Two wheels are increasing in popularity as a form of transport. You may be thinking of joining the cycling community, whether it is for fitness, leisure or commuting.
There are many options for consumers who are considering a bike; one of the options available is an electric bike.
You may be considering an electric bike and deciding on the right one can be a daunting prospect. Previously we discussed hub driven electric bikes, comparing front and rear hub motors.
In this blog, I will compare hub and mid-drive motor bikes. By the end of this article, you will have enough information about electric bikes to help you buy confidently.
As stated in the last blog, hub motor bikes place the electric motor at the centre of the front or rear wheel. These are the most common electric bike available.
Mid-drive motors place the electric motor closer to the centre of the bike, using a chain to transfer the electric power. They have become a lot more common over the past 2-3 years, which has seen them cut into the hub motors market share.
Both bike types have many advantages and disadvantages that are unique to electric bikes. Your requirements will help you figure out which motor type is best for you.
Advantages of a Hub Motor Bike
A significant advantage of a hub driven e-bike is that they need very little maintenance. Hub motors are independent of the drive system. The motors components are all within a case which ensures there is nothing to maintain and less to fail.
You get two types of hub motors; geared and gearless hub motors. Geared hub motors have internal planetary gears. They reduce the speed of a higher RPM motor.
Gearless hub motors have no gearing directly connecting the lower RPM motor stator’s axle to the bike.
Over time, the gears in a geared hub motor can break off, which will see the nylon gears strip. Gearless hub motors have no moving parts; this means that there is nothing to wear out.
As hub motors don’t connect to the pedals drive systems, no extra stress is added to the chain or shifters. The chain will last longer as the hub motor will carry the majority of the work.
With the hub motor and pedal system independent of each other, if you are out and one fails, it doesn’t mean you are stuck. If the chain breaks, pop it into your bag and, if fitted, use the walk assist to cycle home (albeit, somewhat slower) and vice-versa.
Hub motors are great for riders who don’t need high-performance levels but still want help getting about. The bike and battery are often smaller and lighter, making the bike perfect for commuters.
Hub motors are generally cheaper than mid-drive motors. They are mass-produced and the designs remain constant over time. This makes them cheaper to manufacture.
Disadvantages of a Hub Motor
Hub motors are better suited to flat land cycling due to their single gear ratio. Climbing hills need a lower speed but a higher torque gear. A single gear motor isn’t as efficient, when used at a lower speed.
Changing tyres on rear hub motors can be tricky. Often you have to disconnect the motor wire or wrestle a heavy wheel while connected to the bike. The positioning of the hub also means you can generally only use certain types of components. These are components, such as rims and tyres that come with the bike. If you had a preference on the type of tyre you’d like to use, it may not be suitable for your bike.
Advantages of Mid-Drive Motors
These motors are designed to overcome the shortcomings found in hub motor bikes. Fundamentally, mid-drive motors are different to hub drive motors. This is because the motor is positioned more centrally on the bike. The most significant advantage mid-drive motors have over their counterparts is their gear ratio.
Riders power the rear wheel through the same chain and gear set as the pedals. This allows you to select lower gears which help you climb steep hills and climb them for longer.
The motors tend to be smaller and lighter. The smaller size of these motors means they often are incorporated directly into the frame of the bicycle. This disguises the fact that it is an electric bike, as most people don’t realise.
Due to the positioning of the motor, the handling of the bike is more agile. The motor is near the crank, providing optimal weight distribution and a low centre of gravity. The positioning of the motor of the battery allows for shorter cable runs.
Significant maintenance issues for bikes, in general, are the tyres. Changing tyres on a rear hub motor can be trickier, as the motors are connected to the bikes wheel. The tyres on the mid-drive motors are far easier to change, as you don’t have a heavy motor connected to the wheel. Another bonus is that you can use any bike components you prefer. So, if you wish to change the cassette or see some rims that you like, it’s easy to interchange such components.
Mid-drive motors also benefit from allowing the use of true torque sensors for the pedal-assist system. The system regulates the power of the motor. It is based on how hard you push the pedals and measured on the crank. The motor system reacts quickly to rider behaviour. Hub motors use a cadence system that regulates motor speed based on pedal speed. This can make the motor timing jerky or awkward, affecting the ride, especially when riding uphill or avoiding object, more expensive hub driven bike do have torque sensors though.
Disadvantages of Mid-Drive Motors
The single most significant disadvantage to a mid-drive motor is the wear and tear on the bike, specifically the drive system. To put this in context, a healthy person can put out approximately 100W of power for a reasonable amount of time and around 250W sprinting.
Mid-drive motors can output 250W continuously (Over 250W motors are available, but not legal at the time of writing this blog, in the UK). This can cause massive wear on the chain and other components of the bike. Typically, cheap chains don’t last long and snap.
Generally, you’ll find that retail mid-drive bikes have an upgraded chain. This lasts a bit longer but wear on the chain is the primary maintenance issue for electric bikes.
Mid-drive motors have more moving parts, which means there are more points of failure. As a result, it is more expensive to replace the motor, unlike its counterpart, the hub motor, where you just swap it out.
A consideration when buying a mid-drive bike that most people fail to consider, is that you can’t shift gear unless the bike is moving (the same as when riding a regular bike). If you are moving and have to stop suddenly, you must remember to downshift. Otherwise, you’ll be stuck in a higher gear, affecting acceleration.
Which Bike is Best for me?
After reading this, you may be wondering which is the best bike for me. The simple answer is that it depends on you.
Are you a commuter? Will you go off-road? It all depends on what you’re going to use the bike for. Whatever motor you decide on, they all have their unique qualities.
Due to weight and better gear usage, mid-drive bikes are better suited to riders who prefer off-road riding and distance. They also tend to be more agile and have more effortless and natural handling. They are generally suited for those who are looking for a high-performance bike. Yet, they are often more expensive and have higher maintenance costs, but they have more versatility in the components they can use.
Hub motors are generally cheaper, lower maintenance, reliable and generally quieter. There is also an added layer to this. If you decide, a hub motor is suitable. You then have to decide whether a front or rear hub motor is the best bike for you.