The Allen key piston spacer trick works quite well, at least on 4-piston SRAM brakes. A friend did it on 2-piston Shimanos and one of the pistons extended a bit crooked and leaked fluid, so I guess a bit of care is needed.
It’s easy enough to push the pistons back in with a tire lever if you pull the Allen key out. I suppose the other pistons could over-extend when pushing one piston in, but it hasn’t happened to me yet.
March 12, 2021, 9:28 a.m. - DMVancouver
The Allen key piston spacer trick works quite well, at least on 4-piston SRAM brakes. A friend did it on 2-piston Shimanos and one of the pistons extended a bit crooked and leaked fluid, so I guess a bit of care is needed. It’s easy enough to push the pistons back in with a tire lever if you pull the Allen key out. I suppose the other pistons could over-extend when pushing one piston in, but it hasn’t happened to me yet.