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Got a 2nd-hand frame that has a PF30 bottom bracket with a Race Face Atlas x type chainset. I'm new to x-type/press fit bottom brackets.
I want to run 1x11 but it looks as though the chainline is way out as the chain readily falls off the chainring in the top 3 gears. I'm assuming having a 32T middle ring on the front of a triple chainset is the problem?
If I take the couple of nylon spacers out from the between the chainrings and the bottom bracket, the chainset then rubs on the bottom bracket so can't see how I can shift the whole chainset in.
Would a specific single-speed chainset resolve this?
And I'm assuming that the PF30 will only take x-type chainsets (rather than fit my old square taper bottom bracket and Middleburg Uno)?
Any help and explanation of press-fits would be great - thanks
I would doubt it's the size of the chainring, but with the crankset installed, measure the [url= http://www.sheldonbrown.com/chainline.html ]chainline[/url] i.e. centre of frame tube to the middle of the chainring - it should be in the region of 47.5-50mm for XC bike or 55mm for DH/Enduros. Only if the chainline dimension is out, would I start playing with BB spacers. You should be able to find a PF30 BB adaptor for most types of external bearing cranks - unfortunately it's not compatible with your Middleburn square taper cranks.
The chainring should be on the middle position on the triple chainset, so on the inside of the 104bcd tabs
Thanks.