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.
Crystalyte Hub Motor on Brompton E-bike
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 free I feel when riding on these tires. Glass, nails and road obstacles are no longer a concern to me and flats are a thing of the past.
Brompton Electric 10 Speed Bike
The Tannus tires ride like a Schwalbe Marathon Plus with 60psi but without the hassle of checking pressure or the worry of punctures.
Another upgrade was the addition of a new Sturmey Archer S-RF5(W) N 5 speed hub, which when combined with the Brompton
Brompton Sturmey Archer 10 speed
proprietary 2 speed derailleur system makes for a very effective 10 speed touring bike. Unlike some of the other after-market gearing upgrades, this one does not alter the rear triangle so the folded bike is exactly the same width and weight as a stock 6 speed.
Cycle Analyst & USB Power Adapter
The new Brompton factory E-bike uses a step-down power adapter so dynamo lighting can be used with their 36V E-bike battery. We incorporated a similar device into this bike which not only powers LED lighting but also allows the charging of Ipads & smart phones from the E-bike battery pack. We also installed
Brooks Cambium C-15 Saddle
a THUN bottom bracket to measure the torque of the crank arms and apply an appropriate level of power to the front wheel so all the rider needs to do is hop on and pedal. All electronic specs are clearly displayed on a Cycle Analyst digital dashboard, including motor temperature, speed, battery voltage, amp-hours used, power output, odometer etc. This bike is currently being used as a commuter/grocery bike so a large heavy battery pack is not
Brompton T-Bag & Rack Sack in Use
needed. I mated the motor with a 36V 5.4ah battery which has a range of 8 to 12 miles, depending on the level of the route. This gets me to the store and back twice on a single charge but keeps the overall weight of the bike under 40 pounds. I can easily carry it up the stairs to my balcony apartment in the folded or unfolded position.
We topped the build off with a Brooks Cambium C-15 black saddle for comfort & weather proofing and a set of Busch & Müller dynamo lights. The bags used are the Brompton T-bag (Touring Bag) and the Brompton Rack Sack. This gives a total of 47 liters of space; plenty enough for a medium grocery shop.
This bicycle is for sale on St Thomas island in the US Virgins by St Thomas Bikesmith. Why not pick one up on your next Caribbean cruise?
Just an idea!
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.
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 (2×3) 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 a standard 10 or 11 speed chain to fit between the 3 narrower cogs. This conversion costs around $500 USD.
There is an 8 speed Sturmey-Archer Brompton-width hub available which will effectively boost a single speed Brompton to an eight speed but it changes the chainline quite a bit and adds some weight to the build.
All of these methods have their pro & cons. My ideal modification is to keep the standard 2 speed “derailleur” chain pusher system and overall drop-out width of 111mm but add additional gears within the internally geared hub. Sturmey-Archer manufactures a 5 speed hub (S-RF5 W) with 28 Holes, 111mm O.L.D. & 148mm axle which fits two gear sprockets. No modifications need to be made to the Brompton frame and only the shifter needs to be swapped out for a 5 speed Sturmey-Archer thumb shifter. This kit essentially gives you a (2×5) 10 speed freewheel with a gear spread of 362%. That’s 27.0 – 97.0 gear inches as compared to the factory 6 speed Brompton’s 28″ – 85″ gear inches using a 44 tooth (-12%) front chainring. This seems to be the perfect balance of usable gears without compromising weight or having to permanently modify the Brompton frame and parts. The fold is exactly the same width as an unmodified Brompton and all original parts are interchangable with the exception of the shifter. Plus, this modification is reasonably priced at around $150 USD if you re-purpose your existing spokes and rim.
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 elevators. Being the bicycle junkie that I am, I decided to dissect the Brompton to find out what made it tick. At the heart of the bicycle is the venerable and bomb-proof Sturmey-Archer 3 speed internally geared hub. During the turn of the last century Brompton used similar hubs from Sachs (now Sram) for a few years when supplies began to dry up. Both of these hubs have a reputation for longevity and strength. This is just one of many factors that contribute to the Brompton’s excellent resale value. It is not uncommon for ten to fifteen year old bikes to sell on the used market at prices north of $1000 US. Other than tire & brake shoe wear and the occasional nick or scratch, there is not much that can go wrong with a Brompton bike. Add to this the fact that the design has not changed much since the beginning and you can understand why these small bikes hold their value. The Brompton company, like many British outfits, is fairly obsessive about keeping and offering small replacement parts for their bikes. There is also a thriving after-market for Brompton accessories including Rohloff speed hub conversions and electric hub motors. So, armed with the knowledge I had learned about the workings of a Brompton, I set out to build my version of the ultimate travel bike.
