Sturmey Archer drum brakes

It is almost two years since I got the front hub I am currently using on the DL-1. In that time, it has been built into two different sizes of wheel and used on two different bikes (originally bought for use on the Kona Africa Bike) and probably done around 5,000 km in all weather. In all that time, I never actually got around to exchanging the V-brake lever I had been using it with for the proper type of lever (a cantilever-type one), until now.

I found a pair of Sturmey Archer drum brake levers on eBay for a decent price, so I decided I would indulge myself with some improved braking performance. The new levers improve the modulation of braking, whilst allowing very strong braking to be performed without extremely hard pulling of the lever. The only reason I put up with the wrong type of lever for so long is that I have relatively strong hands, so I was still able to get the braking power I needed just by squeezing extra hard. The new levers male hard braking much easier, whilst giving a slight performance boost over the old ones. They are also fairly aesthetically appealing, and  I would recommend them to anyone with drum, roller, caliper or cantilever brakes.

The only problem with the new levers was that I found the front drum started to lock-on after very hard braking. After first checking that cable-freeze wasn't the cause of the problem, I decided that I should take a look inside the front drum. Sturmey Archer drum brakes are mechanically very simple and easy to work on (although they generally require little in the way of maintenance). Disassembly is straightforward:

Intact wheel

Removed locknut

Removed spacer

Brake mechanism slides out from drum

Brake mechanism (top)

Brake mechanism (underside), showing the brake shoes

After cleaning the brake dust from inside the drum and re-assembling it all, I took the bike out for a test ride. The front brake is as powerful as it ever was after almost two years of heavy use and no-longer locks-on after very hard braking. This is the only maintenance (or real cleaning) I have done to it in that whole time. I feel that it is a real shame that drum brakes are not more popular, especially when I think back to all the time I've spent adjusting and maintaining other types of bicycle brakes during the time I have been using this one, both on my own bikes and those of friends and family.

Re-gearing the DL-1

After lowering the gearing on the Brompton in December, I found the bike much easier and much more enjoyable to ride. The downside of this was that the gearing on the DL-1 now seemed to be ridiculously high by comparison. Whilst I had lowered the gearing on the DL-1 when I first purchased it, by replacing the rear sprocket, the stock gearing was obscenely high and this reduction never really felt like enough. Whilst an even larger sprocket could have been substituted on the rear, the reduction in gearing this would have brought would be limited; the current sprocket is a 21-tooth, and I believe they only go up to 24-tooth sprockets for this type of hub. Add to that the spatial constraint imposed by the chaincase and the only option left was to replace the chainset.

The chaincase made finding a replacement chainset difficult, due to the problems with crank arm clearance. There didn't seem to be a lot of information out there online, so I took the plunge and bought a Stronglight chainset which looked like it might fit. It quickly became obvious that it would not fit, and so this became the chainset I used on the Brompton instead. Eventually I spotted a promising looking chainset on David Hembrow's shop and asked him about the dimensions. Reasonably convinced I could make it fit, I ordered the chainset and it arrived last week.

The new chainset is a 38-tooth, replacing the original 46-tooth one. It sits within the confines of the steel chaincase pretty well, although the chainset cover had to be modified with a metal file.

The chainset cover is basically a paint-tin lid with a hole in it to accommodate the crank arm and a removable plate to allow it to pass over the pedal. The base of the new crank arm is slightly thicker than the original one, so it had to be filed a bit to accommodate it

The filing is a bit rough, but functional. It doesn't look this bad when fitted to the bike. The result is much the same as it was with the Brompton, the bike is generally much easier and much more enjoyable to ride. Whilst I did use the highest gear occasionally, oddly enough I do not find myself missing it.

I also attempted to switch the left crank so that the left and right would match, however the left crank is stuck on so well that it broke my crank puller tool. The tool was originally part of my Edinburgh Bicycle Co-operative cycle tool kit, many of the tools from which have since broken through normal use. Needless to say, I would not recommend. Until I get a replacement, it appears I am stuck with odd cranks.

Sturmey Archer recommend that you use at least a 2:1 ratio for the number of teeth on the chainring relative to the sprocket. With this modification, I have gone below that minimum, to around 1.8:1. Whilst not officially recommended, I expect this will not cause any problems. It is likely that the 2:1 ratio is erring on the side of caution, and combined with the large wheels of the DL-1, I expect that I will not be pushing the hub beyond what it can take. The new smaller chainset will prove beneficial when I eventually realise my dream of re-building the rear wheel around an eight-speed hub to increase the useful range of the bike sometime in the future.

