About a Brompton: C line Electric Review


I’ve developed an interest in folding bikes as well as small wheeled bicycles over the years.  Lately, I’ve also wanted to explore the growing world of e-bikes.   I combined all of these interests together in purchasing this Brompton C line electric bicycle.

Before delving in to my impressions of the bike, there’s first a lot to unpack about Brompton bicycles in general and the e-bike version specifically.  First and foremost, this is a folding bike with tiny 16 inch wheels.  It folds into a squarish size that can easily fit behind a desk or in even the smallest hatchback.  The folding process is quick, involving only a few steps, and is arguably ingenious as there’s no other (rideable) small wheeled bike that folds up this small and this easily, to my knowledge.  I won’t go into the folding process here, as there are multiple resources on the web to help you learn.

In practice, I have rarely fully folded the bike, but have found this “kick stand mode” very useful, both outdoors and inside.

Of the many quirks and oddities of Brompton bicycles, the most important is the fact that since this is both a folding bike and a “one size fits all” bike, virtually every component is purpose built and cannot be upgraded or swapped without voiding the 7 year warranty (frame only, 3 years for the e-bike components).  Essentially, everything on the Brompton, down to the cables and their housings, is custom made.  I learned this after purchasing the bike with the taller version of the handlebars.  Only one style of handlebar is available with the e-bike version, and it comes in two different heights, achieved by different stem lengths.  Swapping bars is an expensive undertaking and can only be done by the dealer.  Fortunately, having only a few miles on the bike, I was able to swap it out for a different model with the shorter stem.  Even so, I find the medium height bars too tall for ideal comfort.

Likewise, the shape of the bars, necessary for the bike to fold, means that there is no swept-back angle on the grip portion, which instead are perpendicular to the stem.  This rotates your shoulders forward and twists your thumbs and wrists into an uncomfortable position.

I removed the stock grips and wrapped multiple layers of cloth tape to the grip area, opting for a funky two tone look.  This helped to make the grip area less thick, making it less painful for my thumbs to lock under the bar, and I like the feel and moisture absorbency of cloth tape.

Because of the bike’s non-standard design, all of the visual cues that one might use to set up the ergonomics are missing. I needed to get out my angle finder and tape measure to get the bars and saddle set up in the most tolerable position for riding.  One size fits all means some ergonomic compromises.

The utilitarian saddle clamp is made less effective by its single bolt design with the bolt positioned so that one must mount the saddle (I removed the uncomfortable Brompton saddle) on the upper rails of the clamp in order to access the bolt.  If mounted on the lower rails, you can see that the saddle can’t be positioned correctly because the bolt becomes inaccessible from the side. Traditional saddle clamps have the bolt accessible from underneath the saddle.  The clamp itself allows for micro-adjustment, however.

I wanted to use my leather Cardiff saddle with this bike, but ended up swapping it for a well worn WTB Deva which provides a little more cushioning, necessary due to the bouncy ride.  Even though the bottom bracket is offset ahead of the seat tube, I still needed to push the saddle back to account for the forward mounted (and must not be reversed for unknown reasons, per the owner’s manual) no-set-back saddle clamp.  I also angled the handlebars inward toward the saddle to bring my hands into a comfortable position with some elbow bend to provide much needed shock absorption.

Rear suspension block

Short spokes make for a harsh ride

Rear wheel not centered between chainstays

Small wheeled bicycles, with their shorter spokes, are improved by front and rear suspension to help smooth out the ride. I’m amazed, given how harshly this bike rides, that Brompton hasn’t invested in engineering some kind of front suspension.  Alex Moulton figured this out back in 1962 when he designed the first Moulton with full suspension front and rear.  It too featured 16 inch wheels.  The folding stem would admittedly present engineering challenges. Brompton has only managed to engineer a simple rear suspension block, perhaps choosing instead to spend its money on branding every single component of the bike, down to the rear fender flap.

The little 250 watt motor housed in a relatively small flange hub, still eats up a big portion of the front wheel’s diameter, making the spoke length very short. I don’t hear riders of regular Bromptons complaining bitterly about the harsh ride, but maybe that’s because they have three things going for them:  longer spokes on the front wheel, a lighter and more flexible fork, and more (and better) tire options.  Brompton has specified only two tire options for this e-bike:  the Schwalbe Marathon Racer and the Schwalbe Marathon, both harsh riding tires with heavy, stiff sidewalls.

