by Patrick M.

One thing I can tell you for sure about the ERT External Sinewave Controller Kit: don’t take it through airport security.

I made this mistake twice, and lived to regret it both times. Seems the aluminum controller box, with lots of wires sticking out from it, looks suspiciously like the 4-letter B word on a luggage scanner’s screen. And it causes you to receive a nice, long, very thorough TSA baggage examination. Why did I bring my new ERT 72/84v External Sinewave Controller Kit for the BBSHD (hereafter called “the ERT kit”) in carry-on luggage with me twice? Long story, but the short version is that I had planned to use it on a bike I was building in Ukraine, and carried it there with me from LA. When I couldn’t locate a quality 72v battery pack during my time there, it came back with me from Ukraine to LA. After going through all this, and the trouble of building my own 72v pack – and installing the kit – was it all worth it to have 72v power from my BBSHD? Abso-damn-lutely.

_____________________________________________

The long, 4-month wait for 72v pooooower!

I purchased the ERT Kit way back in early December, even before buying my first BBSHD kit. Because, at the time, I didn’t think I could ever get my hands on a Ludicrous controller for the BBSHD, and I knew from previous experience with high-performance scooters that 1500w just wasn’t enough power for me. ERT’s external sinewave controller kit is advertised as a user-friendly way to push your BBSHD above its stock 1500w limit – way above – up to 3300w and even a bit more. I’d originally planned to put the kit on a fat bike for use in Ukraine, however when I tried sourcing a 72v battery pack from Luna Cycle, none were available on their site. I waited, waited, and waited some more for the 72v packs to appear, but they never did (I learned later the absence of 72v packs for several months from the site was due to ‘corporate sabotage’ by a competitor). Desperate, I came really close to pulling the trigger on a 72v pack from Aliexpress, but further reading about the risks of purchasing Chinese packs made me wary. Tired of waiting, and wanting to get the bike going, I decided to scrap the 72v plan and run it stock with a 52v Shark Pack.

I got back to the US in March, and about a month later began building my own battery packs for various e-vehicles in my stable. Realizing that my ERT controller kit was still waiting patiently to be installed, I decided to build a compact 72v triangle pack for the project, and finally get my 72v bike on the road. The 10Ah pack is only a 4P configuration, but since it uses Samsung 25R cells, it can provide up to 80A max continuous – more than enough power for my bike.

72v compact triangle pack uses Samsung 25R cells – only 4P, but good for 80A continuous. Beefy BMS can handle more than the rated 60A

I decided to do the install on a bike I really loved – and had promised myself never to electrify because I like riding it human-powered so much. It’s my Euro Version 2016 Mongoose Tyax Pro hardtail. Mongoose holds a special place in my heart, because the brand was just rising to fame in my early BMXing days. I have fond memories of the original Mongoose BMX bike and those super-cool MotoMag wheels. This Tyax Pro is special too, as I had to go through a long process of shipping it from Ukraine to the US, which proved to be much harder than shipping things in the other direction. Why not just buy the same model in the US, you ask? The Euro versions of each model are equipped differently than their US counterparts. I found that my Euro version had much higher-spec components (brakes, gearset, etc.) than the US version. The Tyax Pro is by no means a hard-core off-road or trail bike – it’s really a road bike that can do occasional very light off-road duty. No matter, I love pleasure riding it around my neighborhood, along the strand in Santa Monica and Venice, and through my favorite road course – the side streets of Beverly Hills.

Gosh, I have a warm nostalgic place in my loins for Mongoose. What’s this ad have to do with the ERT controller kit? Absolutely nothing

___________________________________________

Executive Summary – Pros and Cons

If you want the short version right away, and can’t wait to read through my lengthy details, here you go – the pros & cons of the ERT kit. These will serve as an ‘executive summary’ and outline for the review, and I’ll expand upon each point below.

