Should I Buy a Pre-Built Electric Bike or an Electric Bike Conversion Kit?

Should I buy a Pre-Built Electric Bike or an Electric Bike Conversion Kit Featured Image

Electric bikes are great for getting you cycling more. They can get you cycling further and for longer, to expand your cycling horizons. You may be someone who finds cycling difficult. This could be due to a lack of fitness, or if you’re of advancing years. In which case, an electric bike could really help you here. So if you’ve decided on an electric bike, should you buy a pre-built electric bike, or add a conversion kit to a regular bike?   

Choosing between a pre-built electric bike or a conversion kit is down to personal preference. Neither option is necessarily better than the other. Conversion kits are a great way to save money, due to the fact that you can add one of these to an existing bike. This is rather than buying a whole new pre-built electric bike. If you buy a pre-built electric bike though, then you’re good to go straight away. Additionally, with conversion kits, there’s a degree of technical skill involved in setting them up.

Here, in this article, I discuss at length how pre-built electric bikes compare with electric bike conversion kits. 

Pre-built electric bike Vs conversion kit infographic

Electric Bike Conversion Kit Pros

You Can Save Money

If you have a regular bike already, then you can save money by buying a conversion kit and then adding it to this bike. A decent electric bike can be in the thousands, but a decent conversion kit can be in the hundreds. This is either for dollars or pounds by the way.

You Get to Keep Your Existing Bike

You may already have a decent regular bike that you really like. In which case, adding a conversion kit allows you to still keep it. This is rather than possibly having to sell it to generate enough cash to buy a pre-built electric bike. You always have the option to remove the kit whenever you like, so the bike is back to what it was before. 

Couple off-road cycling

Allows for Customization and Upgrades

Conversion kits allow the flexibility for customization and Upgrades. You typically don’t get this though with pre-built electric bikes. You can have the option to change between different batteries and even motors. So you can switch between different capacity batteries. This is useful if you want a high capacity battery for more range for longer rides. You still then have the option to change it for a lower capacity battery for shorter rides, to save on weight. 

Having the ability to switch out motors is handy as well. You may have a low powered/wattage motor to start with. This may be to save money and may still be powerful enough for your needs. You can still have the option to upgrade later to a more powerful motor, if you choose. This may be due to you moving to a country, or a state where the laws allow for a higher powered motor. It may be that your needs change. For example, you may later decide to go on more adventurous cycles, like up the mountains. This is where you’ll likely need a lot of power to get you up those tough climbs.

Man converting a regular bike bike to become an electric bike

Conversion kits giving you the flexibility to upgrade parts can save you money. For example, if you’re upgrading to a more powerful motor, then you’re only paying for a new motor. This is rather than paying for a whole new electric bike.

You Can Swap the Conversion Kit Between Different Bikes

You can even swap a conversion kit to another bike. This is useful if you have a different bike (or wish to have a different bike) for different purposes. For example, you may have a mountain bike for off-road use and a road bike for commuting. So if you wish to have electric assistance on both these bikes, you can then always swap a conversion kit between them. This will save on cost compared to buying pre-built electric versions of both bikes.  

Provides a Great Starting Point

Conversion kits are a great starting point if you wish to try electric biking, without forking out the cost of a pre-built electric bike. This will mean it is less of a financial risk, in case you find having an electric bike doesn’t suit you. If you find electric biking really is for you though, then you may eventually buy a pre-built electric bike later. 

Woman casually riding an electric bike through the park

Fun For DIY Enthusiasts

You may be a DIY enthusiast. In which case, you may get a sense of achievement upgrading your regular bike with a conversion kit.

Electric Bike Conversion Kit Cons

Technical Skill is Required

There is a degree of technical/mechanical skill required with adding an electric bike conversion kit to a regular bike. Not to mention it’s generally an effort anyway. Some kits are less technical and easier to attach to a bike than others, though. Nevertheless, if you’re not very technically minded, or you just don’t fancy the effort involved, then a pre-built electric bike may be the best option for you. However, if you like the idea of a conversion kit, but not the idea of attaching it, then you could take your bike to a shop. Some bike shops will be able to attach a conversion kit to your bike for you. This is providing you can find one in your area. 

There May Not be Enough Space on the Bike to Fit Parts

You may not have enough space to fit the controller and the size battery you want. Electric bike batteries and controllers as part of conversion kits, often fit to the bike frame, within the front triangle of the frame (as shown below). There may not be enough space though, in the area within the front triangle of the frame to fit these. In which case, you may have to compromise on the capacity of the battery, to have one that fits. 

Electric bike with battery and controller showing externally on the frame

You may be able to locate the battery on a different part of your bike, though. For example, if you have a pannier rack at the back of your bike, you could place your battery on there. There are even conversion kits where the battery can sit in a backpack. Here, a lead runs down from the battery to the bike. This option may, or may not suit you, though. It depends on whether or not you don’t mind riding with a backpack, with the weight of a battery inside it.

