This is very hard to explain, but I will try my best.
I recently got a Shimano Ultegra cassette, crankset, front and back derailleurs, chain, and cables installed on my Giant TCX SLR1 2015 bike.
Every time I pedal, I feel a subtle click or slip on my left foot at a specific interval (when the left arm is going down). However, there is no sounds, I can only feel it in my feet. It’s very subtle.
However, I do not feel it when I put a lot of pressure or when off the seat. I really cannot pin it down to anything, hence I would be grateful for any opinion.