Disk Brakes are fairly easy to maintain, Hyrdo's have to be bled 1 or 2 times a year, mechs, will need new cable 1 or twice a rear, pad wear can be checked by metal currency, if it is thinner than a dime they are worn out, above a nickel, the pads are fine for awhile. Just remember not to touch the pads or the rotors with your fingers, the pads and rotors will contaminate if you have to touch them for some reason, use powder free latex gloves.
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Appreciate the old bikes more than the new.