Hi got a 2011 rockhopper SL with shimano crank... i have never serviced a crank. But am a vehicle mechanic so happy to take on the job.
Whats likely to require attention when its creeking slightly when pedaling hard?
You most likely have a sealed Bottom Bracket , so no service is possible. Photos of BB would help. Creaking could be from other areas make sure all is tight especially pedals the seat and check the seat post.
Never Give Up!!!
First things to check are:
- remove, regrease threads, and reinstall pedals
- check tightness of crank arms onto BB
- check for side to side play in BB bearings
- If continues, might want to remove BB, check bearing smoothness (regrease threads and reinstall if bearings ok)
- creaks can also come from wheels, seatpost, seat, headset. The sounds tends to travel through the frame so it can be hard to pinpoint source. But the cranks are the most common cause and best place to start. This is a normal indicator of a loose crank which will damage the crank arm if ridden loose for long, so don't ignore...