Originally Posted by
Leisesturm
"how much faster do you think you will be on a recumbent at all?"
The simplest linear (or rowing) action will be very much more complex than a conventional chain drivetrain. Simple works. It works very well. You have to work very, very hard to beat simple and efficient. It isn't usually worth the effort. I would have little to say about it if you were able to prove me wrong by building a prototype and putting a Youtube video of it online. If you have to sub-contract fabrication to people with specialized knowledge of welding or metalworking or framebuilding you are dead in the water. It won't be worth it. I approached a talented metalworker in my area to collaborate on an idea I had and he didn't want to have anything to do with it. Framebuilders are much braver than metalworkers. They know their creations will be used by humans in possible risky ways. I don't know how they protect themselves legally but they seem to have figured it out. In Brazil there probably aren't as many lawyers making anyone who builds something for someone else nervous about liability but you still have to weight the cost of their labor vs what you get in return. TL;DR: Buy that sweet lowracer you linked to (700C rear) learn to ride it, and enjoy riding it. Do that for as long as you possibly can.
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Well, on an easy ride this week at 180w I did 35.5km/h avg with clip on bars on my road bike. I calculated Crr and got an avg CdA of 0.265. The recumbent builder told me most riders get a CdA of around 1.9 (with 559 rear wheel), hardly below 1.5. Not sure how he got that, but supposing he knows what he's talking about, for the same easy ride I'd be 40km/h avg and with just a few minor tweaks I'd be going faster for sure. Like both wheels discs, 3% less inclined (that's what he told me about 559 vs 406 rear wheel), narrow handlebar for tucked arms, tight lycra etc. So probably .18 or lower... Sounds good for me.
I've seen some rowing-bike systems already, they look cool but not really aero since you can't lay down!
We'll see what about those really short cranks, but I'm betting they will work well, I did my research before buying...
Liability for framebuilders around here isn't an issue, never heard about anything related. Actually for anything, liability isn't usually an issue! Plus the builder is also a friend, he'll do whatever crazy projects I ask for!
And for the custom machined parts, I'll see it, pricing etc. But as told by a biomedical and mechanical engineer friend, you just have to show up to a machining workshop with the SolidWorks file and pay for the machine time and the alloy block, that's it, they'll do it. He has done that several times for wheelchair and prosthetics parts, hand cycles and so on. Maybe sometime in 2020!?