I was under the impression that I could fit a 24t sprocket on the FSA. I chose 3 new chain rings 48-36-24 to replace the OEM 50-39-30. I think this will get me in the ballpark for a good climbing gear......24 front 27 rear.....that works out to 24 gear inches....Not that bad even for the Appalachians.You are correct about a 24t fitting. My mistake, sorry for the confusion. I did not know it had a 74bcd inner.
24 gear inches isn't exactly a stump puller, but you may find it satisfactory. I had a 21.9 when I did the TA and it was barely adequate. I was wishing for lower a few places in the Appalachians and Ozarks, but was happy in the Cascades and Rockies. Some people find a 22 34 a necessity and some ride road gearing. I will say that the one guy we met on the TA that had road gearing was the first to the top of the climbs in Oregon. Unfortunately he also went home only about 800 miles into the TA due to knee problems and wound up requiring surgery and losing most of a year of riding.