Pros Cons Great power, immediate responsiveness You’ll probably need to purchase a new 72v triangle battery pack Smile-inducing acceleration and hill-climbing ability External controller and wiring bundle aren’t too attractive BBSHD retains its silence, thanks to the sinewave controller No included cover for the opening left when controller is removed – must DIY a solution for weatherproofing ‘HD feels much more lively at 72/84v PAS is gone 50% higher top speed (over 48v) in each of the lower gears Maintenance will likely be required – regular greasing with Mobil 28, due to faster spinning internal gears Relatively easy installation – only a few hours Included thumb throttle not good for off-roading, other throttle options not the best quality (Domino option needed) Smooth, progressive throttle response at 72/84v – not ‘lurchy’ Long-term reliability of the BBSHD at higher voltage is yet to be seen Doesn’t overheat – motor stayed below 46C, controller 29C Not good at 52v & high amps – feels ‘lurchy’ Inexpensive Wiring harnesses/connectors, and controller programming, done for you Can program CA3 for three different power/amp levels Great synergy with 30T Mighty Mini chainring Performance still good at low end of battery discharge (63v)

____________________________________________

Hot-Rodding the BBSHD by Overvolting

Overvolting is a time-honored tradition of electric vehicle hot-rodders, an easy way to get more performance out of a given motor. It’s been done for years, and often with surprisingly good results. A brushless motor that was designed for 36v, often can produce more power and RPM at 42v, 48v, or even higher – up to the point where that extra voltage stops producing power and just produces excess heat.

As Ron (spinningmagnets) wrote in this great EB article from 2012:

“The power that you need (or want) is further complicated because the true limit of the power you can put through a motor is how much heat it can survive. If you take a given motor and begin raising the volts, you will get some extra power, and also the motor will spin faster than it did at a lower voltage. If you begin raising the max amps, the acceleration will get faster, but…adding more amps will cause most of the heat that will kill a motor (and sometimes the controller). Factory power ratings are rarely accurate. Legitimate sellers under-rate their kits, because so many buyers will overheat their E-bike and want to have the motor and controller replaced due to heat damage.”

Many owners of the BBSHD are already overvolting it a little bit, by running a 14S (52v) battery pack with the motor. The motor is rated at 48v, however early hot-rodders found that the controller can handle up to 60v – just above the 58.8v of a fully-charged 14S pack. The advantages of this are two-fold: first, the motor spins faster, meaning all other things equal, your bike will go faster. Also, as the battery drains down through its discharge cycle, the voltage remains higher to the point of LVC (low voltage cutoff), meaning better performance throughout the entire discharge curve.

The ERT Kit takes this concept to the extreme, with two controller choices that let you run the BBSHD at up to 84v and even beyond. The reason it was interesting to me, and other BBSHD owners, was that at the time I purchased it the ERT kit was the only add-on way to get more power from the BBSHD. The Luda Ludicrous controller provides more power from the ‘HD by supplying more amps to it, but it’s only available with the purchase of a complete Luna e-bike. For those who want to only get an add-on controller and not buy the entire bike, the ERT kit is currently the only game in town. Plus – hot-rodders also know that more amps equals more heat, while higher volts and less amps (as long as you’re not above the point of overheating the motor) can put out the same power with less heat, and therefore greater longevity.

OK, let’s get down to the meat of this review. To start, the ERT kit comes in two versions:

ERT Sinewave Controller Kit ($349.95 with CA3)

ERT Grin Phaserunner Controller Kit ($529.95 with CA3)

Both kits come with the optional CA3 display, speed sensor, and all wiring and connectors already pre-configured for you, for easier installation. The main difference is that the first kit uses a 12FET, sinewave external controller – which is a pretty large black box. The second, more expensive kit uses the Grin Phaserunner controller. Both controllers can be connected to a computer for programming and fine-tuning. Alan, the owner of ERT, told me the main difference between the two kits is that the Phaserunner provides smoother throttle response, can handle more power, and is of course much smaller and more stealthy than the beefy 12FET external controller. I chose the sinewave kit because I wasn’t sure how much I’d like running the BBSHD at 72v, and wanted to limit my expenditure on this experiment to as little as possible. I shouldn’t have worried about it – as it turns out, I really like the way 72v/84v works with the BBSHD.

