"We've sold a hell of a lot of bikes today," the manager of one of the Evans Cycles stores in central London told a press agency reporter.
"People are coming in and buying bikes because they can't get home today."
Grant Young, co-owner of Condor Bikes in west London, said sales on the day of the attacks.
"It was just one person after another coming in out of desperation," he said.
"People have said to me, great business, but it's not really. It is nice to be able to sell bikes, but for another purpose. Things will go back to normal, so if there are 500 new cyclists now and 200 of them stick to it, that's great."
Evans Cycles' nine London stores sold 400+ bikes on Thursday, four times as many as usual.
Cycle rental businesses ran out of hire bikes quickly.
"We're all out," said an employee at On Your Bike, near London Bridge.
Much of London's public transport network is running a normal service today but Transport for London has urged motorists to avoid driving into central London. The £8 congestion charge was suspended yesterday and there will be no charge today either.
Media reports this morning say there are more people walking and cycling than usual. This is on top of increased cycle usage in the capital since the introduction of the congestion charge.
Becks, a poster to the Singletrackworld website said: "I have just biked in as usual and there were an awful lot more people out on bikes today."
Roger Bate, a London-based reporter for America's National Review magazine, said:
"Since I can't use public transport and all the cabs are gone, I've bought a bicycle. There appear to be far fewer people in London than yesterday and it's easy to get around."