Not to sure what it's coming from I don't have the tools to take the crank off or adjust the bb. The funny thing I don't get is that the creak is gone the next time I ride my bike then when I may go over a root or something and hour and a half into my ride the creak comes back then get progressivly worse the more I pedal. Then the harder I pedal the sounds gone. The lighter I pedal the sounds there. Th e only side it comes from is the left. I dont get it at all. I'm. It really bike inclined which is odd since I work as a vehicle mechanic. Any one have any suggestions.oh and the bb is a shinamo un-26 sealed square tapered bearing. And the bike is 2 months old
There are many possible causes. But it's likely the cranks are slightly loose on their axle. Vigorous pedalling and warming up during the ride make the situation worse.
I have posted a detailed answer here. Please scroll down to see the answers from me and Deemar.