First step… acquire a “donor” bike.
A quick search of Ebay and CraigsList will reveal a treasure trove of used Brompton bike listings. Many of these are located in the UK and have hefty shipping costs associated with them. It is not uncommon to add an additional $135US – $175US for shipping to the states and trying to get a bike sent to the US Virgin Islands is next to impossible. I had my eye out for a certain type of listing. Many professional Brompton sellers use multiple close-up photos to highlight their bikes and detailed descriptions of the add-on features. I was looking for a US seller who had no idea what he was doing when it came to reselling a Brompton. I located a listing with one very grainy photo of what appeared to be a clean Brompton for sale in the eastern United States. The description was simply “older 3 speed folding bike, average wear and tear”. I decided to sit back and watch the auction progress. After four days the bidding reached $1000 and I decided it was too rich for my bank account so I let it go. Remarkably, the exact listing showed up a few days later with the same blurry photograph. For some reason the sale did not go through so the seller re-listed the bike. I began scrutinizing the blurry image and could easily see a total of four cables running from the handlebars, two from each side. This could only mean that the bike was actually a 6 speed and not a 3 speed as it was advertised. This is an easy mistake to make because the 2 speeds on the left are usually not marked and the 3 speeds on the right have a clear (1-2-3) marked on the shifter. It was obvious that the seller was unfamiliar with the bike. Either it had been stuck in a closet for some years or just neglected but the owner had forgotten the details of the bike. This auction seemed promising. I waited for 7 days until the last 20 seconds of the auction. The bike had been bid up to $560 but I knew there were buyers in the wings ready to pounce. I bid $950 just to be on the safe side and won the auction at $799. Wahooo!!! Now came the part where I wait for the delivery and hope I was correct in my assessment of the item/seller. The bike arrived and I could not have been happier. It turned out to be a 2003 model which had never seen the light of day. The tires had not a speck of dirt on them and the brake shoes were flawless with even the tiny strip of rubber running down the center still. The bike sported an original Brompton saddle and a Sachs 3 speed hub with the Brompton proprietary 2 speed cog & “derailleur” system (entering Brompton production in May of 2002) which essentially made this a 6 speed bike. The paint job was perfect and a beautiful gloss metallic silver with gloss black fork & rear triangle. Gloss paint jobs are uncommon on more modern Brompton’s which are usually a matt color. The bike also has a 30mm shorter wheelbase, being an earlier build so it folds up a bit smaller. Another added bonus was the discovery of a dynamo generator and Halogen lights which are in perfect working order as well as the original Brompton frame pump. A good value estimate of this bike would be around $1400 so I am very happy with this purchase.
The first step on building the ultimate travel bike was completed.
I had read about and seen various electric hub kits on YouTube that were specially built for the Brompton 16″ front wheel. Most of these operated with a basic thumb throttle and were more of a scooter than a bike. I wanted a true pedelec type system with a torque sensor that would add a level of assist to the riders pedal stroke. I also wanted a motor with enough power to muscle up the hills on St Thomas without burning up. Almost all of the existing hub kits were using a 250 watt motor but I was looking for something closer to 500 watts. Also, many of the existing Brompton kits needed the front forks to be “cold set” out to 110mm from 79mm which was a stretch for an already small set of forks not to mention the change in folding width of the finished E-bike. I wanted a hub motor which would fit between the stock Brompton fork dropouts with no modifications which could weaken the bike. Another prerequisite was to have a temperature gauge in the motor with an automatic shut-off if temps reached overload. I have seen too many electric hub motors fried on the steep slopes of this island and knew there needed to be a fail-safe built into this bike to save users from themselves. All these extra bells & whistles called for a special electronic component to bring them together into an easy to use display.
