Disable index shifting to create friction shifting possible? I have a 6 speed freewheel on a Diamondback. I tried to replace some busted shifters with an 8 speed indexing shifter that was on clearance. It appears that each shift's spacing of the shifters is going to be a little smaller than that of the gears.( It takes about 7 shifts to cover the 6 gears ) Can I turn off the indexing in the shifters so that they work as a friction shifter? If not, I will have to check out recycled cycles for and old 6 speed set. Should have done that first. Don't know if 6 speed shifters are even made/sold new anymore. Thanks
Typically not -- a few index shifters (like my Shimano 105SC 7 speed ones) have this option, but its primarily downtube and bar end ones for &lt;=8 speeds. I don't think there exist any other shifters that do this other than possibly some grip shifts since they pretty much are letting pawls catch. 

However, you can buy friction shifters pretty cheaply these days from companies like Sunrace.