Chantal Winstead of Arlington, Virginia expected to pay $2 for her ride on Capital Bikeshare.

"I thought we were literally going to have the bikes for 10 minutes," Winstead said.

But when Winstead went to return her bike, she made a mistake. She didn't lock her bike into the Bikeshare dock.

And the next thing she knew, she had been charged $157. "The next day in the middle of the afternoon I just happened to be checking my bank account and I saw I had this crazy charge," she said.

Winstead had to return to the bike dock, find the bike and make sure it was locked into the dock.

Bike sharing is a popular way to get around these days. But what you pay depends on the terms of service -- and how well you understand them.

It's an issue that more consumers are facing as they try the service out.

Jessica Kitchen, a new Capital Bikeshare rider, admitted she didn't read Bikeshare's 133-page disclosure when she got her pass. "I skimmed through it the first time, and the second time I’m like, 'OK, this is confusing, I want to know what’s going on.'"

She was puzzled by an added charge after riding more than an hour, even though the disclosure says that the first 30 minutes are free, and usage fees begin afterward.

Turns out that if you plan on riding longer, you have to dock your bike within every 30 minutes to avoid getting charged extra fees.

"Yeah, I didn’t know that," Kitchen said.

Keeping consumers informed is a big issue for Capital Bikeshare. "I know sometimes it can be hidden in some of our very lengthy documents, but not hidden is you have to press a button on a screen that says usage fees apply to trips over 30 minutes – do you accept? Yes or no?" said Kim Lucas, Capital Bikeshare program manager for the D.C. Department of Transportation.

Capital Bikeshare says it stands behind its signage and explanation of fees. And it caps usage fees at $94 per day.

Bikeshare is also making changes, including launching an app that allows you to rent and track bike rentals in real time. It now offers text alerts that warn bikers they are over 30 minutes.

And Capital Bikeshare has George Mason University reviewing its fare structure, along with bike share programs across the country and around the world.

Meanwhile, Winstead got her money refunded -- after making several phone calls.