For some reason, known only to Shimano, when they went 12spd they decided to increase their offset by 3mm universally... Prior to 12spd Shimano, 52mm was "BOOST" chainline (and remains so for SRAM), 49mm was regular (ie. old school 142x12 and 135QR) chainline... SRAM have since moved everything 3mm further over with their T-Type setups, and introduced a 55mm chainline crank/chainring setup too, but the cassette sits 3mm closer to the dropout than it did with Eagle 12spd or it does with Shimano's 12spd...weeksy wrote: Mon Mar 30, 2026 8:34 am Debating trying the 65mm riser bars today on mine. But arguably it's more for the actual tech than the XC side of things i'm thinking, but there's not a lot of tech over here to try it out on anyway. But there's certainly no downside to getting them fitted and giving them a days out there.
I also swapped my cranks back to the 52mm chainline... Which is slightly weird as the bike initially came with a 55mm chainline. I had the 52s on there by mistake for a while and due to lack of options to buy. But then a reasonable set of 55mm came up, so i bought them.
What i've found (and so has the boy on his) is that the largest cog on he rear is now a bloody awful chainline, so must so that the chain feels twisted in it and draggy, i doubt the reality is that, but it feels it for sure. Putting back to the 52mm gives it a nicer chainline in that gear, even though the cranks are close to the chainstay, they don't touch (i ran them for 8 months).
I think i'll like put his back to 52mm as well.
Thus... Exactly as you've found... As long as it physically fits and doesn't interfere with anything when pedalling, when running Shimano, I and many others I know in the trade, recommend running 3mm less offset than Shimano recommends...
