Old 06-19-21, 01:00 PM
  #48  
70sSanO
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So I did a quick and dirty calculation that basically took the BB center-to-center to rear axle measurement and 1/2 a cassette width. The CTC varies but around 15.5 to 16 is probably close enough. 400mm splits the difference and is a nice round number. This is pretty rudimentary and is not intended to analyze any other factors. But I wanted to know what angles are we really talking about.

For a 1x11, I used 400mm and 20mm (about 1/2 cassette width) to get a roughly calculated angle of 2.86 degrees. Which is the maximum chain angle running at either end of the cassette.

For a 1x6, I used 400mm and 15mm (about 1/2 cassette width) to get an angle of 2.15 degrees maximum chain angle.

Just for fun I took a 2x8 setup and cross chained it. Using 400mm and 20.2mm (1/2 cassette width of 17.7 + 2.5mm chainring adjustment) to get an angle of 2.89 degrees. This would be big-big or small-small.

Where does the cross chain "angle" become an issue? Is 2 degrees the limit? 2.5 degrees?

An obvious response is anything beyond a single speed causes theoretical wear.

I was pretty surprised that the angle we are talking about is less than a degree.

John
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