Will the 50/34 combined with 13-29 give me trouble with Campy Chorus 10sp short cage derailleur? I'm looking to do this conversion for short term use. I regularly ride 50/36 with 13-26. I'm doing a 10,000' climb of Haleakala in Maui and want to train on the same combos I'll ride the volcano in. Once I'm done with this ride I'd want to go back since where I usually ride I have no real need for such low gearing. If I had to live without the big/big combo because of chain/der problems I could live with that. I also have 2 wheels, so I could swap while training, only taking the low when I'm doing the climbing training, but using the other for my normal rides. And really, with the time it takes to get to the extended climb I'm using (Bear Mountain), I doubt I'll do it more than two or three times. I'll also ride some up in the Berkshires, but only over Thanksgiving. My Maui trip is over the Xmas holiday.

I did Bear Mountain, ~5 miles, 1300' and 5-6% grade, in my 36/26 and it wasn't really hard, but Haleakala is longer and higher by 7x. 36 miles and 10000'. But the overall grade is about the same except I'm allowing for more variation.

I'm still on the fence about taking my own bike vs. renting. The airline will charge $200 r/t for the bike, about the same as the rental, but I would need a travel case. My experience with a travel case isn't good either, they're really big and don't fit in a car. You need a van, plus we're a family of 5, and the kids are all big. I'd have to make a second run to the airport to pick it up.