changing from 105 cassette to tiagra

k3vinjam3s
k3vinjam3s Posts: 266
edited February 2013 in Workshop
My dad wants to change his 105 12-27 cassette to a more hill friendly tiagra 12-30 cassette. The bikes a Scott cr-1 team and how do I know if this cassette is compatible. Also will they be much of a difference for him when climbing as this seems the more cost effective than changing to a compact on the front.

Comments

  • Why not get a SRAM 11-32 to give a wider range of gears. May need a longer rear derailleur, but probably not.

    http://www.ribblecycles.co.uk/sp/road-track-bike/sram-sram-cassettes-sram-10-spd-pg-1050-cassette/sramcass260

    The cassette is 100% compatible with 105 shifters.
  • lc1981
    lc1981 Posts: 820
    k3vinjam3s wrote:
    Also will they be much of a difference for him when climbing as this seems the more cost effective than changing to a compact on the front.

    You can work this out by dividing the number of teeth on the chainring by the number on a cassette sprocket, to give the gear ratio. The lower the number, the easier it will be on the hills.
  • plumpy
    plumpy Posts: 124
    There are 2 types of 105 rear derailleurs, short cage (SS) and medium cage (GS). If his bike has an SS it won't handle 12-30 or 11-32. A GS will handle either.

    You might also find that fitting both a larger rear cog and a longer cage derailleur (if applicable) results in the chain being too tight in some combinations. He'll notice because the shifting will get cr*p! But wait and see before lashing out on a new chain.

    If he's got a standard chainset (as I think you're suggesting) then I'd agree with the SRAM cassette idea. 39/32 will feel MUCH easier than 39/27.
  • plumpy wrote:
    There are 2 types of 105 rear derailleurs, short cage (SS) and medium cage (GS). If his bike has an SS it won't handle 12-30 or 11-32. A GS will handle either.

    So how do I find out which is on the bike? Is it labelled in some way?
  • keef66
    keef66 Posts: 13,123
    Easier to look at pics of both and compare with what's on the bike? Shimano techdocs should have illustrations you can use. Eg this is for the 5600 series

    http://techdocs.shimano.com/media/techd ... 646682.pdf
  • zx6man
    zx6man Posts: 1,092
    Those docs also tell you the max teeth allowed for the rear mech 5600 state 27 I think
  • jomoj
    jomoj Posts: 777
    medium cage looks like this
    20110.jpg
    short cage like this
    64854-shimano-105-rd-5700-ss.jpg

    the medium cage mechs still only go up to 28T in theory, 30 would probably be ok , 32 possibly a couple of teeth too far. You might also need to add some links to the chain if it's too short for the 52/30 combo - shift into that by accident and it'll be a big mess..
  • zx6man
    zx6man Posts: 1,092
    5700 105 does go to 28T, and I think thats whats on the 2012 and 2013 models.
  • sungod
    sungod Posts: 16,888
    go to http://techdocs.shimano.com

    look at the SI-* document for the exact model of 105 rear mech (i.e. 5500, 5600, 5700, 5700-a), check the specification

    there are two numbers that matter

    i) the maximum sprocket size
    ii) the maximum capacity, capacity is the sum of the differences between largest-smallest on front and rear, so for 53-39 and 12-30, the capacity will be 14+18 == 32

    for short cage 5700-a for instance, the figures are 30 and 34 respectively, so you'd be ok

    if the results are within specification, follow the set-up instructions for the rear mech in the SI-* document, including for chain length

    if the results are not within specification, but only slightly over, you may be able to get away with it, but there may be problems with chainslap on smaller sprockets, and if you went on largest-largest there's potential for something much nastier to happen

    btw i'm sure the wheel hub will be a 9/10 speed compatible type, on this hub the tiagra 10-speed cassettes do not need a spacer on the hub, whereas other shimano 10-speed cassettes do need a spacer, sram 10-speed cassettes do not need a spacer
    my bike - faster than god's and twice as shiny
  • zx6man
    zx6man Posts: 1,092
    I dont get why they claim 28 to be the highest then. bit weird
  • sungod
    sungod Posts: 16,888
    zx6man wrote:
    I dont get why they claim 28 to be the highest then. bit weird

    even with a range, like 105, depending on vintage/context there can be significant variations in what is 'correct', so going to the exact model specification is the only way to be sure

    the cynic in me suspects that the marketing people prefer to keep things opaque!
    my bike - faster than god's and twice as shiny
  • zx6man
    zx6man Posts: 1,092
    The 5700 does say 28 T though spec wise :-)
  • zx6man
    zx6man Posts: 1,092
    I only have 2300..... so like to be involved with upper class gear :-)
  • sungod
    sungod Posts: 16,888
    zx6man wrote:
    The 5700 does say 28 T though spec wise :-)

    ah, but i said 5700-a, which is 30T :-)

    http://techdocs.shimano.com/media/techd ... 746860.pdf
    my bike - faster than god's and twice as shiny
  • zx6man
    zx6man Posts: 1,092
    It does indeed, just nipping to specsavers...
  • mr_poll
    mr_poll Posts: 1,547
    I am having a similar issue - I currently have 105 5600 Compact running 12-28.

    According to Shimano tech specs the compatibility chart essentially says I have to stay with 5600 or upgrade.

    http://www.shimano.com/publish/content/global_cycle/en/us/index/tech_support/tech_tips.download.-Par50lparsys-0025-downloadFile.html/01)%20Drivetrain%20Compatability%20Chart.pdf

    Essentially I want to downgrade - I have just ordered a summer bike so I want some hardwearing cheap parts as my drive train is currently at the end of its tether, probably to tiagra or even sora. Main issue is the Cassette, Chain and large chainring. Unlike the OP I am not after a hill solution just inexpensive and compatible. Any ideas?
  • Monty Dog
    Monty Dog Posts: 20,614
    You'll be fine running a Tiagra cassette on 105 - any suitable 10 speed chain will be OK and you'll get away with a 9 speed chainring
    Make mine an Italian, with Campagnolo on the side..
  • arlowood
    arlowood Posts: 2,561
    Fully agree with Monty Dog

    Too many people getting hung up on mech sizes and capacities. If he's already running 11-28 then I'm sure he'll be fine swapping over to the 12-30 Tiagra cassette. Just go ahead and try it - the 12-30 only costs about £20. Might have to lengthen his chain but I doubt it.

    This thread summarises my experience about 9 months ago. I had no problems whatsoever.

    viewtopic.php?f=40004&t=12850935&p=17597505#p17597505
  • mr_poll
    mr_poll Posts: 1,547
    Thanks for the advice Monty Dog - just seen this at a crazy price, as much as i said i was wanting to drop down it is all down to price. As I have a compact i believe i need a 110mm - can I use this http://www.chainreactioncycles.com/Models.aspx?ModelID=35788