Clunking noise/feel at end of day

aputschoegl

I have been noticing a clunking/creaking noise that I swear is coming somewhere from the drive train. I don’t notice it in the morning when I bike to work, only on my commute home at the end of the day after my bike has been sitting outside. It seems more prominent after a hot day. It seems to make the noise at random and more when I’m just starting to bike. It doesn’t seem to associate with a certain time in the revolution of my pedals or wheels. It’s a starter level trek hybrid bike that I’ve had for a number of years and have it professionally tuned and do some maintenance myself with a recent deep clean of the chain, which is now very quiet. This noise and the feeling while pedaling is definitely a nuisance. I’m wondering if my bottom bracket needs to be replaced because of worn out ball bearings that are worse in hot weather. Any help is greatly appreciated. Thank you!