I agree with you guys - 13 - 15 mph is not slow especially for a new rider. Again in my newbie rides we have lots of folks who struggle to maintain over 5 mph for 15 miles. Even now depending on my mood and stamina - I have trouble with 13 for a period of time.

My advice is to give a look see first. Then try and ride.

Also I highly doubt a newbie group will be pacelining,. If they are, I wouldn't ride with them. New riders are usually such a bunch of squirrels!!!!