" ... Bicyclists can ride the bridge June 12 or Sept 18 as part of two-day spring and fall Shoreline Scenic Tours sponsored by the Mackinaw Area Chamber of Commerce. Each event includes a ride along the Lake Michigan shoreline on a Saturday, followed by a Sunday sunrise pedal across the Straits.
For Information, contact the Mackinaw Area Chamber of Commerce, (888) 455-8100, or online at www.mackinawchamber.com.
Riders also cross the bridge Sept. 4 at the conclusion of the DALMAC, a five-day ride from Lansing to St. Ignace. That tour is fully subscribed for this year (www.dalmac.org).... "
In the past, the Shoreline Scenic Tours crossing has been south to north (Mackinaw City to St. Ignace) as a one-way trip only - I presume it's the same this year....