Is it possible to use 30t with 48t chainrings?

siddy1972
siddy1972 Posts: 180
in Workshop
Just wondering if anyone has successfully used a 30t inner with 48t on a double chain set?
It seems the usual combo is 48/32 or 46/30, which I guess gives the usual 16t gap. But I’d kinda like to keep the 48 if possible.

Comments

  • mrfpb
    mrfpb Posts: 4,569
    edited March 2020
    Clearly it depends on the chainset if you are just looking to swap rings. FSA super compacts do 48/32 and 46/30 apparently with the sames BCD. I don't know about any other makes.
  • siddy1972
    siddy1972 Posts: 180
    I already have a 48/32 (it’s a cannondale 90/120bcd).
    I was really wondering if the 48 and 30 would work ok together or if the gap is too much?
  • jollygiant
    jollygiant Posts: 117
    GRX 810 does a 48/31 with a 34/10, if thats any help.
  • daniel_b
    daniel_b Posts: 11,576
    edited March 2020
    The official line for Shimano is 16T, but I swapped the inner on my 53\39 for a 36, and it shifts absolutely perfectly.

    Various people tried to dissuade me on here, but my thinking was that if any groupset could handle it, it would be 9100, and I'm so pleased I took the minor risk of spending £36 on a 36T inner!

    I googled a plenty beforehand, and there are multiple videos out there of people having done similar or larger gaps even, but some suggested the shifting between the two would suffer.
    No issue for my setup, maybe one more tooth would make a difference, but surely worth a punt depending on how much a new inner is?

    Pro riders run with huge gaps, think I saw Caleb Ewan saying he sometimes ran with something like 55\34 - don't qoute me on that!
    Felt F70 05 (Turbo)
    Marin Palisades Trail 91 and 06
    Scott CR1 SL 12
    Cannondale Synapse Adventure 15 & 16 Di2
    Scott Foil 18
  • siddy1972
    siddy1972 Posts: 180
    Thanks for the reply. I’ll give the 30 a bash. The alternative is a fair bit more expensive. I’ll post how I get on.
  • button.jinksBz86nnWV
    button.jinksBz86nnWV Posts: 1
    siddy1972 said:

    Thanks for the reply. I’ll give the 30 a bash. The alternative is a fair bit more expensive. I’ll post how I get on.

    I'm looking at doing the 48 - 30 also. Did it work ok for you?
  • womack
    womack Posts: 566
    I needed a new front mech for my triple. The only one I could find had a Shimano Max recommendation of 20 t but it works just fine on my 22 t gap if that is any help
  • siddy1972
    siddy1972 Posts: 180
    button.jinksBz86nnWV said:

    siddy1972 said:

    Thanks for the reply. I’ll give the 30 a bash. The alternative is a fair bit more expensive. I’ll post how I get on.

    I'm looking at doing the 48 - 30 also. Did it work ok for you?
    Yes, works perfectly. No discernible change in shift performance. And was just the job for winnats pass.
  • daniel_b
    daniel_b Posts: 11,576
    siddy1972 said:

    button.jinksBz86nnWV said:

    siddy1972 said:

    Thanks for the reply. I’ll give the 30 a bash. The alternative is a fair bit more expensive. I’ll post how I get on.

    I'm looking at doing the 48 - 30 also. Did it work ok for you?
    Yes, works perfectly. No discernible change in shift performance. And was just the job for winnats pass.
    So you had a bike with 46/30 and changed the outer to a 48, and it's fine?

    I may be buying a gravel bike with the same gearing at the front, but it's going to be for mostly commuting and road duties, so it may be I might want to do the same thing.

    Did you have to nudge the derailleur upwards, or add any links to the chain?
    Felt F70 05 (Turbo)
    Marin Palisades Trail 91 and 06
    Scott CR1 SL 12
    Cannondale Synapse Adventure 15 & 16 Di2
    Scott Foil 18
  • siddy1972
    siddy1972 Posts: 180
    No- the other way around. I had 48/32 but wanted the 30 small ring. So for me it was easy, just a case of pulling the crank off and switching the small chainring over.

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