Decleir was born in Belgium in 1971. He was a promising football player for former Belgian first division club,
K.R.C. Harelbeke. After a motorcycle accident in 1989, his left leg was amputated in 1995. Soon after Decleir started
powerlifting and in 2000 he switched to
handcycling. Decleir is married with two children and is a bank manager. In 2012, he made the national news headlines when his mistress was murdered by her husband. ==Sporting career==