I can't make a team goal out of it (because I'm not a leader) But I could start a thread to track it and make it a team challenge.
The others like this that I have done require each person to keep track of his/her own miles and periodically update the "Team Total" in their post to that topic. Like this
My miles: 21
My previous total Miles: 1224
My total miles: 1245
Previous team miles: 12,003
New team total miles: 12,024
You could leave out your personal previous or your Total if you want, but you would have to keep the TEAM previous and total up to date as you post. You must also be careful that someone else doesn't update it while you are also trying to update the total.
When I do this on a different team, I use a spread sheet that I setup just for this purpose. With this tool I can just copy the previous team total from the most current post ans paste it into my spreadsheet then type in my "miles", copy the wholespreadsheet and paste it into a new post.
| current weight: 190.6