My bike came equipped with the Marathon Racers, which measure 34mm wide on the Brompton rims.  I’ve had to experiment with tire pressure, as there is a trade off between rolling resistance and ride harshness, which I’ve found to be balanced at about 70-75 lbs. front and rear.  You’ll note from the above photo that the rear wheel is not centered between the chain stays.  There is only about 2 mm of tire clearance on the drive side, with about 9 mm on the non drive side.  At first I thought that the rear wheel was out of dish, but upon checking I discovered that while out of dish by about 1 mm, the culprit for the lack of centering is that the drop outs are out of alignment, appearing to be so by design.  Theorizing that the purpose for this had something to do with the bike’s folding characteristics, I contacted both my local LBS and Brompton itself via email, several times, and never had a response.

At any rate, the lack of clearance means that it is impossible to install wider tires on this bike.

The drivetrain consists of a wide ratio Sturmey Archer 3 speed hub with two cogs, 16T and 13T, mated to a 50T chainring up front.  This gives a gear inch range of 33 to 100, which is a good spread for just about any kind of riding.  There’s an oddball “chain pusher” clamped to the chain stay that shoves the pulleys, which are plastic, from one side to the other of the the also plastic chain tensioner.  The (plastic again) shifters have the cog shifter on the left side and the internal hub shifter on the right side.  I found the half step gear shifting pattern to be non-intuitive until I made the above gear shifting chart.  Now, it’s easy to remember that any time I am shifting the rear hub, I’ll need to do a double shift to maintain cadence.  The whole system is noisy as can be, with something always whirring and clicking. Combined with the thunking and rattling noises caused by the harsh ride, it’s taken a while to get used to, and has at times caused me to think that something is seriously wrong with the bike.

There’s also a lot of friction in the drive train, which you can note by trying to spin the crankset backwards.  It simply doesn’t.  Normally, there would be about a 5-9% loss in power due to the internal gear hub as compared to a derailleur geared bicycle, but this drive train feels more sluggish when “unplugged” than my vintage 3 speed bikes.  I suspect this is caused by the pulley placement on the chain tensioner:  there is almost no clearance between each pulley, barely enough room for the chain to fit through.  Add to that the drag from the front motor, and this becomes a bike that’s not fun to ride with battery turned off.

But, many faults and flaws can be overcome with the addition of a little battery power and a motor. The bike comes standard with a soft case to hold the battery, which clips into a specially designed front bracket.  The case is very small, but can hold a U-lock, cell phone, and wallet.  I opted to purchase the larger commuter bag and have found it very useful, and big enough for a change of clothes or a day’s shopping.

The bike comes with some thick owner’s manuals and the learning curve for this bike is  steep, especially if you haven’t owned a Brompton or an e-bike previously.  But, I’ve learned a few tips that I can now share.  First of all, when you insert the battery onto the bike, make sure it is fully clamped in by giving it an extra shove, otherwise the battery can pop out/turn off unexpectedly while hitting a bump.  Secondly, the battery, sensors, and motor are re-calibrated each time the battery is installed, so do not turn the cranks or move the bike for the first few seconds.  Wait until all the lights come on, and even a few seconds after that.

There are three power modes.  Don’t waste your time on power mode 1, as it is too wimpy to overcome the bike’s drive train flaws.  I’ve found that using mode 2 consistently, with the lights always on, gives me about a 30 mile range before re-charging.  Mode 3 is great for steep hills, hot days, and miserable rain, but will use the battery more quickly.  According to the owner’s manual, the battery likes to be recharged early and often.

As per British e-bike standards, the power cuts out at 15 mph, for which I am thankful.  This little bike with its tiny wheels can be scary on descents, especially if encountering a bump or pothole, which can turn the fork and even swallow the front wheel.  For me, it’s also nice to not overtake super-fit riders.  I’m not riding to get there as fast as I can.

There are many other quirks and “Bromptonisms” that need to be learned.  I’ve found the videos by Brilliant Bikes especially helpful and humorous.

Poorly designed rollers

Roller on fender which doesn’t actually roll

One locking solution for quick stops.

I did consider selling the bike until just recently, as I’ve come to think of it more as a commuting appliance, rather than a bicycle.  There have been so many notable flaws, including the fact that this bike isn’t suited for multi-modal transportation (except via car).  It is too heavy (about 39 lbs. with battery) to comfortably carry up steps, and the poorly designed “rollers” to be used when the bike is partially folded, simply do not work on this bike.  Perhaps because it is heavier than regular Bromptons are, but the bike doesn’t roll when folded on anything but the smoothest polished surfaces.  There are aftermarket rollers available, but it is disappointing that Brompton would not properly engineer these rollers to work with the e-bike.  Because of the weight and inability to roll when partially folded, you can’t take this bike with you into the grocery store, as you can with regular Bromptons.  That means you have to figure out a way to lock it.  I’ve come up with one solution, shown above, that locks the battery as well.  So far, so good.

