Originally Posted by
davidad
Friends who have trikes ride with 20 and 16 inch wheels and mountain derailuers with no problems.
What size tires are they running? I bolted up a long cage Deore LX, and found that the cage rubbed against the 20x1.9" tire when in the largest cog. A narrower tire may allow it to clear, but then I don't want a narrower tire on a tandem that sometimes weighs over 400lb loaded up.