I looking to modify my Trek 520 touring bike to use for randonneuring. It is geared low with a Sugino crank at 26-36-46 and using the Cyclotouriste 13 cassette from Harris Cyclery that goes from 13 to 34. It computes at 95.5 to 36.5 gear inches with a 170 mm crank. This works great for pulling loads up hills but is lacking in speed on level or downhill.
I looking at changing the cassette to a 12-25 which would give me a gear inch range of 49 to 103 or a 11-23 cassette yielding 54 to 112 gear inches.
I've not done any randonneuring before, but don't think my current set up has enough in big gears. Don't want to try a 200k event and suffer because of the gearing. The cassette swap is a fairly cheap and easy change.
Anyone have an idea on what would be the best?