Disc brakes I am using on a new diamond back are lame. Would it be the pads or are they just poor?

Question

I've tried adjusting and cleaning.

Answer 1

Disk brakes require a break-in period to reach full braking power.  Prior to this, their performance will be poor.  Have you performed the proper break-in process?

Different manufacturers recommend different procedures and you should check the documentation for your particular brand of brakes.  Magura, for example requires 30 high speed, hard stops to properly break-in new pads.  Prior to doing the break-in, performance is pretty weak.  Afterwords, the brakes feel like they would stop a Mack truck.

By the way, cleaning new brakes isn't likely to help.  During break-in tiny bits of metal from the rotor winds up being embedded in the pads.  This is part of what gives the pads their power.

Hope this helps.