Chain Off Again.

[The Jogger]

I have a Boardman CX which I have been having trouble with the chain jamming when I go to change from the small ring to the large also the chain was coming off. I recently had it serviced and I explained this was one of the problems I was havig with the bike. Today I went for a wee ten miler (first ride since the service) and when about to go down a small hill I switched to the large ring and hey presto, the chain came off. I really want to say this bike is better than my Trek 7.3 fx but I'm finding it hard to do so........

 

[MrJamie]

Id watch a front derailleur video on youtube and have a go at setting it up yourself properly, could just be the limit screw allowing the derailleur and chain to move too far outwards.

You could take it back to Halfords until they set it up properly, but its a good thing to be able to do yourself and easy in my opinion as a newbie

 

[PpPete]

Did the chain go over the top of the big ring and on to the crank? or bounce off the big ring and end up on the BB shell ?
If they listened to your problems with it LBS should have checked the Front Derailleur limit screws, which ought to eliminate the first option.

 

[ianrauk]

You could take it back to Halfords until they set it up properly, but its a good thing to be able to do yourself and easy in my opinion as a newbie

Or take it to a bike shop that knows what they are doing
But, yep as you say, get on to You Tube, there are plenty of vids at how to set the front derailleur.

 

[lulubel]

Check that the front derailleur is straight. It can be quite tricky because the edges of it will be a bit wiggly, but it you imagine a straight line running through the middle, it should be exactly parallel with the chainrings.

I had a problem with the chain jamming and coming off that didn't get fixed after 3 trips to the lbs. In the end, I took the bike to another shop, they took one look at the derailleur, straightened it up and said, "There you go. No charge." It took them all of about 15 seconds to solve the problem.

 

[The Jogger]

Thanks all, I'll have a look at youtube but...... i could give it a go but my mechanical abilty is like my spelling, shite.

Pete it went over the top. If all else fails even though I have a service plan with Halfords, I'll take it to a lbs...... the service plan was free with the C2W scheme.

 

[Smurfy]

I switched to the large ring and hey presto, the chain came off.

Pete it went over the top.

I assume that means it ended up resting on the pedal. If so then this might mean that the mech is set too high on the seat-tube. When that happens there is too much of a gap between the big ring and the mech cage, and the chain can escape. You could try moving the mech down the seat-tube 1mm at a time and see if it improves. Put some tape first or use a fine OHP marker pen in case it makes the shift worse and you want to move the mech back exactly where it was.

Also, is it a double or triple. A double should be fairly easy to set up as when you only have two rings there are fewer compromises to make everything work.

Edit: And make sure the outer part of the mech cage (i.e.nearest the pedal) is parallel to the chain rings

 

[The Jogger]

Hi Tim, thanks, it's a double, this sounds a bit technical but I'll give it a go.........after my weekend in Ireland

 

[Smurfy]

Hi Tim, thanks, it's a double, this sounds a bit technical but I'll give it a go.........after my weekend in Ireland

Happy to help!

The manual for the SRAM Apex front derailleur is here

http://cdn.sram.com/cdn/farfuture/c...5-7915-010-000 Rev B - Road Derailleurs_6.pdf

If the link above doesn't work, go here:

http://www.sram.com/service/sram/3,378,254

and click on the link for the user manual at the bottom of the table.

In the pdf you wil find all the dimensions for setting up the derailleur. Dimension number 3 is the one I was telling you about.