Updated March 18th, 2023
Ebikes are a lot of fun to ride and allow people with injuries and other physical conditions to bike. Mountain biking is a really fun sport allowing you to enjoy being out on the trail. An electric mountain bike is the perfect choice for someone who wants an ebike and wants to hit the trails. There are many great electric mountain bikes out there or you can make your own. How do you convert a mountain bike into an ebike? We are here to help with our 15 step guide to convert a mountain bike into an ebike.
15 Steps to convert a mountain bike into an ebike
From selecting a bike and drive system to installing it, there is not that many steps. Simple hub motor conversions can be done in under an hour. Let’s get into the details of how to convert a mountain bike into an ebike.
Step 1 – Choose a mountain bike for your ebike conversion
The first thing to do is decide on a mountain bike you want to convert to an ebike. Some mountain bikes are much easier to convert than others. If you want to do the easiest possible conversion, choose a low priced mountain bike in the $300 to $400 range. One that has cable operated disc brakes and 7 rear cogs or speeds. These are the easiest bikes to convert with low cost rear hub motor conversion kits. These bikes are only suitable for beginner level mountain bike trails. See our article on the best mountain bike for ebike conversion to learn more.
If you want an electric mountain bike that is built to handle trail riding, then I would suggest you use a mid-drive. There are rear hub motors that have Shimano HG cassette freehubs. You are stuck with the rear wheel that is attached to that hub motor unless you want to build it into a new wheel. There isn’t much variety in wheel designs. Don’t expect to find a rear hub motor built into a Stans rim or anything like that. There are no hub motors available that work with thru-bolt axles or boost spacing either. If you want to make a truly trail worthy ebike out of a higher end mountain bike then your best bet is a mid-drive system.
Step 2 – Decide if you want a mid-drive or rear drive
There are advantages and disadvantages to both rear hub motors and mid-drives. I would not recommend using a front hub motor for a mountain bike if you ever plan to ride it on trails.
Mid-drive motors make use of the bikes driveline and gearing since they drive the chainring. They are much better for climbing steep hills and for high speeds. They are less reliable because they use the bikes pedal driveline. If the chain breaks, the derailleur breaks or the freehub strips out, your electric power is gone too. They are more difficult to install because you need to remove and replace the bottom bracket.
Rear hub motors work great for high speed riding. They are much more simple to install since you don’t have to replace the bottom bracket and cranks. They do not climb hills as well since they do not use the bikes gearing. They directly power the rear wheel. They make your bikes balance strange since the rear wheel hub motor is heavy.
Step 3 – Choose a motor or conversion kit
Now that you’ve gotten the mountain bike you are going to convert to an ebike it’s time to get a motor. Conversion kits are a great way to go. These include the motor, controller, display, brake levers or switches, throttle, and pedal sensors. This takes a lot of the guesswork out of trying to find compatible parts to make a complete conversion. Some include batteries as well. Most do not.
When choosing your motor or conversion kit you need to pay attention to what parts your bike has. If your going hub motor and the bike has 9 or more rear cogs you need a hub motor that works with a cassette. If the bike has hydraulic disc brakes you need brake lever switches rather than brake levers. If your buying a mid-drive conversion kit, you need one that works with the bottom bracket style on your bike frame.
See our article on the best hub motors to learn more about hub motor conversion kits.
See our article on ebike voltage, watts and amps to learn more about ebike power systems and what all the numbers mean.
Step 4 – Choose a battery
For trail riding and climbing steep hills you want more power. For climbing hills in general you want more power. If your a heavier rider you will also want more power. A higher voltage battery will give your bike more power and speed.
More battery voltage and capacity also means more battery size and weight. Keep that in mind. You need to be able to fit your battery on your bike. Many riders put their batteries in a backpack also. Many full suspension bikes have very little space inside the frame. Mountain any kind of battery can be difficult.
The motor controller and motor you are using will have a range of battery voltage it will work with. If you plan on riding trails with steep climbs I would go with at least a 48 volt battery. Choose a battery with enough amp hours to give you a few hours of riding time.
Now that you’ve got all your parts assembled it’s time to break out the tools and get to work. The conversion process is a bit different for rear hub motors and mid-drive motors. Let’s start with the mid-drive motor setup. Skip below to the Rear Hub motor section if that is what you will be working with.
