Problem - SRAM red front derailleur is rubbing

Discussion in 'Cycling Equipment' started by martinot, Nov 22, 2009.

  1. martinot

    martinot New Member

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    The problem is that I am unable to adjust the low limit setting to avoid excessive rubbing of the chain against the cage inner plate.
    With the low limit is set for a minimum clearance (less than 1mm) between the cage inner plate and the chain (with chain on the largest rear cog and small front chainring) I get no rubbing on all but 3 smallest cogs (still while on smaller front chainring); I can understand if the rubbing happened only on the extreme gear combo: smaller chainring and the smallest cog BUT all 3 smallest cogs?
    In order to eliminate the rubbing on the 3rd smallest (rubbing only on 2 smallest) cog I must entirely eliminate the clearance between the cage inner plate and the chain (with chain still on the largest rear cog and small front chainring) and therefore introduce the rubbing on the smallest gear (largest rear cog and smaller chainring).
    Moving the front derailleur higher on the seat tube or setting it slightly at an angle with respect to the chainrings does not produce better results.
    It seems that the cage is slightly too narrow for its chain rub-free operation.
    No issues with rubbing while on the larger chainring; none of the cogs.
    Does anyone have an idea how I can resolve this issue?
    Many thanks.
    Ian
    My setup:
    • 2009 SRAM red gruppo (with FSA SLK-Light BB30 compact 34-50 crankset)
    • SRAM red 11-28 cassette
    • SRAM red braze-on front derailleur fastened using Parlee CF clamp
    Front derailleur is installed creating approximately 2mm clearance between the bottom of the derailleur's outer plate and the large chainring and perfectly parallel to the chainrings.
     
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  2. Peter@vecchios

    [email protected] New Member

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    Pretty much inevitable with Red shifter/FD setup. As you have seen, to eliminate the rub, you have to move the FD so far out it drags on the bigger cogs. This will also have an effect on shifting to the big ring. The ONLY solution(and I know you don't want to hear this) is either live with it or shift to the big ring and up the cogset to a bigger cog to get around the same ratio. This is a common problem with 'positional' front derailleurs that use shifters that have a limited(small) number of clicks in them.
     
  3. dhk2

    dhk2 Active Member

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    Is there no "trim" click like Shimano or Campy? Seems strange SRAM would market an FD that with this problem that couldn't be trimmed to eliminate chain rub.

    Just a thought, but if the cage is screwed together, might it be possible to shim it wider.
     
  4. Peter@vecchios

    [email protected] New Member

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    Trim when on the big ring(new for 2009). Before that none at all. Of the FD 'action' out there, sram stuff clearly is in the basement. shimano probably the best with their uber stiff chainrings. sram seems to be going for the price/weight/gizmo card with a certain disregard for function or reliabillty. Big on ceramic and 'Gore' and such but poor bearings, pulleys, chainrings, cogsets..mostly Red stuff. Not very long lasting, IMHO, of course.
     
  5. martinot

    martinot New Member

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    Thanks guys for the replies.
    Yes, there is a trim on the big chainring but I have no rubbing on this ring at all while ony any rear cogs (with the shifter cable fully engaged/tight); no need to trim.
    I hoped that the adjustments of the front shift cable would allow to move the trim onto the small chainring. Does anyone know if this is possible?
    Cheers
     
  6. Peter@vecchios

    [email protected] New Member

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    Not really. Shift to big ring and then small trim for big ring and bigger cogs to reduce chain rub, then back onto small ring. Nothing else. Unfortunate that you can't retro fit a wider cage FD. sram road shifters compatible with ONLY sram road FDers.
     
  7. martinot

    martinot New Member

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    This kind of sucks. I'll try to widen the cage by inserting the spacer into the connection point (like dhk2 suggested); will post later if it worked. Now off to Whistler to plunge into the pow. Later
     
  8. alfeng

    alfeng Well-Known Member

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    FWIW. My recollection is that someone at SRAM decided to make RED shifters different from the FORCE & RIVAL shifters by putting the trim on the large ring rather than the inner -- clever, eh?

    There are two obvious solutions ... the first is to get a FORCE or RIVAL shifter ...

    The other which may-or-may-not work is to get a couple 1mm shims (which you will probably have to make) & put them inboard of the bearings (here's ONE reason why those BB30 cranksets are probably not as clever an idea as some frame builders think) ...

    OR, get some 10-speed Campagnolo shifters -- the Campagnolo shifters can be used with the SRAM (and, Shimano) derailleurs ... there are a lot of naive people out there who are still keen to buy SRAM "stuff."
     
