The new MK3 version wide-profile brakes are significantly more powerful than previous versions. This is due to their longer arms. Longer arms increase mechanical advantage. But just as important is their excellent adjustability. They now have spring tension adjustment for easier centering.
We've kept the traditional wide-profile design of the MK2. And they still have slots for up and down adjustment of the brake pad. This means they fit perfectly on more frames and forks; not all canti studs are in exactly the same place due to manufacturing tolerances or intended specification. There is also an adjusting mechanism at the end of the straddle wire for easier setup and for fine tuning pad clearance and wire angle. (You'll wonder why all canti brakes don't have these adjusters.) Finally, the brake pads are fully adjustable for toe-in and angle.
The graph above shows the mechanical advantage of the three models of the Grand Cru Cantilever brakes at various yoke heights. It's good for comparison, but keep in mind that mechanical advantage also varies with different brake stud location, rim width, distance from pad to brake, exact arm position, and brake lever type. Also, you can't reasonably get the yoke below 100mm, so ignore the far left section of the graph.
Should you order the MK2, MK3, or Zeste brakes? Compared to the Zeste, the MK3 and MK2 are easier to set up because they are not as sensitive to yoke height variations. They are also more traditional, and perhaps cooler, in appearance. But they have a wide profile that can snag on panniers or heels if your bike has short chainstays. The Zeste brakes have more power and that may be important if you ride a loaded touring bike in the mountains, but they cost more. They also have a low profile. The MK2 brakes are still very good and a super value now that they're on sale.
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3 comments:
I enjoyed the aesthetic of the MK2, but the stopping power of the Zeste is unbeatable. It appears that the MK3 attacks both features, and like most wide-profile models, are easy to set up. I neither have big heels nor panniers, so the MK3 is a welcomed option.
I enjoyed Casey's previous article on cantilever brakes. Perhaps he can be challenged to write about cantilever brakes vs. disc brakes. Disc brakes are the new gospel in all manner of bikes, but I'm not sure they are necessary, or ideal, in all situations.
The individual spring tension screws are also welcomed. For touring purposes, can you find a way to replace the large hex bolt on the back that attaches the pad (the post, really)? The threaded v-brake style pads on the Tektro CR-720 only require a 5mm Allen. I recall the VO brakes call for a 12 or 14mm wrench. Admittedly, I often carry and adjustable 6" crescent wrench, but I'm sure you see the value.
Just to get some clarification here of these concepts. A brake with higher mechanical advantage is going to need more cable to be pulled for equal movement of the pads. However this doesn't necessarily mean that it's more powerful. Maximum power has to be achieved with a ninety degree angle between the line of the pivot and the attachment point of the yoke cable and the yoke cable itself. This is all a matter of taste though because you would need to match the brake setup to the brake lever of your choice. And mechanical advantage of the lever is something different again. And modulation and feel are things that shouldn't be argued about. Just sort of asking or saying. 'Spose I'm just saying for the sake of it.
If I understand correctly, the difference between the Mk2 and the Mk3 is primarily the length of the arms. I have some 25 year old Mafac cantilevers on two of my cycles. One is an Andre Bertin cyclocross model. The other, a long wheelbase Gitane tourer. The two sets of Mafac cantilevers came with two different length arms, I think the short ones were on the cross bike. Due to weight transfer under braking, almost all vehicles have more powerful brakes on the front than the rear. (And bicycles, with their high centre of gravity and short wheelbases, have more weight transfer than most vehicles.) I split the sets of cantilevers, putting long arms on the front of each bike and short arms on the rear. Power on the front where it's needed, less fear of premature lock up at the rear. (It's another matter, but I also use slightly larger section tyres on the rear than on the front, for the greater weight when not braking.)
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