From what I gather, "Knightriders" didn't do very well at the box office when it was released. Upon watching it, it's easy to come up with plausible explanations for this. While the poster seemed to promise wall-to-wall action, there isn't that much of it, and what action there is often becomes monotonous. The movie tries to do so much that many of the plot threads feel unfinished at the end. And of course, the unbelievably long running time - 145 MINUTES!!!
Yet at the same time, I can't really call this a BAD movie - I would lean more to calling it "misguided". That's because as problem-filled the movie is, there are some good things about it. The actors give their characters a lot of heart - Brother Blue is especially good. (And I thought Savini actually wasn't bad in his role as well.) While the action scenes become monotonous, there are some impressive stunt sequences. The medieval-style music score fits like a glove. And there are some moments that are just *perfect*, the best being the opening sequence.
If you do watch it, I recommend that you split up your viewing into several sessions, so that you don't become too bored by how the movie keeps, well, spinning its wheels. There's a great movie hiding in there - perhaps with a lot of work (and a little magic), it might one day be successfully remade.