Mid-transmission

Mid-transmission is to lead power from the pedals into a front wheel via a double chained "gearbox", and at the same time it channels chainline from above the front wheel and again to center of the front wheel into gear cassette. Construction consists of double bearings and highly lightened aluminium gears, addition to this, bigger gear is reinforced with carbon sidepanels. All is kept smooth with no openings, with no extra cavity to keep air drag at minimum. It's a long shot, but everything is based on small things, lets say that this is the "small thing" here ;).
Weight without bolts and axel is 160 grams. If the speed range of the bike must be changed during a competition day to desired range, the bigger gear is quickly replaced by opening the 6 bolts and pulling it out by hand, no tools are required and the chainline is untouched.
It's obvious that construction takes a lot of force into itself, so it's again a balance between strenght and weight. But as the strenght and credibility is very important on a racing bike which is attended to eat miles as fast as possible and taking few nasty bumbs and hits while doing so, I wouldn't risk it for a few tens of grams. Loose spinning gear inside your closed cabin would be a unpleasant surprize..

One teeny-weeny detail must take into account, how close to the gear you will go during your pedaling is still unknown, I would mind hitting my feet into high rpm razorblade ;). This will go around about 4+ times per second at 80 rpm cadence and it's as close as few centimeters away from you!

Picture is a projection from two different sides of one unit and it does not include axel, bolts or any other attachement elements.