Good question Gruss, I didn't include bikes in this article because there didn't seem to be any particular charities who use old bike parts to make wheelchairs like in other states. Click on this link:
http://www.givenow.com.au/otherways/bikes#QLD to find three charities who are willing to accept bike donations but you might need to make a phonecall to see if they will take one needing repairs.
good luck,
Shannon