The Brompton gearing upgrade kit arrived from Taiwan this morning and I’ve already built it into a new wheel, complete with a Tannus “No Flat” airless tire. The kit consists of a Sturmey Archer S-RF5(W) N 5×2 10 speed freewheel, 5 speed Sturmey Archer thumb shifter, two rear sprockets (12t & 17t) and hardware bits to put it all together. The finished product is fantastic with an additional 60% boost to the overall range of 362%. This adds two more higher gears for speed and another two lower climbing gears putting this Brompton in the running for an all-round 10 speed touring bike.
The thumb shifter has a positive indexing and feels solid & comfortable, unlike the original Brompton plastic 3 speed. The whole kit went together quickly with only a few snafus. The first was the fact that my donor Brompton was a 2003 Model so it had a different dust cover on the hub. I had to shave down the back of the new Sturmey Archer dust cover to make room for two sprockets. I also had a bit of trouble fitting the 17 tooth cog. A 16 tooth would have fit without modification but the 17 was just a smidge too big to fit in the Brompton frame. I spent an hour carefully filing inside the drive-side dropout area to give me the 2mm of extra space needed. This job was a lot easier to do before the hub was built into a wheel and experience paid off here. Rather than rush to the truing stand, I took my time fitting all the loose parts first. The end result was a clean professional install which looks and functions better than the original.
Enlarge the image for a close-up of the adapter.
While I was at it, I installed a Grin Technologies USB Power Adapter. This plugs directly into the Cycle Analyst and provides two USB outlets, 1-amp (for use in charging a smartphone) and a 2-amp (for running bicycle Dynamo lighting). The power for these USB plugs is supplied by the E-bike battery pack. Here is a photo of the USB Power Adapter in use on the Brompton.
Here is a photo of an H-Track Dynamo Standlight and an LED headlight being powered by the USB Adapter while simultaniously charging my phone. Overall, these were two very essential touring upgrades to the new Brompton E-bike. Hilly terrain and night riding are no problem now. This bike build is completed and offered for sale at St Thomas Bikesmith. It is ready to tour the world. We specialize in making good bikes better.
