Originally Posted by
reppans
You need to put a foot down much more frequently off road, sometimes suddenly, and on uneven terrain. Sloping tubes are for crotch clearance and to protect the family jewels.
That makes sense. Thanks!
...but why aren't cyclocross bikes the same way? Urban commuters? ALL bikes? Is there any advantage to level or nearly level top tubes? And if so, you'd think at least a couple mountain bikes would be made with a more level top tube.