BY JONATHAN MELBY
Updated February 25, 2006
Garmin released their new Edge GPS units early in 2006. They're designed specifically to be attached to a bicycle, blending Forerunner style GPS functionality with features found in more traditional bike computers and heart rate monitors.
Here's a summary of how the new Edge models stack up.
Basic Functionality Similar to Forerunner
Although very different in physical appearance, the basic features of Edge 205 / 305 appear to have a much in common with Forerunner. Both product families provide real-time data displays as you ride and then keep a history of summarized data for past rides. Like most Forerunner models, data can be uploaded from Edge to Training Center software on your PC.
Several features familiar to Forerunner users are carried forward into Edge:
Edge models also include some new features not found in older Forerunner models:
Some of these features are included in the newer Forerunner 205 & 305 models.
Course Recording Feature
This feature lets you create a course map that includes speed data from a past ride. You can directly compare your current ride with past performance as you travel along a saved course.
Because data from past rides includes natural speed variations in response to turns and elevation change, performance targets provided by the courses feature are more realistic than targets from Virtual Partner on Forerunner 201 / 301.
This feature is included in many of Garmin's handheld GPS models but was absent from older Forerunner models.
It graphically shows elevation changes over the distance of your ride. The sample screen to the right appears to show elevation data from a saved course.
Edge 305 models are equipped with a barometric altimeter, which is much more sensitive than GPS for measuring gradual elevation changes. It measures elevation changes by detecting an increase or decrease in the ambient air pressure as you descend or climb during a ride.
Anyone who's looked at elevation data from Forerunner (or any other GPS for that matter) knows that it's not all that precise. It tends to drift up or down by 15 to 30 feet as you move along a relatively flat course. Elevation readings from Edge 305 should be smoother than the GPS-based readings from Edge 205 or Forerunner.
Wireless sensors provide Edge 305 CAD with data needed to calculate pedaling strokes per minute. According to Garmin's specifications, data is collected from a cadence magnet that you attach to your bike's crank arm. Edge 205 and Forerunner lack this a basic feature found in many bike computers.
Speed Based on Wheel Rotation
Similar to the setup for gathering cadence data, a wireless sensor and a magnet mounted to the rear wheel enable Edge 305 CAD to detect wheel rotations. Specifications indicate this feature is self calibrating, so it appears Edge may automatically determine distance per rotation using GPS data. Wheel-based distance and speed measurements should allow for more accurate data, particularly in situations where GPS reception is spotty.
This feature is not available in Edge 205 or Forerunner.
Edge 305HR vs Edge 305CAD
Right now, it looks like Garmin will package Edge 305 with either a heart rate monitor (305HR) or a speed/cadence sensor (305CAD) - but not both. People who want both will need to purchase the second accessory as an add-on.
People who want a device focused exclusively on biking are likely to find Edge 305 very attractive compared to Forerunner models. With bike-based speed and cadence sensors, Garmin finally has a device that provides the type of data many people expect from a bike computer. For people who want a single device for running and bicycling, Forerunner models are likely to remain popular choices.