GPS

A GPS that functions as a cycle computer

What the GPS unit offers that other computers don't is the ability to pinpoint one's exact location down to a few feet. A large LCD screen plots a rider's course, leaving a visible trail that can be followed for a return trip. Waypoints are easily set (mark the base camp, the car, a stream, the Mr. Softee truck, whatever) and can be turned into navigational markers. The display can point the way straight back to any point, and plot the distance and time to return, a handy feature when lost in the woods.

The Summit also adds a real-time altimeter and a digital compass. Standing still or moving, the device can display heading and bearing to degree-level precision, as well as longitude and latitude information. (GPS units without a digital compass cannot determine direction when standing still; they have to be in movement, which is a problem when you have stopped and are looking at a map.)

The Summit can display current speed, average speed, maximum speed, trip time, trip distance, current direction, remaining distance, time to a waypoint, and multiple routes. The altimeter displays total ascent, total descent, and an elevation profile of the ride. Combine this with a PC connection and the GPS unit is a tremendous training tool, and a great help for planning rides. Topographic maps can be loaded into the unit so that the rider's position is displayed on a virtual map on the display. And of course the GPS can be used camping, on a boat, or in the car.

Heart Rate Monitors

A few units offer heart rate monitor features in addition to basic cycling data. A sensor is strapped around the cyclist's sternum, where electrical impulses are picked up by small diodes. The data is wirelessly sent to the computer, where the heart's current effort is displayed in beats per minute. Cyclists in training can use this data to see the true level of exertion as opposed to perceived effort. (If that last sentence didn't mean anything to you, you probably don't need a heart rate monitor.) HRM features aren't cheap, and they don't appear in units until around and above the $100 mark.

PC Interface

Some units offer PC interfaces. Hours, days, or months of data can be downloaded into a computer for later analysis. This is a pricey option and isn't of much use to the casual cyclist. For racers and endurance athletes, this training information can mean the difference between a first place and last place finish. Combine a HRM with a PC downloading unit and you get a training device capable of plotting physical exertion against the heart's reaction. Repeated running of the same course over time will reveal the body's level of training. This is very cool information, but at a steep price; these units hover at the $200 price range.

Flight Decks

Shimano's unique and notable Flight Deck series of computers integrates the computer into the shift levers. Via clever engineering, a series of wires are attached to the shifters, where small buttons are molded into the shift levers or brake hoods. Pressing these rubber-coated buttons changes the display. By connecting directly to the drive train's controls the computers can display gear selection (via an optical display that removes the need to look down at the drive train), cadence, gear ratio, and an easily controllable lap counter and stopwatch. A wireless version is available too, although it doesn't remove the need to run wires to the shift levers. All this functionality costs a fair amount, and the installation is killer and should be performed by a dealer or someone willing to spend a long time opening up the shifters to do some technical tweaking.