American frame builder Mark Lynskey paid a visit to the BikeRadar offices this week to show us the interesting and relatively new Helix OS titanium frame.
The Helix tube set has been around for a few years and we were impressed by the 2010 frame we tested 18 months ago. Mark admits the helical design wasn't the result of millions of dollars and six years worth of research - it came about through an accidental misalignment of the dies used to shape tubes. But once he started making custom frames out of these tubes for riders who wanted something a little different, he realised he might have stumbled across something that improves the ride quality.
Mark - speaking as an engineer not a marketeer - says this is not down to the type of material, it's more to do with shape. The diamond shape with a gradual 90 degree twist along the length of the tube helps resist torsional and bending forces, which are two of the biggest that act on a frame. What this does is increase the frame's all round stiffness without adding weight compared to standard round tubing.
Not all tubes on the frame have the twist, however. The seat tube is round because it doesn't experience the same torsional forces as the rest of the frame. The chain stays are similarly spared the helical treatment.
Compared to the Helix, the Helix OS (oversized) has an increased diameter downtube, an oversized headtube and a press fit 30 bottom bracket. It's also $US4000 (UK£2999.99) instead of $3000 for the "standard" Helix.
The Helix OS frame weighs roughly 1.4kg (3.1lb), which might be considered heavy by cheaper carbon fibre frame standards. However UK importers Hotlines specced this particular frame with SRAM Red and Enve components to create a 7kg (15.1lb) machine, which will be tested in an upcoming issue of Cycling Plus and featured in Procycling. We're looking forward to putting some time on it too if we can steal it from under their noses.