Condensed Answer: Most 10-speed rear derailleurs aren't compatible with a 7-speed indexed shifter and cassette. There is one exception, however. Shimano's 10-speed Road derailleurs can operate with a 7-speed Shimano…
Description of the problem: The b-tension screw of the rear derailleur is too short to adequately do its job. In consequence, the top pulley of the derailleur is touching the…
Condensed answer: 8 and 9-speed derailleurs have the same rear shift ratio but only when both models are made either by Shimano or SRAM. In consequence, a 9-speed derailleur can…