Chain comes off front dérailleur

[Payneys]

Please can someone help.

I've been doing recreational cycling - completed London Brighton twice and do only around50miles a week. I know nothing about mechanics , gear ratios , or dynamics of cycling etc. Etc . I get them serviced at a shop and ride them .

My problem is I just completed my first Sportive (Isle of Wight) and had a disater ( got lost ! Got a puncture ) all stuff I will learn from !

My problem is my chain kept coming off the front derailleur when changing down from the big ring to the small when climbing hill.

I have the bike for 4 years it's a Scott speedster s 40 and never ever had this problem before I asked a mechanic at the sportive and he said it might be MY fault as the adjustment looked ok to him - he said change down early before the hills .

I tried this ..... Chain came off .

Can someone tell me if I am doing something wrong ? I am open to offending remarks about my ability ! I'm used to having people cycle past me often enough so I'm pretty thick skinned !

Its just that if I am doing something wrong why has it never occurred before and yes I do got up hills when training I live by the south downs in Sussex ( ok it's not the Pennines but nothing different to Isle of wight )

Thanks

 

[anyuser]

I suspect this is nothing to do with your technique. My first check would be that the low limit screw is set properly on the front der. If it is, then check that your rear der hanger is not bent, I had exactly the same issue as you last year and it was a bent rear der.

 

[CopperCyclist]

Is the limiter screw set correctly? The front mech has two screws, one to limit how far to the left the cage can go, the other to the right.
If you are falling off when changing down, it could be set too far left, allowing the cage to push the chain all the way off. Tightening or loosening the correct screw may solve this.
I'd recommend checking YouTube to get a visual view of how to do this - its not a difficult fix, if this is your problem.

The only other thing I'd check is that you are changing under low torque - I.e. ease up on the pedalling when you change, as changing with loads of pressure through the pedals can do this.

 

[Payneys]

Thanks to all for yr replies - as advsied although I've been riding for about 4 years off and on I really have no idea on the finer points - I know the screws you are talking about and I will check those out many thanks .
If all else fails I'm taking it back to the service shop .

Paranoid I maybe I thought after 47 years I had no idea how to ride .... Probably got something to do with riders that leave me for dead on a Sunday morning ride ! Although I did get some enjoyment from the Sportive as I actually managed to overtake some of the field on climbs and the flat...... Did my ego the world of good if only it lasted longer due to my bloody chain !!!

Thank again for yr input

 

[fossyant]

Just slightly adjust the lower screw so it pushes the cage out slightly. What's happening is it's shoving the chain a little far, and un-shifting it. The other option is to get a chain catcher or a dog-fang, but you should get the adjustment spot on first. If not sure google some videos on adjusting mechs.

 

[Browser]

Not that this should cause the chain to come off when doing as you are saying, but do you change all the way down to the furthest left sprocket on the rear before shifting the front? If the chain is all the way over to the left at the rear the chain has a certain amount of sideways pressure on it before you shift the front deraillieur, which might cause the chain to jump off.
As others have already said however, it is more likely to be a problem of incorrect setup/adjustment.

 

[cyberknight]

Also check the height of your changer above the top of the big ring, you should only have the width of a 2 p coin

Sounds like the mechanic was an unhelpful sort .......
You could also look at installing a chain catcher if all else fails .
http://www.sigmasport.co.uk/p/20544..._medium=pricecomp&utm_campaign=GoogleShopping
make sure you get the right size for your bike.

 

[Gravity Aided]

That's an excellent recommendation for spacing, Cyberknight . I knew the American Penny was good for something !

 

[Paulus]

Also, sometimes when the chain is worn out, there is so much slack in the rollers that the chain will ride up and over the teeth and come off, no matter how well the limit screws are adjusted. This can occur when shifting from the largest or or smallest chainring, and the chain on the largest or smallest cog on the cassette.

 

[Pat "5mph"]

Also check the height of your changer above the top of the big ring, you should only have the width of a 2 p coin

Sounds like the mechanic was an unhelpful sort .......
You could also look at installing a chain catcher if all else fails .
http://www.sigmasport.co.uk/p/20544..._medium=pricecomp&utm_campaign=GoogleShopping
make sure you get the right size for your bike.

Excellent tip! ta!