DIY Recumbent Electric Bike

The following story was submitted by Roger Kaza of St. Louis, Missouri, and is a great narrative on how an electric bike can transform your life into something healthier and funner–while saving money and being greener.

I’ve been a bike commuter for most of my life. Whether for school or work, it’s always been my goal to live close enough to make the trip on two wheels. But a few years ago my family moved to the suburbs of St. Louis, Missouri so that our daughters could attend good public schools. Now my commute became a hilly 25-mile round trip, with several congested intersections en route. I tried biking it a few times, but quickly realized this wasn’t going to be something I could sustain on a daily basis…too stressful, too far. But what if the hills weren’t an issue, and I could keep up with the traffic in the bottlenecks? I had sketchy acquaintance with electric bikes at the time, but a hunch told me it might be worth investigating. After a couple months researching online, I made the plunge and converted my old recumbent bicycle to a recumbent ebike.

Why a recumbent bike? I’d been riding “bent” since 1989, after seeing a cool picture of one in the Sharper Image catalog. The bike was a Tour Easy, made by the legendary Gardner Martin of Easy Racers Cycles. His bikes had won the DuPont prize for breaking the 65 mph speed barrier, and one of them hung in the Smithsonian Air & Space Museum in Washington, DC. Gardner’s recumbent design is known as LWB, or long wheelbase, with the pedals placed between the wheels and slightly below the seat. This allows a comfy upright sitting position, an extended frame geometry that is strong yet flexible, and a splendid view of the road.

Riding a recumbent has a different feel than an upright bike. Although you can’t stand on the pedals, you do gain tremendous leverage pushing against the seat back. There’s no pressure on hands or crotch, and no chance of getting thrown over the handlebars in a sudden stop or emergency. Your feet are always near the ground…you can even execute a “Flintstones”-style stop if the brakes aren’t sufficient.  Gardner’s bikes are also speedy machines, thanks to their sleek profile and the aerodynamic fairing surrounding the handlebars. Unlike some recumbents, however, the LWB Tour Easy isn’t an ultra low-rider, so motorists can still see it easily. I use a flag or safety triangle for extra visibility.

When considering the e-conversion, I first looked at a mid-drive system, Ecospeed, which specializes in recumbent conversions (as well as upright bikes.) It appears to be well-designed. But it was pricey, the motor mechanism quite obvious, and I had heard that chain drives, for all their advantages, could be finicky. So I decided to first give hub motors a try. Deciding between front and rear-wheel drive was a no-brainer: recumbents, especially LWB recumbents, tend to be rear-heavy to begin with. Also, I planned to load up the rear rack carrying my French horn and other gear (I play music for a living.)  So, putting the motor up front was an obvious choice.

Ecospeed mid drive gear system is a popular choice among recumbent and cargo bike riders.

What about geared vs. direct drive motor? I needed torque for hills, and wanted to be able to pedal without drag when the motor was off–a drawback with direct-drive motors. Speed wasn’t a huge concern. So I chose the BMC V2 hub, a geared hub motor with a 5:1 reduction. BMC makes two versions of this motor: the V2-S for speed, and V2-T for torque, assuming laced into a 26” wheel. But since the hub was going to be put into a 20” wheel, I would automatically be gaining extra torque, while sacrificing a bit of top speed.  So the V2-S model was a perfect compromise. (Note: the V2 is being phased out and replaced with the V4.)

The motor controller is a BMC 18FET 36-59 volt, 35-50 amps. My seller limited it (via its internal shunts) so it draws a maximum of 30 amps. My battery is a Chinese-made 10 amp-hour, 48 volt Lithium Iron Phosphate (LiFePo4) pack that came as an option with the BMC kit.  (Unfortunately, someone scratched out the manufacturer’s name. A 15 ah battery of the same make is available here.) I opted for 48 volts instead of 36, because the 600w BMC motor easily handles higher voltages, and, knowing as little as I did about ebikes, I didn’t want to take a chance this bike might be underpowered! The battery is rated at 3C, or 30 amps maximum continuous draw during operation. Since the BMC motor can take more current than that, this is probably underpowered. But there wasn’t quite enough room for a larger battery in the frame, and I wanted to keep weight to a minimum.

