The Idler is for a good anti-squat property. the only way to get a good anti-squat property is to have the right chain path. and good anti-squat bike have a bit of kick back.
Hi, Most of time, I’m riding with 27.5 rear wheel. I think it’s better to put 27.5 than full 29 because tire doesn’t hit my hip agility(maneuverability) comes up and a bit high BB that full 29 Titan has is adjusted by 27.5 tire.
Manufacturers said boost optimsed front gear is necessary, but the difference is just 3mm. Titan has longer chainstay, it mean the effect of chainline is less than other bikes and can get enough clearance between chainstay and chainring. ...But finally, I choose M980 because of the good design.