I'd contact Hope directly to see if you can just purchase the calipers or talk with your LBS and see what they can do. Also, if you're not aware you will need to purchase new rotors to go along with the new calipers as the old style wavy, or gothic rotors will not fit properly. The old rotors will be too thick and diameters have been changed (reduced 5 mm e.g. 165mm to 160mm etc.) to match those of the competition
Another thing to consider. I've had a chance to demo a set of the Mono Mini's and I have to say they didn't meet my expectations in terms of power. They have truly gone the way of a "pure" cross-country brake. IMO they would be GREAT for cross country racing, OK, but a little lacking for all mountain trail riding, and bad, bad, bad for freeride/DH. Like you, I'm running the old style minis and my original Mini's seem to have more power. Why? I've concluded that the smaller rotors and smaller brake pads (smaller surface area) found on the new design give this brake less power than its predecessor.
If you're looking for a performance upgrade to the old Mini's look no farther than the new Mono M4's. I've also had a chance to demo the new M4's and here is an excellent all-purpose brake in my opinion. It’s OK for cross country racing (a little heavy), GREAT for all mountain, aggressive cross country trail riding and GOOD for freeride/DHing. It has mucho power with the typical (and excellent I might add) modulation of Hope products. Again, new rotors would have to be purchased for this upgrade.
and was told that the cost of the caliper and rotors alone would be only slightly cheaper than the whole break system, so I'd be better off just selling my old Minis and buying a complete Mono set. I haven't verified this myself yet.
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