all of the bikes mentioned are good choices. maybe call around chicago before you go to see who has what. if no luck there and your happy with the dealer you bought your trek from i'd probably go with the 520. a good bike shop can make a big difference. but like i, and others have said they're all good choices and the differences between the 3 are going to be minor.
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No matter how fast I'm going, I'm in no hurry.
there are no bicycles in the valley, the only bicycle you find in the valley is the bicycle you ride down there.
Ride in the front, this space is available to anyone that wishes to take it-jjmolyet