Originally Posted by
jrickards
Cool! That leads to a question I have about this. My bike also has a 6sp cassette and I wanted to upgrade to 9sp. I presumed that downtube shifters were gone by the time 9sp cassettes came out so I thought the idea was out of question but I hadn't considered friction mode (of course, a 9sp rear derailleur would be req'd) and chain too but then, would the chain rings need to be changed? If so, it would sound like a wholesale rebuild of the drivetrain would be req'd to go from a 6sp to 9sp cassette.
Shimano makes indexed 9 & 10 speed downtube shifters, so you could have an indexed downtube set up if you want.
If you stick with friction, I would think your original rear derailleur will work.... but probably not with indexing due to cable pull ratios.
I've used old "6 speed" cranks with my 10 speed bike... works perfectly