LONDON (Reuters) - London's streets creaked and rattled with nervous new cyclists Friday after bicycle sales rocketed in the wake of bomb blasts on three underground trains and a double-decker bus.

Seasoned cyclists told of weary walkers offering them up to 300 pounds ($500) for their bikes as they headed home on Thursday, and of giving impromptu lessons to shaky beginners.

Tim Davies who manages Cycle Surgery near Holborn, said: "the shop is so close to where the bus got hit that we thought we'd be evacuated.

"But by 11 o'clock we were running around like crazy. We'd normally sell five to 10 bikes a day, but we sold at least double that in a few hours.

"We had people who hadn't ridden for over 10 years asking for refresher lessons -- we even had a judge."

Others, who had walked home, dug long-forgotten bikes from sheds and garages for Friday morning's commute. Fernando Gandioli said he noticed "a lot of rusty bikes and squeaky chains" as he cycled in to work at accountancy firm KPMG.

Shop assistant Maja, who works at Evans Cycles near Clerkenwell, said they had sold triple the usual number of bicycles Thursday, mainly folding bikes or cheaper models.

"It was mainly workers and executives," she said. "People who didn't want to waste money on a hotel and said: 'sod it, I'll buy a bike.'"