ERT chart comparing two external controller options vs. stock BBSHD

Now, a little more info and background about the BBSHD is needed. One of the most important specs for any motor is its kV rating. That simply means how many RPM the motor spins, per volt, when it is unloaded. Motors can be wound and designed for all different kinds of applications – high RPM and low torque, or lower RPM with lots of torque. So their kV ratings will vary widely. For the BBSHD, all the research I did could not uncover an official Bafang spec for the motor’s kV. I e-mailed the company to inquire about this, but haven’t gotten a reply. But from the published specs, one can pretty closely estimate the kV of the motor. The ‘HD has a 21.9:1 overall gear reduction to the pedals. At 48v, its published maximum RPM at the pedals is 160RPM. That means the motor is spinning about 3500RPM at 48v. This translates to a kV rating of 3500/48v = 73kV. You can then calculate how many RPM the motor should be spinning (the motor itself, and at the pedals) at higher voltage – as long as it’s not being pushed into just creating heat from excess voltage. At 72v, the motor should spin about 5200RPM, with a pedal RPM of 240. At 84v – the voltage of a fully-charged 72v pack – the motor is spinning a whopping 6190RPM, with a pedal RPM of about 282. This kind of RPM at the pedals is definitely not made for PAS, unless you have superhuman leg speed!

The BBSHD was designed as a dual system, to work with both PAS and throttle. This is great product design, because it makes the ‘HD usable for a very wide variety of bikes and riding styles. That’s why it is geared with such a big reduction – the low pedal cadence speed is guaranteed to be pleasing and inoffensive to granny and grandpa, for relaxed cruising around with that huge stock 46T chainring. The ERT kit is definitely not made to be used with the stock 46T chainring – the 30T Mighty Mini is a perfect match for this beastly setup (more about that later). And it’s definitely not made for PAS – this is a throttle-based system. Although you can upshift a few gears, apply a little throttle, and pedal along – much the same way I described in my recentTangent Ascent review here on EB.

At 48v, the stock BBSHD spins 160RPM max at the pedals, with a 21.9:1 gear reduction – that’s about 3500RPM

___________________________________________

Installation and Setup

Not much to report about installation, it was pretty straightforward and only took me a few hours. The kit comes with all wiring terminations and connectors done for you, with each cable clearly labeled. ERT’s instructions for installation on their site could be a little more clearly-written and better illustrated, but I got the idea and didn’t run into any big roadblocks.

After 4 months waiting for a 72v battery, the ERT sinewave controller kit is ready to be installed

I decided to first install the CA3 and run its associated wiring, before diving into the only part of the install that worried me a bit – removing the stock controller and wiring in the new one. I got the thumb throttle with my kit, because I’d never tried one before. The twist throttles offered with the kit are the half-grip type, which I’m not very fond of. Honestly, none of the three throttle options offered with the kit are super great – by far the best throttle on the market is the Domino full-twist from Italy. An option offering this throttle as an extra-cost add-on would be a huge improvement to the kit. After the CA3 was wired up, I located the controller onto my bike’s downtube and zip-tied it in place.

CA3 mounted, cable routing in progress. My first thumb throttle – not the best for hard off-roading

The only difficult part in the controller swap was very carefully removing the silicone around the hall connector. I did it very slowly, with a small knife and screwdriver, and was able to pull out the connector without damage. Then begins the process of connecting all wires – pretty simple as everything is clearly labeled. Special mention goes to the kit’s temperature sensor wire – this connects to the little-known temp sensor inside the BBSHD and provides very useful (and possibly motor-saving) temp information that’s continuously updated while you ride.

