I'm going to replace my cranks soon on the second hand Yeti Arc I recently bought. The chain went and has been replaced along with the cassette, it turned out to be cheaper to buy a new crankset than chainrings. Instruction sheet attached. All seems fairly clear except the part about which spacers to use which is clear as mud. Measure the BB shell width ok. Then it has a table with two sections: Normal Type and Chain Case Specifications ? Each of those is further subdivided, Normal into Band Type and Bracket Type, the other into Band/Chaincase Stay/Bracket Type. Can anyone clarify this please ?