Inside the Brompton Wide Range (BWR) Hub

It has been quite a while since I have written anything technical about bikes. This is largely a result of the fact that for the first time since I started cycling again as an adult I have been relatively happy with my bikes and their configurations, which has left me free of my usual desire to acquire shiny new bicycle parts. However, this state of relative satisfaction with the bikes does not mean that things don’t occasionally wear out or break. Last week  I noticed a familiar clicking sound coming from the rear hub of the Brompton.

I have written previously in reasonable detail about the Servicing the Sturmey Archer AW hub. The BWR hub used in the six-speed Bromptons is also a three speed hub gear made by Sturmey Archer, so I thought I would show how the BWR compares to the pictures I took of the 1976 AW hub for the aforementioned post.

The planet cage differs significantly between the old AW hub and the BWR. The planet cage on the AW sits on top (drive side) of the sun pinion and can be simply lifted off during disassembly. This is also the case with the new AW and S-RF3 hubs without the ‘intermediate gear’ (sometimes referred to as NIG versions). The BWR differs in that the planet cage is split into two pieces, the bottom of which slides on from the bottom (non-drive side) and the top slides on from the top (drive side) and is fixed onto the bottom piece with the 4 M3 cap head screws shown in the picture above. The result of this is that the planet cage is stuck on the sun pinion. I decided not to disassemble to two-part planet cage as the first screw I tried to loosen was very stiff and it didn’t seem worth risking snapping the screw for this job. The low gear pawls seen at the bottom of the planet cage on the BWR are similar to those on the NIG AW and S-RF3 hubs (which are also retained with a circlip). These pawls are what produces the characteristic ‘tick-tick-tick’ of Sturmey Archer three speeds in their second and third gears.

The planets of the BWR have 12 teeth and revolve around a 34-tooth sun pinion, which produces wider-spaced gearing than the AW which has 20-tooth planet and 20 tooth sun pinion. These smaller planets require smaller pins than the standard range three-speed hub.

The clutch of the BWR differs noticeably from that of the old AW, but is the same as in the NIG AW and S-RF3 hubs. The axle key is fitted in the slot underneath the clutch in this shot (not fitted in the picture of the AW) and is also the same as in the new standard range hubs.

The gear ring has 60 teeth in the old AW, new NIG hubs and BWR. The differences between the 1976 AW hub and the BWR shown are largely superficial. The easily lost wire pawl springs are still used in the BWR gear ring. The gear ring pawls are disengaged in first gear, which is why there is no characteristic ‘tick-tick-tick’ sound.

The ball ring is another part which has changed little between the old AW and BWR shown. The only major difference appears to be the addition of two extra notches for removing the hub internals using a C-spanner or hammer and punch. The AW ball ring has a metal dust/bearing retaining cap which has been replaced in the more modern hubs with a plastic retaining ring for the ball bearings.

Here we can see the difference between the driver of the old AW hub and that of the BWR. Whilst the AW is designed to take a single three-splined sprocket, the BWR is designed to take a pair of Shimano-style nine-splined sprockets. Like the clutch, the internal portion of the driver was changed between the old AW and the new NIG AW, S-RF3 and BWR in order to fix the issue of the ‘intermediate gear.’ Other than being extended and having a different spline pattern for the two-speed cassette, the BWR driver is the same as that used in the NIG AW and S-RF3.

Aside for the problem of water ingress, the driver was where I found the source of the problem I was having with the BWR hub; the bearing surfaces on the driver and cone nut had some pitting on them. This is an issue I have had with every variant of the Sturmey Archer NIG three-speed hub, but oddly never the old AW. This does not seem to be a problem which afflicts other people with the same frequency and may be a result of the way I ride or the conditions my bikes are subjected to.

Thankfully in the past I have been able to order a replacement driver from SJS Cycles (who stock a great range of Sturmey Archer hub spares) but I could not find the BWR driver  (Sturmey Archer part number: HSA800) on their site. I emailed SJS to enquire about this part and was told that Brompton only issue them for service, in order to be supplied with a replacement driver from Brompton you need to send the old one back to them. I was quite surprised by this; as my primary means of transportation I can’t afford to have my Brompton out of action for the sort of time required to perform such an exchange. If I lived somewhere with a Brompton dealer who did Brompton servicing in a meaningful way (i.e. not Chester) perhaps there would be a better way of doing this, but here in Chester I would have to go through The Bike Factory who do not keep Brompton spares in stock.

