dAKET
e-Bike
Designing a component in electric commuter bicycles in order to decrease the risks of frontal accidents
Thesis Project
The Most Popular Form of Transit
Alongside bikes rapid increase in popularity, peda-cyclist fatalities are also on the rise. At present, one of the few effective ways to protect the user in accidents and crashes are helmets that cut the head injury by half. However, according to research by The Insurance Institute for Highway safety still, 17% of people who died in accidents in 2014 were wearing helmets.
Frontal Accidents
To find the main reasons behind bike accidents, observational research was conducted on more than 1000 crashes recorded on camera. It has been cleared that more than two-thirds of the accidents were from the frontal area. An interesting finding was that low-speed didn’t have an altering impact on these types of accidents, and the result is falling of the user.
Falling over the Handlebars
When the cyclist hits a block or takes a hard brake on the front wheel, according to the inertia law, the back of the bike and the user’s body tend to keep moving forward; hence the center of gravity keeps moving forward, and the bike rotates around the fixed front wheel. This will result in a tumbling over the handlebars.
To reduce the amount of rotation of the body around the front wheel, a counter force should be implemented. This force can be the relocated center of gravity that can resist the inertia with the added mass (M) and gravity force (G)
In Nature
We can see similar mechanisms in nature and the solution is the result of thousands of years of evolution. In horseback riding example, when the horse wants to stop while riding at a fast pace, it tries to sit on its back which relocates the center of gravity and also creates more friction. This is known as reining.
In a series of interviews with professional cyclists, it’s been found that their method of encountering this issue is to move their bodies towards back and go lower before using the front brake/crashing. This will create the highest amount of force against the torque. Can we design a system to easily achieve this in a bike?
How to implement a counter-inertia system in a bike?
Introducing DAKET DAKET
Daket is an E-bike with a moving mechanism to relocate the cyclist on the bike. This relocation creates an angle and distance that increases the force to encounter the created inertia at the time of frontal accidents/sudden braking; hence, this will prevent the user from tumbling over the bicycle.
This movement happens through a linear servo
What is the Difference?
Based on accidents analysis, the servo mechanism activates when the cyclist uses the front brake. This activation pushes the seat pole to the back of the bike. The relocation of the user means more mass and intensified gravity force at the back of the bike. So the bike needs more energy to tumble and change the center of gravity.
Saddle's Mechanism
The mechanism of the seat consists of a linear servo motor that moves the seat pole. The pole is connected to a ball bearing that moves on two sets of rails. This way, the friction factor comes down to a minimum.
If we consider the maximum weight of the user 140kg, the seat in the horizontal position, and the friction factor of the ball bearing 0.0050, the amount of servo force required to move the seat would be based on the following equation.
Handlebar's Mechanism
The handlebar is the initiative of the whole system. A wire from the front brake is connected to a pin inside the handle box. When activated (user push the brake), a pin inside this box is released, which not only lets the handle move freely inside that box but also sends a signal to the servo.
Modified Version by Aluminum Extrusion
Another variant of this Product is designed primarily by Aluminum Extrusion. The mechanism in this one is manual with only the saddle moving back and forth.
The wall thickness is slightly more at the bottom of the extrusion since there is more pressure on it.
A pin welded to the body, holds the railing extrusion. When the cyclist uses the front brake, it activates the pin and release the railing extrusion which can now freely move on 4 sets of wheels. When not being held back, the saddle can lock on the pin again until later brake. This happens everytime the person uses the front brake and after a while they will get used to this saftey movement.
