By analogy with the compact and unpretentious Citroen 2CV, I tried to develop a concept of an inexpensive city bike that would combine simplicity of production, practicality, ease of use and low weight of 15-16kg (33-35lbs), which, if necessary, can be easily lifted on several stair flights, and in the basic configuration, it is easy to transport the necessary things or purchases, while from the outside it looks like a regular, not electric bike.
Traditionally, bicycles use aluminum tubes that are connected at the ends. At the same time, in order the bicycle frame can take the given shape, the tubes must first be cut, and then, after being installed on a special stand, welded all the parts together, having previously processed their ends to ensure a connection without gaps. The main processes take a lot of time, manual welding requires proper qualification from the performers, and it is difficult or expensive to automate many processes. Along with this, when welding, it is necessary to mitigate the side effects of heating the metal in order to minimize possible nodes deformation. At the end of the production cycle, it is necessary to carry out the heat treatment of the metal in order to relieve the stresses caused by welding. As a result, many bicycle companies tend to manufacture their frames in Southeast Asia, in countries where labor is cheap and environmental and working conditions are minimal.
In remote mass production, it is difficult to promptly make the necessary changes to the configuration or improvements to the design, and the delivery of products takes a long time and is not cheap. Since the production of my concept is planned to be established in Europe, the cost of producing the frame became decisive when developing this concept.
The concept of an inexpensive city e-bike weighing 15-16 kg (33-35 lb) with 26-inch wheels is based on a patent-pending frame, which is made of two symmetrically bent, made from 6061T6 alloy aluminum tubes that simultaneously form both the top tube and down tube, as well as seat stays and chain stays. They are connected to the head tube and seat tube with the special internal locks. As a result, the implementation of this technology eliminates welding, which can weaken the frame material, creating heat-affected zones at the joints of the frame components. Along with this, the number of operations for the manufacture of such a frame becomes less, as well as the requirements for the qualifications of workers in production, become less.
The bike frame itself is not painted, which eliminates painting costs and makes the structure lighter, and all its elements for corrosion protection are anodized in the color of the customer’s choice. When ordering a bike, you can easily create your own creative version of a city e-bike based on the basic version of the frame by placing an order for the manufacturer for additional accessories of the desired design and size.
Constructive features of the concept of my urban e-bike frame provide for the possibility of installing both a chain in conjunction with a single-speed system or with an 8-speed transmission system, as well as a single-speed belt drive – depending on the buyer’s preferences.
The weight requirements of my concept dictated the need for a lightweight and capacious removable battery. A compact 36V, 10.5Ah (378Wh) battery based on 18650 cells 3500mAh from Samsung company was specially developed for this. A lightweight rear Hub Motor 250W is used as a drive, the operating mode of which is easily adjusted using the controlled display. It is planned that, depending on the Pedal Assist settings, such a combination of the battery with the drive will be able to provide a range of 50-70 km with a single charge.
The planned budget price determines the configuration of only the most necessary for the comfortable and safe operation of the bicycle in urban conditions. There is a drive control display and a warning sound signal on the wheel, the full-featured fenders on wheels protect the cyclist’s clothes from raindrops and dirt, there are front and rear lights for driving in the dark time of the day, as well as a USB port for charging the phone.
The basic configuration also includes a rear rack, which can carry up to 15 kg of cargo. If required, an optional front basket with carrying handles can be added, designed for loading up to 12 kg, made in the style of the frame from the aluminum tube, and fabric walls made of durable Cordura material. You can take such a basket with you for shopping and put your purchases in it, or, for example, put in a change of clothes and take it with you to your workout at the gym. I also plan to design a front small bag for phone and documents, as well as a bag for luggage or laptop. Each can be installed between the top and bottom twin frame tubes.
My concept for an inexpensive city e-bike can be fully of European production, including the frame, battery and most of the accessories. The only exception will be the rear-wheel-drive motor and some accessories. The bent frame design allows it to be manufactured in Europe, largely using automated processes. As a result, both the manufacturer and its customers will save money on labor and transportation of bicycles, for example, from places like China, as well as create new jobs in Europe and support production that has no negative impact on the environment.
At the same time, due to the rather low bevel of the upper frame tube, both men and women can use my inexpensive city e-bike, and the 26-inch wheel diameter with a wide tire will provide an opportunity to move comfortably both on damaged city surfaces, and on the unevenness of country paths, like on Citroen 2CV.
I thank all the participants in the discussion of the concept I proposed on my page and in thematic groups on Facebook and Reddit for their criticism, assessments, interesting comments and suggestions that were very useful to me.
In detail https://avialbikes.com/news/avial/