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my bike currently has a combination of 50X34 crankset and an 11x32 cassette and it looks like my rear derailleur is a long cage. I'm buying new wheels and I want to take the opportunity to try and buy a more compact cassette, maybe an 11x30 or 11x28. My question is, will I have problems with my current derailleur? Do I need to make some modifications?

Thanks in advance

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    Aside, the prefix "compact-" would normally refer to a crankset with a relatively small inner ring. A "Compact Cassette" sounds like a music tape. You might be thinking of a Corncob cassette where each gear has a tooth difference of 1, so an 11 speed 11-22 would be a corncob used on flat ground.
    – Criggie
    Dec 9, 2020 at 22:12
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    @Criggie - Yeah, I tried it once and the tape got all tangled up in the cogs! Dec 10, 2020 at 16:23
  • A very minor quibble: compact crankset is a standard term that refers to 50x34 chainrings. Compact cassette is not actually standard, and I actually thought the title referred to fitting a larger cassette at first.
    – Weiwen Ng
    Dec 11, 2020 at 13:42

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Unlikely to cause any problems. A long cage R7000 (Shadow type) is rated for 28-34t cassettes. The short cage is rated for 25-30t, so going from 32t to 30t or 28t would be fine.

Expect to need to make normal adjustments for the new cassette, but it should work fine.

Of course it depends which precise RD you have, and since you didn't say I can't be 100% certain.

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  • Thanks for your help !! My current RD is a shimano 105 r5800
    – Cristian
    Dec 9, 2020 at 19:47
  • that one is specced 28-32t. 28t will be fine.
    – thelawnet
    Dec 9, 2020 at 21:32
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Although Shimano recommends not using long cage with 28 teeth, since they are usually rather conservative in their recommendations, it will work. You may just want to tune the B-screw to move the upper jockey wheel closer to the large sprocket, and check that your chain is not too long (slapping).

(Personally I use a long cage 105 RD with cassettes with max. 34 to 28 without problems and no change in chain length.)

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  • Thanks for your help, i also use a shimano 105 RD but my model is the R5800. I hope I have no problems either
    – Cristian
    Dec 9, 2020 at 19:50
  • The chain will be unnecessary long but not too long since the small-small combination is still the same.
    – Michael
    Dec 9, 2020 at 20:27
  • Very slight quibble: Shimano specs the R7k and R8k medium cage RDs for 28-34 max cogs. The 5800 RD is the same.
    – Weiwen Ng
    Dec 11, 2020 at 13:44
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The long cage derailleur should not be an issue when going to a smaller size big gear in the back (i.e. 30 or 28 vs. 32). Some people say that when using a long cage derailleur with smaller cogs in the back the shifting is less "crisp", but that most likely will not be noticeable unless you really were looking for it.

May I ask why you are switching cassettes vs. going to larger chain rings and keeping an 11-32 in the back?

Are you trying to avoid certain gear ratio jumps between some of the cogs, which makes cadence feel like it is changing more suddenly? If the answer is yes here, then an 11-28 or 11-30 can help. See below for the number of teeth each cog has in the cassette. Notice how the jumps on number of teeth are less for some cassettes.

11-25: 11-12-13-14-15-16-17-19-21-23-25

11-28: 11-12-13-14-15-17-19-21-23-25-28

11-30: 11-12-13-14-15-17-19-21-24-27-30

11-32: 11-12-13-14-16-18-20-22-25-28-32

12-25: 12-13-14-15-16-17-18-19-21-23-25

14-28: 14-15-16-17-18-19-20-21-23-25-28

Do you think an 11-28 will make you faster than an 11-32 with the same chain rings up front? If the answer is yes here, that unfortunately would not be the case as with all the cassettes the smallest gear in the back has 11 teeth.

If you want to go faster and can push the harder gearing without worrying about the gear ratio jumps, I would suggest going bigger on the chain rings and keeping the 11-32 cassette in the back. This way it gives you some options to still be able to climb very steep hills while being able to put power down when you are cruising on descents around 40 MPH + -

Note there I have 50X34 upfront and am considering as my next upgrade larger chain rings for 2 reasons.

  1. I feel like I could benefit from them on flats after a bit more training with what I am running now. For me when I am pushing cog 10 or 11 without crossing my anaerobic threshold consistently at around 80 RPM, I will make the switch to larger chain rings while keeping my 11-32 cassette in the back. Right now, I can do that with cog 9 in the back so I have some room to improve.

  2. On descents with the larger chain rings, I should be able to hit 40 MPH at the same cadence or so that I am hitting 38 MPH now. For me as someone who does not like high cadences other than when climbing that is a plus.

Hope that helps

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