How much flex? Please help....

Hey Guys,

OK, I'm into my chain linkage project, and I need a huddle with you guys.
I don't have a pic yet (but will soon), but here's what I did....

Due to tight quarters and not wanting to drill any holes in the frame, I wanted to mount the bracket for the chain clutch linkage to the 2 existing holes right behind the crossmember. This however, gave me some very steep angles to get to the clutch fork and attach point on the pedal. And it sure didn't look like I'd have the clearance to run the chain. So I stared at it for a while (a long while), and I came up with an idea. Why not run 2 sprockets so that the chain will run basically straight with the fork and the pedal attach point? So I got another sprocket, and put one high and one low, and proceeded to hook it all up. It worked quite nicely when I did a dry run, but I did have a concern...I had a friend work the pedal up and down while I looked it over, and the bracket is flexing (not deforming) a bit, and you can even see the frame flex in some. This concerns me.

Thinking it through, I think the large part of the trouble is how high the one sprocket is mounted. This induces extra leverage on the system, causing flex. So it is here I need some opinions....

How much flex is too much? Should I see any at all?

I'm using 3/16" steel, should I bump up to 1/4" or reinforce somehow?

What about going to one larger sprocket instead of 2 smaller ones so that the pivot point is lower?

What about going to a lever instead of the sprockets?

Now that I've revealed all my dark secrets with this project, I'm hoping that you'll help me out with this brainstorming session so I can get this done. Gotta move outta my house in a month.

 

I used one large sprocket and ended up some flex. A little is okay but it shows at the pedal (freeplay). Maybe you can add another brace to the upper frame rail too. One of my problems was the cable with all the attachments was too long so the chain bottomed out against the sprocket so I used a Cj2 cable. Try the two sprockets with a top brace. Pics please.