Garmin Cadence Sensor

 I'm considering getting either a forerunner 205 or 305 and one of the things I see as the difference besides the heart rate monitor on the 305 is the optional cadence sensor.  If all I want for biking is speed and distance do I need the cadence sensor ability?  I will mostly use it for running though and want to know my pace and distance with the gps.

No you don't, but the good thing about the cadence sendor in addition to cadence is that it is rear wheel mountable and gives you speed as well, so what that means is that during the winter or whenever you need to do a ride indoors on a bike trainer, it will give you your speed.  Since the bike isn't actually moving, you will end up with no speed data.

It's not a must have, but it is very helpful.  It also will provide you data should you lose the gps signal.
when outside.

I think it was certainly worth the money I spent on mine.

Scott

I also think eventually you'll want to work on cadence. (Controlling your cadence is a way to bike more efficiently so you get the maximum output for your effort.)

So, if you get one that doesn't do cadence, like I did, you'll eventually have to get one that does and so you won't have saved any money.

 Thanks!  I will get the 305 in case I do decide to get the cadence.