Cycle Ipswich is the main forum for cycling issues in and around Ipswich. Check out their new website for more info and links to other cycling organisations: Cycle Ipswich See their site for a good list of bike shops and bike repair places.
Cycle Ipswich runs an active and friendly discussion group which anyone is welcome to join: Cycle Ipswich Google Group
There is also an active CTC group (Cyclists Touring Club) and there are local people involved in Sustrans.
You can pick up the new cycle map for Ipswich from the Tourist Information Centre in the centre of town.