How the BBSHD looks with the controller removed – mine had quick disconnects

One notable negative – the ERT kit contains no replacement cover for the stock controller. The opening must, of course, be covered and sealed up before you ride so it’s weatherproofed. You definitely don’t want water getting into your newly hot-rodded ‘HD. Some users have gutted the ‘HD’s stock controller, drilled a couple holes for the wires, and used that as a cover for the opening. I didn’t want to gut my controller – being the pack rat that I am, I figure one day I’ll probably need to use it. Of course the probability of this happening is about 0.2%. My plan is to use high-temp sheet material I bought for battery pack protection, cut it to size, then paint it black. A custom 3D-printed cover, included with the kit, would be a very welcome addition. But as the ERT kit is sold, the buyer is left on his own (or her own) to DIY a weatherproofing solution and cover the controller opening. Once I got all the wiring connected, covered the controller opening, and attached my Mighty Mini chainring, she was almost ready to ride. I zip-tied up the Luna triangle bag, put some dense foam padding in, and mounted my 72v triangle battery pack.

Naked HD mounted on my frame

___________________________________________

84v Riding Impressions: Holy Crap, This Thing LEAPS Forward

Once everything was connected, I powered up and did some basic set-up programming in the CA3. One thing that’s good about this old-school-looking display is that you can program up to three power level presets (three amp levels). This is super-handy, for example, if you are using the bike with different power level (max. amp) battery packs. Or if you want to lend it to a friend but don’t want them killing themself or the bike, with 3000+ watts… Anyway, I programmed 3 settings to begin with: 20A, 30A, and 40A. From reading several of Alan’s blog posts on the ERT site, and watching his ERT YouTube Channel, I knew that he’d successfully used the kit at up to 50A and 84v. I wanted to start conservatively, trying it at 20A and 30A before experimenting with 40A or above.

With a fully-charged battery pack at 84v, I set the CA3 to 30A. That’s an effective maximum power of 2520w. I pedaled to get up to about 10mph, then gradually applied the throttle… “Holy Crap” – again, same as my first words with the Tangent – was all I could think to myself. The bike leapt forward: it jumped ahead with an immediacy I had never felt with the BBSHD at 52v. As mentioned in my Tangent Ascent review, with the BBSHD at 52v it feels like your request for acceleration goes through a committee first. Then, once approved, you’re rewarded with smooth, progressive acceleration – kind of like a 747 taking off. Not here: there’s no committee – the bike just leaps forward with each application of the throttle. So much so, that it passed my “spontaneous laughing out loud” test. It was a riot.

At 84v, the BBSHD feels much more lively, if I can describe it that way. The acceleration is more immediate, more violent, more aggressive than at 52v. It’s a perfect match for the tiny 30T Mighty Mini chainring: at 52v, the MM feels too short to me. Yes, you can wheelie in 1st gear no problem with a stock BBSHD, but then you run out of steam at 12mph in first gear. Running at 84v, a huge benefit is that, because the motor has a 50% higher maximum RPM, you can wind out each gear to a 50% faster top speed than you could before with a 48v or 52v setup. The high-revving BBSHD at 84v is a perfect match for the little Mighty Mini. For example, with the stock 11-36T 10S cassette on my bike, I found that with the MM I would max out at about 15mph in 2nd gear with the stock ‘HD. Running this same setup at 84v, the bike will wheelie like crazy in 2nd gear, and run all the way up to 22mph in the same gear. Of course, the chainring is spinning waaay too fast for you to pedal along at this point – but it’s a small price to pay for such added power and RPM.

84v controller mated with 30T Mighty Mini: A wheelspin- and wheelie-producing match made in Heaven for the high-revving ‘HD

I never realized it before I tried 72/84v, but one limitation that bugged me about the BBSHD running at 48/52v is its low maximum pedal RPM. As I mentioned, it’s designed for a low pedal cadence so it’s compatible with a wide variety of riders and bikes. But this low maximum RPM demands using a larger front chainring (42T seems ideal for many applications) to get most from the motor – 30T just runs out of steam at way too low speeds in any gear under 5th or so. I found that I really, really like the ‘HD when it can run up to 240-250 pedal RPM: the powerband is wider and much more usable, at least if you’re not trying to use it as a PAS. As I found with my Tangent Ascent, there is a workaround to use this as a PAS – you can just upshift a few gears, dial in a little bit of throttle, and pedal along. If you’re a PAS guy (or gal) and ride that way 99% of the time, this system is not for you. If you’re a power-hungry, acceleration-loving, ex-motocross speed junkie on a budget, who loves doing burnouts in dirt on his Mongoose while other responsible adults look on in disgust, then this is the perfect system for you.