I am not sure why Brompton has chosen to restrict the supply of BWR replacement parts. Outside of a big city with a selection of Brompton dealers, in order to be able to depend on a bicycle with this hub there needs to be a supply of spare parts available. I doubt that Brompton are selling the BWR driver at a loss, so even if some of them went to tinkerers and enthusiasts (e.g. turning a S-RF5 into a ten-speed on a Brompton) it would not be detrimental to their business. It is a truly baffling move by Brompton which serves only to make the BWR a less viable option for people like me. Whilst decades-old AW hubs still have spare parts readily available, I am not sure that I will be able to fix this BWR hub up as easily as the 36 year-old AW shown in the pictures above, and that leaves me a bit disappointed in Brompton.

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After the gritting

The recent snow and the resulting gritting had not been kind to the Brompton and I had not properly cleaned the bike since just before the Japan trip. After the snow melt the original chain and sprockets which came with the bike were in need of some attention. The 2-speed and BWR 6-speed Bromptons use Shimano cassette splined cogs (the SRAM 6-speed uses standard 3-spline sprockets) which have an asymmetrical pattern preventing the sprockets from being reversed when worn.

When worn beyond a certain point, it is necessary to replace the chain and sprockets together, although I started the job under the impression that the sprockets on the BWR hub would be reversible like on the other hub gears I’ve used. This problem was confounded by the fact that the replacement 16/13 tooth sprocket set was out of stock everywhere which didn’t have extortionate delivery rates and Chester’s only Brompton seller doesn’t stock spares, “We can order that in for you though.”

Whilst waiting for my sprocket set to arrive, I decided to try some cheap, reversible cassette-splined single speed sprockets. Whilst these were full-groove sprockets which were not designed for derailing, older hybrid gearing systems like Cyclo and Dacon encouraged me to try. Suffice to say, 16-to-13 shifts do not work with the Brompton’s rather basic 2-speed derailleur, but at least I have the parts needed to run the bike as a 3-speed should there be future shortages of the necessary replacement sprockets. 

Original sprockets on the left, basic 3/32″ single speed sprockets on the right.

Whilst the 13-tooth sprocket looks like it would probably work in combination with a Brompton 16-tooth sprocket, but in the end when I received the larger Brompton ‘official’ sprocket it did not. Somehow, it seems the gap between the two sprockets seems oddly too small for the chain to stay on the smaller sprocket.

The sprocket incompatibility was discovered because the 13-tooth Brompton sprocket I eventually received was a three-spline type for use with most other types of hub gear. Subsequent tests also revealed that the 13-tooth sprocket contained up to 60% horse meat. I emailed the supplier (SJS) and was informed that the item was out of stock and that it “was not possible” to remove the sprocket I needed from one of the kits allowing the BWR to be run as a three-speed (which showed up in stock) and replace it at a later date. Instead I was offered a 12-tooth sprocket as a stop-gap and the 13-tooth sprocket would be forwarded on in a few weeks when the stock shortage was sorted. The 12-tooth sprocket works fine, although the gear steps are a bit uneven.

The rear brake pads also required a bit of attention. When I got the new Brompton I changed the front brake pads for Kool Stop salmon pads but left the rear ones as stock. These have since worn out, so I replaced them with a set of Kool Stop pads ordered with the Axa bottle dynamo. When these were delivered, the box turned out to be two pairs of pads and one set of shoes, which has left me with a spare set of brake shoes and pads to fit to Ms C’s Brompton, which still has the old style so\ingle pivot caliper on the back.

The last round of replacement parts was the telescopic seat-post. This part has improved the experience of riding the Brompton, but at less than 1 year old I am quite disappointed by the significant loss of the chroming on the lower tube and the fragmenting of the plastic upper sleeve which is not available as a separate replacement part (instead it comes bundled with the lower part of the seat-post). In time I will try to patch up the original lower seat-post (stay tuned) but for now I have ordered a replacement lower part of the telescopic seat-post which should solve the issues for a while.

