An Ebike Story of Evolution – The 2WD

June 16, 2013

This story was written by Kingfish, contributing writer who is known for building bikes and doing epic 1000 mile +  rides on them.  Kingfish is a talented engineer and problem solver. This story is focused on the building of his magnificent ebikes, and not the rides themselves which is another story

I’ve always been a purveyor of All-Wheel Drive (AWD) systems and it probably comes from time spent off-roading with my cousins as a squirt. Both my uncles have 4x4s, and buggies, and ATVs, and on and on… When I grew up, ordered up my 4×4 truck exactingly from the factory. It pulls the moon! There’s just one problem: Mileage… which is in the ditch.

But damn I love the feeling of control and power at all wheels when conditions are dodgy!

When I set out to build my second electric bike in the winter of 2009, I ordered a full-suspension frame and two full ebike conversion kits (F & R rim brake) from Excited too when the packages arrived shortly after Christmas! But the Engineer in me couldn’t be repressed and I took apart a controller and the rear hub to see how it worked: They’ve remained that way since, although serving a purpose as a frequent model for measurement and contemplation.

Felt Compression Frame

Began with the 2009 Felt Compulsion-1 Frame purchased off of eBay for about $800 USD.

With only a front hub system left, my AWD ebike would have to wait, instead converting my 19-yro Specialized Rockhopper MtB into a Front-Wheel Drive (FWD): Rode it hard and aggressive right into the ground, lasting barely a year. Much was learned from this wild tangent, namely working through the um… “unique characteristics” of Chinese engineering, and applying mods along the way. Joining Endless-Sphere (ES) was immensely helpful with collective minds solving everyday problems, and especially rising to interesting challenges. For my part, I was on a mission to ride (pedal) from Redmond Washington to California and back – fulfilling a childhood quest.

For where I live in and around hills and forest and city, there was no hesitation: I desired a 2WD ebike because we have dodgy winter conditions that make it very difficult to get beyond this little Redmond hamlet up over the steep hills to work. Plainly my 4×4 could do it and I wanted that out of my ebike too!

As such, the first year (2010) was spent sorting out basic noob issues: Batteries, charging, charging in the field, packaging batteries into ever-increasing assemblies, controller mods for more power, try every tire, every seat, every light, every gadget, every garb, and even every helmet. By Christmas, the MtB shocks were blown out – and without parts I finally made the move to the Felt Compulsion frame.

Kingfish Chilly Hilly

“P0” started out as a 1991 Specialized Rockhopper conversion. The variant above was used for the February 2010 Chilly Hilly event with two battery packs and a range > 75 miles.

Being completely new and late model there were lots of great choices for building up what has become my favorite bike to date. It started out as a leggy FWD pony with the over-sized frame adopting every electrical component from the previous ebike. Although I took the path of rugged aggressive urban assault very seriously and embraced new disc brake versions of the same 9C 2806 hub motors, ordered about February though arrived late May of 2011. That delay put a crimp on the summer schedule.

Sidebar story: In the first year – 2010, I ran out of time for my California challenge trying to assemble the full-suspension ebike. With no time left I used the FWD Rockhopper instead, threw it onto Amtrak in Seattle – riding it down to Klamath Falls and saving 4 days. Over the next two weeks, I traversed 458 miles over 3.5 days in the saddle down to Sacramento and then caught the midnight train back to Seattle. The trip was a partial success, although the hardtail frame beat me to death… and I swore never to wear a backpack again.

Back to 2WD build: The 2011 trip to California would require extra planning and capacity so I built this custom trailer using a “jumper” style BMX bike frame with a pusher RWD motor; together I’d have this “push-me pull-you” system. You think 6 months would be enough time for planning and assembly, but the last 6 weeks was intense, working from sunrise to 1 AM trying to finish it up. Finally, all appears ready, committed to leaving, jump on the bike, hit the throttle – and nearly died from the torque and oscillation that was running through the frames. Failure: Back to Square One.

The delay to re-engineer fixes cost about 3 weeks, though solved the basic problem by moving the RWD onto the bike – thus creating the original 2WD dream! Other issues were corrected as well: When you have a bike & trailer loaded up with 100 lbs. of LiPo and tools and supplies and clothes and food… well it gets pretty heavy and that load has to be placed precisely otherwise the slightest wind or divot in the road can cause a spill. Fortunately I live in and around one of the steepest plateaus of the region and was able to model progressively larger loads, learning how to drive it at the same time, discovering the tipping points, and the limits of both man and machine. Make no mistake – that bike was loaded to the gills, and then I headed on down the road to California leaving Redmond about Noon – in the rain.

ebike opportunity charging

P0 Opportunity-charging beside a vending machine: July 1st, 2010 – my first road trip to California and ran out of power.

