We keep spotting this one at the tour, Shimano's carbon Dura-Ace cranks. It can hardly be top secret anymore considering it's been seen on a few of the team bikes. The one pictured was aboard one of the Specialized Gerolsteiner bikes, we've seen others on Rabobank Colnagos.
Even with the cranks on such public display we've still had no further details from Shimano so it's down to guess work on the details. Obviously styled on the current alloy cranks the carbon variant loses the preload cap on the left arm and adopts a preload collar for adjusting the bearings instead. This is identical to the setup used on the current XTR mountain bike cranks. It's a easier to use than the current preload cap and 5mm pinch bolts and it also takes the guess work out of preloading the bearings. The only difference here is that the Dura-Ace collar has been slimmed down to give it a lighter, road orientated appearance. It also looks like the cranks run on the regular Shimano external bearing units.
We've only got the pictures to go on so far but the cranks look very tidy even if they are only prototypes. Round the back of the spider everything looks typically tidy and surgically Shimano with no out of place carbon weave in sight. We're going to try and get hold of one of the team mechanics to see if we can get a weight. It'd also be interesting to know if those arms are hollow and if the spindle is carbon or alloy.
That's the technical details, now we'll open the debate on the looks. No doubt Shimano has been forced into making a carbon crank by its numerous competitors turning out cranks made from the black stuff. It's still the material of the moment and no doubt we'll be seeing carbon derailleur, shifters and brakes in the near future from Shimano. The thing is with all
that carbon around at the moment the alloy stuff looks pretty damn good.
With all of Shimano's history and engineering know, how much better do a set of carbon cranks really perform over the current Dura-Ace model? If it's big weight saving matched with an increase in stiffness then why not. But there's also a certain amount of engineering romanticism about forging and machining a component out of a block of alloy.
So, are you a fan of the new carbon cranks or do you like a bit of shininess in an otherwise dark world?