Possible? Heres my thinking...
Disassemble an extra 7spd cassette
Choose the 3 cog range I want
Use spacers to bring cogs to outside of freewheel
Use triple front shifter, and set limit screws on 7spd der
Or is there a option that gives this already in production.
Why you say, well... I normally run SS, but sometimes I would like a lower gear for bombing DH or around town, and a little higher for those longer climbs. I run 38/18 now, but would like a little more and little less depending on the situation, but not all 7 cogs.
And to be honest, to be a little different. I know I could do the same with a tensioner, but have to get off the bike, loosen a bolt, move chain, and tighten bolt again. And my thinking is a der would help when the chainline is out a little when in the lower or higher gear. Chainline would be set for middle ring. If I'm crazy, or being stupid and making it harder than it needs to be just let me know. I also have all I would need already, just collecting dust.