Im sure there are more than enough threads on this but after reading I am still unsure what adapter I need. I have a 2013 Trek Marlin. im only looking to put a 180mm on the rear but unsure of what adapter I need. I currently have the stock shimano hydraulic brakes, pretty sure it is the BR-MT500 system. im looking to buy a complete new rear brake system. suggestions for what brake system I should use? what rotor?