Sram T3 cracks when pedaling, but it works, in all three gears.The bike is three years in use My rear hub SRAM T3 cracks when pedaling, but it works, in all three gears.The bike is three years in use.What shoud be done, and how urgent is the problem?
I think it's something with the rear hub because the cracking sound is slightly different after each shifting of the gears.
A crackling sound could be a bad bearing in the hub. Does it also feel gravelly (as if you have dirt in the hub) or do you hear a grinding sound as well?

Note that a single crack when changing gears is relatively normal. If all fails, go to your local bike shop to get a real opinion (internet opinions don't count).