* Bomb hits second-hand bike market in Shi'ite neighbourhood
* Other violence elsewhere kills at least 11 (Adds background, additional violence)
By Kareem Raheem
BAGHDAD, Feb 27 (Reuters) - At least 42 people were killed Wednesday as a motorcycle rigged with explosives detonated in Baghdad's Sadr City and militants targeted mostly Shi'ite neighbourhoods around the country.
The motorcycle was parked in a second-hand market in the Shi'ite Muslim neighbourhood that sells used bikes and was filled with people, mostly young men, when it exploded late Thursday afternoon, killing 31 and wounding 51 others, Iraqi medical and police sources said.
Blood covered the ground, storefront windows were shattered and shoes and motorcycle parts were strewn around the market, according to a Reuters' correspondent at the scene. Dozens of people were screaming for information about their relatives.
A wounded man, who identified himself as Ahmed, rested in a nearby hospital. "I was about to leave the market when a huge explosion happened," Ahmed said. "I was hit in my face and my hands and when I got up, everyone was screaming and running towards me away from the blast."
It was not clear who was behind the bombing but violence against Shi'ites is often blamed on the Sunni Muslim Islamic State of Iraq and the Levant (ISIL), an al Qaeda-linked group.
Baghdad has been hit by wave after wave of bombings since April as the precarious peace enjoyed since the end of Iraq's sectarian war in 2008 has unravelled.
Explosives and suicide bombs have been favoured by Sunni extremists as they seek to target Shi'ite areas and intimidate their own religious community.
The latest bloodshed comes as Prime Minister Nouri Maliki wages a war against Sunni militants in western Anbar province neighbouring Syria, and has become a base for ISIL. Despite the offensive, the pace of attacks around the country goes on undiminished.
In other violence Thursday, four people died from bombs on two different mini-buses in Shi'ite sections of Baghdad.
A militant smashed his explosives-packed vehicle into a checkpoint, killing three soldiers and wounding six others in Mushaada, a Sunni district, in northern Baghdad, police said.
In Salahuddin province, a pro-government Sunni-manned checkpoint in the town of Shirqat was hit by a bomb that killed two fighters and wounded four others, police said.
Also to the north in Tuz Khurmatu, a bomb in an outdoor marketplace frequented by Shi'ite Turkmen killed two people and wounded 11 others.
(Writing by Suadad al-Salhy and Ned Parker; Editing by Tom Heneghan)