The Controller is mounted behind the front wind shield.

The battery sits in a custom-fitted tray made of 16-gauge sheet metal. I made the tray using a $38 bending brake from Harbor Freight Tools, a saber saw and drill. It was a very easy task, and cheaper than hiring someone to fabricate it. Painted red and cushioned both top and bottom with closed-cell foam, it holds the battery securely with a couple Velcro straps. I mounted the tray (with zip ties and hose clamps) to the horizontal frame tubes adjoining the bottom bracket. This keeps the weight low and centered. I shortened the discharge cord on the battery to about 6” and attached Anderson terminals. (Be very careful of shorts if you do this…52 volts DC!). These terminals mate with another set of Andersons anchored to the bike frame and wired to the power train. The battery can thus be easily removed for recharging away from the bike. (Another good place for batteries on a recumbent is in shallow panniers hanging from an under-seat rack.)


The throttle is a Crystalyte full-length ¼ turn. (A couple wires must be switched so it can work with a BMC controller.) One nice feature of this throttle is that it comes with a matching grip for the left bar. In my experience, a full-length throttle is superior to half-length or thumb throttles. I reversed my derailleur thumb levers, so that the left lever now controls the rear derailleur and can be shifted while the right hand is operating the throttle. I almost never change the front derailleur, but often adjust the rear, depending on my speed and the terrain.

The Cycle Analyst computer, stand-alone model, is mounted on the center strut of my handlebars, a perfect spot. The motor controller attaches with hose clamps between the Tour Easy’s chopper-style handlebars. It’s protected from the elements by the fairing, yet still receives good air circulation. My supplier had wired everything pretty much ready to go, including an On/Off toggle switch that I super-glued to a joint in the frame. The wire routing needed a bit of organization, so I used zip ties to keep it all together. The last detail was securing a torque arm from the hub axle to eyelets in the fork to prevent motor spin-out.

So: how does it ride?  Well, let’s just say that, from the moment I hit the throttle, the notorious “ebike grin” appeared on my face and has never left!  Actually, it amazed me how well the conversion turned out. Having extra mass up front on a LWB recumbent seems to improve the handling, by balancing the forward/aft weight distribution.  The bike feels stable and solid, and tracks wonderfully. The speed?  On my test ride I immediately accelerated to 26 mph with no pedaling; later, after mounting the fairing, it increased to 28. That’s not a speed demon, but plenty fast for my commuting purposes.  My main concern was hill-climbing. I’d heard stories of hub motors stalling out on hills. Not this bike! I have yet to find a hill that defeats the BMC motor. What I find is that I naturally slow down a bit, climbing hills at around 18 mph while pedaling in a lower gear. Trying to go top speed up a hill immediately maxes out the amp draw to 30, the limit on my battery. So I watch the Cycle Analyst and try not to goose things for more than a moment. This is kinder to the motor as well.

I ride my ebike as I would a regular bike…I pedal harder on the hills, but I pedal along at all times anyway, striving for an organic meld of human and electric power. I love cruising between 20-25 mph.  It feels normal and bike-like at those speeds. (The average speed in the Tour de France is about 25 mph.) Of course, going down steep hills the bike easily hits 40 mph. Practically speaking though, the e-assist merely evens out the average speed: hills and headwinds are no longer issues; quick starts at intersections are a piece of cake. The “all-wheel” drive is a nice perk, and traction is quite good. An interesting ergonomic gain: having a front wheel that pulls the bike has the counter effect of pushing you against the seat. This gives even more leverage for pedaling, especially uphill, and also contributes to a secure “grounded” feel.

