The Magic has a higher crank to seat. So even though the crank is lower to the wheel, the seat is much lower to the wheel. So you are correct in aero assessment, but it is also for greater efficiency that the crank is relatively higher. It gives the rider more power.
Pretty sure they all used 165's. Do not go shorter, unless you like wheel-flop! You could get away with a longer shock if you just it give it a bit more sag when you set it up, to keep your geometry similar.
Yeah. That would require a 28.6 seat post diameter for the stem to clamp to. But the frame needs a 31.4. But bit of aluminum tubing replacing the post, and a shim to fit the 28.6 tube in the frame, might work pretty well.
An interesting challenge. What about mounting an adjustable stem to the straight tube? Then remove the stem faceplate and you have a nice set of four bolt holes where you can bolt it to your seat back.
Is the seat post a compatible diameter for a stem?
Cool! :)
You might want to move your seat backwards, and thus down as well. Still rides with plenty of traction. You can raise your bottom bracket up a lot higher that way.
I currently have bullhorns on mine too. It gives a very good "on the hoods" hand position. It is how I always rode my upright, so actually quite comfortable. The ergonomics are pretty great!
I would recommend moving the seat back a little if you can. Even if it's by drilling more holes in the base plate. Then you can get your cranks up a bit higher. You will probably not effect traction much, if at all.
Nice. That is a very clean solution! :)
Using the existing steerer-clamp is a great idea, as it already has the great through-bushing, that is very solid.
If I ever redo mine, I will go with the internal slider instead of the external 1.5 inch tube I chose. It required a bit thinner tube-wall...
Pretty sure it was a Control Tech stoker stem for a tandem. Like this:
https://www.ebay.com/itm/Controltech-Tandem-Adjustable-Stoker-Bike-Stem-25-4-29-8-190-230mm-215-255mm-/202077132483?_trksid=p2385738.m4383.l4275.c10&&var=502072683879&varId=502072683879
Or this...
I'm considering this seat. I like that it has a low folded edge for rigidity, and less pronounced stiffeners along the bottom. I'm guessing it will mount better. Plus colors! :)...
It will make your boom a bit heavier, and so have a bit more swinging momentum. How does Efneo stay in orientation? I had a Peterson Metro 2 speed on another bike, and it relied on a stopper against the chain stay to prevent rotation.
I'm liking the bullhorns pretty well. My hand position is like riding on the hoods on an upright bike, but also can have quite a bit of position variability. Not sure it's any better for holding on to, but I like not having the shifter hanging below the bar like my other setup.
I only have one...