Since Velomobiel.nl came up with its Quattrovelo model, other velomobile manufacturers have also started thinking about four wheels. The QV is a very popular model, and this velomobile makes a lot of sense, especially for practical everyday use. It is more stable than three-wheeled machines and provides much more cargo space in the rear.
Velonauts are very interested in the development of another four-wheel model, which is mainly done by Ymte Sijbrandij. Ymte is a former co-owner of Velomobiel.nl and today the owner of the rival company Intercity Bike, which produces the three-track DF velomobile and its larger brother DFXL for riders up to a height of 200 cm. And it was the combination of two DFXLs that laid the foundation for the new four-wheel DF4 model, or better to say the very first prototype as the current version is a lot different. The first prototype was on display at the SPEZI show in 2017 and development is still underway. Now a video has appeared in public on which Ymte is testing another prototype. You can see on it that all four wheels have open wells and that the rear part is shorter and wider to improve the practical use of this bicycle.
In contrast to the Quattrovelo, with which it is very often compared, Ymte went in a different direction mainly in the rear of the machine. Its aim is to further increase the space between the rear wheels and thus enable the transport of larger loads while maintaining the lowest possible center of gravity. Therefore, it is not possible to have a complex drive and suspension mechanism between the wheels, and the DF4 instead has only one rear wheel driven by the chain and human power, and a new method of suspension is being developed as well. The drive of the second wheel should be provided by an optional electric motor. This is also a big difference from Quattrovelo, because in Velomobiel.nl they do not like the engines and are supporters of purely human power.
Many questions are about the date when this bicycle will be launched on the market and also about the price. In particular, the price cannot yet be determined at this stage of the project. In addition, Ymte is still only talking about the DF4 as a concept that needs to be verified, and then it will be possible to determine whether this machine will be offered at all. On the other hand, if so much time and money have already been invested in development, there is an assumption that DF4 will one day really be on sale.
I asked Ymte directly about the project. “First 700 km made this month. The concept now is 1 wheel drive 1×12 speed derailleur. 4 drum brakes, all wheels are the same, can be mounted with 1 screw so taking a spare wheel for quick change in case of flat is possible.
The bike will be light and aerodynamic enough to be driven by pedal power only but we will test a 250w hub motor to drive the other wheel with a chain, so you can choose your own torque and speed without changing the software but by changing the sprocket. Max 25 km/h so it will only be useful for acceleration and uphill since a speed of 25 km/h will be very easy to maintain on the flat. Over 25 km/h motor and chain will stand still so no extra friction, only the weight to carry.
We also test a new rear wheel mount with elastomer suspension, it is weight and space saving compared to a swing arms and very stiff and easy to maintain and suspension can be easily adjusted by changing the foam rings from the bottom, they are in the black carbon box you see on the floor.
It is all to be tested and we cannon say if, when and how it will come on the market.”
It is very difficult to assess the influence of the new suspension and drive method on the driving characteristics and on the overall usability of the wheel. Especially when the load space is fully loaded. It is also a question of what is more important for the future owner, whether a turn is a few kilometers per hour faster, or the possibility of transporting larger objects.
I will definitely continue to monitor the whole project, because especially bicycles with an additional electric motor make a lot of sense to me and in the future I would buy one myself.
And here is a video from the SPEZI in 2017. You can see some differences, of course.