Originally Posted by
BobbyG
Last year I bought a 2006 Felt F-65 with its original 2x10 Ultegra gear set. ...
The Felt has a relatively narrow rear gear spread, and the front double is wide, and I don't necessarily want to put a smaller cog up front, but would if that is the most expedient choice. I want to keep everything light-weight, as this is the theme of the bike.
Also, is it possible to replace just the lowest rear gear sprocket? ...
To determine feasible lower gearing, you got to first identify the existing 2x10 Ultegra drivetrain: what chain rings and cassette are on the bike?
Without that information, I randomly guess that an Ultegra 12-30 cassette may provide lower gearing.
Shimano Ultegra CS-6700 Cassette (Silver) (10 Speed) (Shimano/SRAM) (11-25T) - Performance Bicycle (performancebike.com)