Gearing Problem / Chainring Rattle

autobahn
autobahn Posts: 114
edited September 2009 in Road beginners
This may seem like a stupid query to some, but I have a problem which is driving me crazy. Help Please!!
I have my got my first road bike 2 months ago and I'm and loving it (Giant Defy 4) and have covered nearly 500 miles. Its like being a child again!!!
Anyway my problem is that when I change to the larger chainring, I get a terrible rattle in all gears. The rattle stops if i keep holding the break lever/shifter firmly across, but I need to keep holding this, if I let go the rattle returns.Surely I shouldn't have to hold this permamently in this position if I want to ride in the large chainring?
The noise disappears if I fiddle with the barrel on the gear cable however when returning to the small chainring it seems I have then upset the setting and this causes rattle on the small chain ring. Surely I can ride in both small and large chainrings without rattle. Im in the correct gears.
What is wrong? What am I doing wrong. Hopefully I'm explaining myself correctly and any advice is greatly appreciated.

Comments

  • amaferanga
    amaferanga Posts: 6,789
    Do you have a trim function on your shifters? If your shifters are set up properly then you can use the trim function to stop the chain rubbing on the front mech.
    More problems but still living....
  • Velonutter
    Velonutter Posts: 2,437
    Autobahn wrote:
    This may seem like a stupid query to some, but I have a problem which is driving me crazy. Help Please!!
    I have my got my first road bike 2 months ago and I'm and loving it (Giant Defy 4) and have covered nearly 500 miles. Its like being a child again!!!
    Anyway my problem is that when I change to the larger chainring, I get a terrible rattle in all gears. The rattle stops if i keep holding the break lever/shifter firmly across, but I need to keep holding this, if I let go the rattle returns.Surely I shouldn't have to hold this permamently in this position if I want to ride in the large chainring?
    The noise disappears if I fiddle with the barrel on the gear cable however when returning to the small chainring it seems I have then upset the setting and this causes rattle on the small chain ring. Surely I can ride in both small and large chainrings without rattle. Im in the correct gears.
    What is wrong? What am I doing wrong. Hopefully I'm explaining myself correctly and any advice is greatly appreciated.

    The Gears have obviously not been set up correctly, your LBS should have had the bike back after say 100 miles to check everything and re-adjust.

    If not new then still take it to a LBS and and ask them to set the gearing up.
  • Thanks folks

    Have had my bike back to LBS twice and mentioned this issue. Bike checked twice now and have been told gears fine and set up correctly.Trimming was mentioned, could someone explain what this is further? (Is it clicking your gear lever slightly, to get rid of any excess rattle, if so it works fine on small chainring, not on large)
    Its only when I get away from the shop and am next out on a good run that I discover the problem. Trimming seems to work if there is a slight rattle in the small chainring.
    Its a big hassle to load my bike up and take back to LBS shop each time combined with felling slighty embarassed,as I am convinced the answer must be simple and its me not yet used to the gears.
    Should I adjust the barrel?
    Again many thanks .
  • Velonutter
    Velonutter Posts: 2,437
    What make & model group set?

    Does it happen in all gears?
  • Had a few similar problems with my Defy - covered around 1000 miles on it so far and the bike never ran smoothly on the big ring while down on the smaller rear sprockets, also had problems with the chain rubbing on the front mech on nearly all the gears while on the big ring at the front at the one point.

    After 3 trips back to the LBS for adjustment (they made it no better than I could get it myself) only when they fitted a brand new chain did it run better, smooth in the smaller sprockets at the rear, and only gets chain rub I happen to cross chain and use the 3 largest rear sprockets while on the big ring.
  • CiB
    CiB Posts: 6,098
    Rer-read original post. Too many words here, except for the bold bit (below).

    The front changer should have enough steps [indexes] to move the chain from the lower to the upper. On my Shimano it always needs two clicks of the indexer to get across properly; experimenting to get it to do with one 'click' has proved (to me) that there isn't enough movement in one step.

    So - how are you using it? You should need one click to shove the chain across and another to finish the job. When the chain is on the bigger ring there should be one further click available to push the changer further to the right, without pushing the chain off the ring. Trimming is the act of adjusting the changer so that the last click doesn't push the chain off the ring, and ensuring that when the chain has made the jump to the next ring it's not in constant contact with the changer. The changer needs to push the chain just far enough to allow it to hook up to the next ring (going up or down), but without being in constant contact with the chain. Still with me?

    Ideally your cables should have in-line barrel adjusters to make trimming an easy process. It sounds like you haven't, so it's trial & error. Drop the chain onto the small ring, release the cable pinch bolt and pull the cable through a bit - an eighth of an inch should do it. Retighten the clamp, ride around and see what difference it makes. From now it's up to you. Adjust a bit at a time in either direction depending on what happens. It's not rocket science - all you're trying to do is to get the gear lever to click into a position that matches where the changer needs to sit.

    Concentrate on cable tension & length. Don't adjust the limit screws, unless it's obvious that they need a tweak, otherwise your chain will start falling off on a regular basis.

    Two things - your LBS aren't doing their job properly by the sounds of it. secondly ask them or a better LBS to fit the in-line adjusters. They're only a couple of quid and make life much easier. And the third thing is that it's a good investment to learn how gears work; it saves a fortune in unnecessary trips to the LBS for simple adjustments.
  • Thanks folks for your advice, all very helpful