DETROIT, MI -- It started with about 10 bikes rolling slowly through the city.

They multiplied over the last three years, and some 1,600 bicyclists rode through Detroit's neighborhoods Monday night in the extraordinarily diverse weekly gathering.

But the Slow Roll has gotten so big that city officials have taken notice after hearing some complaints about clogged roads.

The attention could threaten to complicate the free, informal gathering.

"I have nothing against bike riders, but... They're blocking the traffic quite a bit," said City Council member Brenda Jones on Tuesday.

"I don't want to see them stop, but they need to know that there needs to be something in place."

She said she was stuck in traffic herself Monday as the bicycle horde rolled through

an intersection and that other drivers were turning to her for intervention.

"There's no way you're going to ticket all of those participants," Jones said. "I'm not saying ticket them... but traffic was really, really backed up."

Council President Saunteel Jenkins directed administrative liaisons to inquire about permitting requirements related to the Slow Roll and a similar monthly event called Critical Mass.

"Every week it's getting bigger and bigger and bigger and they're still conducting it as if they're 20 or 30 riders," Jenkins said. "They need to be notified of what the requirements are."

Mike MacKool, the Detroiter who founded the Slow Roll along with fellow bike hound Jason Hall, is hoping to keep the event informal at least through the end of the season.

"As of right now, we are trying to go under the radar," MacKool said. "I don't know if that's working. We actually are looking to try to work with the city. We're just trying to keep it rolling through this year without having to go through the permit process quite yet."

The last Slow Roll gathering of the year is scheduled for Oct. 28, a Halloween-themed ride.

MacKool acknowledged that some drivers are inconvenienced by the horde rolling through intersections.

He said it took about 7 minutes for the horde to get through each intersection Monday.

"We need to come to a solution on how to make it work," he said.

The annual Tour De Troit took 6,000 bikes through the city on Saturday, fully permitted and with police escorts, but that's an official event with a $35-$55 admission fee.

The Slow Roll is an entirely different affair.

It's a free event that attracts experienced bikers, novices, suburbanites and city folk riding racing bikes, mountain bikes, flashy and absurd custom bikes with helmets, funny hats, baskets, honking horns, bells, reflectors and mounted stereos of all kinds.

"You bring out such a wide range of people and it becomes really infectious," MacKool said. "People get intrigued... It becomes such a sight to see that many people riding together as one through completely random parts of Detroit."

And it's not without rules. MacKool before every ride tells the crowd via megaphone to stay on the right side of the roads, to communicate with hand signals and "be respectful."

He said he didn't expect Slow Roll to grow like it did, and to become a way of introducing different parts of the city to thousands of people.

"It changed our perspective on what a bike ride could be for the city," MacKool said.

"We've gotten people really looking forward to Monday nights now. And that's beyond all of us."

The next Slow Roll gathering meets at Ottava Via, 1400 Michigan Ave. in Corktown at 6:30 p.m. on Sept. 30.

Detroit's Slow Roll group bike ride 5 Gallery: Detroit's Slow Roll group bike ride

Follow MLive Detroit reporter Khalil AlHajal on Twitter @DetroitKhalil or on Facebook at Detroit Khalil. He can be reached at kalhajal@mlive.com or 313-643-0527.