It does work extremely well. And yes, you have to carry a chain extension. As for misalignment, there are three ways to do it. First is the way I did this one: the larger sprocket is an overlay sprocket. It is normally (as in the pic) parked on an aluminum flange that holds it out of the way. To use the large sprocket you have to break the chain, remove the four bolts and nuts that hold the big sprocket to the flange, place the large sprocket directly on the small sprocket (the small sprocket fits inside the center hole of the large sprocket), clamp the two sprockets together with the four bolts (which then engage teeth on the smaller sprocket), add the chain extension and put the chain on the large sprocket. There is no chain misalignment, but as you can imagine it is a huge hassle. It is also difficult to change the size of either of the two sprockets. This was, however, the factory setup on the Honda CT200 Trail 90 from the mid '60s. The second way is to bolt two sprockets together, with washers to separate them just enough to not cause chain interference. This does still require a chain extension, but misalignment is not really a problem because on most bikes the counter sprocket floats on the shaft and compensates for a certain amount of misalignment. That is a much better way to do it. The third and best way to do it is to bolt/pin both two rear sprockets and two front/counter sprockets such that you have a larger rear sprocket paired with a smaller counter sprocket. It's also helpful to lengthen the axle slots in the swingarm. With that setup you don't even have to break the chain. Just loosen the axle nut, slide the wheel forward, move the chain from the large counter/small rear sprocket set to the small counter/large rear (or vice versa), then pull the wheel back to proper tension, tighten the nut and go on your way.