Derailer travel
I'm upgrading an older road bike that came with a Shimano 600 non-indexed derailer. I've installed a 105 8 speed STI shifter and an 8 speed cassette. The problem is that some shifts are correct, while others skip a cog and go to the next. I've spoken to several bike mechanics and they said my derailer should work fine since the indexing is done at the shifter. Here's what I found; The cable travels a toltal of about 7/8" out from the shifter to go from 1st to 8th gear. The derailer, however, requires only about 1/2" to 5/8" cable travel to move from the smallest to the largest cog. This results in the derailer going the full range of gears before the shifter has had a chance to advance it's full travel and so, it seems that maybe the ratio of derailer cable travel to derailer movment is not what it should be for this shifter setup. Bottom line; Do I need a new derailer? Are there varying ratios for different derailers?
Thanks,
Rich