Grin Technologies of Vancouver BC manufactures and sells a unit called the Cycle Analyst that does just that. They also have put together the perfect Brompton e-bike kit which ticks all the above boxes brilliantly. The kit can be ordered with a THUN bottom bracket torque sensor which can accurately measure rider power output and then apply a level of electric assist from a 500 watt Crystalyte hub motor. One of the major drawbacks of touring with an electric bike are the restrictions on checking lithium-ion batteries with airlines. Even the postal service refuse to ship e-bike batteries. There are a few exceptions and work arounds that Grin Technologies have taken advantage of when creating the new LIGO battery system. These are very small (under 98watt, 2.7ah 36V) sealed battery packs which are legal to fly with when separated. Once you arrive at your destination you simply snap the batteries together in series to get the required battery size for range of distance and then plug them into the bike.
The second step on building the ultimate travel bike was completed.
Changing a flat tire on a Brompton can be challenging with the combination of internally geared hub and mini-derailleur system, not to mention the struggle to mount certain tires onto the small 16″ rims. Add to that the hassle of dealing with a front electric hub motor with its wiring and torque arms and you can see the beauty of a flat-free airless tire. Tannus tires of South Korea manufactures a specialty tire for the Brompton 16×1.25 (349 Rim). These tires are made from a Micro Closed Cell Polymer Resin called Aither and are a solid foam with no tube or air. It is impossible for one of these tires to go flat. They come in various hardness’s which mimic standard tire pressures such as 60psi or 100psi. Tannus tires are guaranteed to last for 5000 miles but users claim anywhere from 6000-8000 miles (depending on the road surfaces). Using Tannus tires on a long tour eliminates the need to carry extra tires, tubes, patch kits or a pump. Not only does this lighten the load quite a bit but the Tannus tires are actually lighter than conventional tire/tube combinations they replace. They even come in an assortment of bright colors. I selected a basic asphalt gray to match the bike.
Bicycle touring requires some sort of rack & luggage system to carry all the day-to-day camping and survival gear. I dug out all of my touring panniers, rack packs & bar bags and began loading them onto the Brompton in different configurations. I pondered using Ortlieb front panniers on the rear rack of the Brompton but they came awfully close to dragging on the ground. I investigated the unique Brompton Pannier Rack by Kinetics which allows the use of two Ortlieb panniers up front on the Brompton carrier block. Another interesting idea was the Xootr CrossRack seatpost rack, which allows the use of a single large Ortlieb pannier mounted on the Brompton seatpost. These both seemed like solid solutions, however they both involved extra hardware which would need to be removed and packed away when transporting the bike. Soft panniers can be flattened and used as bike padding during transportation but alloy or steel rack systems are harder to pack. Brompton makes a pair of fantastic touring bags which would be the start of my luggage system. The Brompton T-bag is a 31 liter roll-top touring bag which mounts onto the accessory block in front of the steering post. The other bag is called the Rack Sack and attaches to the standard Brompton rack. This bag has a capacity of 16 liters, bringing the total volume of space to 47 liters for the pair. This is still short of my usual requirements of 42 liters (Ortlieb Bike Packer rear panniers) 20 liters (Ortlieb front roller panniers) and 5 liters (Ortlieb Ultimate 5 bar bag) or a total of 67 liters of space. I turned my attention towards the new rack-less bike packing offerings from Ortlieb. The Ortlieb Bike-Packing Seat-Pack at 16.5 liters and the Ortlieb Bike-Packing Frame-Pack at 4 liters would bring my total to 67.5 liters. I would be picking up an additional half a liter of space without needing the heavy steel racks I had grown accustomed to lugging around on my touring bike. Using this system would give me the benefit of the Ortlieb waterproofing plus the ability to scrunch down the lite-weight packs for air travel. This all seemed good on paper, but… would it work in the real world? I quickly ordered the various bags from the least expensive sources I could find and waited patiently for the deliveries.
While I waited for my touring luggage to arrive, I installed a few upgrades to the new Brompton. The old foam grips made way for a pair of Ergon GP2 grips and the basic Brompton padded saddle was replaced with a black Brooks Cambium C-15. I also mounted a new Sturmey-Archer 3-speed SLS30-T Thumbshifter to replace the ancient Torpedo shifter. The Torpedo shifter was in “like new” condition but it just felt flimsy
The third step on building the ultimate travel bike was completed.
After a long week of waiting, the bicycle luggage arrived and it all fit together perfectly.
I just love it when a plan comes together!
