Ultegra + single ring : quite unusual ! What chainring are you using? Did you manage to find a 4-bolts wide ring for 1"1/8 chain ? Or is it for narrow chains?
it's a cheap narrow wide chainring from ebay (j&l) i use it with a 1 1/8 chain, i think with that it no longer has is antidrop use but being single speed or fixed it doesn't mater.
Ultegra + single ring : quite unusual ! What chainring are you using? Did you manage to find a 4-bolts wide ring for 1"1/8 chain ? Or is it for narrow chains?