Just getting started on experimenting and seeing what kinds of modifications I'll need to do. Starting off with a lame Photoshopped image of the concept, sans full mods.

As you can see, I've removed the upholstery from the "butt plate" of the kneeling chair, clamped the wheel to it, and mounted it back to the frame to see what position it's in to see how much I'll need to move it. As I suspected, it's WAY too far forward for comfortable racing. It's also a smidge low, though I haven't actually modified the green chair for the project to know for sure.

What I'd like to do is figure out a way for the wheel plate to move up and forward. I can do this permanently with scrap wood, but I'd like to make it adjustable, but locking, so that my kids can use it to some extent as well. For now, I'll assume the pedals will be in pretty much the same place they are in the pics, though mounted so that they don't move. With another 1/2" of plywood under them to mount them, they'll be that much closer to the seat, making the wheel that much more "wrong".

I'll be chopping off the little hooks of wood on the kneeling chair that are for the knee rest part. I may or may not find another use for those chunks... probably not. I also will be chopping the legs of the chair off, but I want to be sure I chop off the right amount. Better to get that one right the first time. ;-) Then I'll need to figure out a way to attach the chair to the wheel/pedal construct. Again, I want this to be adjustable so that my kids can use it if they want. Sure I'll probably have to toss a pillow behind them. Heck, I might even be able to just sit them in one of their kid chairs in front of the wheel/pedals section.

A closeup of where the pedals go. It's almost like the kneeling chair was designed for this. hehe. :)

Above you'll see that I've given in and chopped off the legs of the chair so that it sits low and at an incline. Knowing myself, I'd probably fret so much over wanting to get it right that I wouldn't ever actually do it. So, I'm just diving in and chopping things up. Like I said, I'm making it up as I go along.

Again, I just started chopping. I took off the hooks that held on the knee plate, did some trial and error on the bars to support the pedals, and screwed them on. I used velcro squares on the pedals and wood to hold the pedals on (mainly from slipping). The velcro part on the wood has been stapled in 'cus they don't stick so well to wood. I'll probably end up getting more velcro and putting a lot more on for better hold, but this is fine for now.

Here's a preliminary mockup of how the seat and wheel/pedal assembly will be when together. Now I just need to figure out an adjustable, yet lockable way to attach the wheel/pedal assembly to the chair, as well as an adjustable/lockable way to mount the wheel. Currently, where the wheel would be if I mounted it on as in previous mockups, it's about 18"+ too far away from me, and several inches too low for comfortable driving. Ideally, the whole thing can remain in two pieces for easy transportation and storage, but if worse comes to worse, I'll just attach the pedal assembly to the chair with some scrap wood, and worry about the wheel mount only.