For example of good local activism, look at London, or Cambridge, or Oxford.
These are cities (and there are many other towns and cities as well) which have seen a resurgance in cycling. This resurgance has a common factor - motivated local campaigners.
London owes much of its cycling renaissance to the London Cycling Campaign and its local groups, and to the CTC local groups. It was these people who got involved in things like CRISPS and CRIMS, who went to the planning meetings locally to push the case for cyclists, who campaigned for the introduction of the Congestion Charge Zone and Boris Bikes, who are pushing local authorities to increase facilities and who are making their mark by simply cycling around the city. It's the same with other places like Cambridge, Oxford and Sheffield.
It wasn't the national organisations like CTC National Office or Sustrans who have brought about these changes. It was the local activists, who have kept plugging away, holding their local councillors to account, bringing pressure to bear on planners and who hold the festivals and rides that attract new cyclists.
Want contraflow cycling? Priority on busy roads? Planning that is beginning to put cyclists first (e.g. on the Hills Road bridge)? Come to Cambridge.
Want to see kids cycling to school? Parents cycling with their kids? Supermarkets, schools and hospitals providing good quality cycle parking? Come to Cambridge.
This has all happened because of local activists using the clout that they have. It's all too easy to sit there and say that you can't change anything. You can.