Buying guide for best electric bike conversion kits
Electric bikes (or e-bikes), have a lot of benefits, not least of which is help going up hills. Unfortunately, electric bikes can be quite expensive.
However, many people who are considering buying one already have an ordinary bike, and if you’re one of them, an electric bike conversion kit can be an attractive option.
We at BestReviews have been researching the available electric bike conversion kits to find the ones that deliver the right balance of performance and economy. We've distilled that information into the following shopping guide to help you with your purchasing decision.
Types of electric bike conversion kits
There are lots of different ways to convert a standard bike to an efficient electric bike. A wide range of components allows you to custom-build a precise solution for your needs. The challenge with the custom-built approach is that high-end components can be expensive, and if you’re not already knowledgeable, there’s quite a steep learning curve.
That’s why electric bike conversion kits are so popular. Manufacturers have put together a whole range of compatible parts, so all you have to do is fit them to your bike.
But that still leaves a few things to take into consideration. The biggest decision is the type of drive. There are three types generally available: front-mounted, mid-mounted, and rear-mounted drives. Two of these involve swapping out an existing wheel. The other attaches where the pedals go. Let’s look at each in more detail.
Front-mounted drive
This kit involves removing your existing front wheel and replacing it with one that has a motor in the center. It's important to check that you're replacing the same size wheel, and that it will fit between your existing fork, but this is seldom a problem. If your bike has a rear gear set – as on most mountain bikes – you can still pedal and change gears as before if you need to. A front-mounted drive is best for level or slightly undulating terrain.
Pros:
Cons:
Changes balance and handling (On a traditional bicycle, drive is at the rear. With front-mounted e-bike conversions, you're pulled along from the front.)
More weight on front fork
Not always compatible with disc brakes
Increased front tire wear
"Your investment in an e-bike conversion kit will unfortunately make your bike more attractive to thieves. If you don't already have one, buy a good-quality bicycle lock. Make sure your bike is insured and that the conversion parts are covered, too."
STAFF
BestReviews
Mid-mounted drive
Rather than change either wheel, you can attach one of these kits to the bottom bracket, where your pedals are. This is a powerful and efficient solution, especially for people riding in hilly areas, but the initial price and general running costs are higher than for other models.
Pros:
Cons:
Rear-mounted drive
Similar to front-mounted conversions (many manufacturers offer both, and some components are the same), but for the other end of your bike. It's important to check for correct wheel size and fit. Rear-mounted electric bike conversions are often considered the best compromise, with more traditional bicycle ride characteristics than front-mounted conversions, but not so expensive or complicated as mid-mounted drives.
Pros:
More like normal riding than front-mounted drives
Better power transferral; more efficient than front-mounted drives
Comparatively easy to fit
Lots of choices
Affordable
Gearing may change, but derailleur shifting retained
Cons:
Slightly more complex than front-mounted drives
More expensive than front-mounted drives
Increased rear tire wear
Can’t be used with existing hub gear systems
Can cause front end to feel light
For your safety
Always wear a bike helmet. Pavement is much tougher than your head. It's even more important on an e-bike because you'll probably be going faster than when you pedal.
STAFF
BestReviews
Other e-bike kit considerations
Speed and range: These make good "headline" figures for manufacturers, but you need to think carefully about what you expect from your electric bike conversion kit. While speeds of up to 30 mph are theoretically possible, an e-bike conversion kit is heavily reliant on the bike to which you’re attaching it. It will seldom deliver the performance of an electric bike that has been designed for the purpose from the ground up.
Motor: Two motor sizes are generally available, 36 volt 500 watt, and 48 volt 1,000 watt. Some manufacturers offer both. The larger motor delivers up to 30% more speed and greater range, but the battery required is more expensive.
Batteries: Old-fashioned lead-acid batteries are comparatively cheap but not very efficient. We strongly recommend lithium-ion (Li-ion) batteries. When choosing a battery, check the ampere-hour (Ah) rating. Higher numbers give more consistent power over a longer period and usually recharge more quickly.
Pedelec or throttle-control: It’s important to know the type of drive. With pedelec (also called pedal-assist), the pedal crank is powered, so the pedals rotate – sensing your input and delivering power accordingly. You still have to pedal, though little effort is involved. Throttle-control models (usually front and rear hub motors) don’t operate the pedals. In effect, you’re freewheeling but being driven along by the motor. You might decide you want to assist by pedaling and so save some of the battery power, but it’s not necessary. In both cases, putting in some effort, particularly on hills, will reduce power consumption and so increase the bike's range.
