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Trevor Smit, CEO of Zip Inc, said his company’s bike – equipped with Dura-Ace throughout, aside from the Alex 330 aero wheels – weighs a shade under 15lbs, light but not radically light.
Unlike the pre-WW1 Dursley Pederson bicycle, the ZipCycle doesn’t have extruded metal tubes tensioned with wires, the whole frame is made from wires, albeit hi-tech Kevlar ‘string’ wires, made specifically for the ZipCycle.
The bike has a standard saddle. The seatpost is held in position by a slotted aluminium tube, also held in place by wires. Smit says the seatpost has less than 3mm of lateral ‘give’, with as much natural suspension as the Zertz elastomer inserts on Specialized’s Tarmac roadbikes
The ZipCycle was designed by Smit’s German brother-in-law, Markus Fürst, and ZipCycle Inc was formed in 2003 in order to bring the machine to market. It was displayed at the recent trade show in Taipei.
There are Quicktime movies of the production machines, and the all-important tensioning system, on ZipCycle’s website.
As well as allowing for a lighter frame weight, Smit said the tensioned wires give a 3-7 percent boost to the rider’s thrust capabilities, depending on the weight of the rider.
The wires are tensioned via aluminium routers.
"In order to have a strong support in front for the suspension of the seatpost, and at the same time to hold the top pivot for the front fork, the ZipCycle has one wire from each end of the bottom-bracket tube running to a tensioning point, where they are joined and tensioned by the routers," said Smit.
"Two other wires run from the tensioning point to the rear ends of the wire seat stays, forming two wire-tensioned triangles, joined at the top angle; where they carry the seat from the front fork pivot, and are held apart in the two other angles by the bottom-bracket barrel and spindle from the rear-wheel. This is the real body of the frame, and the great strength of it."
"To form a strong support behind, from which the seat is suspended to its support in front, there’s a tensioned wire from each end of the bottom-bracket barrel running to the basal router, where they are joined and tensioned; and from there a wire runs down on either side, where they are connected to the rear ends of the wire rear stays, forming two other perfect triangles, joined at the top."
The ZipCycle – made in Taiwan by Abrillia and with a RRP of £1995 – will be on stand 105 in Hall 1 at the Bike Show, starting Friday, ending Sunday.
