What do you think the conversion is between a 5k road race to a 5k cross country race (or vice versa). Assume similar elevation changes/hills and same distance obviously. But I am wondering how times change as running on grass/dirt is a lot different than on roads. Ex. Let's say I can run 17:30 road 5k. How do you think this would change if done in an xc race?
I usually figure about 30 seconds difference for an average cross country course. If the course is extremely fast, with very good firm footing and gentle turns, probably more like 15-20 seconds and a course with really bad footing, tight turns, etc. would be even more than 30 seconds.
If they are both really 5000 Meters, I would agree with PP around 30 seconds. Maybe more if you are heavier and or the ground is soft or the grass is tall.
A big problem in comparing is that XC Courses are on the average shorter than a road course. (measure correctly that is).