I need new a new rear V-brake. The Shimano LX I've got seems unusable. So, I need the Single Digit 7, Shimano DX (impossible to find?) or the SRAM 9.0?? If I can't find any of the above used, I'll just buy a deore with replaceable pads for 10£ new... Could I stick with the Shimano LX levers I've got until I break them?