Likewise, failing to provide for a bottle cage mount is another disappointment.  Fortunately, I found a suitable solution with this clamp made by “Monkii”, but it is puzzling that such an important feature is left for the consumer to problem solve, especially on a bike in this price range.

To end on a positive note, I’ll say that one redeeming feature is this adorable pump, engineered to fit perfectly on the left side seat stay.  It works fine, too.

So, why do I still have this bike?  In addition to commuting on hot days, cycling on unpleasant errands, and riding through rain storms, I’ve also taken this bike on some almost fun jaunts out of town.  I’ve expanded my normal routes to include previously unconquerable hills.  While not my favorite bike by any means, I have found it helpful to have an e-bike on hand when I want to ride even though conditions are bad. Its folding capabilities mean that I can take it with me on out of town trips even when I am bringing another bike, because I can squeeze it in just about anywhere.  But, I cannot recommend this bike as one’s only bike, except maybe in an environment with very smooth roads. Wired Magazine declared this bike un-rideable in its recent review.  Let’s hope that as competition in the e-bike market increases, Brompton will be required to address some of this bike’s glaring shortcomings.

Portland Bikeshare 2.0 – E-bikes!

Many cities have gone to e-bikes for their bikeshare programs, and Portland is one of them.  Its first bikeshare launch several years ago was pretty much a bust, although PBOT and the Biketown folks will certainly never admit this.  Those bikes were clunky, bad handling, heavy, and exceedingly unpleasant to ride.  I used that system exactly 2 times, swearing to never ride them again, and as I love to ride all kinds of bikes, that should tell you something.

In early September, the “old” fleet was decommissioned (not without some controversy), and the new e-bikes hit the streets.  The new system is run by Lyft, which will be a familiar platform for many city dwellers who use ride share.  The launch experienced some unfortunate timing problems:  dangerous wildfire smoke enveloped the city for many days, causing a temporary shut-down of the new bikeshare program, then torrential rains and winds followed shortly thereafter, meaning that no one was biking in Pdx.  But finally, clean air and good weather returned, giving me the opportunity to test out these bikes in Portland’s ideal fall weather.

My first test ride was totally unplanned:  I came across a stable of these bikes on one of my noon walks, and decided spontaneously to hop on and go for a ride.  The process was very easy.  I downloaded the Biketown app, scanned the code on the rear fender, and bam! the bike was unlocked.  Before doing this, I checked all the bikes in this line-up for the one with the best feel on the brake levers and tires, and checked to make sure that the seatpost clamp would hold (something I learned from my prior and limited experience with Portland Bikeshare).  The bikes are tall, and weighty – somewhere between 75 and 85 lbs, according to various web sources.  They feature a front disk brake and rear drum.  The gears (using a continuously variable rear hub) are controlled by a simple grip shifter.  The drive train uses a chain instead of the unpleasant shaft drive on the previous models.  The power is always on, and theoretically delivers juice based on the cadence and force on the crank.  The front and rear lights come on once the bike is underway.  There is a minimal front rack (more on this later), which is (over) rated for 25 lbs.

On my first ride, learning how to unlock the bike wasn’t immediately intuitive.  I tried pulling the cable straight out, but it wouldn’t budge.  Finally I jiggled it a bit and it broke free.  Once out, you put the locking end into the pink “holster” shown above, while riding.  When you are ready to terminate the ride, you park the bike (properly  – more on this later!) and secure it by putting the lock back in place.

The Schwalbe tires were fine, offering some shock absorption, but the bike did bounce around and rattle a quite a bit while underway. The front-end handling of this bike is vastly improved over its predecessor, but even so it wants to fall into corners and is wobbly while getting underway, a fact made much worse by its sit up and beg riding position which doesn’t allow the cyclist to weight the bars for control.  Even so, slowing down while approaching stop lights, I was able to avoid putting a toe down (a long ways down it is!) for the most part, so slow speed handling is not bad for such a heavy machine.  While stopped with your foot down, the bike’s front end will flop over, so you have to actively keep the fork pointed straight ahead it to keep it upright.  The battery is mounted on the sloping downtube, and contains some very simplistic instructions on how to unlock and lock the bike.

