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Long story short, I've been given a Giant Revolt frame (warranty replacement).
Its 12mm axle and 142mm wide at the back. Want to use my old wheels which are 135mm so have fitted the appropriate end caps and now wheel sits in frame fine. All good so far.
Decided I want to go single chainring so have bought a GRX 1x chainet and suitable bottom bracket. This gives a chainline of 50mm however with chain on its only straight when in about 8th gear on the cassette. This leads to a horrible angle when on the biggest rear cog and the chain just comes off the front chainring.
What are my best options to help 'centre' the chainline on the cassette? I 'm thinking of some chainring spacers to move the chainring inwards?
Is it a 68 or 73mm BB? Can you move a 2.5mm spacer to the non-drive side?
Being road based, it'll be a 68mm BB, so no spacers.
I used Wheels MFG chainring spacers to move mine in 2mm - makes a fair difference.
Before doing that it was draggy in lower gears, but chain never came off. You using a Shimano chain?
Edit - you are using a road BB - aye?
yeah 68mm unforutnately so no option of any lateral movement of the BB