10 speed shifting problems

John C.
John C. Posts: 2,113
edited March 2008 in Workshop
My riding Buddie has a Focus , Ultegra spec compact chain-set bike, he is having problems with the chain being spat off on the inside of the chain-set when he drops it onto the 34 ring. I have checked the clearance of the front mech when he is in bottom gear and it is about 1mm.
The only way he seams able to change down is by changing down when he is only about half way down the block.

Any ideas ?
http://www.ripon-loiterers.org.uk/

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Comments

  • John.T
    John.T Posts: 3,698
    edited March 2008
    First check the alignment of the cage. The outer edge should be parallel to the big chain ring. If it is in only a small amount it will do this, more so with the wider tooth difference on a compact. Set the lower limit screw so that the chain just clears the cage when under tension. It may just rub when spun light. Lastly what is he doing changing to the 34 when on the large end of the cassette. He should have done it sooner and been on the 34 and the smaller end. I treat my gears like a high and low range set and use the appropriate one for the terrain. I live in Harrogate so know your area pretty well. If I go west I hardly use the 50 but if I go east then I am hardly out of it.
    My Fleet.
  • aracer
    aracer Posts: 1,649
    John.T wrote:
    Lastly what is he doing changing to the 34 when on the large end of the cassette. He should have done it sooner and been on the 34 and the smaller end. I treat my gears like a high and low range set and use the appropriate one for the terrain.
    Surely with a compact if you change down to the 34 when still in the middle of the cassette then you're actually totally missing out on some gear ratios, as there's no way when in the 34 to get the gears at the big end of the cassette with the 50.

    Can't really add a lot to the adjustment advice, but would just suggest getting one of http://www.dotbike.com/ProductsP559.aspx?A=11&TRACK=DPL - makes sure the chain doesn't drop off it it does overshift. Not sure mine's done anything useful, as I think the adjustment is correct, but it's there just in case.
  • onbike 1939
    onbike 1939 Posts: 708
    This can happen if the FD or the cable requires lubing. In this case the sudden release following one of these being stuck can cause the chain to over-shoot.
    I would also check that the 34 ring is round and has not been bent in any way.
  • John.T
    John.T Posts: 3,698
    50/19 is the same gear as 34/13 at 69". This is my most used ratio for normal riding. I use a 12/27 cassette and only avoid the 34/12 and 50/27 gears. (I use these at times when I get it wrong but try not to.) If you are changing down to the 50/21 and think you may need lower still you will be better using the 34/14 which is the same ratio but has a better (closer) set of climbing gears below it. You need to think ahead.
    Correctly set up all gears should be usable with no mishaps. I have 3 bikes using this setup, two on 10sp and one on 9. All work fine.
    My Fleet.

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