The chrome layer flaking off inside the tube too.

Finally, I decided to take advantage of the fact that I was working on the Brompton to do some rust-prevention on the frame, by spraying Waxoyl into the tubes of the rear frame, main frame and the stem. Waxoyl is spray which leaves a flexible waxy layer over the inside of the frame tubes when dry, designed to get rid of existing rust and prevent any further rusting. I had considered doing this when the bike was new, but at the time it was summer and rust-prevention didn’t seem such a pressing matter. Until it dries, this stuff flows inside the tubes, so it is best to spray roughly parallel tubes and keep them fairly level until the foam dries, before moving on to other tubes. I avoided spraying the seat-tube as the waxy layer left behind would likely lead to significant seat-post slippage. I’ll get around to the head-tube and fork when I have to do some work on the headset. Some of it ended up on the chain and seems to be quite good as a ‘dry’ chain lubricant.

Brompton by air

I decided to try another type of multi-mode travel with the Brompton; bicycle and aeroplane. My existing suitcase is not wide enough to accommodate the Brompton, so after a bit of research on Seven League Boots I decided to opt for the Carradice Folding Bike Case.

Unlike their  excellent saddlebags, the Carradice Folding Bike Case (more of a bag than a case, really) is made from Cordura-type polyester material rather than cotton duck. Whilst I am a fan of cotton duck, the extra weight it would require would not be desirable when using this bag for air travel. However, considering the material used, I feel that this bag is a bit over-priced.

The bag came with no padding, but thankfully it does adhere to gaffer tape quite well, making these stiff foam pieces ideal for protecting the rollers/rack in transit.

The bag is more than sufficiently large to fit any Brompton with a saddle attached, although configurations which differ significantly from stock may not fit. The Seven League Boots post suggested removing the saddle when using the bag for flying due to the risk of damage (particularly to a Brooks saddle) and storing it between the wheels of the folded Brompton. I use the telescopic seat-post, so I will turn the telescoping part of the post around to minimise the number and size of protrusions from the folded package, with the remaining protrusions covered over with bits of foam.

Naturally I removed the clamps from the frame as these were an easy target for damage. I wrapped the clamps up in gaffer tape and stuck them to the frame in the middle of the fold.

As recommended in the Seven League Boots post mentioned before, I taped the saddle into the relatively well protected space in the middle of the folded bike

A D-lock can be locked through the frame to save space, with the gap in the middle of the fold useful for stashing bits like a locking cable. The frame from my T-bag is pushed down the side of the bike in the bag to offer a bit of extra protection as well as making the T-bag itself a less conspicuous, odd-looking piece of hand luggage.

 

The final step in packing the bag is to place your trousers, jumpers, jackets etc into a standard suit bag and wrap it over the top and sides of the bike before zipping it up. This gives a bit more protection to the bike and also means that you don’t use up your entire luggage allowance on a bike. A toiletries bag can easily be seated on top of the folded bike underneath the suit bag.

Add a couple of luggage straps and pack your hand luggage into the frame-less T-bag and you are ready to fly across the world. I’ve unpacked the Brompton at the other end and rather pleasingly, it has faired well. Now all I need to do is get to grips with cycling in a strange new land.

B&M Toplight Line Plus Braketec rear light

For a while now I’ve had my eye on the B&M Toplight Line Plus with Braketec. The standard Line Plus uses a pair of LEDs and some clever optics to produce a line of red light rather than just two spots. The logic behind this is that diffusing the light into a line makes it easier for following traffic to judge the distance of the light, whilst also being less likely to irritate those following.

The Braketec version of the light also features a signal processor which detects the change in the dynamo AC frequency when the bike slows rapidly, momentarily increasing the brightness of the light to indicate the rider is braking. Whilst I have my doubts about the usefulness of turning signal lights for bicycles, I expect that a brake light will at least be correctly registered by following motorists despite the relative rarity of brake lights on bicycles. However, the main reason for wanting to try this light out are not because of the potential minor safety benefits which come from the brake light function, but because it is quite a clever idea, executed in an interesting way.

