Sort of good thought, but not practical as far as design goes. First off, the pin mechanism would have to withstand considerable sheer forces. Second, the location of the pin dictates how much post you can have in your seat-tube, therefore limiting the adjustability needed for proper bike fit.

Or just change out the standard quick release lever on the bike for a seat collar that requires usage of a wrench... and save yourself the hassle.

amazingly clever

check out macneilbmx.com and their pivotal technology seat. it eliminates the use of rails and may provide an alternative strategy to acheive the bend

interesting.
it reminds another design, where the whole seat is used to block the wheel. it was designed for those short stops,
because like this one it could not be attached to street furnitures.

Just switch out the quick release for an allen key collar (like was already said). The person could still steal the wheel and seat no? Too much hardware, chance for failure, and weight to be worthwhile.

I totally agree with daniel. This concept has no future in any market nowadays, neither in the future. Conception is wrong at all levels, and doesn't bring anything else than troubles.

And by the way.....is it that in UK bikes have the transmission in the other side!!!!?????? I usually go to London, and I never saw it.

really nice idea, but couldn't you just pick up the bike and walk off with it?...adapting it to attach to another object eg: lampost/railings or something... or am i just being picky, sorry... i do like it.

cool idea. i have to say my concerns would parallel the first comment but as a city rider i would say the extra security would be nice. less for the seat and more for the rear wheel. i took all the quick release stuff off my bike and still worry about thieves with tools. shear strength is a good point of contention but i more often stand and dont spend that much time in the saddle anyway. still, a cool idea either way.

I am not sure if that works tho,
If the guy really wants to take you bike,
he can just come with a pick up, put it in the trunk, and gone.
He can figure out how to unlock the bike later.
One of my friends locks his bike using a big chain with a telephone pole.
When he came back, the chain still connected but the bike is gone.
If that is the case, it is hard to secure the bike by locked itself.