How close should the rear derailleur be to the spokes with the American Classic coversion cassette? I am using a set of Alex A-Class ALX400's. When the deralleur is shifted to the largest cog it misses the spokes but just barely. Any little flex in the wheel and it would be rubbing the spokes. The way the cassette is made the large cog sets closer to the spokes than a regular cassette but this seams too close.