Cyclists negotiate rush hour traffic in central London on Nov. 15. Fourteen London cyclists have died so far this year, all in accidents involving heavy goods vehicles.
Credit Oli Scarff / Getty Images
A cyclist receives emergency medical treatment after being involved in an accident with a truck on Monday in London.
Credit Peter Macdiarmid / Getty Images
London Mayor Boris Johnson (shown last year in London) has angered cyclists by suggesting that cyclists should be more careful, in response to recent deaths on London streets. He also says he won't be bullied into wearing a helmet.
Here are some ways to think about the Tour de France.
When I'm out on my road bike and I head down a very steep hill, it starts to feel pretty damn scary if my speed creeps up over 30 miles an hour. That means I'm zooming down a steep grade and the bike feels right on the verge of being out of control.
Tour de France riders go much faster than that on a flat terrain, generating their own power. Speeds of 35 miles per hour are common. Bursts of 40 are not uncommon. Going downhill, they're up over 50 miles per hour. I get anxious just typing that.
In 1896 -- a time when Scientifc American ran a regular "Cycling notes" column -- the following item appeared. "Count Leo Tolstoi, the Russian novelist, now rides the wheel, much to the astonishment of the peasants on his estate."