Is 46-30 chainset compatible with 11-40 cassette

bluebus200
bluebus200 Posts: 15
in Workshop
Hi all...having changed my tiagra chainset to a 46-30 absolute black combo I am thinking about also changing my cassette for an 11-40 (using a wolftoth to adjust the position of the tiagra rd). Does this sound doable or am I going to run into problems with derailleur capacity? Would it be better to use a j-tec shift adjuster and get an MTB rd??

Thanks in advance..

Comments

  • bluebus200
    bluebus200 Posts: 15
    Ps...this is on a croix de fer with tiagra 10sp shifters
  • thecycleclinic
    thecycleclinic Posts: 395
    Shimano would say no and so would I but I could function if you have the medium cage rd. I doubt shifting will be good though. It's likely to be hesitant at one end of the cassette.

    Even with grx you run out of capacity with 46/30t and 11 to 40t according to shimano.
    www.thecycleclinic.co.uk
  • flasher
    flasher Posts: 1,734
    30-40 :o
    What are you planning climbing up, Everest?
  • bluebus200
    bluebus200 Posts: 15
    😂 actually somewhere close to Everest.....I live in the mountains in asturias (Northern Spain) I use the bike to carry climbing gear/ camping gear. So regularly have heavy loads. Agreed 46/30 chainset would be a little small for the average Sussex ride but not around here..... Actually I think the gearing on most gravel bikes is a bit draft considering what they are for. A lot of folks are ditching the compact for super compact... If I could I would swap the tiagra derailleur for an MTB one but the shifters are not compatible.
  • bluebus200
    bluebus200 Posts: 15
    How about fitting the rd with a wolf tooth?
  • thecycleclinic
    thecycleclinic Posts: 395
    Wolf toothroad link does not increase capacity that a function of cage length. The grx RD is already compatible with a 40t sprocket but it does jot have the capacity for chai tension in all gears throughout the normal.service life of the chain with double chainset and 11-40t cassette.

    www.thecycleclinic.co.uk
  • lesfirth
    lesfirth Posts: 1,382
    Lack of chain wrap capacity is not a problem.
    Make sure your chain is long enough in big chainring /big sprocket and do not use your small chainring with small sprockets. If you forget and do, it is not a problem you will just have a droopy chain.
    I ran a triple chainset and 29t sprocket with a campag short cage rear mech for about 2 years on one bike.
  • step83
    step83 Posts: 4,170
    Its not the wrap length its as Malcolm said the tension is going to be the problem, say you went 36/11 its going to be super slack at that point. have you considered maybe an single ring front with the 40t rear?
    If my maths is right you would get a lot of cross over with that 2X setup. You could run say a 38t and your not far off ratio wise the 2X setup
    Nice little side perk, it also sheds a tiny amount of weight.
    Titanium Px Spitfire
    Easty commuter
    Tripster AT
  • thecycleclinic
    thecycleclinic Posts: 395
    With a slack chain, even if there is tension when the chain is new as it wears the tension in that gear an disappear.

    The problem gears are going to be 36t with 11, 13 and 15t. i would say that a drivetrain that does not work.

    www.thecycleclinic.co.uk
  • step83
    step83 Posts: 4,170
    True, to accommodate the chain on the two larger rings. I would say go the other way with a triple but it's still going to have the chain issue trying to work with.


    Out of interest what's on there now? We could be going mad with ideas an your rocking an 11-25 for all we know.
    Titanium Px Spitfire
    Easty commuter
    Tripster AT
  • tsarouxaz
    tsarouxaz Posts: 70
    I see no reason why not. go ahead
  • bluebus200
    bluebus200 Posts: 15
    Hey all... Quick update. So fitted a 46-30 absolute black chainset, a sunrace derailleur extender, swapped the cassette out for a sunrace mx3 11-40. All works fine... Shifts pretty well through all the gears and no slack in the chain at all in any combo... Tried it out fully with fully loaded panniers, much much better on the hills than the compact set up the bike came with...
  • bluebus200
    bluebus200 Posts: 15


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