What problems would a long chain cause? or HELP!

[jethro10]

I rebuilt my wifes bike into a new MTB frame over Christmas, everything was off the old bike except the front deraileur which had to be a top pull as her old one was a bottom pull, a larger diameter seat post, and new cable outers and inners of course.

I don't have the old frame to measure but I never though of the chain being an issue. But the chain has popped off the inside front cog perhaps 1-2 times per ride.

I have the low stop adjusted correctly (I feel) as if I adjust it a smidgen more, when in first gear (front and back) the chain just catches the deraileur. Axle measures up as being centred ok.

Only issue I can find, is when I check the chain length last night, it was a pair of links longer than recommended by various sites, eg Sheldon Brown.
what made me think was on Sunday we were bouncing down the blue route at Whinlatter and her chain came off, she reckons she was doing nothing, no gear changes no nothing which might imply it was a bit slack.
All Shimano drivertrain
So last night, I shortened the chain and re-set up the cables.
She took it for a spin in the village and punished the gears and all seems ok. But then under those conditions, it was Ok anyhow!

Any thoughts?

Jeff

 

[spence]

Sound's like you've fixed it, probably just shorted chain stay length between the new and old bikes.

 

[twentysix by twentyfive]

Check the front mech adjustments. You can always adjust the front mech and then put it back again if not the problem.
Also check the chain line. If the chain line is particularly skew you may need to adjust the BB position (you'll need an adjustable BB).
Does the rear mech take up all the chain when gears are in small front and small rear? If not shorten chain till the rear mech spring is in use.

 

[jethro10]

Well we've had only one test run for an hour, but shortening the chain seems to have done the trick. Although I did re-set it up

My wife says it's quieter and changes easier.

seems happy now.
Jeff