This week, everybody who's anybody in the bicycle world is in Las Vegas for the annual Interbike show--the largest bike convention in the nation.  

And bikes are big business. Americans bought 16 million cycles last year and the industry generates more than $6 billion in annual revenue.

Our Wheel Thing correspondent, Susan Carpenter, spent the early part of the week at the bike show.

She says fat bikes, with super-wide tires and hefty (but often very light) frames have been around for a while, but they've really come into their own this year, with mainstream bike manufacturers showing fat models that challenge boutique brands, such as Surly, who've specialized in the corpulent bike category.

Then there are electric powered bikes. They've been selling well in Europe, but so far, Americans haven't really gone for them. That might change with some new models that can help riders get up hills and features such as regenerative braking that extend the range of the electric motor.

Whatever the choice, biking is becoming more popular in America's cities and many states, including California, have enacted laws to help protect riders. California is the latest of a score of states to adopt a Three-Foot Rule, which essentially requires drivers to give bike riders at least a yard of leeway.

The law goes into effect in California next week.