Can be an Issue if you have Rear Suspension

This links with the above. If you attach the battery to the bike frame within the inner front triangle, then this can be an issue if you have rear suspension. The battery should be positioned so that when the suspension depresses down, none of the suspension parts catch on the battery. If this happens, then this could pierce the battery, causing it to vent and then catch fire. 

Bike rear suspension shock absorber

Can Have an Untidy Appearance

Attaching a conversion kit to your bike means you’ll have more exposed wiring compared to a pre-built electric bike. This means that when compared to a pre-built electric bike, it will look untidier. You may be able to do a good job though of making the appearance as tidy as possible. This can be through the use of clips to secure the wiring against the frame and cable ties. The more technical you are with DIY projects, the more likely you’ll do a good job of this.

Electrical Parts will be More Exposed 

The main parts of a conversion kit, such as the battery, motor and controller, will also be more exposed. The battery and motor can be exposed on a pre-built electric bike, but this is not always the case. For example, pre-built electric bikes can have the battery embedded within the frame. However, with conversion kits, the electrical parts are more exposed to the elements. These include rain, mud and dirt. You don’t want dirt and water getting into these electrical parts, to possibly cause damage.

So, if you’re buying a conversion kit, you want the parts to have a very high water resistance. Some conversion kits have their parts of a higher water resistance than others. Ebikeling, make a good range of waterproof electric bike kitsOpens in a new tab.. Also, the Bafang 8fun BBs03 mid drive motor conversion kitOpens in a new tab. is a high end waterproof kit.

If you’re buying a conversion kit. You can look out for something called an IP rating. This is a rating for how resistant an electric item is to water and dirt. My article “Can I Ride My Electric Bike in the Rain?” talks further about these IP ratings. You can protect the controller and battery from dirt and water, by housing the controller in a project boxOpens in a new tab. and using a battery coverOpens in a new tab. for the battery. Both of these items can be bought on Amazon.

Ebike battery

May have to Replace Bike Parts

You may have to replace bike parts to accommodate a conversation kit. For example, you may need to replace the wheels for wider ones and maybe also the brake calipers. This would mean extra cost, time and effort. The reason why you may need to replace the wheels is due to that if the kit has a hub motor. Your existing wheels may be too light/thin to withstand a hub motor. You would only need to attach a hub motor to one wheel though. However, if you’re replacing one wheel, then you’ll need to replace the other so that they match. 

Bolt-on Mid Drive Motors can be Low Down Possibly Causing Issues

There are some conversion kits on the market that have a bolt-on mid drive motor. These are sometimes designed to attach underneath the bottom bracket of the bike. This means the motor will be low down and very near to the ground. Therefore, there is a risk of it getting bashed and damaged if it hits obstacles. This will be more likely the case if you’re off-road riding. There is even the risk of you coming off your bike if the motor hits obstacles.  

Pre-Built Electric Bike Pros

You Can Start Riding the Bike Straight Away

Pre-built electric bikes give you the luxury of knowing that the bike is good to go straight away. There is no extra effort or time needed on your part to make the bike electric. You can start riding it from the moment you get it home. This is very handy if you’re not technically or mechanically minded. 

Neater Look

Having a pre-built electric bike looks neater and slicker than having a conversion kit added to a regular bike. The electric parts, like a mid drive motor, the battery and the controller, are integrated within the design of the bike. This is rather than attaching a collection of parts to the bike. Again, you won’t have many wires showing externally with a pre-built electric bike.

Electric bike graphic image

Better Bike Geometry

The electric components being integrated within the design of a pre-built electric bike helps with the bikes geometry. This is aside from the visual aspect. You should expect the electric parts, such as the battery and motor to be strategically positioned, so that there is a good weight distribution throughout the bike. The weight and shape of the electric parts should fit with the overall geometry of the bike as well. This will give the bike good handling and a good comfortable riding feel. This is as long as the bike is good quality and well made by a reliable manufacturer. 

You may not be able to achieve the above quite as well with a conversion kit. Again, this is down to conversion kits being a collection of parts added to a bike. Whereas, pre-built electric bikes are more a system that’s designed for the electric parts to specifically integrate within the particular bike they’re part of. For example, a pre-built electric bike may have full suspension and a battery that embeds within the frame. A battery embedded within the frame will not get in the way of the suspension parts, as the suspension depresses down. It will also help give the bike a neater look and reduce drag. 

