If you are looking for a bicycle GPS, you are probably looking at various models of the Garmin Edge. Which one is right for you?All of the these units offer navigation functionality, virtual partner training capability, and courses where you can compete against your prior cycling sessions. All also offer the ability to use Garmin Connect and Training Center software.GPS features vary between models. The 605 and 705 come with basemaps, the ability to add more maps, and the option to use a microSD card. The 500 does not allow for saving waypoints or routes. The 205 and the 605 do not come with barometric altimeters.Options for tracking your workout also can differ between these devices. The 205 and the 605 do not have a heart rate monitor or cadence sensor. Other models offer these features on at least some versions. All models except for the 500 can maintain simple workouts where you set items such as calorie goals. If you want the ability to set advanced workouts and track workout goals, you will need a 605 or 705. The interval training feature where you can program in rest periods is not available on the 500.If you would like to use third party ANT-enabled power meters, then the 500 is the device for you. Do you want to share data with your friends who are using the same device wirelessly? The Edge 705 will let you do this. The lower-end models have a few hours less average battery life than their pricier siblings.Any of the these systems would be an asset to your bicycling workout. Consider what features are most important to you when selecting between the various models.