Tried to find a magic ratio but no luck. I've got a 34/18 and still need a tensioner. Not got any other chainrings etc to try out.
Might be thicker than 2.5 but I doubt 1mm here or there is going to make much difference is it? I'm running top & bottom guides separately, both rammed in behind the bb on my Alfine setup, I've no idea what spacers there should be or what thickness or what chainline I should be running but it's all working fine.
If you're concerned, just get a rear mech mount one.
@mjsmke, do you know your chainstay length? If so you can use this calculator to work out the magic ratio
https://eehouse.org/fixin/formfmu
Might be thicker than 2.5 but I doubt 1mm here or there is going to make much difference is it?
I have a 2.5mm spacer and the preloaded the non drive side is only wound in half a turn. It won't accommodate an extra 1mm. Unless I file something down, but don't really want to do that.
https://eehouse.org/fixin/formfmuI saw that last week and had a play around. It's pretty good but still could find anything that worked. It said a 34/18 would be perfect but it's too loose, even with a half link. 34/19 was close but not perfect enough without a tensioner. 34/20 works but too low.
I've ordered a cheap Zitto one of Amazon so will see how that goes.
Just measured the thickness of the adapter kindly sent by @Kayla1 which looks like the ones I got from Superstar as part of a whole guard and its a shade under 2.5mm.
Thanks. I bought a Zitto chain device off amazon. Its basically a stinger but with a small jockey wheel and a top guid too. I cut the top guid off and replaced the jockey wheel with a better quality one. Only done 1 ride on it but it works well and is very quiet. Much quieter than my old derailleur hanger tensioner.