The fact that the electrical parts of a pre-built electric bike tend to fit in better with the bikes overall geometry, compared to adding a conversion kit to a regular bike, links with where I spoke about possibly having to replace certain bike parts, if fitting a conversion kit. For example, you may have disc brakes. In which case, a conversion kit hub motor may not fit well with your existing disc brake parts. So you may need to replace these with ones that do fit well. Again, replacing parts requires a degree of technical skill. This may be something you’re not willing to embrace.      

Electric bike against blue background

Longer Warranties 

The warranties on pre-built electric bikes are usually longer than for conversion kits. Warranties can vary for both pre-built electric bikes and conversion kits. However, some warranties for pre-built electric bikes can be as long as 5 years. For conversion kits, some warranties can be as long as 2 or 3 years. The minimum length warranty you can expect either way is for 1 year. Even so, if you want a good warranty you’ll have to shop around.


You have the reliability factor with pre-built electric bikes. They give you the assurance that the manufacturer has put the whole thing together professionally. You may get more peace of mind here compared to if you attach the kit yourself. This does depend though, on your confidence in your own ability to do a good job of attaching a conversion kit.  

Generally Good After Sales Support

You can usually expect better after sales support with a pre-built electric bike compared to a conversion kit. This can be from the shop, website or manufacturer you bought it from.

Graphic image of electric bike

Less Hassle

If you don’t already have a regular bike to upgrade, then buying a pre-built electric bike can be less hassle. You may know exactly what you want (say, in motor power and battery capacity) and be able to find it all in one electric bike. Also, you may be confident that you’ll never want to upgrade or customize your bike later. Therefore, buying a pre-built electric bike can be a very simple, straightforward choice.  

Pre-Built Electric Bike Cons

More Expensive

Pre-built electric bikes are more expensive than conversion kits. You may see some overlap sometimes though. This is where you may see a high end conversion kit costing more than a low end pre-built electric bike. Nevertheless, if you see a conversion kit and a pre-built electric bike both of similar performance, then you should expect the pre-built electric bike to be higher in price.   

Less Scope for Customization

You’ll typically be limited to the original electrical parts that came with the bike in the first place. This means you won’t be able to mix and match parts if you want to tailor your electric bike more to your preference.

Less Scope for Upgrading

Like above, there is little scope for upgrading pre-built electric bikes. There are some pre-built electric bikes on the market where you can get an upgraded battery from the manufacturer though. There’s even some options where you can add an additional twin battery for more range. However, these options are very rare and not the standard for pre-built electric bikes. This is at least how it stands currently in the market.

There are a few other ways to get more battery capacity with a pre-built electric bike though. These include, adding a triangle battery, adding a range extender, or carrying a spare battery in a backpack. I talk further about these options in my article “How to Choose the Right Electric BIke Battery”. Ultimately though, if you want the flexibility to upgrade parts such as the motor, battery, or LCD screen even, then a conversion kit is the way to go. 

Couple Cycling in the Mountains

Expensive to Replace Parts

Replacing parts is typically more expensive with pre-built electric bikes. These parts can include the pedal assist sensor, LCD display, the controller and the battery. With pre-built electric bikes, you’ll usually be restricted to only being able to buy replacement parts made by the manufacturer. You will tend to find the price of these parts at a higher premium. However, with conversion kits, there is more scope for third party parts. These tend to be cheaper than parts that come directly from a pre-built electric bike manufacturer. 

May Not be Legal in Other Countries or States 

If you have a pre-built electric bike, you may wish to take it away on cycling trips to other countries, or to other states if you live in America. If you do this though, your electric bike may not be legal in these other countries or states. This is due to the fact that the power of the motor (in watts) may be above the legal limit, even if it’s legal for where you live. You won’t have the option to replace your motor, for a lower powered one to get round this issue, like you would with a conversion kit. If you have a low powered motor in the first place though, like a 250 watt motor, then this may not be an issue. 


When it comes to deciding between a pre-built electric bike or a conversion kit, it’s down to whatever option suits you best. The cost of a pre-built electric bike may not be a problem for you and you may not want the hassle of attaching a conversion kit. In which case, a pre-built electric bike could be the option that’s best for you. Also, a pre-built electric bike can be a suitable option if you’re not concerned with customization. Therefore, you may prefer the simplicity of an electric bike that’s good to go from day one. Not to mention that you’ll get a tidy looking bike, with less wires and external electrical parts with a pre-built electric bike.  

Conversely, you may prefer a conversion kit to save money and to have the flexibility to mix and match parts. You may even be a DIY enthusiast and enjoy the thrill of attaching a conversion kit. Making modifications and upgrades as you go may also be appealing to you. It may even be the case that you’re attached to your existing regular bike. However, you may have to sell it to afford a pre-built electric bike. Again, here, a conversion kit could be the answer. 

Whatever choice you make, either option works and will provide you with a lot of fun. They will both get you out there on many cycling adventures. 


Recent Posts