"A cycle showroom owner and his employee in Kasba Peth area have been picked up for questioning. We are hoping to get some concrete information from them," said an ATS official.
"We have first hand information that two of the three cycles have been purchased from this Kasba Peth shop," the official said but did not reveal anything about the third bicycle.
Explosives were strapped on two newly-bought bicycles which went off on the crowded Jangli Maharaj road.
Four low-intensity blasts had rocked the city between 7.37 PM and 8.15 PM, leaving one injured.
The investigators are not ruling out terror angle and trying to zero in on the outfit behind the blasts.
"We are not ruling out the possibility of involvement of Indian Mujahideen (IM) or right wing Hindu organisations," a senior police officer involved in the probe said on condition of anonymity.
On February 13, 2010, a powerful bomb had ripped through the popular German Bakery in Pune's Koregaon Park area, killing 17 people, including five foreigners, and injuring 60 others.
The explosion was later found to have been triggered by home-grown terror outfit Indian Mujahideen in co-ordination with LeT.