1. You should be able to run just the 50 tooth ring on that crankset. Either get some SS-specific chainring bolts to replace the stock bolt, or use some chainring bolt spacers to take up the room of the inner chainring. It's just the outer ring that is bizarre, not the spider.



2. Using a 19-20 tooth sprocket is not a problem for the freehub body.

3. Don't just use the individual cog from a multi-speed cassette-the engagement splines are very narrow and will eventually wear some nice notches into the freehub body splines. Plus, they are ramped and can cause the chain to get thrown more easily. Just get a spacer kit with nice alloy spacers and a suitable SS mtb cog, like this: http://mikesbikes.com/product/surly-...e-cog-3317.htm

4. I have never used a derailleur hanger chain tensioner, just an eccentric hub and BB-mounted chain tensioner. You could always take an old derailleur and remove the lower pulley so that you can fold the cage in half and just use the remaining upper pulley as a tensioner. I can't find any photos of this, but my old co-worker did it and it worked beautifully.