60 mile Iron Man

I started riding again 3 years ago. The first year was cut short by going down with bike and breaking my elbow. (I gave up the clipless shoes after that.) Last year I didn't ride much due to personal reasons. So this year I have been riding like crazy. I started out with a 10 mile ride, then 20, then 30and yesterday 40. I also have been taking spin classes twice a week for the last two years and if it's crummy on the weekend, I take spin classes then, too.

I want to participate in the 60 mile Iron Man this Sunday but am afraid it's going to take me way too long to finish the ride. Can anyone give me kind of an average of how long it would take to bike the 60 miles? I'm not a racer! It took me 3.75 hours to ride the 40 so I'm leery about the time it might take to ride the 60 miles. I don’t want to be riding out there when everyone else has gone home. Thanks, K (PS -- There is a century ride and a 17 mile ride as well)