I am really looking forward to this post.. i thought of a similar idea but the only problem that i saw with it was the fact that your gears are always moving if you are moving.. Therefore, when trying to shift upwards, you have a small gap where your chain is not on either gear you may encounter a lurch or your chain being broken in two. I have had a 410 chain break on me several times due to alignment issues and chain tensioner problems. So now i run with no tensioner and its never been better.. And I am sure they have left side deraillures, you just have to know where to look. I want to see this work.. Keep us posted!