Arm & Leg Power

Most people who ride bikes will at some stage have wondered if a linear motion of the legs, as in walking, would be more natural than pedalling. Such reflections prompted my own experiments described here. As so often happens, one later discovers that it has all been discovered by others long before...

Bike specifications

This bike can be adjusted at three points:

There is a pivot just under the seat (the original bottom bracket of the rear sub-frame) which acts as a suspension by means of a stiff coil spring. The height of the spring mount is adjustable by about 10cm, and this affects the seat height, the angle of the backrest, and the angle of the steering axis.
The angle of the steering axis can be set between 92 degrees (on the left) and 75 degrees (picture on right). At 92 degrees the steering axis tilts backwards slightly.
The amount of trail, defined as the distance between front tyre contact patch and the projected point where the steering axis intersects the ground. The trail was kept at about 60mm.

These adjustments affect the wheelbase: Between about 97cm and 120cm.

Front wheel: 32-451

Rear wheel: 26 x 1,25 inch

Linear drive for arm and leg power

The experimental bike originally was driven by alternating linear motion of the feet along two tracks. Following test rides, it was found that a rowing motion in which the feet move together was superior. The two pictures below illustrate this.

Click on the pictures for larger view.

The seat is fixed, and the arms pull on a column that is also used for steering and which is linked by a cable going forwards and over a pulley to the feet. You push with your feet and at the same time pull with your arms. The result is a smooth flowing motion that ends with a relaxation of the body before the legs are pulled in for the next stroke.

More up to date

Not many rowbikes have twin tracks on the outside. Here is a modern homebuilt version seen at the 3rd European Rowbike Championships held in September 2001 in the Netherlands. The builder is Harm den Hollander.

Click on picture for a larger view

Thys Rowbike (Roeifiets)

The Rowbike designed by Derk Thijs in the Netherlands provided my inspiration. It is shown here in his early low racing version.

Click on the picture for a larger view

Other models of the Thys Rowbike are also available, including a back-to-back tandem. In the early 90's Derk Thijs won the 570km Paris-Amsterdam race. He more recently set a record time of 13.53 hours in the Amsterdam-Paris run with a rowbike.

Interestingly, the most recent Thys Rowbike uses a spiral pulley drive train that was invented more than 100 years ago (see US patent 606854 granted to John Bergstrom in 1898). The cable unwinds off the pulley as the stroke completes, which is very efficient ergonomically. It also allows an infinitely variable-ratio transmission.

Nearly all rowbikes now have a bowsprit between the legs, and that seems the most efficient design.

Rowbikes seen at VeloVision 2008, Amsterdam:

(Photographer: Bas Dekker)

The pictures give a good idea of the low frontal area achieved by the rowbike. These state-of-the-art machines put to shame my own humble effort!

Created: 1998. Last updated: November 2008