The light is bright, although the rack mounting on the Brompton makes for rather poor side visibility. Thankfully this is made up for by the reasonable side visibility of the front light an the reflective sidewalls of the Marathon Plus tyres. The brake light function works without any calibration required, regardless of whether you are using a hub dynamo with large wheels, small wheels or a bottle dynamo. It just works.

The effect is pretty clear in the video, but viewed by the human eye rather than through a digital camera it is much more pronounced.

Brompton rear frame replacement

Ms C’s twelve year old black Brompton L5 has a rusted-through chainstay-bridge. Combined with the twelve year old hinge, this had led to a fair amount of left-right movement in the frame. Whilst still rideable, it seemed like the sort of thing which should be taken care of sooner rather than later.

I had toyed with the idea of getting the existing rear frame repaired, but considering the cost of a brand new Brompton rear frame, the latter seemed like a better option. It also provided the opportunity to bring the back end of the bike up to the current spec, allowing the use of a Brompton six-speed set-up in the future if desired. An entirely new frame also offered the possibility of a different coloured rear frame, which would set the bike apart from the crowd due to Brompton’s policy of using the same paint colour on the rear frame, fork and stem.

The rear frame comes with almost everything you need, non-turn washers, hinge spindle and countersink socket head screws, except for the brass bushes. Whilst these may not need replacing on a less-worn machine (where the rear frame is broken but the hinge is fine), it is still irritating to have to buy an entire rear hinge kit just to get these brass bushes. It would definitely be appreciated if Brompton started including these as a part of the rear frame replacement kit, or at least made them available separately.

The rear frame comes with non-turn washers for both Sturmey-Archer and SRAM hubs.

Replacing the rear hinge requires a special 3/8 inch reamer (shown in this picture guide) which has a pilot section to ensure that the brass bushes are reamed in the same and correct plane. However, this special reamer costs around £200. For the first time in a decade, I was seriously considering getting this job done at a bike shop. I even got a quote for the job and parts from Bicycle Doctor, but thankfully I came across these instructions showing how to do the job with a conventional (cheap) 3/8 inch reamer. Still, this is not an easy or quick job and if you value your time, it might be worth getting it done at the bike shop.

Thankfully, my time is worthless, so I did it myself. The bolts which fix the rear frame to the main frame via the hinge spindle are fastened with a torque wrench in the factory, and held in place with a liberal quantity of thread-locker. The trick to getting these bolts to loosen up is to heat the area up with a hairdryer or heat gun, which weakens the grip of the thread-locker a bit. Once one of them starts to give, tighten it up again, heat the other side up and loosen that off whilst holding the other bolt in place. This may not always work, one bolt might remain stuck in the frame at which point a bit of drilling is required.

The chainset needs taking off to access the rear hinge bolts

Once the bolts are out, the rear frame can be detached and the hinge spindle should slide out relatively easily. The brass bushes are pressed into the frame pretty tight, with no protrusions which would help remove them. Thankfully brass isn’t all that hard and seeing as we aren’t interested in keeping the old bushes, they can be forcibly removed by winding in a 13/32 inch tap and knocking it out with a hammer. I didn’t fancy buying an obscure imperial-sized tap and so decided (after trying to bash the bushes out from the inside using a screwdriver) to file away what remained of the original bushes. This was probably a bad idea, but on this fairly old frame it actually worked out rather well, which will be explained in more detail later.

The new brass bushes can be press fitted with a quick-release skewer from a front wheel or a piece of suitably sized studding and some washers & nuts. I used the (non-QR) skewer from the Brompton dynamo front wheel. The first attempt didn’t go well and the bush started to bend, but thankfully I managed to repair the damage with pliers and it went in (after a bit more filing) on the second try.

Once removed, the damage to the old rear frame was even more obvious

Next comes the tricky bit, reaming the bushes without the special (and expensive) Brompton-specific reamer. The bushes are brass on the outside and some sort of yellow plastic-like material on the inside. The above linked guide suggests that it is important to not remove too much material, but I had to remove what seemed like rather a lot of material. Eventually I put the reamer in a battery drill, which helped to keep it straight. The reamer I used (made by Dormer) was just long enough to remove material from both of the fitted bushes at once, which kept the holes in the bushes in the same plane (the intention behind the design of the Brompton-specific reamer).

