If your bike groans every time you push hard on the pedals, identifying the cause can be surprisingly tricky. Try these fixes if a persistent creaking sound is driving you crazy.
Seat post: If you have a metal frame and post, apply a thin layer of metal grease to the post. If your frame or post is carbon, use an assembly compound.
Saddle rails: Remove the saddle, coat the rails with grease, wipe it off, then re-tighten the clamp.
Pedals: If the threads connecting your pedals to the crank are dry, they can creak with every stroke. Pull them out and apply metal grease to the threads.
Stem and handlebars: Apply a layer of fresh assembly compound to both clamping portions of your stem and use a torque wrench to re-tighten the bolts.
Rear dropouts: Take the wheel off, clean the dropouts and quick release, then put the wheel back on the bike.
Bottom bracket: If nothing else works, remove your crank and bottom bracket and apply a generous coat of metal grease to every metal-on-metal connection point.
Two products to help keep things running smooth:
Tacx Carbon Assembly Compound ($25) prevents carbon parts from slipping and silences squeaks.
Park Polylube 1000 ($5) eliminates creaks and blocks corrosion of metal parts.