Do pushbikes cause traffic congestion?

It's pretty hard to get a letter published in The Sydney Morning Herald. There has been a running debate on those pages about people riding pushbikes in Sydney. In salon des refusés spirit, here's one of my letters that didn't make it:

'Greg Last (letters September 6) thinks bikes increase traffic congestion. True, they go slowly up hills but if you have a long look at the nearest traffic lights you will find that, in fact, cars hold up far more traffic. I have also observed that the new cycle lanes in William Street solve Greg's problem very nicely by separating cars and bikes. The RTA, however, now wants to remove them in order to 'reduce traffic congestion'. Can we have a reality check please?'

As you can see, in William street it's the buses causing the holdups because Frank Sartor's granite vision did not include bus bays. Doh!