Re-gearing the Brompton

Second-hand bikes can be a great way to get a good bike at a more affordable price. The downside is that you  get a bike which has been set-up according to the preferences of its previous owner. When I purchased the Brompton back in February, it had been set-up with obscenely high gearing, a 50-tooth chain-ring with a 13-tooth rear sprocket. With the Sturmey Archer S-RF3 rear hub, this gave gears with 3.7, 4.9 & 6.6 metres development respectively. I put up with this for a long time because although it was much too high, it still worked. Eventually, the stresses to the sprocket and chain from starting from stationary in such a high gear were too much, and the chain would no-longer mesh with the chain-ring.

Not having a 24mm socket to remove the left-hand folding pedal, I had a look at the official Brompton chainsets which would allow me to leave my existing left crank in place without a major mismatch. Needless to say, they were excessively expensive. Instead, I was fortunate enough to find a Stronglight chainset which, online at least, looked similar enough to the Brompton one for me to get away with leaving the original left crank in place.

The unused Stronglight left crank, with the original Brompton one. They could almost have been separated at birth.

The fitted Stronglight chainset with the Brompton original below, again they are very similar looking indeed. I also replaced the rear sprocket and chain, resulting in 42 teeth at the front and 14 teeth at the back. This produces 2.9, 3.8 & 5.1 metres development, respectively. This means the Brompton can now much more easily climb hills and accelerate from stationary without busting my knees. It may not be a very flashy upgrade but it makes a significant difference to how useful the bike is. If your gears are too high (or low) don't suffer in silence, do something about it. It can make the difference between a bike you merely tolerate riding in certain circumstances to one you actively want to use.

Raleigh Twenty Stowaway

The Sturmey Archer AW hub which was used for the pictures taken to make the hub servicing guide which formed my last post was from this Raleigh Twenty Stowaway; the folding version of the classic Raleigh Twenty. This Twenty belonged to a friend of mine and I was servicing the hub before selling it on her behalf. Prior to servicing the hub, I had done just about every conceivable bit of maintenance on this bike including front wheel, headset and bottom bracket bearings, a complete disassembling, cleaning, greasing and reassembling and replacement of the tyres, tubes, chain and saddle. As a result of this, the bike rides just like a brand new bike, despite being from 1976.

Raleigh used the 'Stowaway' branding on some of their folding Twentys (in addition to several unrelated models).

The main hinge in the frame is perhaps inelegant but very sturdy.

Difficult to see on the picture, but the rear reflector is branded as Sturmey Archer.

Pletscher rear rack, complete with a rat-trap for carrying a newspaper.

Sturmey Archer AW hub, as featured previously.

The original Sturmey Archer grip shifter, controlled by rotating the entire grip to switch gears. In practice it works better than I expected.

Raleigh Twenty 'R-20' branding.

Seat-tube decal.

'The Raleigh' Nottingham headbadge.

Brand new Raleigh Record tyres, as originally specified with the bike.

The Raleigh Twenty design has undoubtedly passed the test of time. It is a shame that the equivalent models subsequently made by Raleigh have failed to match the comfort, handling and practicality of this model. Clones of the Twenty do exist, although they have their drawbacks including price and the use of V-brakes on the UK model. There is nothing to stop Raleigh bringing back the Twenty properly, a good, small utility bike could be a good addition to their range. A few concessions to modern manufacturing techniques and componentry could be made, such as a welded frame (rather than brazed) a unicrown fork (rather than lugged). These minor sacrifices could easily be offset by a few improvements, such as dual pivot caliper brakes (or drum/coaster brakes), 406 mm aluminium rims (allowing a greater choice of tyres and the ability to stop during rain) and a proper headset (rather than a nylon bushing at the top of the head-tube).

After courting the 'sporting goods' and 'bicycle shaped object' markets extensively for the past few decades, perhaps it's time for Raleigh to look back on one of the models which once made them great, and bring it back.

Servicing a Sturmey Archer AW hub

The Sturmey Archer AW hub is 75 years old this year. The reliability of this design means that there are plenty of these hubs still in service. The ease of serviceability of this design means that returning one of these hubs to its former glory isn't all that difficult. Many minor issues such as resistance to freewheeling, hub seizure, general resistance to rolling and problems accessing certain gears can be fixed by taking the hub apart, cleaning the internals and re-assembling it all with some fresh grease.

