More complicated than you think: towing your bike by bike

"Hänsu" Spitznagel likes to ride his bike to the pump track - but not on his dirt bike, which is too uncomfortable due to its freestyle geometry. So he needed a way to ride to the track with two bikes. Together with frame builder Stefan Lorenz, he designed a towing system that offers just that.

At first glance, the "PumpRack" is reminiscent of the follow-me towing system that many parents use to pull their children behind them on their bikes. But beware, that's not what the PumpRack is made for. As the video shows, Spitznagel attaches his dirt bike with the thru axle to a mount behind the rear wheel. The front wheel is attached to the side of the rack.

Anyone interested in the technical details of the system and its manufacture can find them here in the original text from the frame builder. Everyone else can start the video now or continue reading in the second section.

A stainless steel Tubus Cosmo [rack]is used as the basis. We made the adjustments with stainless steel tubes. The tubes were mitred and joined by brazing with silver solder and flux.

A 15 mm tube with a width of 100 mm was created as deep as possible using several struts.
A short piece of tube was attached at an angle to the side; the front wheel can be attached without tools using an SR Suntour Q-Loc axle.
The robust Tubus luggage rack offers space for a spacious Ortlieb bag.

The tubes are seamless hydraulic stainless steel tubes made of 1.4571. The tubes were mitered and joined by brazing with silver solder and flux. My silver solder has a silver content of 50 %. The melting point is approx. 680 °C. A very hot flame is therefore necessary to reach the right temperature. I work with acetylene and oxygen.
The English term for the whole process is fillet brazing. The flux must be removed again after soldering as it is corrosive.

PumpRack remains a one-off for the time being

Series production of the "PumpRack" is not planned, Spitznagel reveals on request, "it was simply a project for me and Stefan [the frame builder]." Even with a different fork or axle, the PumpRack would have to be rebuilt due to the different dimensions. Spitznagel has another practical tip for use: "On the pump track, I ride with an air pressure of 4 bar, which makes the tire bounce like a basketball. For transport on the "PumpRack", I reduce the air pressure so that the bike stays nicely on the ground."

Hansueli "Hänsu" Spitznagel is a photographer and filmmaker. Ride has published countless pictures of him. In recent years, he has increasingly staged himself in short videos, as he has excellent riding technique and a good knack for beautiful edits. Stefan Lorenz has been building steel mountain bikes with modern geometries for several years under the Scar Cycles label.