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[Closed] what chainline?
I've just fitted a new drivetrain. I'm using middleburn rings, PC991 chain and XT cassette. The cranks are RaceFace Turbine LP with an ISIS bottom bracket (that works very well) and offer adjustable chainlines.
My problem is, if I use a 47.5mm chainline (which is what the cranks were designed for) the shifting is clean and crisp but the bottom two sprocket on the cassette cause the chain to catch on the pick up pins of the big ring when in middle. If I move the bottom bracket across to stop this, the shifing is no longer clean and crisp.
So, would you just avoid the gears that don't work but keep it sweet or have all the gears but not as crisp? I'm amazed how much the chainline can bugger up the front shifting.
I think that Middleburn rings are meant to run on a 50mm chainline. The website states that Middleburn rings should run on a 48mm chainline but after querying this I was told 50mm and that the website was wrong.
I'm running steel Deore inner and granny rings on an XT chainset and a 50mm chainline (118mm axle), when I fitted a Middleburn Hardcoat Slickshift outer ring to this set up I found that the chain caught on the shifting pins whilst in the Middle ring and the smallest cog, I don't have this issue with a Shimano ring. I've queried this with Middleburn but not had a reply. It was suggested on here that I should avoid the middle ring/small cog combination but I tend to use it and, to my eye, the chain looks pretty straight.
My Middleburn Hardcoat/Slickshif outer ring is noticibly wider than the Shimano equivalent (possibly down to the Harcoat coating which is supposedly 5x thicker than anodizing) and the shifting pins a fairly thick too. I was a bit annoyed actually.
Bear in mind that if you alter the chainline you'd need to tweak your front mech limit screws to accomodate the change otherwise I'd imagine that your shifting would suffer.