In a widely viewed YouTube video, a cyclist named Casey Neistat deliberately takes tumble after tumble while trying to navigate obstructed bike lanes in New York City. The video is funny — it even includes a crash into a parked police car — but it also has struck a chord with bike commuters facing a seemingly endless array of road hazards.

In urban areas, many riders have reason to be nervous, and that in itself is part of a vicious cycle.

"The most common mistake new cyclists make is not riding predictably," said Ken Podziba, chief executive of Bike New York, a nonprofit group that promotes cycling. "For example, people who are afraid of getting hit from behind by a car will often do things like ride on the sidewalk or ride against traffic, which actually increases the danger that they will get hit by a motorist who doesn't see them. Fear is a cyclist's worst enemy."

Driven in part by riders' demands for a greater sense of comfort and safety on the road, new apps and gadgets are promising to do for the bicycle what air bags and satellite navigation did for the family car. What used to be a simple, healthful mode of transport is fast becoming a tech festival on wheels.

Perhaps it was to be expected. Travel by bike has surged in recent years, spurred by bike-sharing programs and efforts to set aside and improve bike lanes. Bike-share programs are gaining acceptance.

From 1990 to 2012, the number of bicycle commuters nearly doubled in the 70 largest cities, according to data collected by the League of American Bicyclists. Today, Americans make more than 4 billion trips by bike each year.

One of the biggest grievances of all these cyclists is not being seen. Jonathan Lansey, 28, spent so much time dodging cars on his daily commute in Boston that he began a Kickstarter campaign to finance production of a bike horn that could not fail to get a driver's attention. His brainchild, Loud Bicycle, sounds like a two-toned car horn and, at 112 decibels, is about as loud.

"It's embarrassing to get honked at," Lansey said. "But it's more embarrassing to get honked at by a bicycle."

He tested the horn on his commute and found that drivers reacted immediately, as they would to another car. "They're more worried about damaging their car than another person," he noted.

Philip McAleese, 39, of Newtownards, Northern Ireland, also wanted to make cyclists more visible, so he developed a bike light called See.Sense, which has sensors that react to surrounding light levels and movement. If the cyclist swerves or brakes, for instance, the lights flash in a pattern similar to those on an ambulance or a police car. See.Sense also has a broad beam, so the bike is more visible from all angles, helping to prevent a side-on collision.

Who needs bike lanes at all? The Xfire Bike Lane light is equipped with two high-visibility red lasers that project two 3-foot lines onto the road, creating an ad hoc bike lane. The lighted lane is visible to motorists up to a mile away, according to the manufacturer.

But perhaps the most surprising leap in high-tech safety is an inflatable bike helmet called the Hovding, which works much like an automobile air bag. The device, worn around the neck like a quite fashionable scarf, detects the impact of a crash and inflates a sort of instant helmet around the cyclist's head and neck.

Tests performed by the Folksam insurance company in Sweden suggest it may be three times as effective as a standard helmet. But riders in the United States will have to wait to try it; at the moment, the Hovding is sold only in Europe.

In addition to their personal safety, cyclists worry about safeguarding their bikes. A device called BikeSpike, affixed to the frame, lets you track its location on a smartphone, so you can find a stolen bike or just keep track of family members and friends on the road. For a monthly fee, the app also alerts your smartphone when a bike has been in a crash or deviates from its expected course (such as a child riding too far from home) or is tampered with. BikeSpike goes on sale this spring.

BitLock is a bike lock with a twist: It can be locked and unlocked by a smartphone, and not just the cyclist's. Once other users have permission, they can use the app — which also provides the bike's location — to grab the bike wherever it has been left. The result: instant individualized bike-share, without the costly and ubiquitous street racks. The locks should be available by fall.

For cyclists who want to take self-quantification to the next level, there's the Copenhagen Wheel, which replaces the regular back wheel of a bike. It tracks how the cyclist pedals, the distances traveled and calories burned. The wheel also includes a motor that kicks in on longer or steeper rides, which is intended to remove the perennial objection of would-be commuters that a ride is too long or difficult, making it a more appealing alternative to jumping in the car. The wheel is available for pre-order online.

For many cyclists, the most important onboard device is a phone. The Atom, a USB battery pack that is recharged by pedaling, can be connected directly to any USB-powered device such as your phone or bike light, or removed from the bicycle to charge a device after your ride. "We're providing mobile power for mobile technologies," said David Delcourt, chief executive of the manufacturer, Siva Cycles. The device can be pre-ordered online for shipment in July.

Not all cyclists are enthusiastic about the rapidly evolving robo-bike. They say the new technology could become a distraction to cyclists who need to stay focused on the road.

Maybe what's really needed is a course in improving real-world bike skills, perhaps paired with devices like a loud horn or a brighter light to help make the streets less intimidating.

"You can have your bike outfitted with all the latest technology, which is great," said Podziba of Bike New York, which offers instructor-led rides around the city. "But you have to remember that you're sharing the road with drivers, and other cyclists, who are used to certain behavior."