About the throttle: I mentioned the throttle options with the kit aren’t great. I do have to say that the thumb throttle that came with my kit was actually quite good for a thumb throttle: it was progressive, smooth, linear, and provided really smooth and precise control of the throttle. With the CA3, you can map the throttle response to your liking. I kept all controller and CA3 settings stock as ERT had set them up, and found that the throttle response at 72/84v was very linear and progressive. That said, I learned that thumb throttles are not very good for off-roading or motocross-style use: you can often hit the throttle accidentally while riding over big bumps, standing up. But for street use, which this bike got much more of than off-roading, it was actually quite comfortable. Again, a welcome option would be to offer the state-of-the art Domino throttle as an option for this kit.

__________________________________________

Other Surprise Benefits

So the power felt great at 84v and 30A – anything else good about the kit? Yes, there were some other positive surprises in store. First was the ‘HD’s continued silence, even running at 84v. It’s rather astonishing to have this much power on tap, and for it to all come rushing out in almost total silence. From watching some of Alan’s YouTube videos, I got the impression that the overvolted ‘HD was fairly loud compared to stock. Not my bike – it retained its near-total silence, even runing full bore at 84v. Chalk it up to the 12FET sinewave controller, and good programming to match the high voltage.

Next, I found the performance to be great throughout the discharge cycle of my battery pack. That is, 84v on the high end, all the way down to the LVC (low-voltage cutoff) I programmed of 63v. While there is a noticeable reduction in performance going from a fully-charged pack, down to 72v, and then down to the 63v LVC, the ERT-kitted BBSHD still retained its lively performance – wanting to jump ahead with each stab of throttle. This is different from my 52v BBSHD bikes, which start to feel a bit lethargic once you get down to the bottom 1/3 of the charge, about 48v and below.

OK, now onto top speed. I know some of you are wondering – “how fast does it go?” Sadly, I am a bit of a wuss when it comes to bicycle top-speed runs: to me, going 40mph on a bicycle designed for human power feels absurdly fast. On ERT’s site as shown above, the advertised top speed for the kits is 50mph. Of course, that will vary greatly with the amp output power of your battery pack, what kind of bike you put it on, the type and rolling resistance of the tires, rider weight, wind, etc. This Mongoose is actually one of the better bikes as far as top speed is concerned. The Kenda small block tires are really more road tires than serious off-roaders, and I find that pumped up to 40PSI or so they offer very low rolling resistance. That said, I found myself very quickly hitting 38-40mph on this bike, before the self-preservation instinct kicked in and I backed off. (The Hayes Radar brakes, which seemed to work so well under human power, now seemed woefully inadequate when paired with 3000w of power.) I’m sure it could easily hit the mid-40s, and maybe even 50mph under the right conditions. It just requires a rider braver than me to test out.

I did try the kit at both 20A and at 40A, with good results. At 20A, you only have about 1680w at 84v – barely more than a stock ‘HD. Surprisingly, I found the kit still kept its ‘lively’ character even at this low amp setting, although acceleration and power were both reduced a lot. At 40A, with 3300w or more on tap, the ‘leap forward’ feeling was even more magnified. Worried about the health of my ‘HD’s nylon gear, I rolled on the throttle gradually in the 40A setting, and usually pedaled up to 10mph or so from a dead stop. I probably have too much mechanical sympathy.

Black controller doesn’t stick out too badly among black ‘HD, frame pack, and bike accents

___________________________________________

Any Overheating Problems?

