Buying guide for best electric mountain bikes
Combining the fun and exhilaration of off-road cycling with the power and efficiency of an electric motor seems like a brilliant idea. So it will come as no surprise that electric mountain bikes (eMTB) are increasingly popular.
There are lots to choose from, too, but that means all kinds of different features. Some are designed for street use, though they’ll easily take you off the beaten path occasionally. There are fat bikes with wide tires that give superb traction in sand, loose dirt, and even snow. Then there are high-performance models for the toughest off-road challenges. There are lots of different materials, specifications, and motor and battery combinations, too.
It’s not easy to separate the valuable technology from the marketing hype and choose the best electric mountain bike for the way you ride, but BestReviews has been on the case. After a lot of tough miles, we’ve come up with a set of recommendations that will suit those looking for good performance no matter where you ride. Our buying guide discusses the technical aspects from entry level to the exceptional machines that take electric mountain biking to its limits. We’ve included some of our favorites, too.
Key considerations
Understanding eMTB power
Generally speaking, you’ll see three figures: watts for the motor and volts and ampere-hours for the battery.
Watts: This is pretty straightforward: the bigger the number, the more powerful the motor. That doesn’t necessarily mean one electric mountain bike is faster than another (a low-wattage model will still get you there eventually), but it does mean you’ll have quicker acceleration, faster response, and more torque. That last element — the rotational force you can put through the wheels — is arguably what’s most important off-road.
Volts and ampere-hours aren’t quite so straightforward.
Volts: In simple terms, voltage is the energy that makes a motor work, so more is usually better if you’re looking for increased performance. It’s a fixed figure decided by the maker. If your eMTB takes a 36-volt battery, you can’t try a 24- or 48-volt battery. It won’t work.
Ampere-hours: These are a bit like fuel and can vary. If you have two 36-volt batteries, one rated at 8 amp-hours and the other at 12 amp-hours, the second will give you a significantly longer run time and therefore greater range. Unfortunately, it also increases the cost (and often weight). Nevertheless, keen electric mountain bike riders will want to maximize ampere-hours where possible.
If only it were that simple!
Unfortunately, high-end bike builders often don’t use watts, volts, and ampere-hours. Instead, they use newton-metres and watt-hours. Why? Probably because many are European and Asian and those units are more common in those countries. Fortunately, 1 newton-metre equals 1 watt, so that’s easy. To get watt-hours, you multiple the ampere-hours by the volts, so that’s not too difficult either.
Sadly, when you make comparisons, it seems that cheap electric mountain bikes are much more powerful than models that cost five or six times as much! In basic terms, some are, but they’re very different machines. The cheap models are intended mostly for street use with occasional trips to the woods or beach. The expensive bikes probably never see pavement and spend all their time on dirt. They are all electric mountain bikes, but you can’t really make a direct comparison.
Did you know?
The more you pedal, the less you drain the battery. However, these systems are not regenerative. No amount of effort from you will put charge back into the battery.
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Features
When shopping for an electric mountain bike, you’ll want to look at frames, wheels, suspension, brakes, motor position, gears, and lights and display.
Frame
Even on cheap electric mountain bikes the frames are made of aluminum alloy. While it’s not quite as strong as steel, it’s much lighter. Sports models use more exotic materials. Often these are special formulations of aluminum alloy (frequently numbered, which you can check for greater detail), and sometimes they’re made from carbon fiber (graphite). It’s a material that’s extremely strong and very light but monstrously expensive! It’s also just about impossible to repair. If you dent or bend an aluminum frame, you can either ignore it if it’s minor or get it fixed. If the same thing happens to a carbon frame, replacement is the only option.
Wheels
Design: Wheels are mostly different grades of aluminum, though a few are carbon fiber (with the same benefits and potential drawbacks as frames). Most — even on competition models — are spoked, because in the event of a wheel getting twisted they can be loosened and the wheel straightened. Six- and seven-spoke wheels are really just a style gimmick.
Size: Wheel size is another consideration. On entry-level bikes, they’re usually 26 inches, which is a good compromise between maneuverability and stability. Wheels that measure 27.5 and 29 inches are used on more focused machinery because they’re less liable to be deflected by rocks and offer a larger contact area, so greater traction. They also make the bike faster, though it takes more effort to get it up to speed.
Suspension
On electric mountain bikes intended mostly for street use, the suspension is usually just a sprung front fork, and, to be honest, even that isn’t really necessary. You get a surprising amount of flex from spoked wheels and pneumatic tires. On off-road-oriented bikes, front and rear suspension gives you better control. Its job is not so much to soak up the bumps for your comfort but to keep the tires in contact with the ground — because when they’re in the air, you’re not in control. The key here is adjustability for different conditions and the amount of travel.
