Concepts / Hypothesis

As mentioned on our objectives, our team is to design an ergonomic seat which not only provides safety, comfort, aesthetic and ease of use, but it also requires exciting the user as well when riding the electric 3 wheeler. Additionally, we are required to design a suitable siting posture for the rider for maximum comfort. All these factors give rise to our hypothesis on the concept of our ergonomic seat.

Firstly, the idea of achieving these factors leads us to have 2 different riding postures. Initially is where the rider follows the racing motorcycle posture as shown in figure 1.0 below. Notice that the posture demands a forward lean where the stomach of the rider rests on the fuel tank of the motorcycle. This enables the rider to accelerate quicker as the posture itself is aerodynamically shaped, resulting in a lesser wind resistance (or drag force) toward the rider. Based on Figure 1.1 below, the rider’s head is angled in front of the body. The back muscles and the leg support the weight of the body. The arms are relaxed and the elbow is bent. Knees are bent and held against the fuel tank, and the feet are resting on the foot pegs in a position behind the knees [1].

Figure 1.0 Figure 1.1

However, remaining the same posture for several hours without a spinal support rest will definitely result in backaches. Hence, this gives rise to our second riding posture, a normal seating posture with a fully supported backrest. Now how is this possible? It is 2 different things.

The idea is to change the seat itself with a single button. In other words, suppose the rider is tired from the excitement of such posture. With only a single button, the seat is adjusted to a relax posture whereby it is a standard seating posture with an added backrest on it. To put it simply, the seat itself is interchangeable from a racing seat to a standard seat with a backrest on it or vice versa.

Standard posture will allow the rider to sit on an upright position with his lumbar completely lying on the backrest, distributing (balancing) the pressure throughout the spinal area, providing maximum comfort for long-distance rides [2]. However, such riding posture will definitely slow down the actual speed of the motorcycle as compared to the racing posture. For instance, take Figure 1.3 below, the rider’s body is upright and isn’t angled forward or slung back. The hands are extended and the hands rest comfortably on the grips. There is enough space for elbows to remain relaxed and slightly bent. Knees rest against the fuel tank and bent at a height lower than the hips. The rider’s feet rest on the foot pegs at a 90-degree angle [1]. Also, standard posture allows the rider to fully access the control panel in the middle and buttons on the handlebars.

Figure 1.3

For that, we consider the pros and cons of the 2 riding posture and seats:

A. Racing Posture

The Pros: - Sports riding posture is superior in terms of aerodynamic as there will be less amount of wind resistance for the rider. - Riding performance especially in curves will be enhanced. The driving experience will be fun and exciting for the rider.

The Cons: - Riding position is cramped.- Ability to see far down the road is reduced. This is due to the height of the head as the body is bent against the tank.- This riding posture is tiring as only the muscles and leg are supporting the back of the body. It will be difficult to sustain for more than a couple of hours.

B. Standard Posture

The Pros:- The standard riding posture provides increased visibility as the rider sat upright and straight.- Riders can stand up easily on the pegs to surmount an obstacle.- More comfortable and relaxed posture.- The standard position can be sustained for long road trips.-Provides excellent access to all controls.

The cons:-Increased wind resistance due to the upright body position.-Not as exciting as sports riding posture.

In addition, the seat itself is adjustable in terms of height, providing the ease and comfort to different height of people. Since most of the standard seats are ‘Crown’ shape which is flat, the structure will eventually create discomfort to the rider after a short period of time. This is due to reason that the ‘crown’ shape seats create centralized and concentrated pressure directly below the buttocks. Hence, we are using the ‘dish’ shape instead to distribute the pressure evenly. Figure 1.4 below shows an example of ‘Crown’ shape model and Figure 1.5 below shows an example of ‘Dish’ shape model [2].

Figure 1.4

Figures 1.5

Figure 1.6

A more ideal shape for a motorcycle is like figure 1.6 above, the picture depicts the shape of a bicycle seat. There is a lightly contoured pocket in the central area and the wings on the side of the rear. The central area supports the pelvis floor and the front of the pelvis while the two dished out surface on the rear of the seat supports the ischium (Sitting bone) and the buttock muscles. For this seat, the whole lower hip is supported and long term driving can be achieved.

With the concept or hypothesis of our ergonomic seat has been discussed. We can now finally discuss if the concept is actually technologically feasible, economically viable and the impact to the environment.

First of all, the interchangeable seat technology is available in the market. With proper gear alignment and programming, the seat can change its position with a push of the button. The method to do so will be explained in the methodology part. An example of such technology is the Kawasaki J concept [3].

As for the economic viability, it can be mass produced with the proper specifications. The materials used for the seat will be vinyl which is widely available throughout the market and comparatively cheaper than leather. Also, the backrest is layered with vinyl and foam is placed in the internal part of the backrest for light cushion support. As vinyl is a very low-cost production and durable at the same time, it allows the materials to have a longer-life span without the need to replace it [4]. Hence, it is more viable to use vinyl as our cover material.

Although vinyl is a man-made synthetic plastic, it is still easily recycled, allowing the people to reuse it for other purposes which in turn, preserve the environment [4]. Thus, making vinyl a good sustainability material as most of the production of vinyl is from a renewable resource, which are common salts. Additionally, comparing with other materials in the market, the cost and amount of resources required to create vinyl is a lot much lesser and also lower emissions of wastes are released to the environment. This concludes that the impact to the environment is not significant if treated properly.

Finally, it is obvious that this concept of interchangeable seat is legal to be made as this concept brings innovation to the current technology. An idea such as this is currently undergoing prototyping construction in Japan. Such example of electric 3-wheeler is the ‘i-Road’ currently being made in Japan to cater the needs of the people that require transportation without facing the horror of traffic jam [5]. Hence, it can be said that such concept has already been accepted by certain authorities and can be considered legal.

Reference:

1. Susan Rzepka Orion, Riding Right: Finding the Best Riding Position For You, http://www.womenridersnow.com/pages/Posture_Perfect_The_Best_Riding_Position_For_You.aspx

2. Mark Todd, 1996 – 2013, The Road to Comfort, http://www.sargentcycle.com/Custom-Seat-Services/Road-To-Comfort/

3. Steven L. Thompson, 4th April 2014, Ergonomic Advantage: Kawasaki Concept J, http://www.cycleworld.com/2014/04/04/three-wheeled-kawasaki-j-concept-motorcycle-ergonomic-advantage/

4. Geno Jezek, 2006-2013, What Is Vinyl, http://www.whatisvinyl.com/

5. Mike Hanlon, 4th March 2013, Toyota shows the i-Road a fully-enclosed, tilting, electric three-wheeled competitor for the motorcycle, http://www.gizmag.com/toyota-i-road-full-enclosed-tilting-electric-three-wheeler/26498/