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one with conical washers? Got a fork with a 160mm post mount, post mount caliper (shimano), 180mm sram/avid disc. Can i use the sram/avid adapter off the old brakes?
It depends, if it's one of those that only has two tubes (like this:
,)
it won't work. The tubes have a scalloped feature in them so they replace half of the conical washer. In order to fit a non-Avid caliper you will need to remove the washers between the adapter and the caliper, but that is impossible with these.
The ones with a brace between the posts (like this:
) will work, provided that you only use the conical washers on the outside (between the caliper and the bolt head, like this: 
).
it is same as the top one - why does removing the washer make it impossible? could i not keep the washer in there?
The washers will space a non-Avid caliper further out than necessary. I think there are two variations on the top one as well - if yours have both faces perfectly flat and use a full set of washers (8 pieces in total), then it will work.
This is how the incompatible ones look like:
. Removing the washer will cause either the caliper or the fork to sit against a scalloped surface.
How thick should the top and bottom mounts Be? I.e both 10mm?