Bionicon C.Guide V.02 £35

Back in the early Nineties there was a product called Dave’s Chain Device, or DCD for short. You may remember it; you might even have bolted one to your bike all those years ago. Essentially it was a roller sandwiched between two aluminium plates that clamped to the chainstay. The chain ran over the top of the roller to add tension, with the aim of keeping it securely on the chainrings. Frankly it wasn’t very good. The transmission made a loud grating noise until you hit a bump, at which point the chain fell off.

More recently the concept has been reborn, with both Specialized (with its Dangler) and Bionicon (with the C.Guide) developing new designs along similar principles. At the moment Specialized’s Dangler only works with its Stumpjumper models, but Bionicon has devised a more widely marketable fitment.

It mounts to the underside of the driveside chainstay — meaning elevated swingarm bikes such as the Orange Five are not compatible — either by clamping around the gear cable outer casing or by being zip-tied to the chainstay itself. So for anyone with a press-fit BB and no ISCG tabs, it could be the answer to your prayers.

Installation takes five minutes thanks to the split guide tube and clamp. It’s incredibly simple, although by hiding the Allen bolt on the inside it means you have to remove the rear wheel to get a tool in there and tighten the clamp.

As you can see from the specs, the C.Guide weighs the square root of sod all, but the performance is impressive for something so small and simple. The first thing to note is that it’s virtually silent. Running big to big increases the volume somewhat, but compared with
many chain devices, it’s mute. In two months of riding we’ve only had the chain drop a couple of times, but in both instances it only went as far as the inner chainring and we could pedal it back on without interrupting our flow. Nevertheless, the C.Guide can’t perform miracles; it couldn’t solve the persistent drivetrain issues on our Lapierre X-Flow longtermer. Wear is also an issue, and the constant movement of the chain has begun to cut through the plastic after a hundred miles or so.

And then there’s the thorny issue of cost. If the C.Guide was under £20 we’d have no hesitation in giving it 10/10. As it is, our ‘9’ rating is more a reflection of its performance than its price. Danny Milner

MBR rating: 9

Specification: Weight: 18g / Colours: black, red, blue, green, pink and gold / Contact: bionicon.com