If you are using a triple, consider half step plus granny. If you get in a bunch on any of the tarseal sections, you will appreciate the closer ratios. My set up last year was 32/47/50, with 13-26 cluster. There were riders who were making good progress with 50s racing gearing, but I suspect they weere real athletes, not pretenders like me.
I had one snakebite puncture using Ruffy Tuffys, so the extra cross section of something like the Gran Bois Cypres would be an advantage.
If you are doing the 135k course, I would recommend starting early. Last year Courtney Johnson and I got to the biggest climb around midday, and I got well and truly cooked.
If you haven't seen it already, my blog of last year's
Eroica:
http://retroride.blogspot.com/
DB Ak NZ
http://retroride.blogspot.com
http://www.outside-the-tent.blogspot.com/
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