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Change cassette/rear derailleur or go sub-compact?

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  • July 4, 2018 at 4:17 pm #28687
    darrenleroy

    Has anyone ever decided to go sub compact, say 48/30, rather than change the rear cassette? 

    I have moved to hill country. My rear cassette is 12-25 and I struggle on some of the steeper ascents. I have a compact on the front.

    I have a Record rear derailleur (short) that won’t cope with a larger ranging cassette. Instead of changing the rear derailleur and cassette I wondered if going to a sub compact would give me the equivalent of being in the 32 teeth sprocket?

    I am crap at maths and struggled to grasp the tables that work it out for you.

     

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Viewing 7 replies - 31 through 37 (of 37 total)
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  • July 5, 2018 at 4:02 pm #922797
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    LastBoyScout

    I’ve run 53/39 with an 11-32

    I’ve run 53/39 with an 11-32 cassette on a short cage Shimano Ultegra rear mech for a very hilly ride without any problems, even though it’s not supposed to work – just adjusted the b-screw a bit.

    I know it’s not your Record kit, but have you actually tried it?

    July 5, 2018 at 8:25 am #922795
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    alotronic

    Cheapest way to get where you

    Cheapest way to get where you want is leave the 34/50 on the front and buy a £20 ‘road link’ which is a thing that sits on the end of your mech hanger and pushes the rear mech further down. You can then use a 36 or even 40 as biggest sprocket on the back via a MTB cassette – gives you the same range as a subcompact with a 12-28 or 12-32. I put one on my bike for some welsh hills last week for a 34 x 36 granny gear and it worked a treat.

    July 5, 2018 at 3:48 am #922793
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    TypeVertigo

    BikeCalc is an excellent tool

    BikeCalc is an excellent tool for this.

    Assuming you run a 700C x 28 mm tire:

    Your current 12-25 x 50/34 drivetrain has a range of 36.30-111.31 gear inches

    A 12-25 x 48/32 drivetrain will give you a range of 34.17-106.77 gear inches

    An 11-32 x 50/34 drivetrain will give you a range of 28.29-121.45 gear inches

     

    Going wider on the cassette yields more range both ways. You’ll have an easier climbing gear and a harder top gear/higher theoretical top speed

    July 4, 2018 at 9:59 pm #922791
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    darrenleroy
    herrkaa wrote:
    I have a Chorus with a short cage and I’ve been running a 12-29 Miche cassette for years without any issues. Are you quite sure that your Record won’t cope?

     

    I’m not 100 per cent sure but my LBS has said it won’t. It’s quite a jump from 25 to 29. My rear derailleur is already pretty stretched out in the 25 cog.

    I’m thinking I will have to replace the rear derailleur and cassette. Bummer. I might just go the whole hog and change up for an 11 speed Potenza. I hate wasting equipment that works perfectly but I suppose I could try and flog it on eBay. 

    July 4, 2018 at 7:05 pm #922789
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    herrkaa

    I have a Chorus with a short

    I have a Chorus with a short cage and I’ve been running a 12-29 Miche cassette for years without any issues. Are you quite sure that your Record won’t cope?

    July 4, 2018 at 6:19 pm #922787
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    Canyon48

    Short answer; no, a

    Short answer; no, a subcompact would not give you an equivalent gearing as a larger cassette.

    A subcompact 48/30 with an 11-25 would give you a much smaller range than a 50/34 with an 11-32.

    In addition, 50/34 with 11-32 gives you a greater gear range, a lower low gear and a higher high gear.

     

    July 4, 2018 at 6:07 pm #922785
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    rdmp2

    I have a sub compact but on a

    I have a sub compact but on a heavy touring bike so not really a comparison. Would slightly reduce your gearing but at greater expense than changing cassette. If you can’t do the maths this website lets you compare 2 setups side by side

     

    http://ritzelrechner.de/

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