Sugino: Messenger Vs. 75

wheels 75s and rings are machined (not stamped) to very high tolerances have a higher roundness factor (circularity) than Messengers (and just about any other crank - even posh road cranks - where circularity tends not to be a requirement as the derailleur acts as a chain tensioner to take up slack)- so 75s do not to generate binding points or tight spots in the arms rotation.

nice theory, but my 75s have a tight spot...