Is a bicycle chain really necessary? No, not for an igus:bike. Because it has a belt instead of a chain. And since we already had the front drive part with planetary gearbox, crank and pedal, we shifted our focus to developer Tim, because he is completely focused on the rear wheel, or rather, what makes the wheel move.
Developer Tim with his drive prototype
Tim’s rear drive is virtually invisible when installed. Incidentally, it shares this fate with the planetary gearbox located at the front between the cranks, which unfortunately cannot be seen at all. Tim’s development result consists of just a few individual parts. Simply put, the assembly results in an axle on which the rear belt pulley and ball bearings are attached to the side. The wheel is pushed onto this axle and screwed on.
The rear drive prototype
Let’s take a look at the front part of the drive. This consists of the interaction of the components from different developers. When the cyclist pedals, the power is transmitted via the cranks to the planetary gearbox, to which the freewheel and ball bearings as well as the front pulley are attached. And since the force applied at the front has to come to the rear somehow, both drive parts are connected with a toothed belt. This is tensioned between the front and rear pulley, and the teeth of the toothed belt and the teeth of the pulleys engage, thus moving the rear wheel. Actually quite logical.
View of the prototype from the side opposite the belt
The entire drive area of the bike, including the belt, is encapsulated and thus protected from dirt and water. And this is where the belt drive shows its advantages particularly well. Because the toothed belt stays almost the same over its service life, while bicycle chains get longer over time and have to be replaced. Of course, it does not need any lubricants and does not rust.
Since the belt does not get dirty either, it is maintenance-free on the igus:bike. In addition to running quietly, the toothed belt also weighs roughly only one third of a normal bicycle chain. The already high running performance of the belt is further increased by the enclosure. Thanks to the absence of a chain, the trouser legs of the driver are also spared from oil or grease. So, this is perfect for those who drive a lot in the city or commute by bike.