Two suspected Kamtapur Liberation Organisation (KLO) militants were Friday arrested in connection with the blast in northern West Bengal's Jalpaiguri district where a bomb disposal squad member died while defusing the explosive device, police said.
A senior state police officer said the needle of suspicion for planting the bomb in the cycle pointed towards the KLO.
"We have already got some information. We are hoping to get more details," said the officer.
Two others were injured when the explosive device blew up at Chowpothi in Alipurduar sub-division early Thursday.
Inspector General of Police (North Bengal) Shashi Kant Pujari, Special Superintendent of Police (North), CID, Miraj Khalid, and other officers have visited the spot.
A departmental inquiry has been started to ascertain why the bomb defusers went about their job without putting on a life jacket, mask and helmet.