Instead, we will help you make an informed decision before buying your first e-bike. While there are huge differences between classes, brands and models, probably the toughest decision when purchasing an e-bike is what motor to get: a rear hub motor (RHM) or a mid-drive motor (MDM).
Which one is better?
If you ask Google this specific question, hundreds of bike reviewers will urge you to forget about rear hub motors and always choose a mid-drive engine. And while I personally also enjoy the mid-drive, I can definitely say that getting one is not always the best choice. As with everything else in life, it all depends on your needs, riding style and preferences. That’s why it’s critical to understand the pros and cons of both types of motors, so you will enjoy your ride and not just throw money away.
What are the rear hub motors?
As the name suggests, it’s a motor placed in the back of the bike. More accurately on the axis of the back wheel. It’s a big enclosed cylindrical case that sits in the middle of the wheel. There are some e-bikes with a front-hub motor, but they are much rarer and, in my humble opinion, have barely any advantages over the rear-hub motor.
Probably the biggest advantage of the rear hub motor is that it rarely needs any maintenance. All its components are placed in a closed motor casing on the rear wheel, and it’s tough to mess anything up with this kind of motor. Furthermore, they usually don’t have gears, so the chances of something breaking are even slimmer. Their drive system is entirely independent, so if you have a problem with your central axis, chain or anything else, you won’t need to touch the motor at all.
There are two types of RHM – geared and gearless. The former has internal gears that allow you to control the speed better and add help, while the gearless motor offers you its full potential. While it’s definitely nice to control the amount of support and speed with gears, the gearless option is far more secure. There is nothing to break, and rarely any repairs are needed. This makes the RHM’s maintenance not just easy but practically non-existent. It’s an encased system to which neither you nor the elements have any access.
RHMs are also much more lenient towards your bike. Since they are separate systems, they don’t stress your central axis, chains or shifters.
RHMs work on their own
That’s another major advantage of the RHM. The independent drive system allows you to use only the motor without pedalling at all. This means that if your chain breaks, your central axis goes to shreds, you can still get home. And believe me, there is nothing worse than having a broken chain at 1am whilst getting home from a friend’s house.
On the other hand, if the motor goes kaput, you will still be able to get home by pedalling, even if it’ll be a bit harder than usual.
RHM have higher torque
This advantage is especially good for the urban dwellers in the parts of the world where bike lanes are still not the norm. The higher torque the RHM allows you to dash in front of vehicles on a green light, making it safer for you and them. It’s much better for a driver to be able to see you in front and adjust rather than having you next to the side of their car.
One of the most significant disadvantages of the rear hub motor is its weight. It increases the total bike weight by a lot and if you don’t have a ground-level place where you can keep your bike, getting it upstairs is a pain. Furthermore, while weight is not a huge problem in the city, every gram counts when riding in the mountains or forests. The weight distribution is another problem. Since the motor is in the back, the centre of the weight shifts to the back, which makes bike control on swirling trails a bit more challenging.
Not to mention changing the rear tyre if something happens. The rear wheel is hard to dismount and is quite heavy. This is probably the biggest disadvantage of the hub motor. Even though it is practically helpful in the mountains, the risk of getting stuck because of a puncture outweighs the benefits.
Who is the RHM for?
The rear hub motor is ideal for urban rides, commutes, and more accessible off-road leisure rides in parks. It’s perfect for out-of-shape people who long for the joy of riding but can’t handle the pedalling. Also, it’s ideal for riders recovering from injuries, which can shift to the motor once the pain gets too much.
What is a mid-drive motor?
A mid-drive motor (MDM), as the name suggests, is a motor located in the middle of the bike, right between the pedals. Unlike the RHM, this type of motor only helps you with pedalling and can’t operate on its own. It amplifies your efforts and transfers them to the rear wheel via the chain.
MDM gear power
Probably the biggest advantage of the mid-drive motor is its gear ratio. It allows its use on any terrain and helps you climb otherwise impossible steep hills. On a lower gear, you can have a boost start. More importantly, it amplifies your efforts, so it can make you climb faster compared to a RHM. However, it’s good to remember that it’s not a stand-alone system, and it requires your input, so being completely out of shape and taking on Alpe d’Huez with a mid-drive motor is definitely not a great idea.
MDM’s weight and balance
Although it will put some additional weight on your bike, it’ll still weigh less than an RHM. There are some mid-drive motors that are as light as 2.5 kilograms. Usually, a good cross-country bike with an MDM is around 21-23 kilograms, which is pretty light compared to the alternative. However, that’s not the main advantage here. Being at the centre of the bike, the MDM balances the bike, and the weight is directly under the central axis. This helps immensely with the control when it comes to off-road and downhill riding and makes the bike easier to control on swirling trails, pump tracks, during jumps and all other features.
Furthermore, MDMs are much smaller and thus are practically invisible at first glance. This makes the bikes look much better and more picture-friendly. They look tight and sporty, definitely not like a motorbike.
Pedal assistant regulation
This may not sound like a huge advantage, but regulating how much and when the motor should help you pedaling is crucial for becoming a better rider. If you want to get in shape, you are recovering from an injury, or even if you are just a person who loves giving their all, this function of the MDM will allow you to progress with your goals. You can switch off the assistance in the flat areas and pedal your heart out. On the steeper hills, you can switch on the aid but gradually decrease its level over time. This way, you will still go to the top every time, but at the same time, your muscles, stamina and morale will grow as well. The help regulation is probably MDM’s greatest feature that the RHM simply doesn’t have.
The biggest disadvantage of the MDM is the complexity of using it properly. For example, you can’t change motor gears while you are not in motion. Also, while using the motor, you can’t shift your bike gears since you will, at best, rip off the chain or, at worst, destroy your shifters at worst.
The maintenance of the bike is another huge issue. While changing tyres will be easier than with an RHM, the MDM puts a lot of stress on your chain and pedals. Usually, an average cyclist can keep a constant power input of about 100 watts with surges up to 250 for short periods. With an MDM, the continuous power input on the chain is 250-750W. This means that most chains don’t have a chance of surviving that long with a bike like this. Most e-bikes with a mid-drive motor are equipped with an enhanced chain. However, once it wears off, a new one is a bit more costly.
Furthermore, unlike the RHM, the MDM needs constant maintenance since it’s not enclosed. It needs to be cleaned and oiled, and it’s much more prone to damages, especially when you consider where it’s most likely to be ridden.
Who is the MDM for?
The MDM e-bikes can be used in the city for commuting, but their real strength is off-road. They are perfect for cross-country riders, mountain bikers and especially downhill enthusiasts. The stability and the ideal weight distribution are perfect for speedy and technical downhill sections. On the other hand, the levels of help and power input control are astonishingly handy when it comes to climbing, while at the same time, the small size and the lightweight of the motor are perfect for rough terrains.
So, if you ask which one is better, well, it depends on your needs. If you are using the bike only to go to work and cruise around in parks and around the city, then a rear hub motor is the way to go. However, if the mountains are calling you and that slope in front seems like the perfect place to test your skills, then a mid-drive motor is your best bet. No matter which one you choose, the main point is to have fun and enjoy your ride.