On a frame of this age, it is possible that even after replacing the hinge, there will still be some play in the new hinge. Thankfully, my cheapness in wanting to avoid buying a 13/32 inch tap, I may have inadvertently stumbled on a work-around for this. By filing away most of the old bushes instead of fully removing them, I had effectively left a brass shim in place in the frame which allowed the new bushes to be fitted with less play.

About halfway through the reaming process

The new rear frame decked out with the old parts

The new rear frame was bolted on with minimal fuss. Ideally the bolts should be held in place with Loctite 243, but I used Loctite 271 as it was al I had to hand. I will probably regret it if I have to do a subsequent replacement in the future.

Sadly, by this point I had noticed that the rim on the rear wheel had worn to the point of cracking and would not be safe to put back in service. I ordered a new rim and spoke set so that the 4/5 speed hub could be re-built before the bike was fully re-assembled. The old spokes and nipples were a bit past it, and I didn’t want to get 90% of the way through building the wheel just to have a spoke snap or for the threads to strip.

Once the rear wheel was re-built with new spokes and a new rim, the bike was put back together with relative ease. I am told it rides much better now.

Brompton P6R Impressions

On Saturday I was fortunate enough to finally pick up the Brompton I ordered way back in May. When I spoke to staff at Harry Hall Cycles in Manchester, when looking for a P-type to test ride I was told that only around 0.5% of Bromptons sold by them were P-types, with the vast majority being the M-type. Even the S-type is more popular. Undeterred I ordered a P6R without having tried one (as conversion between types is possible). Now I’ve had a few outings on the bike, I thought I’d share some of my first impressions about the differences between the P6R and my old M3L.

P Handlebar:

Before riding the bike, I had read in several places that the P-type handlebar was very flexy, to the point where some riders felt unsafe. Thankfully, this turned out to be a massive exaggeration (or perhaps something which has been addressed since those comments were being made) as the P-type bar feels very sturdy, even more so than my c. 2009 M-type (but not quite as much as Ms C’s 2000 L5). The effective ‘cockpit’ is smaller than on the M, but this suits my riding quite well, as I often ended up riding on the ‘hoods’ of the M-type. The shorter brake levers seem to work just as well as the longer ones used on the M-type. I have not had much cause to use the lower position yet, and being equivalent height to the bar on the S-type I expect I will only use it when cycling into the wind out up a long hill. Thankfully the P-type seems to offer the advantages of the M and S-type bars in one, without the disadvantages of the S (no overstuffed T-bag, aggressive riding posture, looking a bit hipster). I imagine it won’t be long until I rip a few chunks out of the foam grips on the sides of the P-bar, but thankfully I could easily replace it with bar tape.

Rack:

The main reason I opted for the rack is to increase the stability of the folded package, with the option for spillover capacity capacity for camping etc being desirable too. Obviously the height of the track makes it next to useless for panniers, but there is potential for attaching extra stuff to the top using the included bungees. I added the ‘Eazy Wheels’ a few hours after getting the bike, in order to make the folded bike easier to wheel along. If fitting these yourself it is important to resist to urge to fit the wheels symmetrically, as this will make the folded bike less stable. Just follow the instructions and you’ll be fine.

Dynamo Lights:

Yes I know, I already had dynamo lights on the M3L. The idea behind specifying dynamo lights was that it was an affordable way to get a dynamo wheel and light set for Ms C’s L5 Brompton (M5R in new money). The new dynamo wheel had the locknuts overtightened and the wheel did not spin as freely as the old one. It only required a quick adjustment but for someone new to dynamo hubs it might be perceived as normal drag. The included rear light is the same Spanninga-manufactured one I already had which includes the stand-light, but the front light was the bottom-of-the-range Lumotec halogen which does not have a stand-light. It is still an improvement on the battery-powered affair she was using before, but come winter it might be worth getting something better.

