The M2 folding ebike in profile

Engineering Takeover: Why rear-wheel motor placement and torque sensors matter

Interview with FLIT Design Engineer, Harry.

In the ever-expanding world of ebikes, it’s crucial to consider how these innovative two-wheelers perform on the road. If you’re searching for a seamless riding experience with your folding ebike, understanding the importance of motor location and the role of a torque sensor can make all the difference. In this blog post, Harry, Design Engineer at FLIT, unravels the mechanics of the new M2 folding ebike and how it optimises your riding adventures.

Why the Rear-Wheel Motor Location Matters

Arguably, the best position for an ebike motor is in the middle of the bike by the pedals. These ‘mid-drive’ motors provide lots of torque, can be combined with other electrical components like controllers or sensors, and keep the weight in the middle of the bike. However, they are heavy and need special changes to the frame to fit them, adding width to the fold and even more weight. This is why folding ebikes don’t tend to use them, at least not folding ebikes that you might need to carry up a set of stairs.

Unlike most folding ebikes and conversion kits on the market, the FLIT M2 has its motor in the rear wheel, a design choice with a purpose. According to Harry, “This is because most of the rider’s weight is at the back, so by having the motor there, it is best able to help you pull away [from traffic lights and other riders] and go up hills more easily.”

The placement of the motor in the rear wheel also means that it is driving the rear wheel rather than the front wheel. This is what most riders are used to as the chain normally drives the rear wheel on a bike. Motors that drive the front wheel can feel unnatural, almost like the motor is pulling you forward rather than using you along.

Having the motor in the rear wheel also allows the ebike to better assist you in navigating challenging terrains, like steep hills. Because most of the rider’s weight is on the back wheel, an ebike with a rear hub motor can give you lots of power when you need it without having to worry about the wheel slipping. By contrast, ebikes with front hub motors are prone to having the front wheel slip on steep or wet roads, or on loose surfaces like gravel.

The Torque Sensor: Your Partner on the Road

The rear-wheel motor isn’t the only innovation that sets the FLIT M2 apart from other folding ebikes. The inclusion of a torque sensor takes your riding experience to the next level. Harry explains that this sensor responds instantly when you push on the pedals, unlike cadence sensors which have to wait for you to complete a certain fraction of a pedal rotation before activating the motor. This is very useful, for example, for starting on steep hills where you want the motor to assist you straight away rather than waiting for you to ride uphill unassisted before realising that a boost would be appreciated!

Moreover, the torque sensor adds an extra layer of intelligence to your ebike. It senses the effort you exert through the pedals and seamlessly matches it, assisting in proportion to your pedalling force. This technology becomes especially noticeable when you’re starting from a standstill at traffic lights or climbing uphill.

Tailored Power Levels for a Personalised Ride

To compliment the responsiveness of the rear motor and torque sensor, the FLIT M2 folding ebike also has customisable power levels. Harry elaborates, “You can also control the levels of power the motor gives you using the new display on the M2. The new motor has 5 levels of power, so you can set what feels comfortable and right for you.” Because both the power level and the force that you put through the pedals affect the level of assistance from the motor, the M2 is unusually responsive to how you want to ride. Whether you’re looking for an effortless cruise or a workout-enhanced pedal, the FLIT M2 offers the flexibility to adapt to your needs.

You can watch Harry’s video about the motor and sensor here.

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