This was a very big surprise: Even beating on the ERT kit, at 40A, through huge mountain trails, riding for over an hour at a time, it didn’t get too hot. This was something that I was really worried about – going back to Ron’s article linked above, you can overvolt up to a point. But beyond that, all you’re doing is generating excess heat in the motor, which can kill it in short order. I wondered if running the BBSHD at either 72v or 84v was going beyond the point of creating more power, and would also generate heat that could destroy the motor, the nylon gear, or both, in short order.

To test overheating, I fully-charged my pack to 84v and set the CA3 to 40A, and took the Tyax Pro to my favorite local trails in the Santa Monica mountains. These trails feature huge uphill secitons, where you gain over 500′ in elevation along steep mountain passes. Combined with temps in the mid-80s, it’s a definite torture test for any e-bike build. On two different days, I rode the trails for 80-90 minutes, then took temperature readings of both the controller and the motor, using my IR thermometer. I also monitored the ‘HD’s internal temp using the temperature monitor on the CA3. To my surprise, the controller didn’t even get warm to the touch, even after hard mountain riding.

Controller was cool to the touch after a hard workout

And the ‘HD itself stayed surprisingly cool, especially considering the hard mountain riding. During my rides, I watched the internal temp reading on the CA3 – the maximum it reached was 46C – really cool under the conditions. When I stopped, I shot the BBSHD’s case with my IR thermometer, and saw between 38-42C – again, surprisingly cool under hard riding conditions. For comparison, I ride my 52v Ludicrous BBSHD bikes on the same trails, in the same weather, at 52v/50A. The external motor case temps on those run from 37-39C, so the 72v setup is only running a few degrees Celsius hotter than the 52v bikes.

Even after 80 minutes of thrashing in the mountains at 84v, HD didn’t get too hot

___________________________________________

The 3000w Challenge: 72v/84v @ 35-40A, vs. the Ludicrous: 52v/58.8v @ 50-55A

Since both the Ludicrous (using high amps) and the ERT kit (using high volts) can produce over 3000w from the BBSHD, I thought a comparison of the two would be in order. While a drag race between the two would be the definitively cool comparison test, that’ll have to wait for a another day. But since I do have both a Ludicrous bike (my Canyon DUDE fat bike, reviewed on EB here) and this 72v Mongoose in my stable, I thought I’d ride them back-to-back on the same trails and compare how each felt. They can both produce about the same power from the ‘HD, but they do it in very different ways, and feel very different doing it.

First, the Ludicrous: T-O-R-Q-U-E. Torque with a capital T. That’s how the ‘Luda feels to me, like it can pull my solid ass up a steep mountain, while pulling up some really heavy tree stumps at the same time. Now one thing to mention – originally I had the 30T MM chainring on my ‘Luda bike as well (shown in photo). I later realized, as I mentioned, that to fully utilize the 52v BBSHD/Luda and its relatively low pedal speed, you need to use a larger front chainring. The MM simply runs out of steam too early. Using the 42T Luna Eclipse, my Canyon DUDE felt like it could climb any mountain with ease, but still have a fast top end even in first or second gear, thanks to the 42T chainring. The acceleration is more gradual, more steady, more 747-taking-off like, but still very satisfying.

Next, the 84v Mongoose: Snap! Not as in, “oh, snap!”, but as in, snap your neck back from the sudden lunge forward when you pin the throttle. The 84v setup definitely had a little less torque, but I was too busy trying to keep the rear wheel from spinning on the dirt, at full throttle, to notice that. Hill-climbing ability was still good, but where this bike really shined was in racing up to its top end in each gear – you wanted to go faster and faster, just because it can. Due to the Mighty Mini’s far-outboard chainline, I wasn’t able to use 1st gear on my stock cassette – but the acceleration was still pretty shocking even in 2nd gear. The Luda’s great torque actually seemed easier to control and better matched for rough off-road riding. But when I hit the pavement, every time, I was longing for the power and long-legged top end in each gear that the 84v bike provided.

