Uawadall said:Also, I won't have to worry about chain size or adjustments since they are all 12's.
Errr...yeah, you do. You dropped FIVE teeth from the 28 to the 23. You would need to shorten the chain 5 links (four in reality) to compensate for the same wrap. Comprende?
Changing in between the 28 and 26, set up for the 28 and there is no need to shorten the chain for intermittent use. Using the 25 when set up for the 28? Yeah, you really should lose those links. You might want to keep two chains around with a quick disconnect link on them.
A 23 works over lightly rolling terrain for most young guns that are using a 53-39 crankset. With your compact rig that should get you over the most of the local hills and grades, but even with a 34 ring you might need to go lower. It all depends on your strength, climbing abilities, body mass and willingness to suffer going up.
Your 34 x 23 is 39.9 gear inches.
My 39 x 25 low gear is a gear higher at 42.1 gear inches.
If my 62 year old ass can get over the steepest stuff in the Appalachian foothills and the glacial terminal moraines I figure your 40 gear inch ratio will get you over the same stuff.
Stay thin and light. Build power. Suffer in style.
And do remember that even pro's bolt on a 27, 28 or even a 32 (and sometimes albeit rarely, a compact crankset!) gear to get over those massive days of repeated 17%-20% slogs.