must point towards the cable guide roller assembly. If any of these parts are loose or poorly aligned, the gear cable will stick or wiggle around, causing missed gears. Finally, fit a new ‘blue’ ball- locking gear indicator rod, and refit the tensioner and chain.
Final adjustment
Adjustment is critical and needs to be carried out in second gear.You can either use a mirror to observe the blue band on the indicator rod, or very carefully turn the bike upside down, taking care not to move the gear shift.What you must never do is adjust the cable with the bike partially folded, which will give a completely false reading. In 2nd gear, the blue band should be entirely visible, but only just, if that makes any sense. As with the hub bearings, it’s a good idea to reset the adjuster after a few rides.
Upgrades with new parts can be unpredictable, but our conversion worked perfectly, and yours should too.With careful adjustment and maintenance, the revamped Sturmey hub should last for many years and revitalise a tired Brompton.
Bicycle Workshop tel 0207 229 4850 . Brompton tel 0208 323 8484
