Depends on the pedals. Most will take a 15 mm open wrench, and it may need to be thinner than a normal wrench or adjustable. Pedal wrenches are generally very long because pedals can get very tight. Go ahead and see if your adjustable wrench will fit the pedals, and if so, give it a try. Remember that the left pedal has left-hand threads. If you can't get them off even though your adjustable wrench fits, then you need the extra length of real pedal wrench.