Recently I got hold of a new e-bike drive system to test out on my cargo and kid carrying Surly Big Dummy.

The motivation is that for myself and many out there using cargo/sports utes, we sometimes have big loads strapped to our bikes, and in a place like Chapel Hill, big hills to climb with them.

That taxes the standard electric bike hub motor system. Some can handle it, but constantly pushing their limits may ultimately lead to failure.  ( the same can be said for one’s legs – which is why I use a an electric assist on my cargo bike).

One solution to this problem has been the Stokemonkey.  Instead of a hub motor, it uses the bike’s existing drivetrain – and gears.  So, when you’re climbing a hill with it and you shift into a lower gear to give your legs a break, you’re giving the motor a break too.  This increases overall system efficiency, and motor/battery system longevity.

But there have been two limitations to the Stokemonkey: limited supply (it is produced in small batches by our supplier in Portland, Or), and it only fits on Xtracycle-style cargo bikes.

A few brave designers have tried to crack this same nut with a system that doesn’t require an Xtracycle style frame.

The first was the Cyclone.  I don’t have any experience with that system, but have heard certain things that have put me off from trying it – mainly that the installation is very involved.

Now comes the Electric Mountain Drive from the folks at Ecospeed (also from Oregon!).

The Electric Mountain Drive system

It is another electric assist system that uses the bike’s own drivetrain, benefiting from the gearing on the bike to reduce motor strain and increase climbing ability.

I’ve been using it for about two weeks now, so this review is only preliminary.

Here are some benefits of the system:

• Because it uses the bike’s drivetrain, it can handle steep hills without strain (if I shift into the right gear)
• It mounted to the frame in a relatively straightforward manner
• It uses a standard electric bike brushless motor controller, so when the first one died (a note on that later), I was able to swap in an Infineon controller we had in the shop
• Using only a 36 Volt battery with a controller consuming 20 amps, the bike can achieve powered speeds of up to 25mph+ (depending on headwind and hills).  Most of the hub motors I’ve tested – even the high speed ones – can’t do this on only 36V 20A system.  For me those would top out around 22mph on the flats, pulling maximum amps.
• Its installation wasn’t too difficult, and the instructions were very detailed.

For certain kinds of applications such as steep hills to climb on a cargo bike without a spot to put a Stokemonkey, this appears to be THE solution.

But it does have a few drawbacks to be aware of:

• It is somewhat noisy.  It is not louder than the cars on the road – but not a lot quieter, either.  I like to operate in “stealth” mode on my local bike path so as to not get any of the other users upset that I’m using electric assist.  It is hard to do with the EMD, unless I just entirely leave the electric off.  That’s fine… except for that I’m usually in a hurry (note: I never, ever use the electric assist to exceed 20 mph on the bike path, and I always slow down for other users – doing otherwise would not only be rude, but would likely land me in trouble).  Also, the way it mounts on the bike makes it more obvious that the bike has some kind of motor attached.
• I found the overall system efficiency to be disappointing – which means that I can’t travel as far on a single battery charge.  When I used the eZee hub motor, I typically got 18 watt hours per mile or better (at 36V).  That meant I could do a 20 mile roundtrip with my 10 amp hour battery.  With the EMD system, I’m getting at best 24 watt hours per mile, reducing the range to around 15 miles.  I think there are three factors causing this: a) It uses a chain/gear system with a oneway clutch that may loose energy; b) Some energy may be lost in my Nuvinci continuous variable transmission; c) it is easy to go too fast with the system, which always sucks down juice very fast (any speed over 20mph on an e-bike is usually quite inefficient).  I’ve tried to keep the speed low, and still had poor efficiency.  At some point, I’ll try it out on a bike with a regular rear transmission using cassette and derailleur, to see whether that makes any difference.
• The first controller fried within only 1/2 hour of operation.  It turns out that the motor and controller are made by BMC.  BMC makes decent motors… but their controllers have a not so good reputation for reliability (we won’t sell them anymore after a failure rate of over 50%).  We replaced it with an Infineon, which has worked well so far (an is in general a very reliable controller).  To their credit, Ecospeed did send us a new controller right away, and it is a different design.  But it is still made by BMC.  I think I’ll keep the Infineon for now.
• It requires a bike with a circular downtube – the tube from the handlebars down to the pedals (many bikes these days have ovalized downtubes).  And, once installed, it does protrude down a bit.

