SRAM PG1070 11-28 Cassette with 105 mech.

wints1080
wints1080 Posts: 3
edited April 2010 in Workshop
I'm new to fettling, but due to an early season lack of fitness after a hernia op and an entry into the Dragon Ride, I'm looking to replace my OEM shimano 11-25 cassette with a wider range to give me a fighting chance on the climbs that were hard enough last year when I was fit. I've got the SRAM 1070 11-28 in mind, but my question is, what would I need to do to accommodate the larger range. i,e. adjust the rear mech/lengthen the chain/replace the mech completely? The 2010 shimano catalogue shows the Ultegra and Dura Ace rear mechs as being compatible with 28s but not the 105.

Thanks,
Paul.

Comments

  • maddog 2
    maddog 2 Posts: 8,114
    it's hit and miss in my experience

    I've run Ultegra rear mechs (6600) with a 11-28 no problem - just adjust the tension screw to help clear the 28t and it's fine. However, last week I tried a Dura Ace (7800) and it wouldn't clear the 28 sprocket, even with the tension screw at max (and more) so it's not universal.

    My advice is give it a go. It'll probably be okay but you never know.

    The 6700 and 7900 mechs have a wider range and are fine out of the box. I suspect the new 105 is too but I couldn't confirm this.
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • andy_wrx
    andy_wrx Posts: 3,396
    Amongst a number of manufacturers, Specialized used to spec the Tarmac Comp with 105 and the SRAM 11-28 cassette.
    http://www.specialized.com/gb/en/bc/SBC ... nuItemId=0

    So a short cage 105 5600 rear mech will work with SRAM OG-1070 11-28

    In theory you should lengthen the chain a bit, to accommodate it if you were to run 50 front vs 28 rear (which of course you shouldn't, but if you did and your chain were too short you'd bust the rear mech)

    You might have to adjust the B-screw a bit too to get the top guide pulleywheel to clear the cassette
  • wints1080
    wints1080 Posts: 3
    Thanks both, very helpful. Looks liek the best bet is to give it a go. I'm running a short cage 5600 rear mech on my Felt Z35, so the fact that Specialized were spec'ing this on their Tarmac Comp is promising.
  • wiffachip
    wiffachip Posts: 861
    my Giant SCR1 2008 came with exactly that combination and it works a treat
  • ADIHEAD
    ADIHEAD Posts: 575
    It should work but watch the 'b' adjustment as someone else said :wink:
  • ADIHEAD
    ADIHEAD Posts: 575
    It should work but watch the 'b' adjustment as someone else said :wink:

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