Originally Posted by
Captain Argo
Also, I am assuming in all these scenarios that my derailleurs will work fine with new components. My understanding is that the derailleurs simply move however the shifter cable tells them, and that as long as they are capable of sufficient range of motion that they can be tuned with cable adjustments and whatnot.
For friction shifting, that's often the case, but not necessarily for indexed shifting.
With indexed shifting, each click of the shifter pulls a predetermined, non-adjustable amount of cable, which needs to move the derailleur the exact distance from one gear to the next. Because of this, shifters and derailleurs used together need to be designed for the same "pull ratio" -- the amount of cable the shifter pulls to move the derailleur a given distance. Within a given manufacturer's product range, pull ratios are
often (but not always) consistent, which is why (for example) you can generally use Shimano 7/8/9 speed derailleurs interchangeably.
I'm pretty sure your SunTour components use a different pull ratio than Shimano or any other readily available replacement components, which leaves you with at least three different options:
1) Find a compatible SunTour AccuShift freewheel. (Good luck!)
2) Replace your freewheel with a Shimano or other non-AccuShift model, keep your derailleur, and use friction shifting.
3) Replace your freewheel with a Shimano or other non-AccuShift model and install compatible indexed shifter and derailleur.