A proper 2x spider should have a chainline measured from between the rings, and most 2x spiders are non-Boost, so 49mm 2x chainline puts the big ring (middle spot, with bashguard taking the outer spot) pretty close to a 1x Boost chainline of 51mm. Might need/want to move it inboard very slightly, to minimize risk of a backpedal derailing off the big cog, but ~2mm spacers come with many 104 BCD rings >= 32t, and are almost always built-in to <= 30t to keep the chain from touching the tabs.
At least, that been my experience dealing with Specialized's silly choice to only put 2/3rds of ISCG05 on last-gen Stumpy frames, and trying various cranks and DM-to-BCD spiders to make up for that.
What cranks are you running right now? BashSpider/CAMO is made for modern bikes and should do a good job of maintain proper 1x Boost chainlines on pretty much all the cranks they support.
July 14, 2023, 9:08 a.m. - Justin White
A proper 2x spider should have a chainline measured from between the rings, and most 2x spiders are non-Boost, so 49mm 2x chainline puts the big ring (middle spot, with bashguard taking the outer spot) pretty close to a 1x Boost chainline of 51mm. Might need/want to move it inboard very slightly, to minimize risk of a backpedal derailing off the big cog, but ~2mm spacers come with many 104 BCD rings >= 32t, and are almost always built-in to <= 30t to keep the chain from touching the tabs. At least, that been my experience dealing with Specialized's silly choice to only put 2/3rds of ISCG05 on last-gen Stumpy frames, and trying various cranks and DM-to-BCD spiders to make up for that. What cranks are you running right now? BashSpider/CAMO is made for modern bikes and should do a good job of maintain proper 1x Boost chainlines on pretty much all the cranks they support.