I took the bike out for a fully loaded test run to the top of the island and back down the opposite side. It functioned flawlessly. The motor thermometer only reached 74C and the tiny lite-weight battery pack carried me for over 12 miles which is pretty good for a 5.4ah battery on steep inclines. The only problem I encountered was some heal strike on the Brompton Rack Pack but I was able to eliminate all of it by adjusting my SPD cleats to the two back holes which moved my feet forward on the pedals. After that I actually tried to clip the bag with my heals but could not. As always, I have included photos of the build below.
Hub Motor & Controller on Fender
EZ Wheels for folded rolling
5.4ah Battery “LIGO” in T-Bag
Motor Controller mounted on Fender
Bottle Dynamo & 6 Speeds
Ergon GP2 Grips
Cycle Analyst showing Temp
4 Bag Touring System 67.5 Liters
Brompton Fully Loaded
Crystalyte Motor & Tannus Tires
This is an electric touring bike which can be legally flown on commercial airlines including the batteries (under 100 watts each). It folds down into a very compact package which can be transported with no additional fees. When unfolded and luggage attached, it is capable of carrying a complete touring outfit including tent, sleeping bag, sleeping pad, camp stove, pots & utensils, clothing, electronics and food. The ride is comfortable and the peace-of-mind that comes from puncture proof tires plus the ability to carry the bike with you and out of harms way cannot be over emphasized. This could be my new go-to bike.
I started this bicycle build with a new Surly ECR frameset which I commissioned Bilenky Cycle Works in Philadelphia, PA to retrofit S&S couplers to. Then it was sent out for a custom metallic black powder coat and then shipped to me ready for the build. Next I installed a Chris King headset and Shimano XTR BB90 Hollowtech II bottom bracket. Adding Thomson Elite X4 stem and Jeff Jones H-Bar Loop handlebar came next along with a Rohloff speed shifter and Avid Speed Dial 7 brake levers. I used a Thomson Setback seat post with a Brooks Cambium C15 vulcanized rubber saddle for weather proof riding. Avid BB7 S mechanical disc brakes were mounted with 160mm rotor (front) and 180mm rotor (rear) and Jagwire compressionless cables. The drive train consists of a Rohloff 500/14 SpeedHub using a 16T cog mated to a Shimano SLX Crankset using a Surly stainless 34T chainring plus a Rohloff chain tensioner. The wheels were laced with black DB Wheelsmith spokes and nipples on black Velocity BLUNT & DUALLY rims. For a front hub I used a black Shutter Precision PD-8 6V3W dynamo with 36 holes. In the rear I used a black Rohloff 500/14 Hub also with 36 holes. I then wrapped these 29” wheels in a pair of Surly 29×3 Knard tires officially turning this bike into a 29+.
In June 2017 I added a new Xtracycle Leap longtail extention with Big Dummy racks & deck in the rear and a Surly 24 pack rack up front. A pair of Xtracycle X2 cargo bags and a Surly Porteur House Bag rounded out the cargo build. For lighting I used three dynohub powered headlights by B&M and a E3 LED Tail-light. The 29+ tires (3″ Knards) fit well within the Xtracycle Leap drop-outs, however, I had to DIY a couple of custom brackets to fit the width of the original ECR chain-stays. The overall build is a cargo hauling expedition beast which is capable of breaking down into three pieces for travel packing.
Rohloff Torque Arm Placement
Modification to Xtracycle Leap Frame
The assembled wheel in the Xtracycle frame.
Touch-Up Paint after Grinding
Chain-stay hardware assembled into bracket.
New DIY chain-stay hardware.
A Krampus build showing inadequate contact.
ECR showing areas to be reinforced.
Washer plates sandwiched between chain-stays.
Another view of the new plates.
Click HERE for complete build photos.
Here is the complete build list with costs.
SURLY ECR LONGTAIL CARGO BUILD
Manufacturer / Model
Frame and Size
• ECR – Size Medium $750.00
• S&S Couplers retrofit $600.00
• Custom Powder Coat (metallic black) $350.00
• Headset Chris King 1-1/8″ $150.00
• Shimano SM-BB70 Standard Bottom Bracket $26.00
• Xtracycle Leap Extended Longtail Frame $599.00
• Shimano SLX Crankset – FC-M552 $85.00
Crank Arm Length: 175mm
HollowTech II Spindle
• Raceface Narrow/Wide 38T Chainring $45.00
1 x Race Face Chainring Shims $10.00
• 2- Kmc Bicycle Chains “X-1 For Rohloff” $90.00
• Rohloff Chain Tensioner $85.00
• Jagwire Pro Mountain Brake Cable Kit $21.00
• Extended Brake cable for longtail $9.00
BAR – SADDLE – BRAKES
• AVID SD-7 SPEED DIAL BRAKE Levers $26.00
• Avid BB7 Mechanical Disc Brake Front and Rear $279.00
• Avid G2 Cleansweep Rh Disc Rotor Rohloff 180mm $59.00
Handlebar & Stem
• Thompson Stem Aluminum. 4-bolt face.
