After having built several Solar Tilting Trikes (STT) I started thinking about my next project to overcome some of the issues I have experienced.
In particular these were the main points I wanted to improve:
– Comfort: a STT is based on a ‘Front Wheel Drive’, therefore it may have only rear suspensions
– Weather protection: when it’s cold and wet riding on a STT may become quite unpleasant
– Uphill performances: although the STT is based on a 20″ hub motor, which is not overheating very often, I had few occasions in the past where on very long mountain rides I still had to stop few minutes to let the motor cool down.
– Efficiency: being the STT a recumbent bike it is already more aerodynamic than a normal bike but a completely faired one would be definitely more attractive.
Therefore I started to look for a bike type which could help me to improve above points.
After few months I finally found the ideal bike: the Bülk Urban velomobile.
https://www.velomobileworld.com/velomobiles/bulk-urban-velomobile/
This was a brand new model, derived from its predecessor Bülk MK1 but with better characteristics for my new project like:
– accessibility, turning radius, open wheel arches, internal space.
After 6 months from my order I finally received my new velomobile
The first step consists in choosing the components for the electrification.
After having analysed different technical options I decided to go for the following solution:
– one hub motor in each front wheel, with one controller for each one.
– 2 batteries, 1 kwh each, with 72V and 15Ah.
– a Cycle Analyst computer, as I normally use on my bikes.
This solution has already been chosen by several friends on their trikes, but nobody else has ever done it on this type of velomobile.
The main challenges I had to face were the following ones:
– standard front wheels have drum brakes, while Direct Drive hub motor do use DISK brakes
– standard chassis is designed for pedal power, so reinforcing of the structure was required
– all new components needed to be located without compromising the available space inside the velomobile.
Here we can see the inside of the velomobile and the ideal location I have chosen for the batteries, controllers and the busbar.
In order to work in a comfortable way on the velomobile I have installed it on the working platform I normally use for my bikes
The installation of a hub motor requires to find the best solution to fix:
-the disk,
-the brake caliper
-and the torque arm.
I have started to install the motor with a specific support built from a technical specialist on this type of motor:
https://ebikes.ca/product-info/grin-products/all-axle-hub-motor.html
To be able to easily test the hub motor installation I have purchased a spare front suspension for a Bülk velomobile.
This is the result after this first tentative.
Here we can see it installed on this spare front right suspension.
The disk is a 140mm, for the 160mm there was not enough place.
Note that here the brake caliper was installed on the FRONT of the suspension arm.
Unfortunately, after having installed the suspension inside the velomobile, I realized that there was not enough place for the wheel to turn right/left: the brake caliper and its support were rubbing against the inside of the wheel arch.
This was an alternative solution I have tried with a different type of support.
We can notice that here the brake caliper is now on the BACK of the suspension.
Moreover the torque arm is implemented here with an aluminium bar which is fixed on the suspension plate
This is another view of the right suspension where we can see that the brake caliper is installed on the back.
We can also see the spacer that I had to install on the 12mm axle in order to leave the necessary space for the brake caliper.
Unfortunately when trying to remove the left wheel I was not able to do it since the axle was blocked.
So I had to completely remove the suspension with the wheel still attached.
Here we can see that I had to use an extractor to be able to push the axle inside and to finally remove the wheel.
This was due to the fact that they might have dropped in the factory few drops of Loctite during the assembly process.
This is the left suspension with the new hub motor installed, with the 140mm disk, the ‘hybrid’ disk caliper and the torque arm.
We should also notice that with this solution we cannot ‘simply’ fit the hub motor on the suspension while installed on the bike chassis.
We are obliged to REMOVE the suspension otherwise we cannot install the motor because of:
– the disk caliper
– the torque arm
This is a limitation of this solution.
Luckily we don’t need to remove the wheel to change the tire so it’s not really a huge issue.
Here we can see some reinforcing done in two points by adding few layers of carbon fiber:
– where the battery is installed (4kg each).
– where the suspension strut is fixed
Both hub motors are finally installed on their suspension.
Here on the left is the RIGHT wheel, on the right it is the LEFT one.
In order to install the PAS (Pedal Assist System) sensor, I have added an aluminium vertical rod, fixed with carbon fiber.
The 12 magnets disk is installed on the left crank arm.
The PAS cable is then connected to the Cycle Analyst computer
After the installation was completed I had to setup all the various parameters (using a specific application on my PC) like:
wheel diameters
power levels
assistance levels
braking power
screen data
etc.
This is the view from the inside where we can see the various components.
On the handlebar there is just the Garmin computer and the throttle, very clean and easy to use.
On the right hand side we can see the Cycle Analyst computer, where we can also change the preferred assistance modes and levels.
To be noted also that I have chosen the most advanced position for the seat, which I find very comfortable for my size (I am 178cm high).
In this setup I can also use the upper part of the batteries (covered with blue anti vibration foam) to put my elbows while riding.
In this short video we can see an explanation on how all different components have been installed inside the velomobile:
So far I have used the Bulk Urban with electric assistance for roughly 800km.
My longest ride was 160km in one day to Chartres:
https://www.instagram.com/p/DHbjc3GsKoz/?img_index=2
The main benefits I could already experience are the following:
extremely silent and smooth
regenerative braking is very powerful: I have set it up initially to a base level of 1,4kW which allows to stop the velomobile very rapidly.
electric assistance is really powerful: so far I have used max power of 500watts (combined), but it can deliver easily more than double.
in terms of efficiency, I have recorded between 3 and 4 Wh/km: having a total battery capacity of 2 kWh I can count on a possible range of at least 400kms
motor temperature is always very low (so far maximum of 35°C), given that this is just a moderately hilly region: in the future I will also ride in the Alps so the tests will be more complete.
power delivery and braking is always perfectly balanced between both wheels: no need to do anything different while riding.
I have already started to install the new solar panels: stay tuned for the next steps!
Bravo pour cet réalisation et merci pour ces explications détaillées qui vont répondre à beaucoup de questions que se posent les utilisateurs de vélomobiles.
Simply genius, Danielle! This amazing project is made even more important by your carefully crafted write up. I’m excited to see the solar panel install😊
Thanks Gary! Riding experience with this electrification is simply fantastic, hopefully it may attract more velonauts toward velomobiles!