I'm trying to build up my distances, I started at 6 miles, then graduated to 10, 15, now up to 20 miles. I know this is far from world beating but I'm going at my own pace.
Under normal conditions I ride along at about 14 to 18mph (this is not average, this is actual speed read) with a good headwind I find this drops to 10mph. Down hill anywhere between 24 to 32mph, yes 32 was scary the first time but great fun!
The Marin Toscana has an Aluminium frame with carbon forks, the top tube is not too long therefore you do not have stretch to far for the drops. The saddle is very comfortable and the bike is nice and light.