(10 degree angle, 120 extension, Black) $89.00
• Jeff Jones 660 H-Bar $125.00
• Shifter: Rohloff Twist Shifter
• Extended Rohloff Tandem Cables $25.00
• Grips: Ergon GC1 $30.00
• Brooks Cambium C15 Black $175.00
(waterproof cotton & vulcanized rubber)
• Thomson Elite Setback Seatpost $100.00
• Headlight – B&M HL Lum IQ2 Luxos B 70 lux $234.00
• 2- B&M Lumotec IQ Premium Cyo on Front Rack $216.00
• Taillight – E3 LED $136.00
• E-werk Dynohub Charger $207.00
• Anker External Battery $50.00
• Wiring harness for lights
(Schmidt part coaxial Fly type 1.9m w/con) $12.00
• Supernova gold plated wiring connectors $20.00
• Front Hub/Wheel: Precision dynohub (black), $290.00
laced to a 36-hole Velocity BLUNT rim (black)
with Wheelsmith DB 14-guage spokes (all black).
• Front Tire Surly Knard 29×3 $69.00
• tube Surly 29×3 $14.00
• Rear hub: Rohloff SPEEDHUB 500/14 TS DB OEM2 black $1710.00
36h ISO (black) laced to a 36-hole Velocity Dually
rim (black) with Wheelsmith DB 14-guage spokes (all black).
• Rear Tire Surly Knard 29×3 $69.00
• tube Surly 29×3 $14.00
• Surly Tugg Nut $40.00
• Ritchey 29er Rim Tape $10.00
• Shimano PD-M324 SPD Dual Platform Pedal $80.00
• Locking Axle Skewers $27.00
• Surly Porteur House Bag $120.00
• Surly 24-pack Rack Black $150.00
• Xtracycle Cargo Bags $250.00
• Thorn Accessory Bar MK1 $30.00
• Ortlieb Classic Saddlebag for tools (Black) $31.00
• Salsa Down Under Front Racks $65.00
• Water Bottle Cages x 4 $40.00
• Salsa Anything Cage $39.00
• Salsa Anything Bag $45.00
• Bike Buddy Fuel Bottle Rack $35.00
• Da Vinci cable splitters $37.00
• Extra cables for splitters $15.00
• steering tube spacers $25.00
• S&S FINISH LINE GREASE 20g $15.00
• S&S SINGLE SPANNER WRENCH $22.00
• SURLY Bolt-On Seat post Clamp $8.00
• Wheel Labor $70.00
• Bike Build Labor $50.00
Total Cost $7991.00
Here is the completed All-Wheel-Drive E-bike for use on St Thomas, U.S. Virgin Islands. St Thomas has some of the most extreme hills in the entire US. Elevations go from the Caribbean Sea at 0 ft (0 m), to the highest point: Crown Mountain (Saint Thomas) at 1555 ft (474 m). The island is only about 14 miles long by 5 miles wide so most of the land mass is vertical. If there ever was a need for an all-wheel-drive bicycle, this is the place. I completed this cargo bike build last night and took it out for the maiden voyage this morning. The Bafang BBSO2 mid-drive motor was used as the primary with pedal assist but whenever I encountered a really steep hill, I would throttle on the front hub motor in low gear to help pull me up the incline. This worked remarkably well and I was able to cruise effortlessly all the way to the top of St Thomas at a comfortable 12 mph without breaking a sweat. The front hub motor never reached temperatures greater than 52C (126F), which is well below the cut-off temperature. The small sine wave controller and cables fit easily into an Ortlieb saddle bag with plenty of room for a few tools and a spare tube. The front disc brake was a bit tricky. I had to dish the wheel to allow 10mm of extra space on the non-drive side to fit the disc rotor. Even after allowing for the extra spacing, the bottom caliper bolt needed two M6 washers to scoot the caliper out a bit so the rotor would line up correctly. This install takes some finessing and a good measure of cussing but the end result is worth the effort. I opted to run the twin systems from two separate battery packs for redundancy. In the event that I break a chain, I can always scoot back under front hub power and on long level trips the second battery gives me a total of up to 100 miles of cruising distance on a single charge.
