I hope the great minds of STW can advise me.

I have altered my Deore octalink triple to a double and bash (24/38 SLX chainrings).

When in the 24 front and 11/13/15 out back the chain rubs on the 38 tooth ring. My octal ink bottom bracket is a 68/113. The LBS tells me that everything is fine and the rubbing is normal, and I shouldn’t use those gears anyway.

I would rather not have the chain rubbing if I could help it so am thinking of changing to a 68/118 bottom bracket. As far as I can work out that should correct the chain line and prevent the rubbing.

My LBS has made me feel stupid but my logic tells me I’m right.

What should I do?

Doing it your way will solve the rub on the 38t ring…

…but you’ll make the situation worse when you’re running at the other extreme of the gear range 😕

I guess it’s always a compromise. I figured that the Middle ring used to be in the sweet spot. Therefore moving the crank out by 2.5mm would put both rings slightly either side of the sweet spot.

Yeah you may be right…

…but i’m not sure 😕

Better to adjust the mech no?

Thanks Jag, I appreciate there may not be a definite answer 😕

Molgrips, I’ve adjusted the mech and it doesn’t rub, the chain only rubs on the inside of the 38 when in the 24.

oic

benefit of HTII I guess that you can adjust spacers.

I wonder if your Octalink cranks are starting to get further in on the splines altering the chainline a bit for the worse? Easy solution is just to not use the inner rings but I would rather fix it like you.

So if a HTII crank was in use would a spacer be added to the drive side when altering to a double as I have?