You're in for it if you hate hills. Chicago has tons, I mean tons of stout overpasses that are a ***** to climb. You might have to downshift one gear.
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Sorry to be sarcastic but it's easy since I've never ridden in the Chicago area. So I'll take this opportunity to ask: How's the cycling in the Chicago area? Where do you go? Whenever I fly into the city, all I can see is urban development sprawling into the horizon so I have to wonder if it's all just shared bike paths and/or stop and go riding on the streets. And I'm also curious about hills? Got any?