Question about seatpost insertion length
 

I'm building a bike and I bought a Charge Plug 5 steel frame:

http://road.cc/sites/default/files/s...?itok=IthKXZtn

The frame has a sloping top tube and the seat tube extends out a lot above the top tube. I have long legs for my height which means if I ride a bike that's comfortable in terms of length, I usually have to extend the seatpost a lot. That's the case here too. In terms of sizing the bike feels perfect, however there is an issue i'm a little bit worried about.

I have an FSA Afterburner seatpost that is 35cm long. I don't have the bike fully assembled yet but I set up the seat height.

With the correct seat height the seatpost is 14cm deep inside the seat tube measured from the top of the seat tube, and the seatpost extends around 7cm below the bottom of the top tube weld.

http://i.imgur.com/q119oNG.jpg

I'm used to longer seatposts and level top tubes, should I get a 40cm seatpost (+5cm) or is this perfectly fine? The bike will see a lot of rougher terrain but I only weigh around 70kgs. I know a new seatpost is not that much money, but it's still something and i've grown to like this one a lot.

I think that would be fine, the minimum insertion point is even level with the junction anyway!

I'd be happy with that. Seat post is well past the top tube junction.

That's plenty. You are good to go.