shimano cassette query

freddiegrubb
freddiegrubb Posts: 448
edited October 2010 in Workshop
:oops: I'm considering buying a boardman team carbon with compact chainset ( 50- 34 T) & shimano 10 speed 12- 25 T. cassette. I would like to change the cass. to 29 tooth at the top end but shim . only seem to go up to 27. Obviously I appreciate the sram cage swing arm will have to be able to accommodate the difference & I will lose some teeth at the bottom end. This was easy to achieve on my last bike (wilier) as it was a simple campag. cass. change. I feel sure this can be done with a shim./ hybrid & any info. would be welcome as the legs are getting on a bit & there are a lot of hills in Cumbria.

Comments

  • rake
    rake Posts: 3,204
    im not sure what the maximum capacity for sram mech is, but i think 29 would be pushing it.
    http://www.evanscycles.com/products/sra ... d-ec017661
    27 tooth max i think. there is a mid cage which would mean buying a new mech.
    http://www.sram.com/sram/road/products/ ... 0-cassette
    look at the spec button it has the sizes available. with a sram cassette and medium cage rival mech you could go to 32 max sprocket.
  • :oops: Many thanks for your quick reply, I may have to settle for the 27 T. top end & lose a bit of weight
  • petemadoc
    petemadoc Posts: 2,331
    I've got a shimano ultagra 11-28

    Only one more tooth but hey, it's only one less than a 29 :)
  • rake
    rake Posts: 3,204
    its still out of spec for a short cage though. i personally wouldn't risk the mech/wheel jam up and risk breaking the frame. more economical to sell the mech and get a medium cage to go that route imo.
  • :oops: Thanks for all replies, I'm going to have to give this an amount of thought & a good "chewing " over. It seems daft to buy a new bike & then start to altering mechs. still I could always sell them on as hardly used kit .
  • verloren
    verloren Posts: 337
    SRAM's mech will handle up to 28 just fine (that's why they sell one, and it works fine on mine). I'd love to try a 29 on mine, as I think it would work, but can't find a suitable cassette.

    '09 Enigma Eclipse with SRAM.
    '10 Tifosi CK7 Audax Classic with assorted bits for the wet weather
    '08 Boardman Hybrid Comp for the very wet weather.
  • John.T
    John.T Posts: 3,698
    Shimano mechs will take 50/34 with 12/27 with no trouble. Some bikes (Specialized) were made with 50/34 and SRAM 11/28 cassettes. This is about the limit but it works OK. Correct chain length is important. As long as possible.
  • morstar
    morstar Posts: 6,190
    If you're looking to achieve 34 -29 ratio and struggling, why not just buy a triple?
  • schweiz
    schweiz Posts: 1,644
    rake wrote:
    its still out of spec for a short cage though. i personally wouldn't risk the mech/wheel jam up and risk breaking the frame. more economical to sell the mech and get a medium cage to go that route imo.

    DA7900, Ultegra 6700 and 105 5700 all have the capacity for a 11-28T cassette and a 50-34 compact crankset with a short cage mech. Anything previous to that is officially 27T but unless you (accidental or othewise) cross chain then it won't be a problem.
  • John.T
    John.T Posts: 3,698
    DA7900, Ultegra 6700 and 105 5700 all have the capacity for a 11-28T cassette and a 50-34 compact crankset with a short cage mech. Anything previous to that is officially 27T but unless you (accidental or othewise) cross chain then it won't be a problem.
    There is adequate chain take up for 50/34 and 11/28 on the earlier Shimano short cage mechs (SS) while still using all gears safely. The reason for the 27 tooth limit is top jockey clearance. This applies equally to the long cage versions (GS). There is however considerable tollerance in this. 28 teeth gives no problem, some have gone to 30 and reported it works OK.
  • :oops: I've thought of the triple ch./set route ,I may be old & grumpy but I can't bring myself to do it. It hardly fits the image that one wishes to portray mind you my image went out of window when the doc. advised a support stocking for one leg , it does work , you just stop looking in mirrors.
  • ADIHEAD
    ADIHEAD Posts: 575
    I run 34/28 and to be honest if I went any lower I'd be going so slow I'd probably topple over! Just go for an 11/28 and wind out the 'b' adjustment! You'll need a new chain I suspect which seems like a waste though hey? Expect you know somebody who can take it off your hands? PS, probably wouldn't ask Halfords to set it up for you :twisted:
  • morstar
    morstar Posts: 6,190
    :oops: I've thought of the triple ch./set route ,I may be old & grumpy but I can't bring myself to do it. It hardly fits the image that one wishes to portray mind you my image went out of window when the doc. advised a support stocking for one leg , it does work , you just stop looking in mirrors.
    Not trying to be argumentative, just curious.
    Why can't you bring yourself to use a triple? You allude to it being an image issue I think. But surely an informed cyclist would see that you are sporting a granny gear with your 29 and an uninformed one will just be in awe of the guy going over all the passes without a care how many teeth the cogs have.
    If you're in need of 34:29, I find it hard to imagine the weight is making a lot of difference.
  • dmch2
    dmch2 Posts: 731
    I don't get the anti triple argument at all.

    If you need more gears then get more gears. Otherwise it's like shopping at the place that makes trousers too big just so you can claim you've still got the 32" waist you had when you were 21 when everywhere else you need a 36" !
    2010 Trek 1.5 Road - swissstop green, conti GP4000S
    2004 Marin Muirwoods Hybrid
  • :oops: Thereby hangs a tale, I still have a 32/33 waist & a full set of my own teeth (true) , but on a serious note picked the b/man up today still boxed & sealed. I really don;t know how h/fords can mess up the "construction " of a bike. Front wheel on, bars in & torqued up, seat post in & brakes cables connected up even the b/blocks were in the correct position & correctly "toed" in. The SRAM leaflet that was in the box says the rear mech. can go up to 28T, I worked out the gearing difference between 28 & 29 & it's hardly worth bothering about. So I shall settle for the 28T. cassette & bid each & every one of you goodnight , I now bring this thread to a close, may it rest in peace.
  • Bar Shaker
    Bar Shaker Posts: 2,313
    The standard 12-25 is a Shimano 5600.

    I have gone the other way and fitted a SRAM 1070 11-25 to get a bit more top end. I find the 34-25 ratio very low and have yet to use it. The hills around here aren't that steep, I suppose.

    Enjoy your new bike.
    Boardman Elite SLR 9.2S
    Boardman FS Pro
  • ChrisSA
    ChrisSA Posts: 455
    Thread hijackk. All interesting info, and this will help me a lot.

    I'm currently running 52/39 with 11-28 (Sora FD-2200; Tiagra RD-4400). I've now got a 50/34 compact - which is out of the range of the front mech by 2T. The proposed combo is also out of the rear mech's range by 4T (33T in total).

    General info on this thread and others is that it will work, subject to correct chain length.

    That said, I cannot think of a time when I used 52 & 11 together, other than down a big hill with the wind behind me, and even then it was too tall for me. I've got a 12 in the shed I could use instead.....I really need to move to 9 speed as there is never the correct gear available on my cassette. More expense!