I’ve not done many miles on my 6-speed Brompton, despite owning it for several years. It’s not that I don’t like it; I simply don’t do many of the sort of miles for which it’s designed – short commutes around the city. Nevertheless, I had two niggles with the bike from new – the cheap and grotty handlebar grips and the rather ugly and fiddly gear shifters. If you don’t know the Brompton, the 6-speed version has a Sachs 3 speed hub to which a pair of sprockets is attached. The left hand shifter selects the sprocket and the right hand one the internal gear. To go up and down the gears one by one, you use the shifters alternately.
While on holiday over Christmas, I found out about the possibility of converting the Brompton to an 8-speed bike with just one twist grip shifter. A kit is offered by Edinburgh-based Kinetics and, in a slightly cheaper form, by Tiller Cylces. Both firms offer other hub options, but I decided on the Sturmey Archer X-RF8(W) 8-speed kit. I ordered it from Kinetics over the Christmas period, paid my £300 plus postage, and waited for the 2-week delivery stated on the web site. By the middle of the 3rd week of January I’d had no acknowledgement of my order and nothing had arrived. I called Ben, the owner of Kinetics, and he explained that he was just building up a batch of wheels with the hubs and my kit would be despatched later in the week. It wasn’t. I emailed and got a quick reply and apology, saying that it would be sent the following week. During the last week of January it arrived.
The web site stated that the conversion takes about 30 minutes. The Kinetic instructions were reasonably clear so I set about the conversion. I’m not quick, but not that slow either…you might do your 100th conversion in 30 minutes, but I challenge anyone to do their first one in that time. It took me several hours, but I was not too familiar with the peculiarities of the Brompton, having never worked on it before. You take off the existing wheel and tensioner, plus all cables and other parts associated with the drivetrain. Then you remove the chainset and replace it with the new, smaller one.
I followed the Kinetics directions to the letter but the tensioner jockey wheels were about 5mm out of line with the sprocket on the hub, so the chain wouldn’t stay on. I emailed Ben at 10pm on a Saturday evening and got a reply within minutes. One of the changes during the conversion is to replace the tabbed washers on the wheel axles with thicker ones from the kit. Ben suggested I revert to one of the original thinner ones in order to move the tensioner closer to the frame. It was bad advice because it caused the tensioner to press against the edge of the hub, preventing the gears from changing. I went back to the original washers and packed out the jockey wheel fixing bolts with some washers to move them the required 5mm. All was well and the gears change smoothly.
SUMMARY: This is a nice conversion and, if you don’t mind the extra weight (perhaps a kg or so?) it makes for a more rideable bike with a slightly wider range of gears. The bike looks neater, has cleaner lines and is not quite so quirky, although quirkiness is something that few Brompton riders will worry about. I was disappointed in the service, the hassle of having to modify parts to get the conversion to work, and the rather cheap and nasty looking drive side crank and chainring supplied with the kit. In my view the latter is nowhere near as nice as the one shown on the converted bike on the Kinetics web site. At £300 plus postage, enough to buy a reasonable bike, the kit is expensive, but I’m hoping to raise £100 by selling the original parts, so that eases the pain a little.