Law enforcement officials and organizers of a mass bike ride expected to send 3,500 cyclists through west Sonoma County on Saturday suggest motorists steer clear of the area if possible.
They said it would be safer and easier for bike riders if detour around the course.
"It's not going to be a good day for driving anyway just because progress between A and B will be slowed by cyclists," event spokesman Paul Skilbeck said. "So it won't be a great driving experience, and then for the safety reasons it's advisable to stay off the roads."
The 103-mile King Ridge GranFondo is a fundraiser organized by Levi Leipheimer, the three-time Tour of California champ and Santa Rosa resident.
While organizers want to promote sharing the road by cars and bikes, they said the sheer number of cyclists that will be strung out along the longest of three courses for several hours suggests the safest thing is to clear the roads as much as possible.
"There are going to be people angry about it either way," CHP Officer Jon Sloat said, "but if they can avoid it and have a little patience, it will be better."
The ride leaves from Santa Rosa's Finley Community Park at College Avenue and Stony Point Road at 8:15 a.m.
Some cyclists will be pedaling shorter distances on rides called the MedioFondo, 65 miles, and the PiccoloFondo, 36 miles. The route takes all of them down Stony Point Road to West Third Street and Hall Road toward Fulton Road, continuing west on Occidental and Graton roads to the village of Occidental, where the Piccolo riders will turn around.
Longer distance cyclists will continue up Bohemian Highway to Monte Rio, with medium range bikers then heading west on Moscow Road to southbound Highway 1 and Coleman Valley Road for the trip back to Finley Park.
GranFondo cyclists will push themselves up Cazadero Highway and killer King Ridge Road before coming down the coast and Highway 1 to Coleman Valley Road for the trip back.
Santa Rosa police will close city streets closest to Finley Center for the event start between 8 a.m. and 9 a.m. Officers will be stationed along the route with detour signs, Sgt. Doug Schlief said.
The return route includes a length of Santa Rosa Creek trail between Willowside and Stony Point Road where officers will oversee travel back to Finley Community Center for a large festival, Schlief said.
The CHP will have officers stationed at 22 intersections in west Sonoma County to ensure travel is safe for motorists and cyclists alike, Sloat said.
"Avoid it if you can," Sloat said, "but if you have to go out that way, have some patience because there are going to be a lot of bikes out there."
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