Another attribute I noted that is neither plus nor minus is that to optimally use this motor, I had to get in the habit of shifting the bike appropriately.  This requires letting off the throttle a bit, doing a rapid shift, then getting back on the throttle.  At first it was a bit clunky for me – but just like learning to drive with a clutch and gearshift, once I picked it up, it worked well.  I have come to enjoy the challenge of shifting properly through an acceleration cycle to get up to speed.

Bottom line: The EMD will be a perfect solution for people who have big/long hills to climb, and provides a worthwhile alternative to the Stokemonkey, especially if the latter isn’t available or if it won’t fit on your bike.

My assessment is that hub motors will be better for the person who has moderate hills, long distances, or is concerned about noise.  Since I fall in several of the latter categories, I’m likely to return back to a hub motor system at some point.

Finding an ebike or kit can be a challenge in today’s environment. Everyone claims their kits and bikes are great, but how do you really know? If you research ebike kits on popular forums, like endless-sphere or V is for Voltage, you’ll get a wide variety of opinions, often conflicting. These forums are great and have a lot of useful information, but trying to sort the wheat from the chaff, so to speak, can be a real challenge!

When I was researching electric kits, I know how much work it took and how difficult it was to know who to trust. That’s why I decided to have an open door policy on questions, and make sure we provided the best information and answers we could, not just representing one vendor or brand of ebike or kit. I’ve had people ask all kinds of questions, both people buying their first kits, as well as those buying a second or third kit. Here are 3 common mistakes or misconceptions I’ve found many people to have.

1. Putting a front motor on a suspension fork

This is usually a big mistake. Most suspension forks are made out of cast aluminum materials. The aluminum is strong, but not flexible, and can be brittle. A rotating front hub motor puts a lot of stress at the fork dropout – the little U shapes in the fork that hold the wheel to the fork. Under this kind of stress, the drop outs can crack and break, causing your wheel to no longer be attached to your bike. You can imagine the consequences of this, especially if it occurs at high speed. If you are thinking of converting a bike with front suspension forks, it is recommended to go with a rear wheel motor.

Fortunately, steel is a more flexible material and less likely to break under stress. So putting a front motor on a steel fork is perfectly acceptable. I recommended adding a torque arm to these forks, which translates some of the rotational force to the fork arm, and not just the drop-out. With a steel fork, torque arm, and proper installation, a front motor is often a great solution, and results in a bike with “all wheel drive”.

2. Assuming a pre-built electric bike is higher quality than an electric kit

Many people in the market for electric bikes often assume that a bike that is made as an electric bike at the factory will be superior to an electric conversion kit. While ebikes are great solutions for some people (which is why we carry them), for some people, an electric kit could be the best.

The main differences between ebikes and ebike kits are in performance and style. Ebikes have the advantage of being designed around the electric system, so often come with built-in battery compartments, and low-profile, stylish designs. The ebike kits, however, are not integrated into your bike, so batteries are often carried on a rear rack in a pannier or bag, which some people don’t like, and there is additional wiring to run along your frame. One exception is the Bionx kit, which is well designed to fit very cleanly and look great on bikes with a triangular frame.

Another main difference between ebikes and ebike kits is in performance. Because ebikes are sold as a complete unit, they are often powered on the low end to comply with any potential laws about bike speed, and also to protect the companies from a liability perspective. Most ebikes top out at 15-18mph and provide pedaling assistance on hills, but won’t be able to propel you and the bike uphill on their own. Many riders can achieve 15-18mph under their own power, so the electric assist only helps on hills. (Sometimes that is all we need!). Ebike kits, however, are often higher power. Many of them have a top speed of 20-30mph, and have more climbing power. These kits are better performing for the rider who is looking for speed or who is carrying a heavy load.

And lastly, for some of the less expensive pre-built ebikes, the non-electric bike components are often of low quality, just like you would have on inexpensive regular bikes. This might be fine for the user who only rides the bike occasionally, but if you’re planning on using the bike regularly, you don’t want to pay a lot of money for a bike, only to have it start breaking and having to have parts replaced after a year of use. If you are in the market for an ebike, make sure you check out the bike component quality as well as the electric system, and be prepared to pay a little more to get something quality. Or consider converting a quality non-electric bike  using a conversion kit.