I didn’t get very far before thinking this was a crazy mad idea and by the time I reached Renton 30 miles away I was certain I was crazy! At least the rain quit. But from then on, like emerging from under a cloud, the sky brightened as did my disposition, and the Great Experiment proceeded to unfold mile after mile beneath two electrically driven wheels. Not without a hitch; there were constant problems and some critical fixes along the way. Several kindred Friends of ES gave safe harbor to my passage and provided illumination, as well as timely adjustments to my ride. Without that, I certainly would have failed.

The power afforded by 2WD is incomparable to single-wheel of similar measure because there are two wheels turning against the ground, digging in traction, and moving the bike forward. As Samwise Gamgee said to Frodo Baggins in LotR: “Share the load!” And that’s what 2WD does: It splits the load between two motors, it divides the heat of strain – and the motors run cooler because of it. Now we can apply more power, climb hills faster without fear of sag or roasting wires, and we don’t have to pedal as hard. When the road becomes really dodgy, we’ll have two wheels pulling us through the muck. Don’t get me wrong, single wheel drives have their place: They get better economy, they are simpler to install and maintain, and the cost is about ½ as much.

The 2010 road trip had all the single-wheel benefits described above as well as the issues, especially the heating problem. That bike, counting myself weighed about 350 lbs. plus 33 lbs. of LiPo. For 2011, the load was closer to 450 lbs. with 100 lbs. of LiPo. By the end of that trip I had traveled 2515 miles over 28 days, exceeding the official world record by 600 miles. It was tense and stressful at the beginning, though by the end I had mastered control over this heavy assembly using feather-light touch… literally finger-tips to maintain balance. It was an engineering gamble as much as a personal journey and an adventure, with thrills, chills, happy smiles and frights all rolled up. Every day you meet someone new from all walks of life who want to know more about your odd-looking ebike. The rich unique experiences cannot be distilled easily, just as it is difficult to summarize the genuine contribution and help each ES member invested to see me onward. The coin of friendship and camaraderie in this field of study is the best symbol of wealth I have ever collected.

kingfish ebike

P0 on the road, July 3rd, 2010 about midway through the Sierras pausing to review relics of the past.

I have only told part of the story about this ebike.

There was in fact a profound opinion held in my circles of discovery that the pursuit of 2WD “is flawed”, that Rear-Wheel Drive reigned supreme in all forms now and forever. Learning how to coax both motors to cooperate thus was a tangled affair with experience gained in fits and spurts. The biggest challenge was unifying the controllers and instruments. Initially I had a Master-Slave arrangement where instruments went to the primary controller and the slaved controller got what was left. The connections in-between were crude, exposed to the elements, and perhaps under-driven. To make matters worse, the cross-over cable between the controllers was placed directly behind the seat-tube and directly in front of the rear fender with a good deal of dirty overspray.

Assuming knowledge of the preceding year – it is by sheer luck that I was able to complete the 2011 road trip! Two pesky motor issues dogged me the whole way: The first was “contention”; where one motor works against the other. The Naysayers said it could not be resolved using my techniques, however it was managed by making the two wheels different sizes (26” on the front, 24” on the rear), by programming slightly different power outputs with the front down-rated by 10%, and by fortune of environment where rarely was the land level and without wind. Using Cruise Control effectively self-managed load to the wheels: One motor hanging back and contributing as needed.

kingfish electric bike

P1 as FWD with an early version of the front fairing. I was at a Teriyaki restaurant when a man entered and said “Who owns that ebike?”. I waved so he comes over and says “I understand the model name is “Hot Wheels”, but who’s the manufacturer?”

The second and much more annoying problem was loss of power during hill climbs on twisty roads. The rear hub tended to drop out when load reached a certain level… not on a straightaway, but when turning up a winding road – like Hwy 1 along the west coast. The solution was not simple and would have to wait until summer of 2012. Indeed, I cataloged a list of fixes, but the worst developed two months after returning to rainy Redmond when both of these new motors rusted out solid by mid-November 2011.

