Does bike fit change?

Absolutely. Your fit on the bike is going to change for one of the following reasons. Your equipment has changed or you have changed.

Pedals, shoes and saddles all have a significant impact on fit. The pedal/shoe combination impacts how close your foot is to the pedal spindle. The saddle impacts the distance to the bottom bracket based on the thickness and shape. Saddles also impact your fore and aft position related to the bottom bracket based on where you sit on it for maximum comfort. Cranks change everything from the pedals to the saddle. Changes in frames impact seat angle, head tube length and head tube angle. Changing the handlebars impacts reach to the hoods and the depth of your reach to the drops. Handlebar rotation and hood position impact wrist position. Basically, you can change tires, tubes, chains, brakes, derailleurs and cables without impacting fit. Everything else causes a change.

What about you. Here's the list. Increased or decreased weight; increased or decreased flexibility; Injury or degenerative changes. If you put on a few pounds over the holidays, you will note that you can't get into the drops as easily. An adjustment should be made so that you can continually utilize all the handlebar positions. Injuries also impact fit based on your tolerance to assume various positions.

Ultimately, you want to monitor fit so that pedaling efficiency remains relatively unchanged. Just a few millimeters here or there can put you in a position of reduced efficiency. Any time something changs that impacts you ability to drive the pedals, you need to get your bike fit checked out.