Audax UK
Chorlton Wanderers
CycleKnutsford
Cycle Stockport
Cycleweb
Cycle Wilmslow
Cycling Project for the North-West
Fell Club
Folding Society
Greater Manchester Cycle Campaign
Lancaster CTC
Friends of the Earth – Greater Manchester Cycling Events
Macclesfield Wheelers
Pennine Bridleway
Rough-Stuff Fellowship
Seamons CC
Stockport Clarion
Stockport Community Cycling Club
Sustrans
Trans Pennine Trail
Walk-Ride Greater Manchester
If you have an unused bike, why not consider donating it for recycling?
Also, serviceable spare parts (not junk!) can be donated to
Stockport: Cera
Manchester: Recycle for Greater Manchester
A site dedicated to the CTC’s Winged Wheel, showing locations of plaques etc. This site is now sadly not being maintained, so I've amended the link to show the latest snapshot on the Wayback Machine.
Park Tool offer a wide range of articles and videos on carrying out bike maintenance.
The Global Cycling Network (GCN) provides articles on bike maintenance and plenty of other cycling topics.