The factory cables routing uses tubing which is mostly run alongside an adjacent brake cable and it is generally more elegant than my ‘wrapping-around-brake-cables’ approach. A word of advice for anyone who is thinking of doing the same thing as me and hoping to do a quick front-light switch; the rear light connects to the front light via one blade & receptacle connection on the front lamps and one ring crimp at the mount, rather than two blade and receptacle crimps as with most higher-quality lamps. Re-using the factory wiring for the rear light with as new front lamp will require removing the ring crimp, stripping some wire and feeding it through the hole in the blade connector (ideally sealed up with some heat-shrink or at least electrical tape).

Gearing:

The M3L had a Sturmey Archer S-RF3 which, once the stock gearing was lowered was pretty good. The P6R comes with the Sturmey Archer BWR hub which is a three-speed hub with wider steps between gears than the S-RF3/AW. This hub also differs from the S-RF3 by having a differently-splined driver than other Sturmey three-speeds in order to accept an additional sprocket, which is coupled to Brompton’s 2-speed dérailleur. These are combined into a hybrid gearing system which uses the dérailleur to produce an additional step between each of the three gears, the result of which is six well-spaced gears. However this comes at a price, every other shift is a double hub & dérailleur shift. Whilst this sounds like a lot of hassle, in practice you will likely skip some of the gears out in normal operation, whilst appreciating having the option there should you need them.

The range of the current six speed set-up is pretty good, with the fist gear being slightly lower than first gear on the M3L after I lowered the gearing. However, I may still lower the front chain-ring to around 46t in the near future. I opted not to go for the lowered gearing option when buying the bike as it cost an additional £15 for a substitution, whereas an equivalent Stronglight set would only cost £20 and leave me with the original Brompton part as spares/eBay fodder.

Other differences:

Both pedals have been redesigned since my M3L was made. The result is that they more closely match aesthetically and the folding pedal fixes to the crank arm via a socket head screw (looks like 10 mm) rather than a much rarer 24 mm hex head. Whilst the folding pedal bearing is still pressed into the aluminium plate (and thus not officially user serviceable) it appears to have been changed to one which I hope is more durable. The crank arms are now engraved with the icon depiction of the Brompton fold used in much of Brompton’s material, rather than the logo decal used in earlier years.

The brake pad cartridge holders have been changed to a new type with cut-outs in the side. I suspect that this was done to save weight, even though it is likely that it only saves as much weight as a good shave.

I have opted for the firm suspension block, as the standard one on the M3L spend most of its time in the ‘fully compressed’ state which negated much of its benefit. The firm block improves comfort by a surprising amount. I transferred the Brooks B17 saddle from the M3L to the P6R, although the stock saddle wasn’t all that bad.

So far the P6R is a pleasant improvement over the M3L. The bike feels re-assuringly solid, which is appreciated after some of the concessions Brompton had made to the overly weight-conscious over the years. The addition of the rack and the P-type handlebar adds a bit to the bike’s weight, but as is generally the case with weight on bicycles, this is effectively imperceptible when riding. It would make a difference when carrying the bike, but in practice this rarely comes up, as the bike can usually be pushed unfolded to within a few metres of where it will sit when folded up.

Now I need to get the M3L ready for its new owner…

The Long Bike-to-Work

When I took the job which led to my relocation to Chester, one of the things I noted was the chance to use the bike-to-work scheme through Cyclescheme. After being in the job for a few months, I decided to go for it

The process of getting the voucher was relatively painless, requesting it from the Cyclescheme website through an employer-specific link. After a few weeks the voucher was given to me (I’m not sure why it took so long) and I ordered the bike from The Bike Factory. I could have ordered it before the voucher came through, but this being my first time using Cyclescheme, I didn’t want to take the risk of ordering the bike and being refused a voucher for some reason. When I ordered the bike, the salesperson suggested it would typically take 3-4 weeks to arrive from the manufacturer, but a few days later after the order had been placed I was contacted and told that the bike would take 9 weeks to arrive, being ready to collect on the 17th July.

After this I did not hear from The Bike Factory until a few days before I was due to collect the bike. I had seen another person at Chester station with a bike from The Bike Factory  and it had a rather large sticker on the frame advertising the shop. Naturally I wanted to avoid having a rather excessive piece of branding added to my new bike and so I emailed the shop to request they not fit the sticker. On the 16th I received a reply, and was notified that due to a delay with the manufacturer the bike would not be at the shop for up to three additional weeks.