Some advantages over a non-motorized recumbent: the ebike keeps up with traffic in congested conditions. You can “take a lane” and not feel squeamish about it.  At stops you can accelerate just as fast as the cars, eventually moving to the right if warranted, or just staying put. In unexpected situations, such as a light suddenly changing, “gunning” it gets you out of the way much faster than your pedals ever could. Going uphill, you can track a much straighter course at a faster speed…recumbents sometimes have steering issues at extremely low speeds. Overall, in the urban/suburban road environment I feel safer on the ebike than I do on my non-motorized recumbent.

About the only minor downside to a front hub conversion is having so much unsprung weight on a 20-inch wheel. Bumps and potholes are more jarring than they would be with a non-motorized wheel. This definitely isn’t an off-road bike…I try to stay on smooth roads whenever possible!  [UPDATE: the bike recently suffered front fork failure at the steer tube section…the part which connects to the handlebar stem.  While I’m a bit concerned about this–and what it implies for front-drive ebikes–in fairness, the bike was 23 years old, and probably should have had the fork replaced long ago. I’m replacing both fork and stem, and fixing the brakes while I’m at it.]

A few technical lessons learned: Midwest winters are challenging for a LiFePo4 battery.  Best not to use it if it has been sitting in a 20°F garage all night…there will be considerable voltage sag and you may even damage it. So on cold nights I bring it indoors. As long as it starts the ride from a warm state, it’s okay to use in cold temperatures. Hot summer days can also be an issue, and I notice voltage sag when the battery gets warm.  Park in the shade!  Battery temperature issues are of paramount concern to electric car manufacturers such as Tesla, who have integrated sophisticated cooling methods into their design.

I apparently stressed out my first battery, possibly by drawing too many amps continuously, or discharging it too deeply a couple times. For whatever reason, after just a few months it began holding only 4 amp hours of charge. Possibly the cells were unbalanced; my supplier just decided to replace the battery so we never found out the cause. Now I am careful to recharge it after draining 6ah at most, and often less than that. (Shallow discharges are a good idea for LiFePo4 batteries.) For my style of riding, 6ah equates to about 25 miles of range. That’s not a lot of range, but for city biking it is usually more than adequate. I keep an extra charger at work so it is fresh for the ride home. Sometimes I take one with me if I am going to a remote location.

A couple times I apparently tripped the motor controller’s low-voltage cutoff, or else the BMS (battery management system) in the battery. On these occasions, the only thing that seemed to reset things and get the motor running again was to arc the power leads by removing and reinserting the inline fuse while the power was on.

My biggest problem occurred after foolishly leaving the bike outside during a heavy rain. Water got inside the hub motor and it started making odd clicking noises, eventually stopping altogether. Before accurately diagnosing the problem, I did some troubleshooting over the phone with the very helpful Ilia Brouk at We tested the Hall sensors, tried swapping out the throttle and the controller, all to no avail. I eventually just sent him the wheel. He dried it out and replaced the clutch with the new V4 model, reputed to be more reliable.  Since then everything has run fine.

With optional passenger seat, Roger’s recumbent is able to double the fun.

One great perk of an ebike is when pulling a trailer or trailercycle…help is at hand with all that extra weight, especially on hills! But since there isn’t a seat post on a recumbent, the attachment of the trailer must be to either the rear chainstay or the rack. The Burley Piccolo, for example, a geared “tag-along” type trailercycle for kids, attaches to a special rack with a fixed nut in the center. The Burley works fine on a recumbent as long as you’re not going too fast; at high speeds it sometimes gets wobbly. What works even better than the Burley is a sidecar I designed from EMT electrical conduit, steel rod, and a 16” wheel. The sidecar adds stability to the ride, transforming the bike into a sort of trike.  Your guest sits to your right, and the seat is big enough so that even adults can fit. It attaches with four hose clamps in about a minute. Kids love the sidecar…it’s cool! We’ve even gone riding with both the tag-along and the sidecar attached…family biking on one bike!