Ludicrous at 52v, and the ERT kit at 72v, can both produce 3000w – but how different do they feel?

___________________________________________

Negatives – Let’s Address Those Cons

The power, top speed, and acceleration of the BBSHD at 84v are great. What about the negatives? There are some drawbacks to this kit, and to overvolting your ‘HD in general. Let’s go over them now.

72v Pack Needed

Of course, to use this kit you will need a good, powerful 72v battery pack. Most people don’t have the time or patience to DIY a pack like I did, so that leaves you with not too many options to source a good pack for your 72v bike. Two main things: first, get one with genuine and high-output cells. I recommend Samsung 25R or 30Q, both have the high current output you’ll need. Next, make sure it has a BMS that supports at least 50A continuous – that’ll provide all the power your BBSHD can handle, and more. As I see it, there are really only four options for a 72v pack: 1). Luna Cycle, 2). DIY, 3). EM3EV, 4). Aliexpress. As stated, I’d be very wary of buying a pack from Aliexpress, for many reasons, including getting fake cells. While the ERT kit itself is pretty inexpensive at only $350, a good, strong, 72v triangle pack with quality cells should set you back at least $700.

Kind of Ugly

One of the great things about the Ludicrous controller is that it’s a pretty, sexy, CNC’d from aluminum, attractive beast that is integrated right onto the BBSHD in place of the stock controller. It looks like it belongs there, but also tells you there is something special about this motor… it’s not all from China, mixed in there is some modified American muscle. My external sinewave controller, on the other hand… well, at least it’s black. And the wiring is wrapped nicely. As external controllers go, with wiring hanging out of them, this looks about the least ugly as possible. So yeah, this kit has a pretty low WAF (wife acceptance factor). On the other hand, an ugly external controller with wires hanging out is a badge of honor to e-bike geeks in the know, and identifies yourself (to other e-bike geeks only) as a performance freak who values raw, unadulterated POWER over looks any day of the week! (I fit into this category, too, sadly.)

No cover included for controller opening

As I mentioned, no cover is included to close up the opening where the stock controller used to be. You need to DIY a solution, either by gutting the stock controller and using its housing, or figuring out another solution for weatherproofing the motor. Again, a 3D-printed cover included with the kit would be a big improvement.

PAS is Gone

With the sinewave controller kit, you lose PAS. If PAS is really important to you, and you want nice, relaxing, slow pedaling in your granny trike, I highly recommend the stock BBSHD to you. Or BBS02. The power and RPM rush of running at 84v is so addictive, I really don’t miss the ‘HD’s rudimentary PAS at all. Not one bit.

Maintenance Likely to be Required

I haven’t tested this yet from personal experience, but I will soon: the overvolted BBSHD will likely require greasing at much more frequent intervals than a stock motor. This is because the internal gears are spinning so much faster than Mr. Bafang ever intended, the poor stock grease will get flung off, leaving you with unhappy, dry gears. Plan to grease up using Mobilgrease 28 at least every 200-300 miles, to be safe.

Long-Term Reliability Still in Question

Alan from ERT claims that he’s put many, many miles on his overvolted kit bikes so far, without a failure. While I certainly want to believe that’s true, I know from reading the experience of others, like in Karl’s Blog, that pushing the ‘HD beyond 2500w or so can start to make things fail – most notably the internal nylon reduction gear. So far, I’ve put a bit over 200 miles on my bike with no mechanical issues at all, but I have super-high mechanical sympathy. I will keep close tabs on this and report an update here if there are any future mechanical failures in the overvolted ‘HD.

Better Throttle Options Needed

Again, the included thumb throttle is OK for street use, not so much for off-roading. Offer the Domino throttle as an option, wired up to match this kit.

