LightSpeed Dryft with the Rising Sun
LightSpeed Mobility started off with an idea to bring electric bicycles, or battery operated bicycles to Indian roads. Designing these electric bicycles has been a challenging task; deliciously challenging. The design process saw us all deeply involved in deep discussions and debates for a long time as we created our initial prototypes; and we are proud to say that the entire process has been guided by our values and our vision to make commute easy and hassle free.
In putting together our first two models — Glyd and Dryft, we chose simplicity over needless intricacy. We focused on a single objective for the electric bicycles to fulfill, rather than weighing them down with bells and whistles. Dryft evolved into an MTB for the adventurous, while Glyd was molded into an urban mobility solution for the health conscious daily commuter.
Placing the motor
One of the first decisions that we made was regarding the placement of the motor. There are three popular choices for the design:
– Front wheel hub motor
– Rear wheel hub motor
– Mid drive motor
The front wheel hub motor is a good alternative when it comes to an even weight distribution, but a rear wheel hub motor provides a better thrust. Since the rear wheel takes up slightly more weight, the resultant traction helps in converting the torque to a faster speed.
Mid drive motors are really powerful while travelling on steep inclines, but they are over specialized for hilly terrains. So, even though powerful, they do not meet our need for simplicity.
Geared motors on freewheel
A very obvious ongoing trend has been to use regenerative braking across different vehicle categories to add to the feature set. However, during our design process we decided against regenerative braking.
Regenerative braking sounds like a very good mechanism — and for most heavy vehicles, it is. For massive vehicles like trucks and cars, the mass and momentum ensure that there is enough kinetic energy that can be reused as battery power.
For an electric bicycle, however, there is just not enough kinetic energy to meaningfully convert into battery power. At the same time, a regenerative system adds considerable weight to the vehicle. This is counterproductive. Not to mention that in the off-chance case that you drive with a depleted battery, you can feel a visceral drag on the bike, as if the rear tire is flat.
Valuing simplicity, we use geared motors on a free wheel. Such a system ensures that the electric bicycle is a bicycle with in-built Pedal Boost. On a depleted battery or with no throttle, your LightSpeed electric bicycle behaves like a normal bicycle, which is not the case with alternative systems.
Limiting the range to 50 km
We have limited the range of Dryft to 50 km. It is certainly possible to take the range to a higher figure — for example, 100 km. However, selecting a battery capacity of this range adds to the weight of the battery, increases the charging time, and adds substantially to the overall cost of the bicycle.
On the other hand, 50 km is a reasonable range for the electric bicycle. It keeps the overall design functional, without creating any lopsided features. Every recharge cycle is fast enough for a quick reuse.
Choosing the hub for the battery
The battery on LightSpeed electric bicycles uses the Downtube Mount option. This lines up well with our design objective of simplicity, because it resolves quite a few issues. The Downtube mount brings the weight distribution to the center, compensating for the motor on the rear wheel hub. Simultaneously, this happens to be the easiest spot wherefrom the battery can be removed and reinserted regularly after every discharge.
There are other options to mount the battery, but they are all sub optimal. Mounting the battery on the carrier makes the weight distribution lopsided towards the rear, adding near about 6 kg of weight on the back. A below-seat mount makes the battery difficult to retrieve. The In-Frame mount of a battery leaves it un-retrievable for recharges and the cycle needs to be taken near a plug spot, making it a very inconvenient affair.
Pedal Boost mechanism: Throttle along with pedaling
Many electric bicycles sport a Pedelec mechanism, especially in Europe. This has a more regulatory reason rather than technical one. The pedelec mechanism provides electric power based on how you are pedaling. The sensors for your pedaling cadence are quite intricate and the system provides electric boost when you are pedaling. When you are not pedaling, there is no boost. The objective in this mechanism is to bypass the definition of a powered vehicle. Regardless of its merits, it is a very complex mechanism involving sensors and microprocessors that can be a drag if something goes wrong.
Some electric bicycles have only a throttling option, which really does nothing other than making it a traditional two wheeler; and a weak one at that.
LightSpeed electric bicycles are equipped with the Pedal Boost technology. As the name suggests, the electric bicycle retains its nature as a bicycle, but provides an electric boost to your pedaling if you use the throttle. Thus, it becomes a unique bicycle/battery powered vehicle hybrid in its own way.
Single-speed versus multispeed options
We have always fawned over “geared”/multi-speed bicycles while growing up. The different speeds allow the rider to exert proportional force. The lowest speed is ideal for uphill climbs, where the rider’s legs are practically swimming through air while the bicycle gently rides uphill.
For our electric bicycles, however, we have opted for single-speed gear hub on the rear wheel. This was a straightforward decision, since the Pedal Boost mechanism by itself compensates for different speed levels. Uphill climbs can be done while throttling the electric bicycle with absolute ease.
We hope that in this short post, we have provided you a quick introduction to the choices that we have made and the kind of options present out there in the world of electric bicycles.