The bike’s front rack is too small to hold a standard sized brief case, and the very tight bungee cord supplied will squash your bag and possibly even damage its contents.  Fortunately, I was using my “vegan” brief case which can take extreme abuse, as shown above, and still bounce back to normal.  There’s no bottle cage mount, and the rack itself is shallow.  Riding with a bag, even my lightweight one shown above, adversely affected the handling and made the front end more ponderous than in its unladen condition.  I smooshed my water bottle in, and hoped that it wouldn’t pop out while underway, which fortunately it did not.

Biketown does not provide any technical data regarding these bikes, except perhaps upon request, but I have been able to determine that the rear hub is a Nuvinci continuously variable unit as licensed to Enviolo.  I don’t know what groupset this is, but I did feel that the gear range provided was adequate for the steep hills I encounter on my usual routes.  You move the grip shift forward to lower the gearing, and back to ride in higher gears.  Shifting was seamless, as expected, but power delivery was very uneven.  On uphill stretches, it seems that the motor only responds to a higher cadence rather than to pressure on the cranks, which I found out while trying to get myself up Mt. Tabor.  Pedaling an 85 lbs bike up a steep hill with very little power assist is the stuff of muscle strains, as I found out the next day.  Finally, when I shifted to a REALLY low gear, the power kicked in and I was spinning away to the top.

Braking performance was adequate, but with such a heavy bike it takes longer to stop, so planning ahead is needed when approaching stops.  The rear brake was almost useless, but the front performed reasonably well on the four different journeys I took.  You’ll notice the difference in the feel of the brake levers – they are clearly operating two different kinds of brakes.  I worry about less experienced riders not understanding the extra time needed to slow down, especially in emergency situations, and given that average speeds are much higher on e-bikes.  But, there’s no danger of doing an endo on these machines.

The Biketown app is user friendly and intuitive to use.  When you want to ride, you open up the app and up pops a map of the bikes available in your area.  The app shows battery life (in miles) for any bike you click on, and also shows you the number of minutes estimated to walk to the bike of your choice, which you can reserve in advance if you want.  That, so far, would be completely unnecessary, as virtually no one is currently riding these bikes.  The above shows a recent screen shot taken from my iPhone app.  The map contains no legend, which turned out to be an important omission, potentially costing a lot of money to unsuspecting riders (see more below).

Pricing of rides has been controversial.  For the four rides I took recently, I spent a total of $15.60 and traveled a mere 7 miles.  At 20 cents per minute (without $99 membership fee which lowers the price to 10 cents per minute), I also racked up extra $1 charges whenever I didn’t park the bike at at “station”.  Even though the instructions on the bike say it can be parked at any “public” bike rack, there’s a $1 charge whenever it is not left at a “station”.  The map on my iPhone doesn’t clearly identify stations, but even if it did, parking the bike wherever one ends up is the ideal situation, and I think it’s unfortunate that the Biketown folks decided to tack on this extra charge, as it reduces the bikes’ usefulness as an alternative to other transport modes.

To determine whether you should spring for the $99 annual fee, I created this formula, where X represents the breakeven number of rides and Y = the average number of minutes per ride.  In the formula below, I’ve set Y at 15 minutes, which then yielded 40 rides per year as the breakeven for buying a membership:


My last ride of the four I took on these bikes ended unpleasantly.  I wanted to ride the bike home, and park nearby.  Of course, there are no public racks in Portland’s residential neighborhoods (but clearly there should be).  So, the next best thing was to leave the bike in Mt. Tabor park, locked up to a sign post, but away from the right of way for pedestrians.  As it turns out, I was charged a $25 fee, later waived, for parking in a “no parking zone”.  How do we know it’s a no parking zone?  As I said, there’s no legend on the map, but I finally learned that anything outlined in red is a no parking zone.  So, beware, and study your map closely before locking up.

All of which is counterproductive to the whole idea behind these bikeshare programs. If the goal is to reduce driving, I can’t see that happening with this program, except for maybe the short “last mile” jaunts or quick trips near someone’s workplace.  If the goal is economic justice and greater access to transit for low income populations, these bikes fail on three counts:  stations are non existent along large swaths of north and northeast Portland, the cost is astronomical compared to public transit, and the bikes are not capable of hauling groceries and work tools.  While they do go faster than regular bikes, that efficiency is quickly lost in the time it takes to locate and walk to one of these bikes. The lack of available helmets, combined with the extra speed and ponderous handling characteristics raises safety concerns as well.

