Several times a week I get asked the same question over and over by loyal readers just like you. What mid-drive should I buy?
Although it seems like a simple question, getting the right motor for your application can be a daunting task for the uninitiated. This article will help future mid-drive buyers make an intelligent and informed decision that will bring you years of fun and enjoyment.
This article is mostly for people who have already decided that they want to go with a mid drive. If you are still on the fence about whether to buy a direct drive, geared hub or mid drive motor you should read this article here. There are benefits and drawbacks to each electric motor system.
Lots of people send me email telling me they are going to buy a 350W BBS01 or some other such nonsense. I’m not sure what kind of god-fearing American would opt to buy a 350W drive train when the legal limit in the US is 750W, but to each his own. The wimpiest mid drive I own is about 8 BBS02 750W units, all with the old crappy controllers. If you insist on having less power then just buy a BBS02 and program it for fewer amps. Under no circumstances should you ever buy a BBS01 in my opinion. The BBS01 is yesterday’s news.
The first question you have to ask yourself when considering a mid drive is are you planning it for a commuter build, or a trail riding build or both. Each different application calls for a wildly different set of characteristics. For commuting, you will want a motor that can run at whatever power level you want to run it at for extended periods without overheating. For singletrack trail-riding you usually want short bursts of power to overcome hills and obstacles, but most of the time is spent with the motor running at very low power because you rarely want to go full speed in the woods. This gives the motor a chance to cool off in between hills & obstacles. When trail riding you will want to gear your motor low enough so that you can climb 20-degree grades with ease. For commuting I usually gear my bikes such that they can climb 10-degree grades with ease, but nothing that is paved is going to be much steeper than that (usually).
The BBS02 works quite well on PAS-only mode which rarely will put out more than 800 watts and with most setups will allow you to pedal around at 25 mph. Once you hit the throttle you can start going quite a bit faster, especially when going down hills. On the uphills if you motor is already really hot and your gear is too high and you give it full throttle then you are risking catastrophic controller failure which is usually enough to ruin anyone’s day.
The BBSHD on the other hand rarely goes much over 1000W when using it in PAS mode, but when you give it full throttle it will go over 1500W if you are running it on a fully charged 52v battery. The BBSHD does not even really get that warm when running it on full throttle for extended periods, as long as there are no hills. With just the PAS, it generally will hum along at about 30mph and with the full throttle, it will go a little faster than that. Once you get above 30mph the wind resistance starts to be a real bitch.
The Cyclone doesn’t seem to work properly with the PAS kit that Lunacycle.com sells with it. At full throttle on a 48v battery it hovers at around 30-35mph on the flats. With a 52v battery you can get into the high 30’s and with a 72v battery which is the most that this controller can take I’m sure you can get over 40 on the flats (this is untested by me). With a 48v battery (2000W) this drive system does not even get very warm running continuously at full throttle. I would say that this mid drive is probably a 2500W nominal unit even though it is sold as a 3000W drive unit.
The next question you need to ask yourself is do you have any interest in actually getting exercise when you go out on your bike. If you want to get exercise when commuting you really need to get a system with PAS. Without the pedal assist I always just end up leaning on the throttle and forgetting about pedalling entirely. If you have to pedal to make the bike go then I find that not only will I pedal, but that I will also tend to push pretty hard on the pedals. At 2500W with the cyclone system your pedal effort always feels pretty much useless (why was I pedalling again?). On the BBS02 and the BBSHD you generally can tell that whatever energy you’re throwing into the drive train is not totally going to waste as these two drive units can struggle on steep hills and at higher speeds.
For trail riding another huge thing is weight. The BBS02 is pretty light and will add about 10lbs to the weight of your ebike, the BBSHD with everything adds closer to 13 lbs and the Cyclone kit weighs in at a hefty 16lbs. Any of these three is still much better than running around with a giant 25lb hub motor, but if you want a light and nimble ebike that feels like a mountain bike then generally you will want the lightest drive system you can that doesn’t suck.