Brakes: Most electric bike conversion kits suggest replacing the brakes, though these aren’t always supplied. Disc brakes have more stopping power than caliper brakes and so are frequently recommended. Our preferred models include levers that look much like ordinary bicycle brakes, but they stop the electric motor rather than the wheels themselves. Regenerative braking is an automotive technology that can be adapted for electric bikes. When you squeeze the brakes, the friction creates energy that can be used to extend the battery life. The technology isn’t common on bikes, though, and is currently quite expensive.
Quick conversion: Some front-mounted kits come with batteries that fit on the actual motor housing. You can convert from electric to pedal power in just a couple of minutes. Power and range are comparatively low, but it's certainly a consideration if you travel relatively short distances.
E-bike conversion kit prices
It's unlikely you'll find a quality kit for under $150.00, but there are several good models between that price and about $200. However, you need to add the cost of the battery, which can be anything from $250 to over $500, depending on power. Expect to pay about $400 to $700 for a kit plus battery.
So does that make "all-in-one" kits that include the battery more attractive? It might, but you have to be careful to compare apples to apples. E-bike conversion kits with battery included often have 36V 500W batteries – much less powerful than our suggested 1,000W models – yet these still cost between $250 and $400. If you're staying close to home, it isn’t a problem, but if you're considering longer trips, you need to check the specifications carefully.
What's great is the choice you get. Think carefully about what you need and you can more or less put together your own shopping list. The result could save you as much as 50% compared to off-the-shelf e-bikes.
Tips
Practice with the controls. Though motorcycle-type throttles are available on some electric bikes, most conversion kits use a thumb lever. This looks much like the speed control you find on a lawn mower. When new, the action can be a bit jerky, and a number of users warn that the lever takes a while to get used to. As with any powered vehicle, you need to take things easy until you get used to how it starts and stops.
Double-check if a battery is included. Specifications are provided, and you'll probably find batteries at the same place where you buy your kit, but they can add significantly to the price.
Know the regulations where you live. In the U.S., an “electric bicycle” for road use must not exceed 20 mph or have an electric motor of more than 750 watts, yet most e-bike conversion kits exceed that. Interestingly, some manufacturers use the terms “motorized bike” or “pedal motorcycle.” That doesn't make the kits illegal, but some states might categorize them as “motor vehicles” rather than bicycles. Each state has its own rules, so the safest course is to check your local statutes before you buy.
- Spread the weight evenly. If possible, it's good to spread weight evenly over your bike. Batteries are quite heavy, so if you can mount them low on the frame, you generally get better control. It's not always possible, particularly with rear-wheel motors, where batteries are frequently on a rack above the rear wheel.
FAQ
Q. Is converting an ordinary bike to an e-bike an easy job?
A. It depends on the kit and the extras you choose, but we found the majority of people using kits thought it turned out to be easier than they expected. On average, the work takes around an hour. Some fear the motor might be complicated, but with most conversions, it's encased in the wheel, so it's just a question of swapping out the old and fitting in the new. Other parts are either bolted to the frame or fixed to the handlebars. The instructions aren't always great, but there are lots of online videos to help. Mid-mounted versions can be a bit trickier, but if you usually do basic bike maintenance yourself, you shouldn't have any problems with an e-bike conversion kit.
Q. Do I need an expensive bike to start with?
A. Not at all. In fact, some expert say that converting a cheap, steel-framed mountain bike is perhaps the best way to go. Town/commuter bikes are also popular models for conversion. Fancy road bikes with carbon fiber frames are great for racing, but they aren't the most robust of rides. Bolting a battery to one isn't recommended.
Q. Can I trust manufacturer figures for e-bike speed and range?
A. Most manufacturers try to give accurate information, though it's fair to say each one will usually show its product in the best light! Any difference between those figures and real-world performance is heavily influenced by the bike you convert. A bike with an aluminum frame is lighter than one with a steel frame, and that will have an effect. Condition of chain, standard of maintenance, and wear and tear are also factors. Electric bike conversion kits are best looked at as great all-rounders. Choose carefully and you can get useful speed and good range. If absolute performance is your goal, a dedicated e-bike is perhaps a better solution, but it is far more expensive.
