Dirk’s solar bike


I had the opportunity to participate to all the 4 big Sun Trips (edition 2013 to Astana – edition 2015 to Cappadocia -edition 2018 to Chine – edition 2021 through Europe)
In the meantime all toghether (incl. other smaller trips) more than 50.000km

I choosed for a combination of a straight bike and a solartrailer.
I like this because I can still use the bike without solartrailer in my normal life. And with such a combination it is possible to follow very small and also very bad routes.

For the 2 first Sun Trips I used a rather small trailer with 2 solarpanels on each other (that can be fold open when I stand still)

This small trailer with 2 panels on each other was a little to small to participate to big Sun Trips. You have to work physical very hard to make enough kms a day.
So, since the 3th Sun Trip (edition 2018 – Lyon to Guangzhou) I am using a longer solartrailer with 2 solar panels in succession so I can get the maximum sunenergy also during cycling.
For me this trip, from my home to the south of Chine was 14.400 km

For the 4th big Sun Trip through Europe (edition 2021 – 11.400 km) I changed a little bit the concept (less luggage + a little bit lighter construction)

Technical description

The bike

I chosed a straight strong trekking bike from the well-known mark SantosBikes (Travelmaster 3+)


  • Wheels 27.5 inch
  • Tyres Schwalbe Super Moto 62 mm
  • Pinion gear (18)
  • Belt CDX
  • SON (wheel hub)
  • Brooks saddle B17 pre-aged
  • Cane Creeck (suspension under the saddle)
  • Multiple hand positions on the handle-bar
  • An extra button for brake recuperation
The motorization

The Santosbike has been transformed with a motor HT3525 from Crystalyte Europe (high-torque motor)

  • max power: 1250Watt
  • maximum torque 110Nm
  • regeneration is possible
The battery

The battery is a 48V – 22Ah Lithium  battery also from Crystalyte.

Solar equipment or solar trailer

For the last 2 Sun Trips I opted to construct a simple onewheel trailer with 20-inch wheel (and with suspension).
This trailer has been made by the help of very good friends.

The two solar panels are from the mark of SOLBIAN (tailored on measure) and delivered by PROJECT-ZERO  (https://www.project-zero.be/nl_BE )

The 2 panels have a surface of 115 x 80 cm80 and 175 Wp.
So together a profit of about 300 – 350 Wp during cycling in excellent circumstances.
So : about 40% help from the sun … and still about 60 % power provided by my own muscles

Both panels can be inclinated in the direction of the sun (also during cycling).
I am using 2 Solar regulators of the mark Genasun (105-350 Watt – 8 Amp)
Especially because, if there is any shadow on the first panel I still get the maximum production of the second one (as par example during cycling with a low sun and my own body makes some shadow)
On my handle-bar I have 2 Cycle Analists (one for the production + one for the consumption) so I have a good overview.


  • Although my construction is long (more than 4m) and width (80 cm), it was easy to handle; but you have to drive careful and with attention
  • Once you are used to it, it had the feeling of riding a normal bike
  • The design of the trailer is simple and easy to repair if necessary
  • The bike can still be used as a normal E-bike (for daily use)
  • Parking the bike is simple (in a triangle)
  • On the big Sun Trips I had an average a day of 170 kms (sometimes almost 300 km)
Areas for improvement

The total weight of the bike (including bike + solartrailer + luggage)  is about 85 kg and is a little bit too much

My next bike/ or next evolutions

To force down the total weight of the solartrailer I would like to construct a lighter construction (now it is a mix of aluminium + steel) and made extra strong for the trip to Chine
A suspension of the rear wheel of the trailer is perhaps not necessary.
Without it would be easier to construct and especially lighter.
Then it would be good to use an big (voluime) tire (with not to much pression in it) as Shwalbe Moto X 62 mm with 1.5 – 2 Bar in it.
Also I would chose solarpanels with a width of only about 65 cm instead of 80 cm now.