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Shift ratio and pull ratio equation

solus

solus

Cadence Cadet
Am I correct in saying the shift ratio on "compatibility [04] rear derailleurs" the equation is: shift ratio=derailleur lateral movement divided by cable movement per click. Also is the cable movement per click the same as the pull ratio on "compatibility [07] rear shifters"?
 
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BikeGremlin
solus said:
Am I correct in saying the shift ratio on "compatibility [04] rear derailleurs" the equation is: shift ratio=derailleur lateral movement divided by cable movement per click. Also is the cable movement per click the same as the pull ratio on "compatibility [07] rear shifters"?
Click to expand...

Short answer: yes, but. :)

Longer explanation:

What I referred to as the shift ratio is: a calculated average of the RD lateral movement divided by cable movement.
For example: if the RD moves by 1.7 mm laterally per 1 mm of cable pull, that's a 1.7 shift ratio.

What I referred to as the pull ratio is a calculated average of cable pull per shifter click.

Not every shifter pulls the same amount of cable per each...
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solus said:
Am I correct in saying the shift ratio on "compatibility [04] rear derailleurs" the equation is: shift ratio=derailleur lateral movement divided by cable movement per click. Also is the cable movement per click the same as the pull ratio on "compatibility [07] rear shifters"?
Click to expand...

Short answer: yes, but. :)

Longer explanation:

What I referred to as the shift ratio is: a calculated average of the RD lateral movement divided by cable movement.
For example: if the RD moves by 1.7 mm laterally per 1 mm of cable pull, that's a 1.7 shift ratio.

What I referred to as the pull ratio is a calculated average of cable pull per shifter click.

Not every shifter pulls the same amount of cable per each click, nor does every RD move by exactly the same amount per 1mm of cable pull at different stages of its travel. And, at least for me, this was practically impossible to measure (or keep track) for every possible poistion and combination.

Relja
 
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