chainring replacement issues

andyjday
andyjday Posts: 9
edited January 2012 in Workshop
1 have sram force compact 34/50 , 110bcd crank and chainrings on my bike. I am wanting to replace the 34t inner with a 39t . Sram do no do a 39t 110 bcd chainringring and so bought a specialites ta 39t 110bcd and fitted it. but i cannot seem to get the chain to shift properly from this new 39 onto the existing sram outer 50t ring. I have spent a day at least fiddling but with no sucess. Are the Sram force rings, (with all the ramps and groves to enable good chain shifts) designed only to work together, and not with any other rings?.Does someone know which rings or combination of rings will work. I mentioned replacing the 34 for a 39, but will also be happy with a 38t ring . Frustrated, Please help. I just find the 34 gives me too low gearing. and want to up it a bit, but at the same time, are happy with the 50t outer, not to change that to a 53t.

Thank you for any assistance in this regard.
Andyjdayandyjday

Posts: 4
Joined: Sun Jan 01, 2012 2:01 pm
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Comments

  • centimani
    centimani Posts: 467
    I'm just trying to remember if my FSA 34T inner had any ramping on it. I fitted a 40T TA Specialities inner which IIRC has no ramping machining...i dont find it shifts perfectly....acceptably yes, perfectly, no.
  • You will find that the difference between 50 and 53 is minima ( I hardly notice)l, whilst the difference between 34 and 39 is significant.
    In my view, it's best to go for a 53 x 39 in the absence of a cheap solution. Often odd rings cost as much as a mid range chainset on sale
    left the forum March 2023
  • John.T
    John.T Posts: 3,698
    Inner rings are not normally ramped but are matched to the outer. See my reply to your other post(s) on this.