- Fully enclosed motor, battery and control system with simulated torque, cadence, gyroscope and speed sensors
- Offers pedal assist up to 15 miles per hour with regenerative braking mode activated by pedaling backwards
- Two modes, pedal assist (requires that you plug the unit in to recharge) or Bike+ that automatically regenerates from your pedaling power and never has to be plugged in
- Not sold as a kit, must purchase as part of an existing electric bike, currently works with single sprocket only
The Zehus BIKE+ all in one system consists of an aluminum shell containing a 250 watt planetary geared hub motor, eight small Lithium-ion battery packs, a regeneration system and a control board. These elements together weigh about 6.6 pounds and the hub can be built into a range of wheelset sizes… basically anything over 20″ in diameter. What you get as a rider is an electric bike that’s clean, simple to use and satisfying to pedal with. It’s similar to a standard pedal assist ebike in that you can charge it with a wall adapter and slowly use the energy without putting any back in (a full charge takes ~2.5 hours) or you can activate the special Bike+ mode that tells the regen system to shave off a bit of power when the bike is operating efficiently and in so doing never run out. That’s the wow factor… it’s an electric bike system that “never has to be charged” because it’s constantly charging itself when you reach higher speeds or use it to stop.
Before you get too excited, let’s break this thing down a bit more. First, you cannot buy the Zehus Bike+ as a kit right now and add it to your own bike. Instead, the company is working with a range of manufacturers to have it integrated-directly and sold as a complete electric bike. They’ve chosen this path because mounting the hub properly requires a bit more finesse than standard hub motors. I’m told that the gyroscope inside needs to be perfectly flat in order to work correctly and this can be tricky to accomplish as a kit with so many bike platform possibilities. Second, the top speed is 15 miles per hour (25 kilometers per hour) which is a bit slower than most U.S. based ebikes (most here are 20 mph). This may help it to comply with European law but may also have been chosen because it reduces the potential for heat buildup since the batteries are right next to the motor and regen system. Note that the batteries used in the hub are specifically designed to deal with heat because there’s less ventilation and the regeneration actively charging could also make them hot. Third, this system is currently setup to work with just one sprocket (due to its width) so you’re either going to be left with a single-speed bike or need to add a Schlumpf hub at the bottom bracket or use a front derailleur with a chain tensioner to add more speeds. Fourth, this kit will add some unsprung weight to the rear wheel (I do not believe it will work with front wheel setups because it relies on the chain to activate assist and initiate regenerative braking). So, rigid city bikes, commuters, folding electric bikes or hardtail trail ebikes will be the best platform for this thing… but that’s the case for all hub motors on electric bikes. One final consideration here is that the hub loses energy when converting mechanical (pedaling or braking) energy into electricity and then back again through the motor to move you forward. According to Wikipedia, motors between 10 to 200 watts experience efficiency between 50% and 90% and since the same motor is used to convert and then use energy on the Bike+ in my estimation it will suffer this efficiency drop twice. It may also suffer from charge rate limitations of the battery pack. If it takes 2.5 hours to charge this thing via wall outlet then it must take at least that long worth of braking and “skimming” to fill itself under human Bike+ power right? I was told by Zehus that the system is “able to reach an efficiency up to 90% on assistance and up to 70% on recovering…the system is specifically designed to enhance overall efficiency of human body + electric engine, by up to 30% in Bike+ mode (measured in the decrease of oxygen consumption in tests). That’s pretty impressive and even if it’s not perfectly efficient I’m okay losing some energy when my body is performing at its best in exchange for a bit of help where I struggle :)
Okay, now that you understand some of the limitations, let’s talk about what makes this system awesome! First, it’s very smart and feels extremely fluid to ride. For many people, starting a bike from rest is the hardest part of the journey and for others it’s the wind or hills. This is exactly what the hub is designed to help you out with. Second, it looks beautiful and stays out of the way. I’ve reviewed several other “all in one” kits and my favorite to date has been the FlyKly Smart Wheel which is actually a very similar design to the Zehus Bike+. This thing is light weight, quit to operate and very stealth so most people won’t even notice. I think it strikes a good balance of power and torque without getting out of hand as far as weight. 250 watts is the standard size for ebikes in Europe and that’s what you get here. The battery pack offers 30 volts of power and 5.3 amp hours of capacity, which is on the small side, but that also reduces weight and the regen mode keeps it going forever in Bike+ mode so battery size becomes a lot less relevant. Third, you really could use this indefinitely; until the batteries eventually expire all of their electrons or if you only climbed a hill all day without charging. With cells from Boston Power rated for 3,000 full cycles, the pack should last multiple years and they do offer replacement cells. Fourth, you get a lot of control over the system. The smart phone app demoed in the video review above shows a slider that lets you choose from more assist (where you have to recharge the system) all the way to Bike+ where the system gently skims energy from the rider when cruising at medium speeds. You can also turn the system completely off and ride like a normal bike or use the Bike+ hub for security because it has a locking mode that keeps the rear wheel from turning.
