Changing GS cage for a SS cage on a RD 6870

sextoke1
sextoke1 Posts: 133
edited July 2017 in Workshop
I have a RD-6870-GS rear derailleur on my bike. The cassette I use is a 11/28. I was wondering for a smoother gear change, I could change the cage from GS to SS ( two cages and axel). Can I change the rear derailleur title then in the etube programme or does it matter?

Comments

  • svetty
    svetty Posts: 1,904
    I wouldn't bother, the improvement in shifting will be minimal
    FFS! Harden up and grow a pair :D
  • sextoke1
    sextoke1 Posts: 133
    OK. I just got the idea as it would only be around €30 for the three parts, I would keep the chain closer to the chain stay, it would keep it higher up of the rain spray(near the cassette) As a replacement Rd is near €200, and a spare gage may not be a bad idea, why not get the SS gage system..........The other question is if one is to fit the SS gage, how do you change it title when you down load the e-tube, or does it make any difference?
  • trailflow
    trailflow Posts: 1,311
    On a mechanical RD. The difference between the SS and GS RD is not just the cage length but the angle of the cage travel. So it keeps the upper pulley on the same trajectory as the cassette and as close as possible to aid shifting. The RD's parallelogram is in a fixed position to work with the maximum size cassette it was designed for.

    R2u8gHn.gif

    If the Di2 RD works in the same way, i imagine it would. with the SS cage mod installed, the GS Di2 RD would still shift in the exact same way. The upper jockey wheel would not be any closer to the cassette.
  • sextoke1
    sextoke1 Posts: 133
    Thanks for that. So in the end if you think you want bester shifting, buy a RD-6870-SS or learn to live with the RD-6870-GS.
  • trailflow
    trailflow Posts: 1,311
    or fit a 32t cassette.

    Are you experiencing poor shifting with your current RD ? if not, leave it.
  • sextoke1
    sextoke1 Posts: 133
    No, shifting is fine. 11/28 is the cassette size and unless I take the bike abroad, I will not be going bigger than the 28T. I was interested if the SS cage would give crisper shifting.
  • sextoke1
    sextoke1 Posts: 133
    A nother question I will ask, is a fella has a bike with a RD-6870-SS and normally has a 11/28T cassette on it, but he want to do a mountain event and wants to put a 11/32T cassette on it for a short time. Does he (1) drive on and just make sure he is in the small ring when in the 32T or (2)fit a GS cage on to the RD-6870-SS. The crankset is a 34/50. I know this is out side the tooth capacity.

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