I am thinking about a straight through seat tube - taking it right up to the saddle. (I am not a traditionalist)

It is not likely to be a practical solution as I would need a 725mm long seat tube which as far as I know- doesnt exist, also it would stop the frame fitting in my bike box so I wouldnt be able to take it on a plane.

But I like to consider the idea anyway :-)

Assuming I could get a long enough seat tube and it were 0.5mm wall thickness, would there be sufficient strength at the ST / TT lug?

I have 280mm from the top of the saddle to the centre of the TT and it has to take my 168lbs. The tube will be cantilevered which is not how any other tube on a frame is loaded and the stress would be concentrated at the top of the seat lug - where the lug re-inforces the tube.

Also I suspect that the top end of the seat tube is often un-butted as the seat post acts as a reinforcement, with a straight through seat tube you would loose this reinforcement at the point of max stress.

Anyone ever tried something like this or have an opinion?

Thanks

Mike