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What the? Flexible down tubes can be changed on this commuter bike

Here’s a bike, debuted at Interbike in Las Vegas this week, to file under curious. It’s from new company Alter Cycles, and is their first bike that has been two years in development, a flat-barred commuter with an interchangeable down tube. Yes, an interchangeable downtube.

The curved downtube can be removed and changed for another, to tune how much comfort the bike provides. It's deisgned to flex you see. Alter Cycles describe it as an “adjustable suspension bike that can be dialed into the weight of the rider.”

That’s the theory anyway. Quite why a commuter would want to alter the comfort of a bike designed for whizzing across town, or why you’d want to make a key structural element of the frame interchangeable is beyond us. The down tube is available in three levels of flexiness, from soft to medium and hard. In a double diamond frame a down tube provides a huge chunk of the stiffness of the frame, so what impact this bow-shaped flexible element has on the handling remains to be seen. It'll also be interesting to see how much deflection the down tube provides. It also looks like there's going to be little compliance come through the back wheel, regardless of what down tube you have installed.

You can do wonderful things with materials these days though. It’s not exactly new territory for bicycle design. The famous Slingshot, a bike first conceived in the 80s, replaced the conventional down tube with a steel cable, spring and fibreglass hinge. The idea was to use the flex in this arrangement to produce a bike that could better handle rough terrain, softening bumps and holes. There was also something about the design ‘storing’ pedal energy and released at the dead spot.

Judging by their Facebook page, they’re riding and testing samples so it must work. We can't wait to ride it ourselves to find out how it performs. No idea whether this bike will see the light of day in the UK, but over in the US it will cost $799, with down tubes costing $99. Excitingly, they’re working on similar designs for road, mountain and cyclocross models too. Check out their website at http://altercycles.com/

David has worked on the road.cc tech team since July 2012. Previously he was editor of Bikemagic.com and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds.