"GPS-enabled computer for cyclists"

Price: Suggested retail of $399.

Included: Three-ounce GPS unit with bike mounting brackets, heart rate monitor strap, cadence unit, USB cable, wall charger, training software and manual.

Summary: Advertised as a "GPS-enabled computer for cyclists," the Garmin Edge 305 has proved to be a tremendous training aid, allowing post-ride analysis of routes, speed, heart rate and cadence. But the unit's internal rechargeable battery, with a run time of 12-hours or less, is likely to limit its use on longer brevets.

Initial impressions: About six months ago, I looked with mild interest at GPS units in the display case at our local REI store. My loving and observant wife made note of that fact, and surprised me with the Edge 305 as an anniversary present. Gotta love our supportive spouses!

A sucker for electronic devices, I immediately charged up the battery and dived into the manual. Before I went to sleep that evening I'd tested out the heart rate monitor.

The unit set-up was a snap. I plugged in a few personal numbers—age, weight, bike weight, and so on, presumably so the GPS could accurately calculate maximum heart rate and calories burned. The unit handles other calculations, including wheel size, automatically.

Attaching the unit to the bike was easier than installing a normal bike computer. Two zip ties attached the mounting bracket within seconds to the bike stem, and the GPS unit—all three ounces of it(!)—clicked in securely. Every accessory should be so simple.

Since our local brevet series was already wrapped up, I put the Edge to work on pick-up rides with the usual suspects: Bob, JoeRay, Jerry and Dan.

Typically, about all the information I've had on the bike is speed and average, distance, and gel packs remaining. The Edge, on the other hand, can overwhelm you with data. A small screen is capable of displaying up to eight items. Cadence, speed, average speed, distance, elevation gain, trip time, time of day, sunset and sunrise, calories burned and current heading. The list goes on and on. It's also possible to select fewer data fields per screen. For ease of reading I chose to include only four fields: speed, distance, heart rate and time of day. A mode button toggles to several other displays—compass, route and elevation profile.

The data screens are not very different from a standard bike computer, and I found most readable at speed. My favorite was the heart rate monitor, although it was slightly alarming to see how often my maximum popped up on hard training rides.

Perhaps the best feature of the GPS is not what it tells you while riding, but what it tells you at day's end.

A USB cable supplied with the device transfers the day's ride into your computer and plots the route on a map. (The cable can also charge the unit).

The title of the included software, "Training Center," suggests the unit's real strength. Clicking on points along the route map shows your speed, mileage, grade, elevation and so on. Data can also be viewed on a chart for comparison with previous training rides on the same course.

It did not take long to recognize the unit's potential for planning new routes. Just bring the unit back home, transfer the day's data across, and voila.

But a question remained: how would the 305 be on the kind of long rides we do? The answer proved to be something of a disappointment.

One major shortcoming is the Edge 305's internal rechargeable battery. The manual claimed a 12-hour run time between charges. For most randonneurs, that would limit its use to a 200K—or a 300K on a good day with a strong tailwind.

I decided to put the Edge through the paces on a July 1 permanent ride from Raleigh to Swan Quarter (see August 2005 American Randonnuer). The distance: about 175 miles.

As I suspected, the battery's run time was a show-stopper.

As we approached the small coastal town of Bath, the unit's low battery alarm sounded at 129.45 miles, or 8 hours, 12 minutes and five seconds into the ride—well short of the advertised 12 hour battery charge. The unit may have continued recording, but I flipped it off.

The bottom line: the Edge might be sufficient on a century or 200K, but it's certain to come up hours and miles short on most other brevets.

In the end, I was sold on the Edge's value as a training aid, and as a tool for designing new routes or verifying existing cue sheets.

For longer brevets, a unit that allows batteries to be replaced, while not as environmentally friendly, is in my opinion the better choice for randonneuring.

—Mike Dayton