Just an idea that crossed my mind -

Making a two seater trike with two front wheels, taking the book chassis or the haynes roadster chassis, cutting the passenger compartment from the rear bulkhead to the pedal box, reinforcing the rear bulkhead in the right places to attach the half bike behind it and connect the front of the locost frame where the suspension arms and steering rack reside directly to the passenger compartment, effectively "skipping" the engine bay.

You can even narrow the passenger compartment down (and save a bunch of weight) by eliminating a good bit of tubes from the "transmission tunnel" since there isn't any transmission that needs to go in there.
Maybe just a narrow lower center consule that would be enough for some cables, wiring, brake lines and such... it can be much lower and take less space.

What do you guys think?

Moti

You may as well just design something completely different from the description you give there The only thing that's going to be similar is the front suspension.

Aside of the addition of a short tapered section between the front box and the passenger compartment it is very close to the original layout.

This might work for someone better than trying to reinvent the wheel altogether.

Anyway it's just a thought and I'm not going to build anything like that anytime soon .

Moti
Rescued attachment Locost-trike.jpg

I can't remember the name of the kit, but this has already been done to good effect before (that's not to say it can't be done again). My concern would be potential lack of traction and conering grip with a single wheel drive set-up - especially if you were trying to use a round section bike tyre in a more or less vertical neutral cabmber) application.

I'm not sute, but I believe you'd sacrifice a lot of chassis strength if you'd remove the transmission tunnel. Certainly the chassis would flex a lot more. You'd have to fit extra bracing to counter this, which sort of negates the weight saved in the first place.. other than that; nice thinking

The transmissionless tunnel doesn't have to be as wide or shaped the way that it is if you don't have a transmission in it.

I can see a few things that will need to go there like a brake line and some wiring, but you don't need that size of structure to host them, it can be much smaller, and even if you didn't eliminate it altogether you can _at least_ narrow it down to get more leg room -or- to narrow down the entire chassis and reduce the frontal area.

The design of the tunnel is a lot more flexible when you don't need to fit a transmission, driveshaft and a diff in it

Moti