Whilst I have written about working on an AW hub previously, the nature of the work means that it is difficult to take pictures whilst cleaning and re-assembling the hub. Thankfully, this time I was able to get a little help with taking pictures. To open up an AW hub (and most other Sturmey Archer hub gears) remove the left-hand (non-drive side) locknut and cone and uncrew the right-hand ball ring using a hammer and a flat screwdriver on the semi-circular cut outs of the ball ring (these are not rounded on the older versions of the AW). This should let you get the internals out, axle and all. This can be further disassembled by removing the right-hand locknut and cone, which allows the rest of the hub mechanism to be taken apart.

One of the notches for unscrewing the right-hand ball ring

Left to right: The left-hand axle nut, non-turn washer, locknut, spacer and cone

Left to right (top): right axle nuts (later integrated into a single piece), non-turn washer, locknut, cone lockwasher & cone. Middle: cone. Bottom: indicator rod (with indicator rod locknut seen above the locknut)

Left to right (top): Dust cap, sprocket snap-ring. Bottom: spacers. Assembled as: Dust cap, spacer, sprocket, spacer, snap-ring.

The driver assembly and clutch spring

Gear ring (left) and right-hand ball ring (right)

Left to right: clutch sleeve, clutch, axle key and thrust ring

Top: Axle (including sun pinion). Bottom (left-to right): Planet-cage, 4 planet pinions (cogs) and 4 pinion pins.

The low-gear pawls in the planet-cage can also be removed if necessary, although when removing these be sure not to lose the tiny pawl springs in the process. The same also goes for the pawls in the gear ring.

Once all this has been disassembled, a good cleaning with some degreaser and a cloth or paper towel should restore the hub to its former glory. Particularly dirty or rusty parts can be soaked overnight or cleaned with wire wool (just make sure to remove any left-over bits of wire wool before re-assembling the hub).

To re-assemble the gear mechanism, hold the axle vertically with the drive-side pointing up (axle hole above the sun pinion).

Add the planet pinions and the pinion pins back into the planet cage and place the assembly over the top of the axle with the planets at the top.

Add a dab of Sturmey Archer hub gear grease to the planet pinions and rotate the planet cage assembly around the axle a few times to distribute the grease around.

Place the clutch sleeve over the axle and line up the hole in the sleeve with the hole in the axle.

Place the clutch over the axle and the clutch sleeve.

Slide the axle key through the hole in the clutch sleeve and axle, with the threaded hole in the axle key lined up with the centre of the axle.

Slide the thrust ring over the axle key and clutch, lining up the grooves in the thrust ring with the protruding parts of the axle key.

Place the gear ring over the planet cage assembly and clutch assembly, being sure to line up the grooves inside the gear ring with the planet pinions.

Place the right-hand ball ring over the gear ring.

Add some lithium grease to the ball bearings within the ball ring (ideally more neatly than this).

Place the clutch spring over the axle, ensuring the plastic (or metal) ringed-end of the spring pointing upwards.

Place the driver over the axle. The clutch spring will push against the driver until the right-hand cone is added to hold the driver in place.

Add lithium grease the the ball bearings in the driver assembly and screw the right-hand cone onto the axle as with any other cup-and-cone bearing system.

Add the cone lockwasher and locknut.

Add lithium grease to the left-hand bearings.

Add the left-hand cone, spacer and locknut.

On the right-hand side, add the dust-cap, a spacer, sprocket, another spacer and snap ring to the end of the driver assembly.

The wheel may be bolted back into the frame, the indicator rod screwed back into the axle key and to the gear cable and the hub is ready to be tested. With any luck, the hub should perform just fine for another couple of decades. The 'no intermediate gear' (NIG) versions of the hub, such as the current AW hub, the S-RF3 and the gear mechanism in the X-RD3 are fairly similar to this, with minor changes to the clutch assembly and the driver, which has its own pawls in this version. There have also been numerous small revisions throughout the run of the original AW hub, although they should pose little trouble when using this guide as reference. The best advice I can give anyone who wishes to service one of these hubs is to just go for it; when disassembled the hub really isn't as daunting as it may appear from reading this guide (or similar guides).