3. Buying a kit that is overpowered

Because most people do not have a chance to ride an ebike or ebike kit before purchasing, I find that many people want to get the highest powered kit that is available. When you aren’t sure if you can get up that particular hill you have in mind (which might be steep or long), it is natural to want to get the most powerful kit to ensure you have enough oomph. However, in many cases, the most powerful kit is overkill and you end up spending too much money and carrying around more battery or motor weight that is necessary.

An illustration of this phenomenon is what we saw with our BMC motors. First, BMC had a V1 motor (a “400watt ” motor) which is internally geared and has great hill climbing ability. Compared to pedaling up a hill without a motor, the V1 makes it so you can pedal moderately, as you would on the flats, and still climb up the hill. This was great and many people were excited.

Then along came the V2 motor, which was even higher powered (“600W”). This motor is for people who want high speed or high torque applications. It’s main advantage is being able to handle more power. This was fabulous and everyone thought it was “top of the line” and the best motor for xyz. The high speed motor is capable of speeds over 30mph even (that’s FAST for  a bike). Everyone was happy until…

BMC comes out with the V3 motor, which is supposed to be a 1000W motor. Now everyone is asking about this motor – is it better than the V2? Is that what I need? The problem with these higher powered motors is that in order to take advantage of the extra power, you need a BIG battery. Because they tend to be battery hogs. And big batteries are pricey and can be heavy.  And most batteries simply don’t last as long when putting out the high currents needed by these high-power motors.

By all means, if you are looking for very high speed, carrying a cargo trailer with 500 lbs of gear, or climbing 30%+ grades, then go for a high powered motor that can handle these applications. But if you are commuting with yourself and a 20lb briefcase, then you might not need to fork out that extra dough. The standard eZee kit at 36V, for example, is an incredible performer, and will easily tackle just about any hill, even on loaded cargo bikes, and is relatively lightweight. If you compare it to riding your bike unassisted, you’ll be blown away by its performance. (If you compare it to a sports car, however…well then you might be disappointed. )

If you have a chance to ride an ebike or ebike kit before purchasing, that is by far the best way to get a feel for performance. If there is no store in your area carrying ebikes, check out some of those forums (endless sphere, V is for Voltage)  and see if there is an ebike enthusiast in your area that might offer a test ride.

Recently, we went to one of the steepest hills around to test the new BMC 600 watt, internally geared brushless hub motors. There are two versions, a “torque” (the V2-T) and a “speed” (the V2-S). We wanted to see how they did for steep hill climbing on an Xtracycle equipped bike, and did some head-to-head rides with them. Note that Morgan is the heavier rider by about 40 lbs, so we did multiple tests by swapping bikes back and forth to get to the heart of the question, “which motor is best for climbing?”

One of the fun things about owning a bike shop, especially an electric one, is getting to try out fun and crazy new things.

We recently received a batch of new BMC motors, dubbed variously “600W” or “version 2″ (V2). They are purported to be for higher speed use.

We decided to set up the BMC motor on the Yuba Mundo as a rear wheel drive, and the Mundo already has a Forsen 1000W/36V motor on the front. Why not? An all wheel drive bicycle with about 1800 watts of power. Somehow that seems appropriate for the Yuba, which can carry over 400lbs of cargo.

Pictures are below. Brief details:
- Yuba Mundo, a longtail cargo bike that is rock solid for carrying kids, gear, groceries, whatever
- Two LiFEPO4 10Ah batteries capable of about 40-50A output
- Front Forsen 36V 1000W hub motor. It is a high speed (up to 40 mph on the stand), low(ish) torque motor
- Rear BMC V2 600W hub motor. It is also a high speed (up to 30 mph on the stand), medium torque motor
- Right twist throttle pointing away from the Shimano twist shifter
- Left thumb throttle
- Lots of fun

The Yuba’s gear range is not super wide, so by pedaling alone, the top speed is around 17 mph. However, this bike will easily accelerate to 27 mph with no pedaling, using the two motors. It sucks down some batteries, however – at 25 mph, it draws about 22 Amps, which equates to about 1000W continuous. With both motors, this bike will accelerate up hill, fast.

One more note before the pictures – everything here is only temporary, so there was no attempt made to make it aesthetically pleasing. On the bike configurations we ride every day, and the configurations for our customers, we work harder on the aesthetics.

I’ll just close with the thought that the Yuba makes a great bike for an electric setup like this – because it can haul so much weight, mounting a bunch of batteries on there is of no concern. The longer wheelbase makes it very stable even with a big load. And, the baloon tires with steel frame take up shocks in the road pretty well.

Morgan