The CB1 brakes have now been on the market for 2.5 years, and Kcnc has decided it's time to make some changes.
The most notable is that there are now two models, the C7(on the left) and the C6(on the right)
Both the C6 and C7 are very similar to each other. So rather than compare them to each other at first, we'll note how they are different from the Cb1.
While the main concept is the same the biggest change is that the front arm becomes a double that sandwiches what was previously the rear arm. This change makes the arm quite a bit stiffer.
The change allows the pinch bolt assembly to move so the cable attachment is in the center rather than sticking off the back of a single layer arm. By moving the cable attachment they further reduced the flex. Overall those two changes make a big difference in the stiffness and feel of the brakes. The new cable attachment is not power cordz compatible without some creative solutions such as is required with the Ax brakes.
Another difference is in the way the front and rear arms are pinned to move simultaneously. Previously is was an aluminum pin sitting in an aluminum groove. Now the pin has brass rollers on the ends which makes for a smoother movement.
Those are the main performance updates and all together make a noticeable improvement on an already good lightweight brake.
The C7 as a set has dropped 2 grams in weight from the CB1, while the C6 is heavier.
The C7 comes with red pads for alloy rims and a set of cork pads for carbon rims. While the C6 comes only with a set of orange pads for alloy rims. While the red and orange pads are an improvement over the original multi compound pads of the CB1, they still aren't as good as a set of Swiss stop yellow or green. Adding the swiss stop really changes the feel of the brake and makes it quite a good performer.
The C6 and C7 don't differ in design, just in materials.
The C6 is 6061 aluminum with stainless steel bolts and springs. It comes in 6 colors and has a retail price of $180. Weight for the set is 215grams.
The C7 is the flagship. It's made of 7075 aluminum and has all titanium bolts and springs. It comes only in 4 colors and has a retail price of $330. Weight for the set is 161grams.