Bad disk braking

Rear brake is acting up. I’m sure the action is sound (ie the piston is properly engaging the rotor) but braking is very poor - I can’t lock the rear wheel while riding no matter how hard I pull.

I’m assuming this is pad contamination (I haven’t changed the pads in 1year but I haven’t done all that much riding), but any other ideas? Is alcohol cleaning of the rotor and replacement of the pad the best thing, or is there anything else I should try?

Well how worn are your pads? What type of brakes? There usually isn’t any adjustment for wear on the piston side but on the caliper side sometimes there is a thumbscrew or an allen key to move the pad closer to the rotor.

If they’re hydraulic they might need a bleed. If the pads are contaminated you’ll be able to tell because they’ll squeal.

Also I had some entry-level Hayes mechanical disc brakes and one of them started acting up. Swapped it out for an Avid BB7. Nothing but love for the BB7.

these are avid 5s (cabled). I don’t get any squeaking, and I’m pretty sure the adjustments are correct - its just they don’t seem to be gripping properly. If I grab the lever as hard as possible I can still force the rear wheel to turn fairly easily. I guess a pad replacement is the simplest thing to try, its possible i have just worn them out.

If the pads aren’t too worn out you can just sand them down and clean the rotor with some alcohol.

the pads work the same whether they are at 3/4 wear or 1/4 wear. If you actually wore all the way through them, then you would hear a grinding metal on metal sound. possible they are contaminated, also possible what john said that you can adjust one side of the caliper.