Step 5 – Remove the chain
Time to get to work on the bike. The first thing to do is remove the chain. Most chains have a quick link feature that you can use to separate the chain. This is easiest to do with some help. Have a friend hold the rear derailleur forward so it takes tension off of the chain. You can then use a quick link tool or pliers to open the quick link and take the chain off. If you have a front derailleur now is the time to remove it also. Remove the front derailleur, it’s cable, any cable housing and shifter.
Step 6 – Remove the cranks and bottom bracket
We need to remove the cranks and bottom bracket so that we can mount the mid-drive motor in the bottom bracket shell. Cranks have various ways to remove them. Some just have a bolt in each crank and they come off after removing it. Others need a special crank pulling tool to get them off. Bottom brackets all require special tools to remove. You need to consult a bike shop or google to find the correct way to remove the bottom bracket in your bike.
Park Tool has an excellent article on bottom brackets and how to identify which type you have. They also have a great series of articles on removing the different types.
Step 7 – Mount the mid-drive motor
Mount the mid-drive motor into the bottom bracket. You need to pay attention to any shifter or break cables that run along the frame downtube. These may interfere with the mid-drive motor after it’s bolted in place. You may need to reroute the cables or add additional cable housing.
The mid-drive motor will mount back in, in the same way your bottom bracket came out. You will need a mid-drive motor compatible with the frame bottom bracket you originally had. After mounting the motor you need to mount the chainring and cranks that came with the mid-drive system.
Step 8 – Put the chain back on. Check length
Now it’s time to put the chain back on. This is easiest with some help to hold the tension off of the derailleur. If you are replacing a 1x driveline with a mid-drive you might need to lengthen the chain. If the chainring going back on is larger than the chainring you took off the chain may not be long enough. If your replacing a 2 or 3 chainring crank, the new mid-drive chainring will fall in between them in size.
Step 5 – Remove the rear wheel
Flip the bike over. Shift the bike into the smallest cog. Loosen the rear quick release or bolt if it doesn’t have a quick release. To remove the wheel you need to take some tension off the chain by pulling the derailleur cage forward. Once you do that the wheel will slide out very easily.
Step 6 – Mount the new hub motor rear wheel
If your rear hub motor wheel didn’t come with a tire, you need to take the tire and inner tube off your original wheel. Deflate the tube, use some tire tools to unmount the tire, then put it on the new wheel.
Slide the rear wheel back into the dropouts in the frame. Hold the rear derailleur cage forward to take tension off the chain while you do this. Once you have the rear wheel seated in the dropouts you can tighten the rear hub drive axle. Torque arms are small parts that help transfer load to the frame seat or chain stays from the dropouts. It is a good idea to use them if you have a higher powered hub motor above 750 watts. Bike frames are not designed for motor loads on the dropouts.
Step 7 – Adjust the rear brake caliper and derailleur
Now that the wheel is in place it’s time to make a few adjustments. The new rear hub motor may not put the brakes and freewheel/cassette in exactly the same place as they started. To adjust the brake caliper, loosen the 2 mounting bolts. Spin the rear wheel a few times. Squeeze the brake lever while spinning the wheel. Do this a few times. While squeezing the brake lever, tighten the 2 mounting bolts back up. This will align the brake caliper to the brake rotor. If your brake squeals while you are riding it, repeat this process.
Test your rear shifter and see if it shifts through all the gears smoothly. Make sure it’s not about to push the chain off the biggest cog. If everything is still working well you are ready to move on. If it’s not consult this guide from Park Tool on how to adjust a rear derailleur. They are easy to adjust if you follow their method.
Step 8 – Remove one crank and mount the pedal sensor
If you are going to operate this bike with a pedal assist mode you will need to install a pedal sensor. To do this you will need to remove one crank. Depending on what cranks are on your bike this can be as easy as unbolting 1 bolt or it can require a special crank pulling tool. If your not sure, consult your local bike shop or Google for your brand of cranks. After removing the crank, you need to put the sensor onto the frame. You need to put the magnetic part of the sensor onto the crank. Reassemble the crank arm back onto the frame.
For both mid-drive and rear drive mountain bike conversions
Step 9 – Replace brake levers or add stop switches
If your bike uses cable operated disc brake, then you need to replace the brake levers. The levers that come with an ebike conversion kits have on/off switches in them. These kill power to the motor when you squeeze the brakes. If you happen to have a bike with integrated shifter and brake levers you may need to get a new shifter also. After installing the new brake handle you need to run the cable back to the brake. Tighten it at the brake and adjust the cable tension so the brakes are to your liking.