If you plan on going through deep, wet powder then the BBS02 tends to be a little underpowered for that. If you gear it low enough then you can pretty much plow through almost anything, but if the drive unit is geared too low then suddenly you’re not really having that much fun anymore. In order to keep your fun up, you must keep your speed up. The BBSHD or the Cyclone both produce as much power as I feel like I need to easily plow through about 5-6 inches of heavy wet powder (which has an insatiable appetite for watts). I still ride the BBS02’s in the winter time, but only when there is less than 3 inches of snow on the ground.
The Cyclone, in my opinion, does not really shine that much over the BBSHD in the woods. The extra weight and the way the controller ramps up power leaves me thinking that the 10 extra amps is not really worth it. Although the Cyclone is a lot cheaper, the components are pretty cheap. When I started trail riding on the Cyclone things started to break on my drive train which got pretty annoying. I ended up forgetting about using a freewheel on the rear and instead settled on a 18T fixie as the Cyclone already has 2 other freewheels, one on the crank and one on the motor gear. This is a huge problem with high power mid drives, they tend to break bicycle stuff which is generally designed for human beings not 5hp electric motors. Although the Cyclone put out insane power when I swapped the 42T front chainring with a 36T chainring, I still felt like the only time I needed the extra power is going up very steep hills. This is the place that the Cyclone really shines as it can fly up steep trails like nothing I’ve ever ridden. The downsides are that the entire frame tends to flex when it’s powered up, the large ziptie that the kit ships with is a joke (use 2 metal hose clamps instead) and when the motor torques under power it gets about 1 mm away from hitting the drive side pedal. The whole system is just a little on the sketchy side for me, and I haven’t even started testing it at more than 52v yet. Yikes.
The BBSHD is a different animal entirely. Over the last 4 months of hard singeltrack abuse it has proven to be very reliable. In the deep powder this drive unit is insanely fun, and it comes in 4 different BB sizes that will fit about any fat bike. If you want to put a drive unit on a fat bike, for riding in the woods and on the snow then I would say it is no contest, get a BBSHD. Although the extra weight and the totally overbuilt construction really pissed me off 4 months ago when I first got these drive units I can say with some certainty that I’m over it now.
If you want to build a high-speed commuter that will scream up almost any hill without overheating and will accept any ebike battery pack from 48v up to 72v then the Cyclone is a great choice. This ebike will run all day long at 35mph with a 48 or 52v pack and close to 40mph with a 60v or 72v pack. Although performance will be comparable with other large DD hub motors that work at the 3000w+ power level, this mid drive will really shine on steep hills, which no DD deals with well, regardless of the power you dump into it. The tradeoff you have to make is in reliability, running 3000W though a bicycle drive train for any length of time and you’re going have issues. This can be a real bummer if it leaves you stranded in the middle of nowhere. This motor works the best if it has gears on it. You can use an N171, Nexus 3 or a Sturmey Archer 3 speed IGH which I have tested with this power level and found acceptable. Any other Nuvinci hub like the 330, 360 or 380 will not survive the Cyclone and likely other IGH with more than 3 gears will likewise self-destruct at 3000W of power. You can use a normal cassette and derailleur setup but the chains will wear out quickly and if you shift under load you’re going to have lots of problems.
One of the biggest issues with builders is cost. Surprisingly the Cyclone is the cheapest of the bunch even though it has the highest power at $390 from Lunacycle.com here. This kit should not be the first mid drive ebike kit you buy as the installation is pretty tricky. The price on the BBS02 has been changing quite a bit lately and can be found for $545 in the US here. You can buy it much cheaper from China but beware of non-reputable Chinese resellers. The BBSHD is the most expensive option at $699 here, however it is also the most refined and robust of all three drive units and has 4 different sizes to fit most common bottom brackets. For the BBS02 & BBSHD I recommend getting an aftermarket chainring with them (Lekkie Bling Ring or Luna Mighty Mini or Eclipse) which will add about $100 to the price.
The BBS02 750W still a decent choice for a trail bike if you are really concerned about extra weight. As long as the snow is not too deep and the hills are not-to-steep then you should still be able to have a lot of fun with this mid drive. If you have a cargo bike, carry an extra passenger or you want to go over 30 mph on the road then you should forget about the BBS02 entirely and opt for a BBSHD instead. If you want to go 35mph+ all the time on the road or have a single track trail bike that screams up hills then the Cyclone is the best bet.