In a race this weekend I found myself in a breakaway with another rider. We were getting updates on the size of the gap we had opened from the race official who was on a motorcycle. This was extremely useful but I found myself wondering if the information could be more useful if I understood the math of the timing a bit more.
So, for a gap of a given time, say 30 seconds, is there a good rule of thumb for how the speed of those in the breakaway relates to the speed of the chase group?
ie - If I'm riding at 25 mph and have a 30 second gap, and my speed drops to 20 mph, assuming the chase group maintains their speed (assuming they are cooperating and working together with a larger group) how long will it take the chase group to reel me back in?
Is there a good way to figure this out quickly while on the bike?