Ultegra gearing 30T?

Armoredinca
Armoredinca Posts: 80
edited February 2012 in Workshop
I have the Ultegra 6700 compact groupset 50/34 x 11/28T on my bike, does anyone happen to know if the rear Ultegra derailleur will take a 12-30T Cassette?
My mate has a Felt Z85 and that has compact c/s and a 105 short cage with a 12/30t 105 cassette and we are both going to the Alps in July.

Cheers
Chris
1nca

Comments

  • Mccaria
    Mccaria Posts: 869
    Shimano recommend 28T as the max for the 6700 and 7900, but I am sure there is some tolerance beyond that.

    I have ridden in the Alps with 50/34 and 11/28 block and very rarely, if ever, used the 28. The hills tend to be long steady grinds rather than steep ramps - if you are reasonably fit I doubt you would need to go above 28 (unless you are carrying all your luggage with you! )
  • jgsi
    jgsi Posts: 5,062
    you may then need a medium cage GS rear mech to get it to work.... effectively.. just a thought.... but the 28 with a 34, should be enough to climb the cols if you prepare beforehand.
  • bus_ter
    bus_ter Posts: 337
    34x28 is some granny gear! I know because I have a 11-28 cassette on my ultegra with a compact, and so far I haven't needed it on a climb. If you can't manage a hill on that I don't think a 30 will make a world of difference, and I wouldn't want to give up the 11 on a compact for the downhill sections.. I would save your money and keep the 11-28.
  • Thanks for the advice, I dont have any problems with climbing my local hills and mountains around North Wales but as I have no experience of riding French Cols and I i'm down for this years Etape Du Tour, I thought the extra Granny gear may be a useful back up.
    1nca
  • robbo2011
    robbo2011 Posts: 1,017
    bus_ter wrote:
    34x28 is some granny gear! I know because I have a 11-28 cassette on my ultegra with a compact, and so far I haven't needed it on a climb. If you can't manage a hill on that I don't think a 30 will make a world of difference, and I wouldn't want to give up the 11 on a compact for the downhill sections.. I would save your money and keep the 11-28.

    Do you ride big Alpine hills though? 34x28 is a useful gear to have when you are at the end of a long ride in the mountains. Unless the hills will be stupidly steep though, I would have thought you wouldn't need anything lower.
  • chrisw12
    chrisw12 Posts: 1,246
    I ride around south Wales and have never needed 34x28 a 39x27 would be my limit. A trip to the alps in the summer taught me a hard lesson, I needed a lot lower gearing. I couldn't get up ventoux on a 39x28, given heat and poor fitness I just ran out of gears!

    My advice get a 34x32 low gear, ok chances are you might not need it but it's nice to have it there to cover any problems. Get a cheapish shimano MTb rear mech if needed.

    Remember in this country if you run out of gears you can walk, that's not really a good option on the long alpine climbs.
  • andy_wrx
    andy_wrx Posts: 3,396
    Agree with above.

    In Britain we have short steep climbs, or on longer hills you go up a bit, it levels off, go up again, it levels again, etc

    You storm up the steep bits and recover on the flats, you vary between seated and out of saddle, and it only lasts minutes anyway.

    But when in the Alps you see a sign saying '7% for 15km' then that's exactly what it means : 7% steady-grade for 15km
    - the road engineers built it at a totally-constant slope and the only flat sections you'll find is if you short-cut across one of the switch-back hairpins

    Now 7% may only be 1-in-14 but when it goes on relentlessly for 10miles you'll want an easy gear you can twiddle in

    I had 50/36 x 12-27 and I was really struggling at the top of some of them, definitely wanted at least one gear lower
    - I was grinding up at 8 or 9mph, I couldn't ride slower as that was an uncomfortable cadence, and I couldn't recover for long by riding out of the saddle as it wasn't steep enough

    A much older woman in the party had a triple with a 22 inner-ring and she spun up, took twice as long but found it easy
  • andrew_s
    andrew_s Posts: 2,511
    Mccaria wrote:
    Shimano recommend 28T as the max for the 6700 and 7900, but I am sure there is some tolerance beyond that.
    30T will often work with a road rear mech, 32T usually won't.

    The limiting factor is the top jockey wheel hitting the sprocket. This depends on the angle the parallelogram is set at, and the length of the gear hanger on your frame. You can get a larger parallelogram angle by buying a 9-speed MTB rear mech. but the gear hanger length is fixed.
    Note than 10-speed Shimano MTB rear mechs are not compatible with road levers.

    I agreed with andy_wrx and chrisw12 about the difference between Alpine and UK climbing. In the Alps a 10% sign means that in 5km you'll gain 500m of height, but in the UK a 10% sign just means there's a stretch of 10% gradient ahead. This may only be 30m long, and if you check heights at the bottom and top of the hill against distance you'll generally find that the real gradient isn't much more than 5%.
  • andrew_s
    andrew_s Posts: 2,511
    bus_ter wrote:
    I wouldn't want to give up the 11 on a compact for the downhill sections.
    11T sprockets are a waste of space in the context of an Alpine holiday. They are only necessary at 40mph and upwards; if it's steep you'll go faster hunkering down and getting aero than you will pedalling; and if it's not steep: well, you're on holiday, so why not just cruise at 35 and enjoy the scenery.
  • chrisw12
    chrisw12 Posts: 1,246
    And I agree with you :P the 11 can be a waste of time in the alps. The scenery is just too nice to want to go whizzing max speed into the next hairpin. Take the descents easy and look after your rims and brakes.