text: faster than 15 km for sure. i ride with a bike club that rides consistently around 20 miles an hour, and there are many women who ride. i'd definitely imagine a road race for women would be able to consistently hold above 6. whatever miles an hour 15 km/h equals. Me and several friends of mine (including girls) averaged much faster than that on mountain climbs in colorado.\n\nas for speeds they can achieve, if its in the mountains, going down it would easily be in excess of 50 miles an hour.