I own a mountain bike but looking to buy a road bike for training on etc. I've seen this Cube Aerial http://www.chainreactioncycles.com/Models.aspx?ModelID=30569 but they only have it in 58cm frame. Is this measurement from the bottom bracket to a top tube or top of seat tube? I'm 5ft 9" .

Dont know much about road bikes so any advice grateful!

could be either chap but i reckon 56 is the bigest you would ever want anyway.
i am 5ft9 and ride a 54 center to top of top tube.

Too big. Could be either C-C or C-T. I like to think that horizontals are measured C-T, but I am old fashioned.
I'm 5'8" and race a small compact geo frame, both my cross frames are horizontal 52 C-T with long stem.

http://www.cube-bikes.de/xist4c/web/aerial_id_36191_.htm

thats the spec for that bike.its to big though.

When I was looking to buy a road bike I was told that fit was much more important than on an MTB. I ride a 53, but a 54 from a different manufaturer was much too long. I'm about the same height as you.

I love my road bike but wouldn't ride it far in comfort if I'd bought the 54. You want to have a go on one really, anyone near you do test rides?

Cheers folks – there's some bike shops near work in manchester (Evans) so will pop up there and try some bikes to get an idea on sizes of road bikes.

I'm 5'9" – my Spesh Roubaix is a 54cm frame, my compact Ribble audax is a 48cm frame.

Sit on a few in shops to get an idea of the right top tube length, if you really must buy blind. But fit is more important on a road bike. It is expensive if you get it wrong and have to buy another – not necessarily the new bike, but the divorce.

Look at top tube length, and to be honest go to your LBS and ask their advice.