What's the best place near the lakefront to rent a bike and helmet?
There is a bike rental concession located in Millenium Park right off of Randolph. It is about a block from the lakefront path. There are numerous places to rent the Divvy bikes, but they do not include helmets.
The NAvy Pier or Millennium Park
There were several locations spread out on the trail to rent bicycles (and throughout the city). I did not see a place for helmet rentals so I cannot help you with that. No matter where you enter the waterfront you will find bike rentals easy to find. Maybe a short walk in either direction.
Hope this helps.
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