chain slipping off

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chain slipping off

Postby OH DIO » Sat Mar 10, 2012 10:33 pm

Hi all im new to the forum the name is josh by the way

What i would like to know is why my chain slipps off allways on my crank set it happens when i go from the bigger gear to the smaller one at thw pedals and when i pedal backwards at a stop to get my foot on top to take off from a stop

What do you guys think this could be the bike is a pinarello fp2 with 105
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by BNA » Sun Mar 11, 2012 12:06 am

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Re: chain slipping off

Postby Mulger bill » Sun Mar 11, 2012 12:06 am

G'Day Josh, welcome outside. :)

My guess is either the low limit screw on the front mech is not set properly and/or your chain may be a link or two too long.

BTW, you'll get more hits putting a mechanical thread in the Shed forum. I'll slip this one over for the resident wrench gods to ponder. :wink:

Cheers
Shaun
...whatever the road rules, self-preservation is the absolute priority for a cyclist when mixing it with motorised traffic.
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Re: chain slipping off

Postby greyhoundtom » Sun Mar 11, 2012 3:39 am

Hi Josh,

The front derailleur adjustment can be a bit tricky to play with particularly if the 105 shifters you have were designed to also handle a triple chain ring.

In this case it may be best to have the mechanic at your local bike shop do the adjustments as part of a service as there are bound to be other other areas of the gearing that may require tweaking.

Nice bike by the way. :D
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Re: chain slipping off

Postby OH DIO » Sun Mar 11, 2012 4:50 am

Cheers thanks for that guys ill keep that in mind when i bring it in for a service i was just worried that somthing was broken
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Re: chain slipping off

Postby Downhill » Mon Mar 12, 2012 12:16 am

Hi Josh,

It's a very good idea to have the mechanics at your bike shop adjust the derailleur at the next service. That said, being able to adjust your own derailleurs is a skill worth learning.

This link will take you to the Shimano web site. If you enter "105" in the search field, it will show you a list of documents relating to the 105. Scroll down the list until you get to "FD Front Derailleurs". Find the model number of your particular derailleur.

If you're not sure if you have the right model number, open the "EV" link for that model and see if it looks like yours.

The links starting with 'SI" are the service instructions. If you open the service instructions for your particular model, it will show you how to adjust it.

There are also heaps of tutorials and videos on the net that show how to go about it. Try searching Google for "video adjusting Shimano 105 front derailleur".
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Re: chain slipping off

Postby johnm_oz » Sat Mar 17, 2012 7:58 pm

I can't claim the experience of some of the people here, but I wonder if it's not adjustment but happening because you're changing gear while you're almost/stopped, so the chain's half way between two rings when you're moving the pedals back to get into position. You need to be in the gear you're going to start with by the time you stop.

Cheers
JM
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Re: chain slipping off

Postby OH DIO » Mon Mar 26, 2012 6:18 am

Hey guys after a closer look at the bike i have noticed that the front derailleur is not a 105 item it is a most i have had the front derailleur adjusted by my local bike shop and i still have dramers on some down shifts from the big gear to the smaller one what do you guys think i should do i have to get a new chain and rear casset from what the gut at the shop said when he was working on the bike do you think i shold look for a 105 or ultegra item to replace the most one
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Re: chain slipping off

Postby PawPaw » Mon Mar 26, 2012 8:29 am

No, don't go and buy a new FD.
If the bike shop didn't fix the problem, take it back and explain clearly what is happening.
From what I understand you are saying, the chain often comes off the small chainring inwards onto the bottom bracket.

As said above, the most likely reason for this, is the inner limit screw is not adjusted outwards (away from the frame) adequately.

Other things that could contribute are
- chain age and amount of stretch
- chainring age and wear
- lack of lubrication on a stiff or faulty chain.
- the wrong width chain has been fitted.

A final possibility is operator error, where you are causing the chain to come off by spinning the cranks backwards very quickly, or timing your gear changes poorly. However, if the limit screw is adjusted properly, this is unlikely to happen.

Re the non 105 FD, did you buy the bike new? is it the original FD? How many k's has the bike done?

It would help if you could answer the questions above. Otherwise, take it back to your LBS, and if it continues to occur, take it to another shop, and never go back to the original one.
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Re: chain slipping off

Postby OH DIO » Mon Mar 26, 2012 6:20 pm

I got the bike second hand i would say its done about 1000 to 2000 km and yes i would say it is after reading up about the bike on the net
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Re: chain slipping off

Postby wombatK » Mon Mar 26, 2012 6:53 pm

OH DIO wrote:I got the bike second hand i would say its done about 1000 to 2000 km and yes i would say it is after reading up about the bike on the net

If it's done so little km's, the problem isn't wear related. As you don't know it's history, one possibility is that
it might have been stacked - and bent the derailleur. But eliminate the simple possibilities before you turn to
that - and really any competent LBS mechanic should have told you about that already.

It's not hard to do your own derailleur adjustments if you aren't a complete mechanical klutz. Plenty of youtube videos
out there, but a more thorough explanation can be found on the Park tools website: Front Derailleur Adjustments.

Cheers
WombatK

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