Below are some photos from my ride.
Shift sensor to allow safe gear changes under load.
The Xiongda front hub motor measures 110mm over the lock nuts so a Surly ECR fork needs to be cold set out an additional 10mm. This is done by using a 12″ threaded steel rod 3/8″ in diameter. Fit the rod with four washers and four nuts to sandwitch the fork dropouts and then slowly spread the forks by turning the nuts on either side of the dropouts until it measures about 115mm. Taking pressure off the fork will cause it to rebound a short way so you might need to take it slow and experiment while spreading & taking measurements. The final measurement should be right at 110mm.
To keep the motor from twisting in the fork when in operation, a torque arm is needed. This is a snug fitting steel washer with an adjustable arm to secure it to the fork fender eyelet. The Torque arm takes the additional stress and saves your delicate dropouts from becoming rounded and stripped. Other items worth mentioning are 2m steel washers for the spokes.
The Xiongda motor has 3mm spoke holes but standard 14 gauge bicycle spokes are 2mm. You either need to get custom spokes cut in 12 gauge or use a small washer on each spoke.
The motor is laced with a 3 cross spoke pattern using 36 278mm 14 gauge Wheelsmith spokes and brass nipples.
The wheel is finished off by attaching a 6 bolt 203mm disc rotor and adapter*, rim strip, tube & tire. It is then fitted into the fork and the brake caliper adjusted. This step will sometimes need the use of extra washers as shims to position the caliper properly. Changing the angle of the fork will also change the angle the rotor meets the caliper so this area may need a bit more DIY attention.
* The larger disc rotor is used to raise the caliper higher on the hub for better clearance and also stronger braking.
After weeks of research and study on the various geared electric hub motors weighing under 10lbs, I settled on the Chinese xiongda 2-speed motor. Luna Cycles had this excellent motor custom modified to their specifications with a tiny 20 amp sine wave controller and a manual High/Low speed switch. The motor is compatible with 36, 48 and 52 volt batteries and weighs only 6.5 pounds. It comes with 36h drillings and is a mere 5″ in diameter. The hub is disc rotor compatible and has an automatic heat sensor which shuts down the power in the event that the motor reaches a dangerous temperature to avoid damage to the nylon gears or windings. It has an OLD of 110mm so I will need to modify a Surly ECR 29″ fork to accept the extra 10mm width plus I will be using a TORQ stainless steel torque arm to protect the dropouts from excessive forces.
I plan to lace this hub to a DT Swiss 545d E-Bike rim and operate it with a 52V 20ah battery with 50 amp continuous 80 amp burst BMS. This package seems like just the ticket for use on the new AWD cargo bike build. The bike will also sport a 750w BaFang BBS02 Mid-Drive motor running to a 10 speed 11-42t cassette and Shimano SLX Shadow M670 derailleur.
When completed this cargo bicycle will be available for sale through the St Thomas Bikesmith. All parts, materials and shop labor are also available as individual modules for your custom builds.
Continue to Part 3 Installing the Front Hub Motor
While testing one of my Surly ECR electric bikes on a very steep hill on St Thomas island, I slowed to make a hard left turn and during a quick acceleration I felt the front wheel lifting from the pavement. This caught me off guard and the bike continued to flip over backwards. Fortunately I was going very slow so I only sustained a few minor scrapes on my elbows and a scar across the back of a brand new Brooks Cambium saddle.
Since then I have noticed something interesting while riding different styles of long-tail cargo bikes. The long wheelbase of these bikes make them more stable on radically steep hills than a standard framed bicycle, although using a heavy rear hub electric motor on a cargo bike cancels out some of this stability. A heavy rear hub will cause a front wheel to lose traction on uphill climbs and therefore lose some steering control.
