Montgomery County authorities found what they called a bicycle chop shop at the home of a teenager whom they charged with assault after a confrontation on the Schuylkill River Trail last week ended in gunfire.

The boy, a 17-year-old from Norristown who was not identified, was charged yesterday in juvenile court with simple assault and was held pending a disposition hearing.

A week earlier, police said, Joseph James DePaul Jr., 27, of Norristown, reported firing six shots from a semiautomatic pistol at two teenagers who he said had harassed and assaulted him on the trail in Plymouth Township. DePaul was charged with two counts each of attempted murder, attempted voluntary and involuntary manslaughter, aggravated assault, and reckless endangerment.

On Friday, police searched the home where the 17-year-old lives with his father. They found 15 to 20 bikes, mostly of the Mongoose brand, and wheels and bike parts, District Attorney Risa Vetri Ferman said.

She declined to say whether any of the bikes had been reported stolen. She said the investigation continued, and she sought the public's help in identifying the bikes.

A number of bicyclists have reported being harassed on the trail the last few months.

Ferman said municipal police would use undercover officers and cameras to monitor trail hot spots.

"We are trying to take a coordinated approach to the security and safety of the trail," she said.