I’ve outfitted my bike with Planet Bike fenders front and rear…essential on a recumbent (unless you don’t mind being sprayed from wet streets!) For lighting, I installed the blindingly bright 1000 lumens Cycle Luminator headlight, which runs on a wide range of voltages and uses the ebike battery for power. A Terracycle mount allows the light to sit in front of the fairing. Taillights are the 1 watt Radbot, set on continuous, and the dual-light Princeton Tec Swerve, set on flashing mode.  I’ve followed the bike at night and it lights up like a Christmas tree.  You are not going to miss this thing, no matter how sloshed you are!

With all my additions, the bike weighs in at over 70 lbs. Hardly a featherweight, but still light enough to carry down a few stairs or lift on to a car rack. Removing the battery during transit saves about 10 lbs.

What could be improved?  The brakes. My 20 year-old recumbent came factory-equipped with side-pull caliper brakes in front, old-fashioned U-brakes in the rear.  But with all the added mass and extra speed, it really needs disc brakes, or at the very least some good V-brakes.  My plan is to braze on mounts for front V-brakes or cantilever brakes.

So, to sum up, after about 18 months of riding, my bike feels pretty close to the ultimate urban green commuting machine.  It wasn’t a cheap conversion; I probably spent close to $2500 for everything described above.  In addition, the Tour Easy alone costs between $1500-2500 new, depending on whether it is a Taiwanese or California-made model. (On eBay they can often be picked up used for much less.)

But the savings and benefits have begun. Instead of $2.00 in gas every trip, (on a 40 mpg hybrid car!) I am spending about 5¢ in electricity. (Ebikes may be even greener than regular bikes, according to this study.) The moderate exercise wakes me up in the morning without drenching my clothes in sweat. You can obviously keep pace with fittest of road bikers, no problem, though it’s kind not to flaunt it! (I usually tag behind a car while passing them so as to appear more moped-like.) Hauling heavy gear…not a problem. The “weight obsession” disappears. You can park a bike anywhere.  (I sometimes lock it, but recumbents usually aren’t tempting bait for thieves.) The pluses go on and on, and no minuses so far. Mainly I’m enjoying every moment of every ride: the outdoors, the light, the wind, the sights, sounds and smells of every season. And getting lots of attention everywhere I go, both for recumbents and ebikes!

In this picture you can see the Cycle Luminator and front BMC motor.

Which brings up a final challenge of my project, and one I hadn’t anticipated: although there was plenty of room in our garage for the ebike, in my mental parking lot I had trouble at first knowing where it fit. Why? Because the decision had always been either-or: bike, or car? So now…a third choice? How does the ebike fit in? Easily, it turns out. For any given trip, if it’s a toss-up between my regular recumbent and the ebike, I go with the regular bike. Why not? Bicycling is great exercise and the simplicity and lightness is wonderful. I have no problem whatsoever switching between the two; one is just slower and more strenuous than the other. But, if the choice is between my car and the ebike, I go with the ebike…the car suddenly seems like enormous overkill just to get a single human from point A to B. So my car is reserved for long trips, trips with passengers, inclement weather, or for hauling large cargo. Sometimes it sits in the driveway for days at a time.  I fill it up maybe once a month, if that.

The ebike bridges the gap between personal wheels with too much oomph, and…not quite enough. It is truly “appropriate” technology. I believe it will become the commuting vehicle of the future.



Recumbent FAQ from the Hostel Shoppe.

An interesting video about water issues in hub motors, and possible solutions, by Justin Lemire-Elmore, the genius from

Easy Racers now offers their own mid-drive electric conversion kit, though apparently for intrepid tinkerers only.

Two Engines of Our Ingenuity radio scripts by the author, one about the history of recumbents, the other on hub motors.

Interesting YouTube video of 8000 watt electric recumbent for the hot rodders:

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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