Hariom Sharma, a resident of Shastri Nagar locality, flung his shoe from a distance at Rahul at Transport Crossing, from where the roadshow started. However, the shoe did not hit him.
Sharma, who claimed he was a journalist, was immediately detained by the police and taken to the city police station.
He was heard saying "roadshow is useless", according to an eyewitness.
Prima facie, the youth has no political links, police said. The matter was being probed.
The Congress VP blamed BJP-RSS for the shoe attack and said he wasn't afraid of them.
"I was just traveling on a bus and a shoe was thrown at me. It didn't hit me. I want to tell the BJP and RSS that you can throw as many shoes at me but I am not backing down. I am not scared of you. I will continue believing in love and harmony and you can stick with hate," Gandhi said at a gathering later.