The Hope V2 caliper is made for Hope's 3mm wide vented rotor, if you run their solid floating rotor (2mm) or a Hayes rotor (1.8mm) you move a lot of the brake fluid from the reservoir into the caliper so the piston will take up the extra space.
Then you might have issues with the reservoirs running empty soon as the pads start wearing down a little, depending on how steep an angle you like your brake levers. (I have mine about 45* down, and they're starting to suck air after about twenty rides.)
Sure, it's easy enough to just open the reservoirs and top off the fluid, but then if you ever want to put new pads in the calipers on the trail you'll have too much brake fluid in the system and will have to open up the reservoirs again and let some out.
I'm thinking a simple machined aluminum spacer/tool might be handy to solve the problem, something to drop into the caliper in place of the pads while you hand-bleed the system. Instead of pushing the pistons all the way into the caliper and using the pricey Hope bleed kit, just push the pistons in all the way, insert the tool, pump the brake until the pistons bottom out against the tool (which allows each of the pistons to come out .5mm or so), then hand-bleed the brake using the old-school (& cheap) pump-n-vent method. No worries about overextending the pistons while bleeding; the tool stops them at the right place for 2mm or 1.8mm thick rotors. And the tool takes care of "lazy piston" issues when only one piston wants to move, so it would be easy to center the caliper on the rotor.
Or just say screw it and top off the reservoirs and deal with the extra fluid when the time comes for a pad change, lol.
Then you might have issues with the reservoirs running empty soon as the pads start wearing down a little, depending on how steep an angle you like your brake levers. (I have mine about 45* down, and they're starting to suck air after about twenty rides.)
Sure, it's easy enough to just open the reservoirs and top off the fluid, but then if you ever want to put new pads in the calipers on the trail you'll have too much brake fluid in the system and will have to open up the reservoirs again and let some out.
I'm thinking a simple machined aluminum spacer/tool might be handy to solve the problem, something to drop into the caliper in place of the pads while you hand-bleed the system. Instead of pushing the pistons all the way into the caliper and using the pricey Hope bleed kit, just push the pistons in all the way, insert the tool, pump the brake until the pistons bottom out against the tool (which allows each of the pistons to come out .5mm or so), then hand-bleed the brake using the old-school (& cheap) pump-n-vent method. No worries about overextending the pistons while bleeding; the tool stops them at the right place for 2mm or 1.8mm thick rotors. And the tool takes care of "lazy piston" issues when only one piston wants to move, so it would be easy to center the caliper on the rotor.
Or just say screw it and top off the reservoirs and deal with the extra fluid when the time comes for a pad change, lol.