Changing Rear Cassette

equinefunk
equinefunk Posts: 323
edited April 2018 in The workshop
Hi,

Hopefully this is the right section for this question, my bike is a Cross bike which I use for commuting, but I know it falls between Road and Commuting. I cannot find an answer to this question when I searched.

Looking for some help with a change to my Cube Cross SL Road 2012. I am doing the C2C on this bike and last year when I did it on this bike, I climbed the hills ok, but had to get out my saddle on a couple of them rather than have a seated climb. So would prefer to have a little bit more range to have the seated climb.

It currently runs a Shimano 105 CS-5700, 10-Speed 11-28 Rear Cassette.
Shimano 105 RD 5700GS Derailleur. Max 30T.
Crankset Shimano FC-R553 Hollowtech II 52x39x30T.

I wanted to change the rear cassette to give me more range by going to a 10 speed 32T. But that means changing the derailleur as well. The current derailleur only goes to 30T, the 105 Medium cage only goes to 32T on a double.

My question is, can I get a derailleur that will cover that range or is too great?

Thanks in advance.
I'm over 6' and have quite a large head.

Comments

  • slowbike
    slowbike Posts: 8,498
    30F-32R seems quite a combination - are you climbing walls or towing a peleton?

    The issue with the mech is 2 fold - how much room there is between the largest sprocket and the top cog - adjustable in part by B screw. Secondly - how much takeup it has - manufacturers will only put together a bike where the gears can work in all combinations - ie 30F-11R and 52F-28R
    as you can work out - 30F-11R needs a much shorter chain than 52F-28R - this is what the mech has to "take up" - but if you're not using 52 front and 28+ rear then you can make the chain shorter or put a bigger cog on the back. The opportunities for screwups are there though, so if you tried this you'd have to ensure you don't shift up at the back without first moving out of the big ring.
  • equinefunk
    equinefunk Posts: 323
    Haha...they feel like walls, some of the climbs.
    Coming more from an MTB background I'm used to the lower gears and seated climbs. For steep climbs I mainly 36T F to 36T rear. Very occasionally I use the 22T front ring to a mid range.

    So I think I've answered my own question....just get a 30T rear and that gives me the 1-1 I normally use.
    I'm over 6' and have quite a large head.
  • slowbike
    slowbike Posts: 8,498
    30T rear should be fine - I do have a CX bike with the option of 30F-32R but I don't use it - well, I say I don't - I've used the bottom gear for climbing a 15% with a trailer and baby onboard or without the trailer and a child asleep in a mounted seat - not so steep - but abandoned the climb as I couldn't keep the bike still and didn't want to wake him.

    But if you like spinning :)
  • keef66
    keef66 Posts: 13,123
    Alternatively fit a 9 speed Shimano MTB rear mech. That will allow you to fit virtually any size (10 speed) cassette and it will all work splendidly with your 10 speed road shifters.

    I also have a road triple chainset with 5603 shifters, a 30t inner chainring and a 12-27t cassette, because I returned to road riding at the age of 50 and following knee surgery. A decade later I'm wanting to ride in the Lake District, and may too be experimenting with bigger cassettes and MTB mechs...
  • equinefunk
    equinefunk Posts: 323
    The shifters aren't Road Shifters, the bike is a Cross Bike but with Flat Handle Bars (misleading).

    Thanks anyway
    I'm over 6' and have quite a large head.
  • mcstumpy
    mcstumpy Posts: 298
    equinefunk wrote:
    The shifters aren't Road Shifters, the bike is a Cross Bike but with Flat Handle Bars (misleading).

    Thanks anyway

    What is the make and model of the shifters? I have a 10 speed flat bar road bike and shifters are “road” with road pull ratio. So worked with Tiagra 4600 (and would with 105 5700 too). I’m guessing your shifter are also “road” given you have a 105 derailleur?

    I turned it into more of a cx rig, and as advised above I went with 9 speed mtb shimano deore derailleur to allow for 11-36 cassette. Works like a dream.

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