BionX D-500 Rear Hub Electric Motor
I found this to be true with the Bionx E-Bike system having a very heavy rear hub so for the past two years I’ve been experimenting with using the BaFang mid-drive motors on long-tail cargo bikes and have found them to be almost perfect for cargo hauling applications in hilly country. There was, however, one scenario which could use some additional thought. Hauling heavy items and/or an adult passenger up a very steep (19 degree +) hill still caused an uncomfortably light feeling in the front wheel steering. This is a two fold problem. The first is a weight issue. There needs to be a bit more weight on the front forks to keep it pinned to the pavement. The second is a torque & traction issue.
BaFang 750W Mid-Drive Electric Motor
At speeds around 8-10mph and under a heavy uphill load the BaFang mid-drives begin to heat up and slow down. I figured what I needed was a small auxiliary front hub motor geared low enough to handle slow assents without overheating to take the stress off of a 750W mid-drive motor and also have a high gear for matching cruising speeds on the flats. In essence, my idea is to build an AWD (2 wheel drive) cargo bicycle.
The next few blog posts will outline my AWD cargo bike build in detail including a few real life tests.
Continue to Part 2 Searching for a Double Speed Front Hub Motor
The tire clearance on a Surly World Troller frame is 26 x 2.75” which means it is possible to run any of the good 2.1” touring tires on up to some aggressive offroad styles just short of 26+. To be clear, the standard Surly Troll (non S&S coupler) has been re-designed to accept up to 26×3” tires if you’re looking for more of a semi-fat setup. Keeping the World Troller in mind, we need a strong set of rims which will also work with tire widths between 2” and 2.75”. It should have drillings for 36 spokes, be a welded rim and preferably be tubeless ready. The Velocity Cliffhanger is a very good rim choice. This is a 30mm wide rim which comes in four drillings 32, 36, 40 & 48. The 36 hole model also comes in Velocity’s reflective finish for positive night visibility. If you are opting for a Rohloff hub, make sure it is ordered with 36 holes. Rohloff hubs are standard in 32 or 36 hole. You want to go with the strongest wheels possible and it goes without saying, the hub drilling must match the rim drilling. If you are opting for a derailleur setup, any good 11 speed rear hub will do such as the Shimano XT 756A. You can go crazy with expensive sealed bearing hubs from White Industries, Hope or Chris King but I have ridden thousands of miles on a $50 Shimano MTB hub with no problems and you can rebuild these hubs yourself with a few inexpensive parts. As always, when ordering any hub make sure the drillings match your rim. The XT 756A hub comes in 32 & 36 hole drillings. Any good quality spokes can be used. I prefer either Wheelsmith or DT Swiss spokes in 14 gauge using 12mm brass nipples for strength. Alloy nipples are too soft and also have a tendency to corrode in the proximity of salty air. The wheel should be assembled and tensioned by an experienced wheel builder to be tight and true.
Dynamo Hub w/Disc
For the front wheel it is best to go with one of the excellent dynamo hubs which put out 6 volts and up to 3 amps of power at nominal speeds. Not only are these good for running the bicycle lights but they also will charge your cell phone, tablet and an auxiliary battery pack. Collecting the power of each pedal stroke by day will supply all your power needs by night and allow you to stay “Off Grid” for weeks at a time. The most popular of these dynamo hubs are the Schmidt SON28, the Shutter Precision PD-8 and the Biologic Joule 3. When choosing one of these hubs, be sure to check if it has a mount for the disc brake rotor and also has 36 hole drillings. Assemble your front wheel with the 100mm hub, Velocity Cliffhanger rim and 14 gauge spokes or have it laced and tensioned by an experienced wheel builder.
Auxiliary Battery Pack
There are many great adventure touring tires available today. The choice you make will depend on the type of terrain that you will likely encounter. If you plan to tour primarily on paved roadways or hardpack, a good choice is the Schwalbe Marathon Plus Tour tire in 26×2″. On-the-other-hand… if you envision getting off the beaten path and into the bush, the Maxxis Ardent 26X2.40″ or Schwalbe Nobby Nic 26X2.35 are good choices. Rather than running these tires tubeless, I like to use a thick tube with removable valve stem so I can put a few ounces of green slime sealant into the tube.
Schwalbe Marathon Plus Tour
This usually protects against all but the largest punctures and still allows the tube to be easily repaired and pumped up at the roadside. I usually carry two spare tubes in my tool kit when on long tours. I used the slime method with a pair of Marathon Plus Tour tires on the Southern Tier route and had no flats from the Atlantic to the Pacific.