A creak under load does not automatically mean the bottom bracket has failed. Before replacing parts, notice whether it happens only while pedalling, also while coasting, or when you change pressure on the pedals. Listen for its rhythm: a sound on every crank revolution often points toward the pedal or crank area, while a less frequent sound may involve the chain. These are clues, not a conclusive diagnosis.
With the bicycle stationary, look first at what you can inspect easily. Is a shoelace touching the crank, does a pedal spin smoothly, is the chain visibly damaged, and is the wheel secure? Derailleur pulleys, spokes and saddle hardware can also make noise. If the sound changes when you stand up from the saddle or turn the bars, that observation can shift the search away from the drivetrain.
A dry chain may simply need cleaning and suitable lubrication; a twisted or damaged chain needs closer attention. Have a mechanic assess persistent creaking or a loose assembly and check fasteners against the manufacturer’s torque specifications. If you suspect a crack in the frame or fork, stop riding and have the bicycle inspected professionally.