>>1678731https://matthewbrealey.medium.com/shimano-drivetrain-differences-fad16147817b- 105 levers are worse (well established)
- brakes are literally identical except the logo (but cost 50% more)
- fd is literally identical except the logo (but costs 50% more)
- rd has better jockey wheels and replaces a couple steel bits with aluminum for weight to save 25g, otherwise identical
- crankset has hollow chainrings and aluminum bolts which saves 35g