#41 gear is designed for chains with a .306" roller like the #415. The #420 chain has 5/16(.3125) rollers and should be mated with a #40 gear. Don't use your chain on a #41 gear. I'm not sure why your clutch is listed as a #40/#41 clutch, they're two different sizes.So I got the 420 chain in the mail last night and it is huge. I tested it on a 41 sprocket, a 40/41 drum clutch, 41 Sach moped hub, and a spare sprocket that was marked 40 and it fit all of them perfectly. I want to test the 40 sprocket again because according to the measurements I found it shouldn't fit. If any of you are planning this upgrade, keep in mind not all 420 chains have a tensile strength of 5,200lbs. EK brand was the strongest I found. In the photo below you can see the 420 chain on the left and a normal 40 chain on the right.
Looking at the pic there doesnt seem to be much trail. I learned about rake and trail building a recumbent. Its a hand full with too little.Lurker, what is the degree of your steering angle? I was told by Timm of Big Boy Cycles that my steering angle seems a little steep. I said yes, I can't ride with the hands off the bars. He said he imagines so. I didn't know about frame geometry at the time. Anyway, your steering angle seems like mine. Can it be ridden at 20mph or so without any hands on the bars?