Hello,
I bought a new bike frame with vertical dropouts and put my Alfine 11 on the rear. For chain tension I use a Surly Singleator and am experiencing chain skipping over the tensioner, which carries over to the cog and skips a tooth. This only happens with the singleator in push down mode and when I put more power through the pedals. In push up mode it's fine, probably because there is more chain wrap. I did put a new chain on the new bike and a new jockey wheel on the singleator, but haven't changed the cog or chainring there. The singleator was on my MTB in push down mode and never had this problem and I crank harder with a smaller chainring. I am okay with the tensioner in push up mode but like the look of the chain line in push down mode better. I suspect it's because the chainline is out by about 1mm between the chainring and the cog, but I don't think it's perfect on the MTB either.