I drive past Dundee Rd on Route 14 in Barrington/Palatine a few times a week. It's a strange intersection, as Dundee as on/off ramps to get onto 14.
I frequently see cyclists crossing Route 14 which is super dangerous because of the speed.
I know Deer Grove Forest Preserve is near by, but is there a common reason why someone would do that? Do a lot of people bike in Deer Grove?
Brian, I'd suspect at least some of the people you've seen are going to and from Deer Grove for the purposes of riding on bike the trails there. Indeed lots of folks ride there, me included. There are quite a few miles of trails, and the scenery in parts is very nice, especially in the fall. Fortunately, there are other ways to get into the site versus crossing at that particular spot.
There are some paved and unpaved trails depending on your flavor. The section to the east of Quentin road is pretty cool too. There's actually a lot to see if you want to go there with a camera and binoculars even if you're on a biking rest day. Some days you may want bug spray. As off-road riding goes, I worry more about a collision with wildlife here more than other places.
As a suggestion, check for the latest Covid lockdown status if you're planning an outing. And of course bring the water bottle.
Brian, there is a 3rd road that also crosses at this intersection that was omitted from your comments, that being Ela Road, which is in generally good condition with a wide, well-marked shoulder to stay safe from traffic. It is a prominent north-south thoroughfare for us NW suburban roadies who ride from the Palatine/Barrington area. While some folks are using it to access Deer Grove FP, most of us are traveling the Barrington/Inverness/Palatine/Hoffman Estates/South Barrington corridor while making the turn you reference. Hope this helps...
The ramps to and from Route 14 have wide shoulders and feel safe, at least to confident cyclists. They allow access to Ela Road heading north to Cuba Road. Some peel off where Long Grove Road t-bones into Ela to ride the Cuba Marsh. (The Bike Palatine Club website has a blog entry about that location - wwwbikepalatine.com .) Others pedal on to Cuba Road itself where eastbound and westbound routes yield some challenging rollers. Shoulders along Ela Road are smooth and relatively wide.