Brakes
Brakes are invariably discs, even on the cheapest eMTBs. At the lower end, they’re operated by mechanical cable. At the other end of the scale, you can have two- or four-piston calipers that give tremendous stopping power and great sensitivity.
Motor
Rear hub: On most street-focused eMTBs, the motor is inside the rear hub. It’s pretty much a sealed-for-life unit, and if anything goes wrong (apart from a serious seizure), the bike can be pedaled as an ordinary bike.
It’s also easy to set it up for the multiple modes common on these mountain bikes, so they can be either full-time electric, assisted pedaling, or full-time pedaling. The disadvantage is that it changes the weight distribution of the bike. It doesn't take long to get used to, but initially it feels like the bike is being pushed, which is pretty much what’s happening.
Pedal crank: High-end electric mountain bikes have the motor on the pedal crank. It gives a more natural balance to the machine, lowers the center of gravity and thus increases stability, and generates more torque, exactly what you want on the rough stuff. These motors may also have a skid plate underneath for additional protection.
Gears
Gears are often misunderstood. They don’t make a bike any faster. What they do is allow you to adapt the energy to the conditions. On an ordinary bike, if you start to go up a hill, you choose a lower gear so you don’t have to use as much physical effort. On an electric mountain bike, doing the same thing means you use less of the battery’s energy, so proper use of the gears should increase range.
As many as 21 gears are offered via three ranges of 7 each. That’s probably overkill, and a half dozen will get the job done. There’s little difference in price, so it’s a personal decision. On full-time dirt bikes you’ll get anywhere from 6 to 12 gears, but they’re almost invariably all on the same gear set on the rear wheel. It’s simpler, so there’s less to go wrong, and in competitive situations they’re easier to change.
Lights and display
General-purpose electric mountain bikes frequently have lights fitted, which is useful if you’re riding around the town or city. LED displays are common, giving information like battery charge level, speed, and distance covered. The battery may also offer a USB charging point. These features are not often found on full-on sports models, though there are exceptions.
Did you know?
Looking after the cycle parts of your electric mountain bike is much like a normal bike — basic adjustment and lubrication anyone can handle. Motor and battery should need little attention, but if you do have problems, we suggest a trip to a local expert rather than trying to fix it yourself.
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Accessories
Helmet: Giro Fixture MIPS Dirt Cycling Helmet
If you’re on a bike, you need a helmet, and this one has been specially designed for off-road cycling. It’s got venting to keep you cool, and the advanced Multi-directional Impact Protection System (MIPS) helps prevent the rotational injuries often associated with mountain bike crashes.
Gloves: Seibertron Dirtpaw Mountain Bike Gloves
There are two reasons to wear gloves. First, for the added grip and control they give. Second, to protect your hands from branches or damage in the event of a fall. These are synthetic leather, polyamide, Lycra, and neoprene with armored backs, so they’re tough yet supple and comfortable, too.
Electric mountain bike prices
Inexpensive: The cheapest electric mountain bikes start at about $600 and are targeted at those who like the comfort and versatility of mountain bike style but are likely to spend most of their time on the street. A more common price range is $700 to $900.
Mid-range: Fat-tire bikes with 300-watt motors start at around $900. Those with more power rise to $2,000. There’s then a considerable gap to true off-road electric mountain bikes, which start at around $4,500.
Expensive: The best electric mountain bikes are like any competition machine: masterpieces of engineering designed for high performance. Most will cost you between $6,000 and $9,000, but we’ve seen them for as much as $12,000.
FAQ
Q. Are electric mountain bikes legal for street use?
A. Unfortunately, it’s a complicated question, mostly because different states make different rules. It largely depends on maximum power and speed, but some places require registration and licensing while others don’t. The excellent PeopleforBikes website is usually updated regularly, but the only way to be absolutely sure is to contact your local authorities.
Q. What kind of mileage will I get from the battery on my electric mountain bike?
A. Lots of things have an impact: terrain, weight, condition of the bike, rider input, so it’s difficult to be precise. Experts quote anything from 20 to 100 miles! Bosch, which makes popular battery packs for some very good electric mountain bikes, has an interesting online calculator you might want to try. Of course, if the battery runs flat, you can still pedal normally. You’re just carrying a little more weight than an unpowered mountain bike.
Q. How long will it take to recharge my eMTB battery after a day’s riding?
A. It depends on the size. The more watts, the longer it will take. However, three to five hours is a good average. Lithium-ion batteries have protection built in so they can’t be overcharged. If you plug in your electric mountain bike overnight, it will always be ready for you the next day.