Naturally I appreciated that the delay was not the fault of The Bike Factory, but I was very unhappy that they had waited until one day before I was expecting the bike to tell me about this significant delay, especially an internet search revealed that other retailers had notified their customers of this same delay at least a week earlier. They did eventually offer to lend me a courtesy bike, but by this point it had gotten quite close to the new delivery date and it didn’t seem to be worth the bother any more.

I have got the bike now, I am very happy with it and I will be writing about my impressions soon. Buying through Cyclescheme was relatively painless, although issuing the voucher took longer than I would have expected. The lead time for the bike was more than I expected and the delay was quite annoying. Whilst this was less than ideal, I was pleased that The Bike Factory tried to make amends in the end by not charging me for the additional options I had specified on the bike which were not covered by the Cyclescheme voucher (including the Cycling Embassy of Great Britain colour scheme).

Electrified Brompton Luggage

Although expensive, I’m a big fan of the Brompton luggage system. Much like the fold of the bike itself, it is simple, elegant and involves the only the minimum amount of fannying about. It is this functional design which inspired me to finally revisit one of my old projects; USB charging using a bicycle dynamo. Whilst my previous attempt was rather crude (both electrically and aesthetically) the Brompton luggage system presented the opportunity to do this idea right.

You will need:

• A Brompton (or other bike which uses the Brompton luggage system, such as the Circe Helios) with luggage block and either an A, C/T or S bag luggage frame (plus bag) made after Brompton switched from their older all steel frame design to their current tubes and black plastic one.
• Switched* dynamo lights (and a dynamo)
• At least six M3 x 5 mm (approx) cheese head screws (flat tops)
• At least eight M3 washers
• At least two M3 nuts
• At least eight small (red insulation) 3 mm ring crimps
• Some double (bell) wire, or two strands to twist together (1.5 m approx)
• A 2.5 and 3 mm drill bit (and a drill)
• A set of pliers
• A flat head screwdriver of suitable size for the M3 screws
• A few square cm of thin (approx 0.5 mm) sheet metal (a bit if old drinks can might do in a pinch)
• It would also be advantageous to have a set of M3 taps, although a screw can be used for tapping if you do not have taps.

If you don’t have any of these parts, consider ordering them from Farnell (for reasons which will become apparent later).

The first task is to drill two holes on the top of the luggage block using the 2.5 mm bit as shown in the picture and then tap the holes (this can be done, with sufficient patience using one of the M3 screws if you do not have taps). Fit ring crimps (remove the insulation and crush the crimp closed with the wire inside the crimp using pliers) to a length of wire long enough to reach from these holes to the connector on the dynamo and connect the crimped ends to the luggage block with a screw and washer each. Connect the other end to the dynamo connector in parallel with your existing (switchable) dynamo lights. If you want the wiring to look tidy, fit a couple of P clips on the luggage block to route the wire.

Next comes the luggage frame. Drill two holes on the plastic part of the frame just above the cut out for the luggage block, as shown in the picture below and tap these holes as before. Make a pair of connectors from the sheet metal as shown below and drill them with the 3 mm bit. Fit these connectors to the luggage frame using a screw and a washer each in the holes tapped in the frame. The top of the luggage block does not usually make contact with the top of the cut-out on the frame, so your contacts will need to protrude downwards enough to make good contact with each of the screws on the top of the luggage block.

Congratulations, you now have a set of terminals supplying ~6V AC on your Brompton luggage. What you do with it is only limited by your imagination.

I decided to build a new USB charging circuit, based on this post. The post contains a list of all the parts you will need to build the circuit neatly on a bit of strip-board (veroboard) from the Farnell catalogue. I added a PCB USB socket from Maplin so that the 5V DC produced by could be used to charge a range of devices such as smartphones, MP3 players or GPS devices and a simple plastic enclosure to keep it all together. I drilled a pair of 3 mm holes for two screws to be used as electrical connectors and linked these connectors to those on the luggage frame using a ~400 mm section of paired wire with 3 mm ring crimps on each end. When using the referenced post, if you buy different but equivalent parts, be aware that capacitors 1 and 3 are polarised type and capacitor 2 is a non-polarised type.

