Category: TechyStuff

I find it hard to throw away any old parts from a Brompton - you just never know when it might come in useful, even if not on a Brompton itself! Spot the old Brompton part I reused to mend my pan lid. Perfect!...

It's not often you see one of these, in such good condition. An original Brompton T5.  This pristine model illustrates so many of the characteristic features of the Brompton of 20 years ago. Here on the left is the rather rigid plastic handlebar grip, and the slim, rod-like brake lever with a bulbous end. On the right is the 5-speed shifter, which operated the 5-speed hub gear. Below you can see the older form of narrow, sandwich type hinges, discontinued in 2002 due to a high incidence of failure in the weld (or brazing). (I know this from my own painful experience!) The T5 came with its own dynamo and lights (a good idea then, but battery lights have become so much better since then).     The rack had these funny, tough little wheels attached, one of which from my old 1995 Brompton has survived as a replacement pan lid handle on one of my saucepans!   This model even has the original, not-very-thrilling right...

I was just enjoying this view, when I looked more closely...         and spotted this view... Problem is, they stopped making the cracked part 15 years ago. This could be a long search......

My son texted me from university 400 miles away to tell me his spokes were rattling. I feel a wee bit responsible, since I built this wheel for him on a Brompton 8-speed conversion. So how do you teach spoke-tensioning by email? I had a go, and thought I would share my attempt here. I don't know if this is how the pros go about it - it's just what I would do. If your wheel has gone a bit wonky, you may be safest taking it in to a bike shop to get looked at. But if you're happy to tinker, read on. This is what I wrote: For tightening spokes, once you have your spoke key (suggesting 14G), invert the bike and: Ping all the spokes and work out which has the highest pitch. Make a note of that pitch as a benchmark. You may need to note a different pitch for each side of the wheel, if the spokes are different...

I've looked at Brompton gearing in a previous post - this graph adds in the gear ratios of two popular 8-speed hubs, the Sturmey-Archer x-rf8(w) (SA), and the Shimano Alfine 8. The top three lines of the graph are the three Brompton 6-speed options. I like my gears low, which is reflected in the choices below. There are four 8-speed options above. The first two to notice are the brown and yellow lines (the top two longest). The brown is the Alfine 8 using a 54T chainwheel, and a 16T rear sprocket. The yellow is the SA x-rf8(w) using a 33T chainwheel, and a 20T sprocket. Both of these start in gear 1 in a similar gear-ratio to one another and to the low Brompton 6-speed gearing. Both end in gear 8 just slightly higher than gear 6 of the Brompton set-up. In other words, these two 8-speed options reproduce the same spread of gears as the low Brompton 6-speed gearing, but obviously...

Gearing: maybe it's not the most exciting part of a bike, but when you can't get into the gear you want, you know about it. Straining up hills in too high a gear, or running out of pedal power on the flat with the wind behind you - such moments could be avoided with a more careful choice of gears. Brompton offer a range of gearing options on their shop-bought bikes, from 1 through to 6-speed models. (Five used to be an option, but four never was!) Here I'm interested in the 6-speed models which, after all, give you the most gears you can buy on a Brompton. For those new to Bromptons, the six speeds are achieved using a 3-speed hub gear in combination with two sprockets (cogs). By switching the chain between the two cogs, and changing between the three hub gears, six gears are achieved. (i.e. 2 x 3 = 6). Although this is not a new idea in...

Two of the most popular hubs for a Brompton 8-speed conversion are the Sturmey Archer x-rf8(w), and Shimano's Alfine SG-S501. There are pros and cons of both. If you're looking to do your own 8-speed conversion, which to choose? Below is a summary comparison table. Sturmey Archer x-rf8(w) Shimano SG-S501  Price: Around £150 Around £150  Internals: Ratchet (noisy) Silent  Direct drive: 1st gear 5th gear  Gear range: 325% 307%  Over-locknut width:  120mm 135mm  Needs frame widening:  No  Yes  Gear changer: Gripshift or lever Triggers  Spoke hole options: 28, 32, 36 32, 36  Needs extended chain tensioner: Yes No   On the face of it, the Shimano hub is simply a better product. For a similar price to the Sturmey Archer, you get a quiet, reliable hub, whose gear changer always delivers a secure change. I have ridden my 'big' bike for 7 years with the Shimano hub. It has only failed me once - at minus 5 degrees C when the internals froze, and I had to beg a cup of boiling water from Costa to pour over it. By contrast, the sound of the Sturmey Archer (SA) has been likened...

Part of renovating my Brompton involved replacing the worn-out rim on the rear wheel. This is an opportunity to revisit the whole task of wheel-building. If you are looking to convert a Brompton to an 8-speed hub, this is a necessary first step. You'll need your hub (in my case a Sturmey Archer x-rf8), a rim, and spokes. I am using a 28-hole Sun-Rims rim. I have used cheaper rims in the past, but two wore out in as many years, so I'm hoping the Sun-rims version will be more robust. Choose a rim with the same number of spoke-holes as there are holes drilled in the two flanges of your rim. A hub with 14 holes in each flange, will need a 28-hole rim. Sounds obvious, but easy to overlook! Rims sometimes come with a narrow air valve hole, and to fit a Schraeder inner-tube valve, you will need to drill the hole larger with an 8mm bit (plus a shade...

 I'm delighted with the respray job done by Henderson's in Edinburgh. The next task was to take these six bits back to Biketrax, and have four new hinges inserted. Two of these allow the stem and top tube to fold; the other two form the hinge between the rear triangle and the main frame. The latter job can be done by an amateur, although I'm told it can be tricky. Renewing the stem and top-tube hinges on the Brompton require a special tool, and choosing the right size of hinge pin - there are slightly larger ones to allow for greater wear. All in all, I decided hinge replacement was best left to the professionals! Laid out on the counter at Biketrax, the frame bits look impossibly small - is this really the bike that I've taken all over Scotland in the past 2 years? Yet the whole lot fitted in a single bike pannier! Biketrax did a great job of putting the...

Brompton have put together a neat little video describing what features are new for 2017. Wider grip areas on the handlebars will mean a more comfortable ride, particularly for those who are trying to cram on extras such as grip-shift gear changers and Ergon grips. The traditional spongy bar grips are retained, but are now bolted on, rather than glued - meaning you don't have to wreck your grips to change brake levers etc. There is also now the option of a wider saddle. Perhaps the most significant change is the redesign of the gear triggers, so they hang below the bar, instead of sitting on top. I had a chance to try these out at the Brompton Junction shop in London last weekend, and they are a definite improvement - though sadly stopping short of a two-finger action such as Shimano's tap fire setup. The bell is integrated and more accessible. There are also some interesting new lighting bracket options - including a saddle-mounted...