We are looking at 11-40, 11-42, and even 11-48 on our folding bikes. Microshift has a mid cage Advent rear derailleur system. The long cage almost works with 11-42 on our 20" folding bikes. We are researching the new mid cage systems to revolutionize our folding bikes. Currently our 11-34 cassettes are the widest in the industry, we are looking to step it up from 300% to 400%. We are still in the researching phase, so this will be at least one year....probably two until it reaches production.