Using a Brompton Bike as Primary Transportation

Four years ago I sold my last truck, climbed onto a touring bike and rode off across the US. Since then I have had no desire or need for motor vehicles. I own a couple of specialty cargo bicycles for such tasks as hauling large parcels from the post office or transporting furniture but for the most part, I use a Brompton electric folding bike for my transportation and shopping. The Brompton folds up into a package that is only 22" x 21" x 10" for carrying onto ferry boats, sea planes or airlines. It also collapses into a neat little shopping cart configuration using the Brompton shopping basket or a Valeria's Barcelona basket bag. Places that would never allow a standard size bicycle make allowances for the Brompton. A few days ago I was down at the Cruise ship docks. They have a standing policy against allowing bikes on the premises. I folded the Brompton into the shopping configuration and just strolled right in pushing the cart ahead of me without any notice from the guards. I think they assumed it was some sort of luggage carrier or hand truck. I've taken the Brompton into pubs and restaurants and…

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Why an electric Brompton bike?

The iconic Brompton folding bicycle has a deserved reputation for hand made quality. With the smallest fold size of any bike and firm rigid handling characteristics, the Brompton has gained a strong following amongst city commuter cyclists and bike tourists alike. Constructed of brazed steel tubing, the basic design has not changed much since 1975. This is one of the main reasons the Brompton holds its value and can be customized with a variety of after-market parts. A typical price for a previously owned Brompton is $1400 USD and even stripped down frame sets bring prices of $700 USD on auctions. Brompton owners are fiercely loyal and tend to hang onto their precious bikes forever so the second hand market for them is very lean. Here at St Thomas Bikesmith, we build custom Brompton wheelsets with dynamo hubs, exotic internally geared hubs and electric assist systems. We also supply quality after-market titanium parts and specialized handlebars & saddles. We work with an excellent powder coating company that has experience in color coating Brompton frames. This can be a difficult job considering their complex hinged areas. We install Tannus solid tires for flat-free riding and even build a special smaller 16"…

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Brompton Touring Bike

A few weeks ago I did a repair job on a pair of vintage Dahon folding bikes. One had 16" wheels and the other, 20" wheels. Although the concept of a folding bike was intriguing, these two bikes were a bit wobbly and lacked the stiffness and quality components that I was accustomed to in working with touring bikes. However, this whole episode got me contemplating the positive points of folding bicycles in general so I began studying the various offerings and their ride qualities. Well, you don't get too far down that rabbit hole before stumbling upon the cult of Brompton owners. The "Brompton" is a British manufactured folding bicycle designed in the 1970's which has a following of thousands of loyal users. The bike folds down into a very small package which is relatively light weight for a steel framed bicycle. The hinges are stout and stiff and the moving parts are minimal and less than sophisticated and the bike does exactly what it is advertised to do. It rides much like a standard large wheeled bike but can easily be folded up into a 22" x 21" x 10" package for carrying onto planes, boats, trains or…

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Brompton Gearing Modifications

Various gearing modifications have been attempted for the Brompton folding bicycle over the past decade to boost the ratios and have these bikes fulfill a broader function. Although the 6 speed (2x3) factory version has been successfully used for distance loaded touring, it barely squeaks by in overall gear ratios for a true "touring bike". Rohloff 14 speed hub conversions are very expensive, very heavy (about a pound heavier) and they add a great deal of width to the original folding size. A typical Rohloff conversion costs close to $3500 USD and that is not including the original cost of the Brompton bike. The Shimano 8 & 11 speed hubs also use wider drop-outs of 135mm having the same problems that the Rohloff conversions do but without the solid reliability of the German made hub. For some years now a few Brompton custom shops have been adding an additional sprocket (triple cog kit) to extend a 6-speed Brompton's gear range from 302% to 368%.  This gives 9 distinct gears and takes care of the gearing problem, however, the conversion is tricky often needing to grind metal from the frame to make room for the additional parts as well as swapping out the Brompton 6 speed chain for…

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10 Speed Brompton Upgrade

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 5x2 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…

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Brompton Electric

It is August 21, 2017 and to celebrate the completion of our newest Brompton build, I rode out to view the total eclipse of the sun. While out riding I took a few photos of the finished bike. This build has all the features of the upcoming Brompton factory electric bike plus a couple of extras I deemed necessary for loaded touring applications. It has a 500 watt Crystalyte front hub motor capable of operating on a 36V or 48V battery so the torque power & speed is increased over the factory version. The UK has restrictions on the motor wattage and top speed of their e-bikes that we in the US territories do not have to abide by so I opted to use a motor with twice the wattage.  The controller for this motor is attached to the fork yoke by a lengthened fender (mud guard) bolt and does not interfere with the bicycle fold. [caption id="attachment_3907" align="alignright" width="300"] Crystalyte Hub Motor on Brompton E-bike[/caption] There is also a pair of Tannus (airless solid foam) tires on this bike as seen in this photo.  Note the lack of a valve stem.   It is important to emphasize how stress…

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