Systems like this are really thought provoking for me because they refine how people work with machines. I have a knee injury that becomes sensitive when I climb a large number of stairs or pedal up steep hills the wheel effectively solves both challenges. I can carry my bike up to my apartment with just 6 extra pounds of weight (not enough to hurt my knee… it actually saves steps vs. removing a battery pack or wheel and taking two trips) and I can get help starting my bike and riding up hills on the way to and from work so I don’t have to over exert myself. In Bike+ mode the motor is basically waiting until I’m at an efficient pedaling cadence and then it’s lightly regenerating electricity. Even though I knew this was going on when I was doing the test rides, I couldn’t even tell. Of course it really kicks in the regen when you pedal backwards and you can adjust this with the app. So the electric motor does what it’s good at (high torque, low speed) and my legs do what they’re good at (low torque, consistent speed)
In case you were wondering, Zehus stands for “Zero Emission Human Synergy” and these things will start appearing in Europe late 2014 with bikes launching in America mid 2015. I’ve seen three colors so far including black, gray and silver (shown in the images and video above) and they might also have one with LED’s inside which is neat. To recharge the unit from a wall outlet you just pop off the rubberized cap on the right end of the axle and plug it in (the charge port is shown in the image just above). The unit communicates with the app using Bluetooth wireless technology and I believe it works with iOS, Android and Pebble. Pretty sweet. You can learn more about the Zehus company and the BIKE+ all in one system in this video interview I filmed with the CEO at Interbike 2014.
- Can work in virtually any rim size upwards of 20″ which means it’s great for folding ebikes, compact designs or standard 26″ and 700c
- Small form factor and relatively light weight at ~6.6 pounds, this thing blends in to create a stealthy ebike setup
- Smart sensors including virtualized torque, speed, acceleration and gyroscope to help you at just the right times without wasting energy
- Use the Bluetooth enabled app to choose more assist (and charge the kit) or Bike+ mode where it charges itself dynamically as you ride
- The backwards pedal braking/regen setup is just fun to use and I’m sure it also reduces wear that your brake pads might otherwise endure
- Relatively affordable… I cannot say for sure as the $1K price listed above is just a guess as the system is not sold stand-alone but the FlyKly goes for just $800 and is very similar
- Available in multiple colors to match the bike platform that it’s installed on, so far I’ve seen black, gray and silver chrome
- Works with 32 or 36 spoke configurations to be even more adaptable with different bike setups
- High quality batteries are designed to endure hotter temperatures without wearing out so quickly (Lithium-ion packs tend to be heat sensitive)
- Solid two year motor warranty with one year or 1,000 cycles on the battery and you can replace the battery pack if it does expire
- Currently limited to single speed applications (or you have to use a bottom bracket gear or a chain tensioner with front chain rings)
- Adds unsprung weight to the rear wheel of bikes, probably not ideal for full suspension setups and maybe not mountain hardtails
- Limited to 15 miles per hour top speed, possibly to reduce heat buildup and to comply with European law
- Currently not available as a kit, consider the FlyKly which uses a very similar system, the Zehus Bike+ has to be mounted perfectly level for the gyroscope to work right
- Loss in efficiency converting from mechanical human energy to electrical energy stored in the battery and then back into mechanical output through the motor and rear wheel, this could be ~20% efficient but is helped since energy is also captured during braking