  9. Peter@vecchios

    [email protected] New Member

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    Force/Rival for 2009 work the same as Red. Spacers on a external BB type crank and unless the shell is 36mm, the cranks won't turn with spacers.
     
  10. Paul Stuverud

    Paul Stuverud New Member

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    I have the same problem and am wondering if you tried the spacer. If so, how much shim did you add? Were you able to unscrew the connector or did you have to drill it out? Thanks!
     
  11. alfeng

    alfeng Well-Known Member

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    FYI. One thing that made the late-70s (2nd generation) Dura Ace front derailleur superior to the Campagnolo front derailleur (and, all the copies) was an inner cage plate which was not parallel to the outer cage plate ... there was somewhere between 1-to-2 millimeters difference in the width at the rear as the front of the cage ...

    To mimic the spread, either use a small, #10 washer or a #10 STAR (lock tooth) washer where the cage is joined at rear of the derailleur cage -- presumably it is screwed together ... if the cage is riveted, then you will have to drill out the rivet & use a small bolt & nut.

    Maybe, you'll need two washers ... hopefully, one will do.

    Install the front derailleur as you normally would so that the plane of the outer cage is parallel to the plane of the chainrings.

    BTW. Next time, buy some 10-speed, non-QS Campagnolo shifters ... OR sell your SRAM shifters on eBay to pay for the non-QS, 10-speed Campagnolo shifters. 10-speed Campagnolo shifters will be allow you to continue to use with your current SRAM derailleurs + Shimano-compatible 10-speed cassette(s).
     
  12. martinot

    martinot New Member

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    Hello, I have not done it yet (it's not a bad skiing season here in Seattle and the area:)) but I'll be doing it within a month. The sage definitely does not need to be drilled to be opened. I unscrewed it already; the screw is tight as a blue locking compound is used. I'll experimenet with shims from less than 1mm to up to 2 or 3 mms. Will post the results. Cheers
     
  13. Paul Stuverud

    Paul Stuverud New Member

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    Thanks for the quick reply. It took some force but I was able to unscrew it and added two #5 washers as a shim. It works much better now! It's hard to believe that the derailleur design is not more robust!

    I have a new rubbing problem now. When I'm in the highest (smallest) rear cog and lowest (smallest) front chainring, the chain rubs a bit against the four rivets that protrude through the large chainring. I assume that the rivets are to aid in lifting the chain from low to high front chainring during front gear changes. In this case, however, I'm not changing gears. It must have something to do with the chainline. Could it be that, in my case, these rivets aren't needed, and I can I simply grind them off? Or is their another solution? Thanks again!
     
  14. martinot

    martinot New Member

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    I am fairly sure the sticking out part of the rivets is not needed but I think it would be super hard to grind them off without messing up the surrounding areas which are machined off to help the chain shifts. Good to know that the shims helped in some way - the most extreme position of the chain (smallest front - smallest rear) can be easily substituted by other positions so I am not too concerned about it but if smallest front - second smallest rear is rub free this is the Victory situation. Please let us know how such a setup works with your #5 washer. Thx mate.
     
  15. Peter@vecchios

    [email protected] New Member

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    With 10s cogsets and chainrings with all sorts of doo-dads to help in shifting to the big ring, this is NORMAL. Just don't ride there. Do NOT grind those pins off or your FD shifting will suffer. No solution needed, design issues, just shift to the big ring and up a few cogs to a similar ratio.
     
  16. martinot

    martinot New Member

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    OK. Same rubbing :mad: against the rivets on my all Red + FSA BB30 crank/front rings with the washer installed on the front d. cage; no more rubbing against the cage :).
     
  17. dhk2

    dhk2 Active Member

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    Glad the shims for the FD cage worked. Have no experience with sram stuff, but the chainring/chain contact you describe (small chainring, last two cogs) occurs on my FSA triple crankset as well. The combination works, and the DA triple FD easily trims for it, but the slight noise of the chain hitting the rivets or ramps on the inside of the big ring remains.

    It never caused me to frown about it though, as cross-chaining isn't a good practice even without the noise. With FDs so easy to shift now, IMO there's no reason to tolerate the extra losses and wear incurred by cross-chaining.
     
  18. paulbrown

    paulbrown New Member

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    I would switch cassettes to a closer ratio. You might not get the gearing you want but should eliminate those miss shifts. 12-25t . The problem might also be the crank. I hate it when manufacturers spec out a different crankset on a grouppo. Good luck with that.
     
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