Ultegra 6700 cassette ratios

markshaw77 Posts: 437
edited January 2011 in Road buying advice
I am in the process of upgrading my best bike from 5600-series 105 (in black) to the new 6700-series Ultegra and am being forced into a change of cassette ratio, so looking for advice

I have always ridden with a 50/34 compact up front (new Ultegra will be the same) and a 12-27 at the back, but the new 6700-series Ultegra doesn't offer a 12-27, so I am left with either a 12-25 or 11-28 - how big is the difference going to be? Which one is the better bet?

Now, i used to have an 11-28 on my old 9-speed bike and while it was great for getting up the hills, the jumps between gears in the middle of the cassette always irritated me - does the 10-speed have the same "gaps" and will they be as noticeable?

The 12-25 is the same sprockets as the old 12-27 until the last two (23/25 instead of 24/27) - this seems like the best option to me (along wth a dose of MTFU for the hills) as it will be the same for most of my riding.

Alternatively, i could just leave the 12-27 I have on there, but that will need changing eventually and Shimano suggest that the new 6700 works best when all the components are the same

What to do? Thoughts appreciated...


  • PeterBL
    PeterBL Posts: 209
    If your 27 gets you up the hills, and you don't need an 11, I would stay with 12-27. The jump from 17 to 15 on a 11-28 would irritate me.

    You can use your current 12-27 until its worn out, but Shimano still makes them in the 105 groupset (5700). You could possibly also find some 6600 12-27 cassettes, if you'd prefer that.

    I'm sure shifting will be just fine, even though Shimano of course would want you to run with a complete groupset.
  • ride_whenever
    ride_whenever Posts: 13,279
    Could you build your own cassette out of both of them? Are they riveted, bolted or one piece?
  • tonye_n
    tonye_n Posts: 832
    I sort of had the same problem.
    Moved the Ultegra SL group(with 12-27 cassette) from my carbon bike to my winter bike. Then installed 6700(11-28) cassette on the carbon bike.

    The main differences in use for me:
    I find the jumps b/w the bigger cogs a quite irritating in use. I could just about live with the 12-27 after using 11-25 for many years when I had standard double. Living in hilly Bristol I use the full range of the cassette quite often b/w both chain rings, and I found the 11-28 just had two many big jumps that it sort of defeated the purpose of having 10 speed cassette.

    On the 6600 groupo I often find that the chain rubs on the outer(big) chain ring when I am in some of the bigger cogs. This issue has all but disappeared with the 6700 groupo. the 6700 chain rings may be space a little bit wider I think.

    The top of the shifter hoods on the 6700 give a flatter perch. You feel that the shift/brake levers are under your hands when on the hoods, rather than 6600 where you have to reach a little forwards to grab the levers when on the hoods.
  • tonye_n
    tonye_n Posts: 832
    Oh,.... and I did remove the 11-28 6700 cassette and replace with a 12-27 6600 cassette. I have not noticed any compromise in shift quality or quietness of the drive train as a result.
  • Thanks all - that's just the sort of input I wanted

    PeterBL - like you , I think the 15-17 jump would really irritate me as the middle of the sprockets is where I am a lot of the time and the smooth moves up and down have been one of the really nice things about moving to the 10-speed (and away from the 11-28)

    Tonye_N - thanks for the info - good to hear that the older style cassettes will play nicely with the new mechs, etc

    I think I will give the 12-25 a go (been training hard over winter and lost a few Kgs, so might be ok without the 27) and if that doesn't work out, find myself a 5700/6600 12-27 cassette and carry on as normal!