Imagine Oliver Hardy saying: “Well this is another fine mess!” How is a person living in the Pacific Northwest supposed to get on down the road if their motors rust right out? Instead replacements, I set out to correct the obvious production flaws. The heart of the issue is that Chinese manufacturers cut costs and didn’t bother to varnish iron stators like you’d normally expect with an automotive starter or alternator. Not the case here: When the motor becomes hot, pressure builds and vents; when the motor cools, water vapor from rainy conditions wicks back in creating Amazon-like conditions which precipitate rapid rusting and ultimate failure. The problem was solved during spring/summer of 2012:

Began by with discussing the issue with my local body shop and they suggested using a product called Rust-Mort which has a high-concentration of Phosphoric acid. Applied in thin coats, the thick acidic gel penetrates rust, converts it into Iron Phosphate crust which is easily removed, and finally seals the surface in preparation for immediate varnish of which several light coats of automotive-grade were applied. Scale on the inside of the Aluminum covers was blasted clean and a set of weep-holes was added along the perimeter so any new moisture would have an exit route. Finally the cheap low-end bearings were replaced with top-flight high-speed stainless steel, with new seals, and upgraded the phase wires to 12-AWG. In brief –the condition of the motors was revised from “dodgy low-end” to “high-speed high-torque and all-weather”.


Beneath the skin: P1 in July 2011 displayed without fairings during conversion from FWD to 2WD.

Moving into summer 2012, I replaced the troublesome Master-Slave controller arrangement into one of equal paring; both controllers were replaced with late models and modified identically, ripping out the redundant GND wires of instrumentation and unifying into one connector (leaving Cycle-Analyst and Programming leads unaffected). In addition, converted the Hall Effect wires to USB, the APP Battery connectors to high-current EC5, and the APP Phase wire connectors to HXT 4mm.

The 2012 upgrades solved two issues: First, removal of the problematic Anderson Power Poles (APP) – the source of charring and melting and highly resistant connections, and second, redesign of the entire battery harness from 10-AWG to Marine-Grade 6-AWG wire with stringers of 8-AWG to each battery assembly. This work greatly increased integrity of power throughout by simplifying connecters and the count of connections, exchanged soldered joints for copper-swaged, and lastly – by lowering the resistance of the harness for higher throughput. In brief, the pesky source of sags was eliminated for the win.

The last item which gives this bike unique distinction is the fairing: It starts out as a funny story about my very first and second-to-last public bike event, which being the only electric bike – I won, although in truth it was not a race. Anyway, they assigned a “number plate” which I stuck on the front and I liked it so much that I kept it for bragging rights… but then I noticed a slight improvement in mileage. In those days the battery pack wasn’t large so it was easy to spot a couple extra miles when you only get 20 off a charge. On a lark, I created a body-fairing from HDPE for the MtB when I took it to California that summer in 2010. I really liked “the look of it” and decided in the fall season to add a front cowling, sort of a rain and wind deflector if you will. Again mileage improved 5 or 10%. About that time I crafted a custom battery bag for the triangle space which could hold a large array of batteries and extending range to about 50 Seattle miles. During the rainier season of winter the pack was getting wet, so I fabricated a water-resistant shell using a combination of marine vinyl and HDPE. This gave the ebike a very distinctive sleek look and was easier to keep clean.

kingfish ebike and trailer

P1 as 2WD with trailer (“P2”) on July 26th, 2011 – the first day of my 2nd road trip to California.

The full-suspension frame had a larger triangle. During the transition from FWD to 2WD I changed the pack from 10S (52V) to 15S (63V), and moved the controllers to reside behind the seat on the rear bike rack. The front fairing was then redesigned to be more aerodynamic. For the round-trip to California during the summer of 2011, I created an aerodynamic-looking trailer that was more egg-shaped with larger-end at the back for drag; the bottom of the trailer was completely flush, covered by a sheet of HDPE. The stability was most profound bombing down west on Hwy 88 from Carson Pass into Jackson California at 44 mph! After that second Cali trip I became more interested in speed: The 2012 rework greatly improved the top end from 38 mph to 47, and the latest fairing changes included more side-panels and flaring around the rear wheels. Right now it can coast faster downhill without pedaling than a roadie in a crouch! Let’s not forget this ebike experiences parasitic drag from two hub motors, so without question the fairings are a real boost to performance.

In all this talk about the bike, I forgot to mention charging: I started out with a 150W charger which is fine for a kit battery but not for cross-country. In summer 2010, I crafted a 350W Meanwell assembly but the 10S18P battery took nearly 12 hours to recharge. I didn’t want to go through that again, so for summer 2011 with the pack at 15S26P built a new 1kW Meanwell assembly and got those numbers down to about 8-9 hours. I’ve charged both at home, in motel rooms, and opportunistically. On the Road, I prefer to charge during downtime – like sleeping, and do so without fear. I also run without a net: No BMS. Instead I prefer to manually balance as required through occasional monitoring. I know what I built, and like an old friend I’m comfortable with it.