Not Great at 52v / High Amps

Here’s one I haven’t mentioned yet – how the ERT kit feels at 52v and higher amps (the same way the Ludicrous works). Let’s say you already have a great bike, already have a BBSHD on it, and invested heavily into a super-duper 52v triangle battery pack with awesome cells, that can put out 50A all day long and 80A on Sundays. You have everything needed, except you want more power… and that evil e-bike tycoon Eric won’t sell you the coveted Ludicrous controller unless you buy it as part of a complete Luna e-bike. Damn you, free-market economy.

Since you already have a good 52v pack, you don’t want to spend big bucks again to buy a 72v pack. But what about using the ERT kit with your 52v pack, and just dialing up the amps, say to 50A? Then you can circumvent “The Man” (a.k.a. Eric Hicks) and achieve the same thing the ‘Luda is doing, only without the ‘Luda, right? Well, unfortunately, no. I mean, technically, yes, but you won’t like the result. I tested this very possibility, and I’m sad to say the results were not as good as I’d hoped. The main problem: the controller is tuned for 72/84v usage, and at 52v/58.8v, it feels very ‘lurchy’. If that’s a word. You know what I mean: it’s the opposite of smooth, progressive throttle application. When you move the throttle smoothly, but the result is the bike lurching, then letting off, lurching, then letting off. It’s the opposite of smooth and linear throttle progression. That’s exactly how my bike felt at 52v – I tired it at both 40A and 50A, and while it worked, it did not feel good at all. The bike was lurchy, and I couldn’t get it to accelerate smoothly using the 52v pack. Maybe the controller could be re-programmed for this lower voltage, but I didn’t try that. For 52v systems, the Ludicrous (or stock) is a much better match.

___________________________________________

ERT kit with the Grin Phaserunner

I’ve spoken to several other ERT 72v BBSHD kit owners, via the Fast Electric Bike Facebook group. Most other owners opted to go with the more-expensive Grin Phaserunner controller option. One of them is FEB member Colin Barfoot, who did a very cool build on his Ellsworth Dare using the kit. Colin did a build reporton the electricbike forum. Initially, he reported that programming the Phaserunner for smooth response took some time, but so far he’s been very happy with the performance and power of the bike. Barfoot also decided to keep the stock controller housing, and removed the potting compound along with all the stock controller components in order to use the cover for weatherproofing his BBSHD.

FEB member Colin Barfoot installed ERT’s Grin Phaserunner 72v kit on his Ellsworth Dare

Barfoot removed the stock controller’s innards, to utilize its cover

Phaserunner is definitely smaller and easier to place than my 12FET sinewave unit

___________________________________________

Conclusion: I’m a 72v Convert

I was really surprised at how much I like the BBSHD running at higher voltage. I figured there had to be some big negative, some catch, about running the bike with the ERT kit at 84v (other than the not-pretty external controller). But so far, there’s really not. It hasn’t overheated. I haven’t destroyed the nylon gear (yet). The controller hasn’t fried. My eyes haven’t been blinded by the ugliness of the CA3 display. The power, top speed, and acceleration of the BBSHD at 84v are smile- and laugh-inducing – and to me, that’s the ultimate test.

84v Mongoose, tearing up the streets of Beverly Hills

Ride silently, but carry a big stick – perfect for the 90210

It’s kind of like a poor man’s Tangent Ascent – really good power and responsiveness, but for not a lot of money. I haven’t tried the Cyclone yet, or the Mini Cyclone, so those may also be good low-budget alternatives to the TA. But for now, I’m really in love with this BBSHD at 84v. I’m not changing it back to 52v. And if you see a bright green Mongoose silently flying through the streets of Beverly Hills, you’ll know the rider is wearing a huge smile behind that full-face helmet.

About the Author:

Patrick M. is a A former coupon-book entrepreneur and travel agency owner, and Patrick developed one of the first consumer-review web sites way back in 1996. In the early 2000s, he worked as a journalist, serving as contributing editor for two home theater magazines. Now, Patrick splits his time between producing documentary movies and renovating homes – but his true passion has always been anything with wheels and ultra-high performance.

_____________________________________________

Written by Patrick M, June 2017