Chain rubbing on chainring?

joestella28
joestella28 Posts: 165
edited April 2013 in Workshop
I've had absolute nightmares with chainsets recently.

I was running the following set up;
6510 Ultegra Shifters (9 Speed)
5603 105 Chainset (10 speed triple)
5603 Front Mech (10 speed triple)
6500 Ultegra Long Cage Rear Mech
SRAM 9 speed chain.

Now with my old frame this set up worked lovely and I never had any issues with it.

I recently bought a Giant Defy 0 frame (current model) which requires a braze on mech. Here is where everything has gone wrong.

It turns out the large chainring on the 105 chainset wasn't original and was in fact a 53t rather than the standard 50t. the braze on bracket wouldn't allow the mech to sit high enough so that it would clear the top of the large chainring (even after some "fettling").

So, I thought I'd take the plunge into a double set up.

Happy with 105, I sourced a 5600 standard double from here along with a 6600 Ultegra front mech and now I have a new problem. When using the inner chainring (39t) I can only go as far as the 4th smallest chainring before the chain starts to rub on the inside of the large chainring? I know of the perils of cross chaining but surely I should be able to get away with a little more than this? It wasn't an issues when using the triple chainset on this frame (it ran on the middle chainring just fine across the cassette).

I think the issue is the double chainset has a shorter axle and no spacers like the triple? Has anyone else had a similar issue? If so, what was the cure?

Any advice would be much appreciated.

Joe

Comments

  • ba68
    ba68 Posts: 156
    I run 10 speed Ultegra with an FSA Standard Double and can use all of the rear gears when on the 39t front crank with no rubbing, I also run 10 speed compact on another bike and that also runs in all gears fine so yes I would expect you to be able to do the same. A couple of pointers:

    1. Are 9 speed chains wider than 10 speed, if so this may explain it to some extent, but...

    2. It sounds more like a chain line issue, when you fitted the new crankset did you fit a new (double) bottom bracket? If not this may explain it. I am guessing that a triple crankset's bottom bracket is slightly narrower to accomodate the three chain rings.
  • jomoj
    jomoj Posts: 777
    with a double, the inner ring is closer to the frame than the middle on a triple so you are liable to get a bit of chain rub on the smaller sprockets but probably only on the smaller 2 I would have thought. What size is the large chainring on your double?

    9 speed chains are fractionally wider than 10 speed and the chainring spacing fractionally smaller so this could also be a factor but not a major one. I run a 9 speed setup with a 48/36 10 speed double chainset and the chain only rubs on the larger ring if I'm on the smallest sprocket (accidentally)

    Bottom bracket shouldn't affect it, if it's hollowtech 2 then the spacing is carried out by the crank, the BB is agnostic to double or triple.
  • sungod
    sungod Posts: 16,853
    what model shifters? depending on shifter, there may be a trim function on small, big, or both, if you know which model you can check it is set up correctly

    are you running a 9-speed chain on 10-speed rings? if so, you'll probably get chain rub, use a 10-speed

    you can check for a missing spacer on the crankset, measure the distance from inside face of each crank to the seat tube, it should be the same each side (there are bikes with offset seat tubes, but the defy isn't one of them)
    my bike - faster than god's and twice as shiny
  • keef66
    keef66 Posts: 13,123
    No spacers for a road double HT2 crankset / 68mm BB shell.
  • joestella28
    joestella28 Posts: 165
    As Keef said, doubles don't have the spacers and have a narrower axle (hence why it's an issue now when it wasn't before).

    It's not an issue with the front mech or the shifters. It might just be that I have to adjust to the narrower chainset and it's different shifting.

    Thanks guys,

    Joe
  • ba68
    ba68 Posts: 156
    Joe, out of curiousity I just checked the shimano tech docs and it does say there may be chain rub on the front mech and / or chain ring when using the small front crank and the 3 highest (I.e. smallest number of teeth) on the rear cassette. Sorry but it looks like a limitation of the 5600 chain set. Here's the doco:

    http://techdocs.shimano.com/media/techd ... 603698.pdf
  • joestella28
    joestella28 Posts: 165
    Hi Ba68, I think it is just a case of the double is different to a triple set up and I'll just have to get used to it. It good to hear it from Shimano otherwise I think I'd be continually changes bits and pieces trying to solve it!

    Thanks,

    Joe
  • ba68
    ba68 Posts: 156
    Joe, according to the doc it says you should get the same rubbing on a triple but you say you didn't, it might be worth trying a 10 speed chain, which although only very slightly narrower may make a difference. You can get a good kmc 10 speed chain for not much more than £20 if you look around.

    Cheers' Al.