When pedalling hard there is a sound from BB (at least it seems so). Like wood kreeking. Only when pedaling hard hard, when just spinning backwards there is no noise. When leaning hard on one peddal, or when pedalling hard there is the noise.

It is a Shimano triple crankset (tourney I think) and square tapper BB.

Any ideas what it is? Should it be fixed/replaced, or is it good to go as long as I don't mind the noise?


If it helps: pedals are greased, and when I'm off the saddle it is also heard, so it's not the saddle or the post.