General Polar or more specific to bike?

[e.e.cummings]

A wrist mount would be nice.

I was checking out the Garmin and I discovered that the 405 is made smaller, and better for smaller wrists. The Garmin customer support person told me that the only significant difference between the 405 and 305 is that the 405 is smaller showing only 3 data fields as opposed to 4 on the 305. The 405 is styled more like the size of a normal watch. It also has a shorter battery life than the 305.

[Dogmama]

Decide what you want to see on your watch during normal operation. For example, I want to see my heart rate and the time. Some people want to see calories burned, time elapsed, etc. Make sure your watch gives you the combination you want without having to switch back & forth.

If you're spinning indoors, sometimes the lights are low. You might want a monitor that lights up.

Make sure that it doesn't get interference from other monitors, telephone poles, etc. All of my Polars did that. Annoying. (I have a Sigma now & I love it.)

Make sure your chest strap is snug. If it is cold & I'm not sweating, I use a electrode gel to get a good connection. I have a small chest & I had to cut the elastic & make it smaller.

When I started cycling, I had a cadence monitor & loved it. Now, I don't & find that I really don't miss it much. You get used to what feels right for your body. Just don't mash big gears or over spin so that your knees hurt.

[OakLeaf]

I was checking out the Garmin and I discovered that the 405 is made smaller, and better for smaller wrists. The Garmin customer support person told me that the only significant difference between the 405 and 305 is that the 405 is smaller showing only 3 data fields as opposed to 4 on the 305. The 405 is styled more like the size of a normal watch. It also has a shorter battery life than the 305.

Check them out in real life before you buy. The display on the 405 is just too small for my soon-to-be-50-year-old eyes. That was a deal-breaker for me on that watch.

Also, if your hands sweat heavily and you expect to want to hit the lap button, change display, etc., during a workout, the 405 kind of has a reputation that sweat interferes with commands to the bezel - but since I've never used one myself, I can't speak to that.

WRT Dogmama's comment, all the Garmins allow you to customize at least one screen for each sport, so you can see exactly the information you want. Some models let you customize two or more screens. The 310XT also has an option to automatically scroll through four screens - not sure if the Forerunner 305 or 405 will let you do that.