pre-CVT system

Also read: THYS 222 manual (PDF)

The Snek is a conical drum made of aluminum with a screw-thread shaped groove in which the 3 mm thick stainless steel drive cable can roll up and down.
Because the groove length is much longer than the stroke, the steel cable can be moved to another part of the Snek using a modified derailleur. This leads to a change in gear due to the conical transition of the Snek. This unique patented drive is extremely low-friction, light, quiet, clean, smooth, and easy to maintain.

The range of the snek is currently 255 %. Assuming a 26-inch rear wheel, as in the THYS 222, the distance covered per full stroke varies from 3.67 meters to 8.78 meters. This corresponds to 239 %.
When making a stroke, you start in a relatively light gear; during the stroke, the cable runs over the snek towards a heavier gear. At the moment you can exert the most force with your arms and legs, the cable is also at a point on the snek where there is a heavier gear. This way, you can transfer your power to the drive of the rowing bike with maximum efficiency. Thus, the gear transition during each stroke goes from light to heavier, averaging about 30 %.

With the “old” Thys 222 rear hub, you could shift in a maximum of 6 steps from the smallest to the largest gear. With the THYS lockable hub of the RR version, you can shift in a maximum of 11 steps from the largest to the lightest gear. So you have more options, but you can also switch with 2 or 3 grooves at once so that you are faster where you need to be.

The principle of the snek. The rear hub is equipped with the grooved snek. The drive cable (1) is wound one and a half times around the snek so that it cannot slip.

With a modified derailleur (2), the drive cable is pushed onto a different groove, resulting in a different gear.

The grooves that run diagonally across the Snek ensure quick and smooth shifting.