repeat Rohloff, chain tensioner, Definitely not cheap @ $85.
Universal Cycles -- Rohloff Twin Pulley Chain Tensioners
I own one of these, the chainline is a shim washer stack to place the pulleys (made by Tacx) under the Cog.
nor, for $6 less, is the USA made one from Paul Comp http://www.universalcycles.com/shopping/product_details.php?id=336&category=2622
though this one at $26 is getting down there in cost
Universal Cycles -- Q2 Chain Tension Master
I'm looking for one to use as a ghetto IGH chain tensioner and don't know which models to look for. I figure low normal would be best for a tensioner because then I could just pull it outward with my hand to make wheel removal easier.
by the way .. you remove the wheel by pulling the Whole derailleur Back. its been like that way before you were Born.
just dont cut the chain too Short.