The circuit on the strip-board (the layout may appear confusing due to an earlier mistake).

I added a switch to the enclosure so that the circuit can be switched off when the lights are in use. The strip-board and components can just about be stuffed into the remaining space in the enclosure, which has had a hole cut in it to allow access to the USB port. In the mark II I will probably think more carefully about the arrangement of parts and the inputs within the enclosure before I start drilling. The wire linking the assembled enclosure to the luggage frame is routed through a hole which had started to develop without any assistance from me in the bottom of the C bag’s left pocket.

The circuit charges my Android smartphone when the front wheel is spun by hand and I will update this post after I take it for an extended test ride in the near future. When running the charging circuit, simply turn off your dynamo lights. When using your dynamo lights, be sure to turn off the charging circuit. Happy charging.

* If you add additional switches, non-switched lights and a bottle dynamo could be used in place of a hub dynamo.

Brompton for beginners?

It has been nearly a year and a half since I acquired my Brompton M3L. Occasionally I find myself wondering how much easier certain times in my life would have been if instead I had bought the bike years ago. I’d certainly have been able to avoid a lot of the expensive trial and error involved in my early bicycle-purchasing experiences. Because of this, I thought it might be a good idea to lay out the reasons why new cyclists might want to consider buying a Brompton.

The Obvious

As much as everyone always bangs on about it, the fold is exceptional. However, rather than focusing on the mechanism, consider the benefits it offers. A bicycle which is easily folded into a compact unit allows people such as flat-dwellers, who might otherwise struggle with storage of a bicycle, to work-around the limitations presented by their living situation. Additionally the fold allows the bicycle to be taken to places which they are not usually welcome; whilst I lived in Manchester my Brompton went with me into Umami, Sandbar, The Ducie Arms, the University of Manchester and The Cornerhouse to name just a few establishments.

You can give up

When you have just started cycling, or just returned to it after a long break, the new demands placed on your body by cycling take their toll until your body adapts. Thankfully this doesn’t take very long at all, but during this time, the Brompton at least gives you the opportunity to fold up and hop on the bus if you get tired or encounter a problem.

You can give up

Two out of every three people who take up cycling in the UK give it up. This is due to the atrocious conditions new cyclists face on the roads. If you decide that cycling on the roads as they currently are isn’t for you, the fact that Brompton bicycles tend to be easy to sell and retain their value well means that you’ll be able to recoup most of your investment quite easily. Even accessories such as Brompton bags fetch a decent price on eBay.

You will buy one eventually anyway

If you are the one in three new cyclists who does stick with cycling, you’ll probably end up buying a Brompton eventually anyway. Each meeting of the Cycling Embassy of Great Britain I go to I see more people who have acquired a Brompton. At the May AGM it was Sally Hinchcliffe and A Grim North. Eventually I’m sure Joe Dunckley will give in. Even Lovely Bicycle has fallen for the Brompton, despite some slightly lukewarm initial impressions in pre-ownership posts.

Accessories

Whilst Brompton-branded accessories don’t really come cheap, they are generally very good. My own experience with both the C-bag and T-bag has been almost universally positive, as has also been the case with the dynamo wheel (other than the part where I was paying for them). A small amount of this outlay on accessories can be clawed back by taking the bike inside with you, which allows you to avoid buying a lock, which would be expensive if you subscribe to idea that it is good practice to spend ~10% of the value of a bike on a lock.

Jack of all trades

Whilst the Brompton isn’t the perfect bicycle for all situations, it is good enough for almost all of them. Despite this, I was surprised at how fast the Brompton can be ridden and how well it copes with this. The generous luggage capacity afforded by the T-bag and a saddlebag allows the Brompton to be a good enough load-carrying bicycle for the needs of most people. If I could only own a single bicycle, it would have to be a Brompton.

So new and would-be cyclists, consider the Brompton. Whilst it may appear expensive at first, at least you can flog it easily if it doesn’t work out, and if you do take to cycling you’ll probably end up buying one down the line anyway (and I can’t imagine they’ll be any cheaper in 2019).

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-operativecycle 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.