I just bought a used Trek T-100 tandem bike. I think it's going to be fine for me and my 13-year old daughter next summer on Cycle Montana, but I have two concerns that you more experienced cyclists may be able to help me with. First, the crankarms are 175 mm. Is this too long? I am 6 foot, and love the 172.5's on my road bike. My daughter is less than 5 foot tall, and I worry about "beating her up" on the flats. Would it make that much difference changing the arm lenghts to 170? Second, my rear gearing only goes to 28T. Is this a disaster in the making? I remember how hard it was to climb Rogers and MacDonald pass last summer on my road bike, and I don't want to needlessly suffer. Any suggestions?