Originally Posted by
Fentuz
The cage length depends of the number of teeth on the larger cog. Also, the cage length have changed order the years. i found that 90’s/2000’s long cage are pretty much nowadays medium cage.
I run sora short cage rated for 30teeth max with a 11-36 9 speed cassette. The sora derailleur has the same length as altus m310 rated for 32 T (fitted on dahon dash 20”, frog 20”). I run m310 with a 11-36 9speed cassette and acera 9 speed shifter on my daughter frog 52 (20”).
I would not want to run a longer cage as this one can touch the ground when i do light single track.
The bottom pulley doesn’t go lower than the wheel rim so ~3” from the ground.
i built a hammerhead with a 7speed 11-30 and used the m310 derailleur with a alivio 7 speed shifter and a 7/8speed kmc chain.
it worked well, shifting is nice and crisp. IMO, It was a good choice for a cheap and low maintenance setup.
This is good info, thanks for sharing it. Assuming he is keeping the existing freewheel and chainring, do you think the OP can make either of the two long cage derailleurs he has available work for what he wants to do with his Dahon?
PS: I really like what you have done with your Dahon builds.