GET READY TO GRAVEL COMMUTING TO YOUR NEXT

THE GRAV KARL GRAVEL BIKE PROJECT

WORDS RÉMY VROONEN PHOTO HOSHI YOSHIDA / OUTDOOR PHILIPP JÜLICH

AUGUST 2020, THE WEATHER IS AT ITS BEST AND PEOPLE ARE OUT ENJOYING RIDING THEIR BIKES. AS WE ARE CONSTANTLY EVOLVING IN A FAST-PACED WORLD, NOW FACED WITH A PANDEMIC, WE THOUGHT AN ENJOYABLE WAY TO COME BACK WAS TO HAVE SOME FUN, BUILD A GRAVEL BIKE AND LAUNCH OUR NEW SR SUNTOUR GVX GRAVEL FORK.

We decided to take the time to build a “local” gravel bike, so we called Portus Cycles, a steel frame builder from Pforzheim, Germany. As soon as the idea took seed, other partners came on board such as the gear box manufacturer Pinion, Gates for the belts and crankset, Hope for the wheels and stem and Vecnum for a nice, clean dropper post.The whole process took two days, from cutting the tubes to powder coating the frame and getting the bike assembled. This dream build began by drawing the frame on a 3D software design tool using the dimensions you choose, head tube angle, seat tube angle, tyre diameter, BB drop, wheel size and so on… Once the drawing is done, the tube cutting can start.

LEFT Portus handmade frame with Columbus Zona tubeset, Pinion C1.12 with 12-speed transmission, Gates Carbon Drive and the new SR SUNTOUR GVX suspension fork with 40mm travel DOWN Alex Clauss is an engineer, a welder and the owner of PORTUS Cycles.

TOP We love welding. We love handmade bikes. LEFT Before the frames gets the powder coating the surface needs to be treated by sandblasting and a lavation.

LEFT The magic moment when everything comes together and everything perfectly fits. DOWN The Portus Gravelbike turned out to be the perfect adventure and travel bike for all seasons.

Then jigs are used to tightly fit the mitering, which is called notching in the frame builder’s world. As the parts are assembled onto the jig, a first preview appears and shows how the bike looks with the selected angles and the different tubes in place. Once the tubes are correctly aligned, the braze welding process can start. From the bottom bracket to the chain stay, welding the joints makes the magic happen, as you realize a bike frame is coming to life.

The raw frame is now a real thing. It is then taken to the sand blasting unit to get rid of any irregularities and to thoroughly clean it before the final step, the powder coating. Enjoy the building process through our pictures and video and get ready to gravel.

EPISODE 1

WATCH THE VIDEOS

EPISODE 2

WELDING THE JOINTS MAKES THE MAGIC HAPPEN, AS YOU REALIZE A BIKE FRAME IS COMING TO LIFE.