when i do one full turn of pedals i have a knocking noise on every rotation, the spd pedals are ok.also when i lift up on the pedals it stops, only happens when i put pressure down

steve, March 2012

If it`s an old bike the top of each pedal stem may be attached by a pin with a bolt, called a cotter pin.These pins may need tightening, but they also may need replacing if the inside flat edge become worn.Most modern mountain bikes do not use this cotter system to fasten the pedals.Examine the pedals and see if anything obviously seems in need of tightening up.

dennis uk, May 2012