I do think that e-bikes represent a great opportunity to get people out of their cars and moving for transit, but I don’t see bikeshare as a way to optimize this.  Someday, I may own an e-bike, and be glad for it, but in the meantime I’m planning on enjoying my vintage, lightweight steel machines, with their wonderful performance and superb handling.



Vintage Mopeds and Scooters: the Precursor to e-bikes?

1962 VeloSolex moped

A lot of DNA is shared among vintage bicycles, motorcycles, scooters and mopeds.  Pneumatic tires, Bowden cables, chain drive, frame and fork geometry, as well as components including stems, seatposts, handlebars, grips and brake levers were utilized in common across these vintage machines.

I had an early introduction to scooters when my parents trucked home a Honda CT 90 to our rural farm back in the late ’60’s.  Once the little motorbike was off the flatbed, I was stricken with intrigue.  My parents made the mistake of “allowing” me to ride this little machine on the rural roads around our hay farm in the Applegate Valley of Southern Oregon.  At age 12, I propped my 9 year old sister on the back, and proceeded to ride far afield of my parent’s requirements, even crashing the bike into a ditch in a particularly unpleasant and embarrassing experience.  But most of the time, my spirits soared whenever I threw a leg over.  Even though I had my internal hub 3 speed bike to explore logging roads and irrigation canals, this gas powered machine allowed me to venture much further beyond the limitations of my little kid muscles and my clunky 3 speed Sears-Puch diamond-framed bicycle.

1897 Millet motorized bicycle

Motor-assist bicycles were first introduced over 120 years ago, back in the late 1890’s.  By this time in history bicycles were widely accepted and utilized for transportation, leisure and sport, but with the advent of the internal combustion engine (first developed in 1794) inventors made headway with adapting an engine to a bicycle frame. The above pictured bike utilized an air-cooled radial 5 cylinder engine incorporated into the rear wheel.  The rear fender doubled as the fuel tank.  It used a twist grip throttle, and could be started with pedals, much like modern mopeds.  The bike reached a maximum speed of 21 mph at 180 rpms.  The pedals served not only to start the bike up, but to provide for an alternative option should the engine fail.

Another fascinating approach to power assist on a bicycle was developed by Wall Auto-Wheel. First patented in 1908, this device could be added to any bicycle.  The 118 cc air-cooled single cylinder engine was mounted in a sub-frame which attached to the bicycle at three points.  There was a lever control at the handlebars which operated the throttle.  The whole unit was “lightweight” at 45 lbs.

1947 Whizzer Luxembourg

In the U.S, Los Angeles based Breen-Taylor Engineering developed the Whizzer bicycle engine in 1939.  This was a motor kit which could be added to any bicycle.  As you can see from the above photo, this was no small feat, and required many modifications and enhancements to allow this 150cc engine to perform with relative safety.  Whizzers were often added to the very robust American steel frames offered by Schwinn and others during this era.

After WW2, many different kinds of motor-assist bicycles entered the marketplace.  One of the most common was the “moped” which used pedals to start the bike and assist it on steep inclines when the engine was stressed.  While VeloSolex dominated the market in Europe, many other manufacturers stepped in to provide competition, such as this VAP model depicted above.

The above photo depicts Motobecane’s offerings from 1962.  French bicycle builders embraced the idea of motor-assist and many manufacturers offered mopeds and motor-assist bicycles.

Wall Auto Wheel added to a BSA bicycle. Photo courtesy of http://www.oldbike.eu

But are these historic innovations really comparable to today’s e-bikes?  In some ways they are:  they attempted to take existing bicycle engineering to add motor-assist to the bike, thus extending the bike’s range and reducing fatigue for the cyclist.  Not all vintage motor assist bicycles incorporated the concept of rider pedal assist.  And, as is obvious now, gas powered engines, especially 2 strokes engines, are not environmentally friendly.  Are e-bikes environmentally friendly?  That’s an issue worth exploring, given that the batteries needed to power these bikes require harvesting materials that may have a negative effect on the planet.  That may be outweighed by a cyclist leaving their car at home and commuting on their e-bike.  And, the health benefits of riding an e-bike have been documented in numerous studies.  The behavior of e-bike cyclists was a concern for me initially, but I have noticed that here in Pdx, e-bike riders behave no differently than the rest of us, for the most part.  So, I say, if it has two wheels, get on it and ride!