I swapped out my Biopace 52/42 chainrings for 48/38 Suginos on 130 BCD Shimano tricolor cranks. I wanted to try compact, but didn't want to throw off the vintage vibe of my Cannondale. The 48/38 was the closest I could get. My rear cluster is 12-26. With the Biopace rings I spent more time toward the 26 end of the rear cluster. I just did a 100 bike ride and noticed I spent more time in the middle of the cluster with the 26 more reserved for steep climbs. I'm glad I swapped out to the Suginos. Although I probably need to be in better shape.