If you have hydraulic disc brakes you need to get switch that can be added to the brake lever. Most companies such as Bafang offer them as accessory parts to their conversion kits.
Step 10 – Mount the controller
Now we are finished with all the remove and replace jobs. Now it’s time to add the rest of the parts and try this thing out. First off is mounting the motor controller. Some conversion kits give you a bag or housing to mount this with. Others do not. You may need to go out and find a frame bag or rack to put this on. Make sure the leads from it are long enough to attach to the motor and pedal sensor in the location you mount it.
Step 11 – Mount the display and throttle on the handlebars
Mount the display and throttle on your handlebars. To mount the throttle you will need to remove one of the handlebar grips to slide it on the handlebar. If you have a twist throttle it will replace one of the handlebar grips. A lot of handlebars grips have small clamping bolts that you loosen to slide them on and off.
If your grips do not have clamps built into them, then they are held on with pure friction. The easiest way to deal with these is to cut them off and get better grips. If you really want to use the original grips, you can work at it a while to get them off by twisting and pulling on them. Eventually, they will come off. To put them back on, first, wipe the handlebar down with some soapy water. This will allow them to slide back on easily. Once the water dries they will stay in place.
Step 12 – Mount the battery
Mount the battery to the bike frame or to a rack. You can also carry the battery in a backpack while your riding. Frame bags that go in the frame do a good job of holding a lot of batteries. Some ebike batteries have a hard shell casing and can mount to water bottle cage mounts. This can give you a very clean professional looking bike. If you mount the batteries on a frame rack above the rear wheel it can make your bike very rear end heavy. If you combine with this a rear hub motor you are adding an extra 25 to 30 lbs of weight to the rear of the bike.
Step 13 – Clean up the wiring
Run the wiring between all of the components. Consult the manual for your controller and motor to learn all the connections. You need to connect the drive motor, controller, brake switches, pedal sensors, throttle, battery and handlebar display. This can be a lot of wiring. Zip ties and cable conduit can help a lot to keep things cleaned up. You don’t want to have large masses of wiring flopping around.
Try not to leave more than a few inches of unsupported wiring anywhere. Leave enough slack for wires going to your handlbar. You should be able to turn your handlebar at least 90 degrees in both directions without stretching anything. Loose wires flopping around will lead to fatigue on the connectors and chafing of the wires. Keep everything as neat and tidy as you can get it.
Step 14 – Charge the battery
Now that everything is hooked up and put together nicely it’s time to charge up the battery and try it out. Use an appropriate battery charger for the battery your using. Always be careful not to over charge or over discharge lithium batteries. Charge the battery to full capacity.
Step 15 – Give it a test ride
Plug the battery in and go for a test ride. Check the motor power levels, pedal assist and throttle controls. Check to make sure your brake switches are cutting off the motor. If everything is working well it’s time to start enjoying your new electric mountain bike.
Mountain Bike Conversion with a Mid-Drive motor
The below video shows the entire conversion process for a Bafang mid-drive motor on a full suspension mountain bike.
Mountain bike conversion with a rear hub motor
The below video shows the entire conversion process for a mountain bike using a rear hub motor.
Convert A Mountain Bike Into An Ebike FAQ
Q: Can I convert my mountain bike to electric?
Yes, you can turn almost any mountain bike into an electric bike. Some are much easier to convert into a electric bike than others. Most under $500 bikes can be converted quickly and easily with a hub motor. Higher end bikes, depending on their setup may need a mid-drive to work. You should not try to convert a carbon frame mountain bike into an ebike. It’s a fast way to make a really expensive junked carbon frame.
Q: Can you turn any bike into an ebike?
The only bikes you should not try to convert into an ebike are bikes with carbon frames. Carbon bike frames are designed to be very light weight. They are designed for very specific loads. They are not designed to take motor power loads through their dropouts. They are not designed to take motor power through their bottom bracket.
I hear stories all the time from mountain bikers I know who have broken carbon frames. These are all regular mountain bikes. Not ebikes. Carbon frames designed to be light. They aren’t designed for durability. Almost any other bike out there can be converted into an ebike by one method or another.