Finally I’d like to close by saying “Work always continues”; the refinements never stop. They say that “necessity is the mother of invention”. Well… I drive nothing else, and I am constantly thinking of things to fix or invent. The 4×4 remains on blocks collecting dust; in a couple more years I’ll be able to register it as a “classic”. In the meantime, the 2WD ebike has proven to be more fun and healthy, and not only that – but I get a kick out of it!



P0 – FWD

kingfish ebike

P0 back in December 2010, just before the front shocks blew out. Schwalbe Marathon Winters held up well.

Frame: 1991 Specialized Rockhopper hardtail w/ original Rockshox, code named “P0”. Retired December 31, 2010.
Key features: Fairing, brake lights, good speed and range, “yellowjacket” theme.
Weight (before/after): 31 lbs/60 lbs. For the 2010 Road Trip: About 190 lbs. sans rider.
Largest Battery: 10S18P LiPo, 52V @ 90Ah/4680 Whr.
Fastest Speed: 47 mph downhill on cross-country. Preferred: 28-32 mph.
Range: Farthest was about 175 miles – mainly downhill from 5,500 feet to sea-level using a 10S18P pack + opportunity.
Motor: 9C 2806 FWD rim brake, programmed to 1.5 hp. Highly modified 36V 6FET controller.
Estimated Cost: > $2800 with a commuter pack of 10S8P.


P1 – 2WD

kinfish ebike 2wd

P1 with sporty fairings and saddlebags in April 2013 just before swapping out the winter tires. Range was about 60 miles at 35 mph; with warmer weather gear – up to 100 is possible.

Frame: 2009 Felt Compulsion-1 F/S bike, codenamed “P1”. Born on January 1, 2011.
Key features: 2WD, full-suspension, better fairing, full indicators, trailer, hill-climbing, speed and range, B&W “orca” theme.
Weight: about 110 lbs. 2011 Road Trip w/ trailer: Between 240 to 290 lbs. sans rider.
Commuter Battery: 15S6P LiPo, 63V @ 30 Ah/1890 Whr. Optional Saddlebags add 67%.
Largest Battery: 15S26P LiPo, 63V @ 130Ah/8190 Whr. About 100 lbs. with trailer.
Fastest Speed: 47 mph on a flat; > 50 mph downhill. Preferred: 30-35 mph.
Commuter Range: > 50 Seattle-hilly miles, about 100 w/ Saddlebags.
Farthest Range: With trailer, 167 miles on a single charge, and 187 miles with opportunity.
Motor: Modified 9C 2806 F&R Disc brake, programmed to 2 hp each. Highly modified 100V 12FET controllers.
Estimated Cost: > $5000. Add $3500 for cross-country pack and trailer (+ 150 lb. capacity).


  • 2009 September: Search for ebikes and kits begins. Ordered in December.
  • 2010 January: Converted Specialized Rockhopper MtB as FWD 37V 10 Ah LiFePO4; range is about 22 hilly miles with the wind at my back. Max speed was about 24 mph.
  • 2010 May: Upgraded to 10S10P LiPo, completed my first electric Century in preparation for cross-country, and repeated the feat again in June.
  • 2010 July: First cross-country trek, from Klamath Falls to Sacramento, 458 miles total
  • 2010 Fall: Built custom battery bag, front and battery bag fairing. Mounted studded tires in November. Commuting 35 miles daily.
  • 2010 Dec 31st, retired FWD Specialized Ebike. January 1st, 2011 – Felt Compulsion Ebike born as FWD.
  • 2011 Spring: Parts ordered for summer road trip, including custom trailer. Assembly begins in May.
  • 2011 July: Felt Compulsion Ebike converted to 2WD; July-August on the road to California and back – 2515 miles in 28 days.
  • 2011 Fall: Commuting 50 miles daily to Seattle. By November both hub motors rusted out solid.
  • 2012 Spring: Fixed hub motors. Inched back into riding again with lots of mods planned.
  • 2012 Summer: Replaced entire Battery harness and connectors. Replaced controllers and entire instrument harness.
  • 2012 October. Replaced front fairing, added new side fairings. Set new personal speed record at 47 mph on a flat. Phatty studded tires mounted in November.
  • 2013 Present: Upgraded saddle bags to EC5 connectors to allow for century rides. Replaced kluge fenders. Planning next mods and trips.

Click here for complete information about these bikes – and more.
Safe travels, KF

Eric has been involved in the electric bike industry since 2002 when he started a 6000 square foot brick and mortar Electric Bike store in downtown San Francisco. He is a true believer that small electric vehicles can change the way we operate and the way we think.


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