Q: What is the best electric bike conversion kit?
If I was going to convert my mountain bike into an ebike I would use a Bafang mid-drive unit. Mid-drive units have a more natural pedal assist feel. They can take advantage of the bikes gearing to be good for climbing or riding speed. Bafang units are very popular and proven for durability and performance. They make a wide selection of parts that can convert almost any bike.
Q: Are ebike conversion kits good?
Yes, ebike conversion kits are good. These simplify the conversion process by giving you a set of parts that will work with a common bike. They work best on bikes that are in the $300 to $400 range. Bikes with 7 rear cogs, cable pull disc brakes and quick release front and rear wheels. As your bike goes beyond that and starts having hydraulic brakes or boost spacing, a conversion kit may not have all the correct parts you need. Conversion kits are a very good way to make an ebike out of a common mountain bike.
Q: Is 250 watts enough for ebike?
It depends on what you want to do and how big you are. 250 watts will get most riders up to 20mph on flat ground. 250 watts will struggle on steep hills if they can go up at all. For reference a professional athlete can generate about 400 watts of power for long periods of time. They can generate 1000 watts for short busts such as sprints. 250 watts is not a small amount of power compared to what the average rider outputs. It’s not going to send you flying up hills.
Q: What are the disadvantages of electric bikes?
Electric bikes are not legal for all types of riding. Some states have rules on maximum power and speed for ebikes. Most use a class 1 through 3 system. You can learn more about Class 1 to 3 ebikes here. Bikes that exceed 750 watts and 28mph top speed are not legal to ride on the road in many places. They have to be registered as a moped or motorcycle.
Many mountain bike trails do not allow ebikes of any form at all. This is changing and I believe in the future most if not all mountain bike trails will at least allow Class 1 ebikes. They have a lot of benefits to older bikers or bikers with injuries. They do not have more power output than regular bikes with stronger riders.
There is an added maintenance and cost factor to an ebike. Motors and batteries aren’t free. Batteries don’t last forever.
Ebikes way more than regular bikes. If you throw on 20 to 30 pounds of ebike gear, the bike gets heavier. If your battery runs out out or motor dies, than it’s a lot of extra weight to pedal around.
Q: Are e bikes good for fitness?
Ebikes can still be very good for fitness. If you are using pedal assist, you still have to pedal. This will allow you to rider farther than you could without it. You will still be getting exercise. If you have a leg or foot injury, ebikes can allow you to still pedal and ride a bike if you couldn’t ride a regular bike. You can work as little or as hard as you want to on an ebike. An ebike can be a great way to get back into exercising if you need a little extra help. Injuries or other physical conditions should not keep your from enjoying biking.
Q: Are electric bikes Good for hills?
All ebikes will provide some help going up hills. A 250 watt ebike won’t be able to go up large hills on throttle alone. A 750 watt ebike may be able to fly up a hill without any help pedalling. Hub motor ebikes are not as good at hill climbing as mid-drive bikes that can use the bikes gearing. All ebikes will make it easier to ride up hills. Some can make it much easier than others.
Q: What is the most powerful electric bike conversion kit?
NBPower makes a 5000 watt rear hub motor. Anything over 750 watts may not be street legal in most places. A 5000 watt rear hub motor may not have as much climbing power as a 750 watt mid-drive motor. The mid-drive motor can take advantage of the bikes gearing. A hub motor directly drives the wheel and can’t.
Q: What is the cheapest electric bike conversion kit?
The JAXPETY 500 watt ebike conversion kit is one of the cheapest ebike conversion kits available. For under $200 you get a complete conversion kit with everything except the battery pack. It is one of the best values out there.
You might also like:
- The Best Ebike Hub Motors Helpful Guide
- How To Make An Ebike Faster. 9 Easy Ways You Can Do It
- Electric Bike Voltage And Watts. Helpful Guide To E-bike Power
- The Best Mountain Bikes For Under $600 Helpful Guide
Co-Founder & Biking Editor
I have been riding bikes and messing with them my entire life. I have always loved the thrill of riding whether it’s down the street or in the woods on a trail. I have a Master’s Degree in Mechanical Engineering and Reliability and am a complete gear nerd. I have 20+ years of product development engineering experience and a lot more years of biking. I currently reside in Michigan but grew up in Pennsylvania.