Hope this is of use to someone. About a week ago the chain started jumping on the rear lower sprockets, - 10 speed. The chain is only a couple of months old, so I guessed it might be a frayed cable. Not the easiest thing to change on my Cannondale 105. Didn't help. Checked the blogs for advice which suggested checking the alignment of the jockey wheels, they were about 7 mm out because the the outer metal bracket was bent outwards. Don’t know why as I would have expected any damage coming from the bike falling on its side when the bending would have been towards the wheel not away from it. Still didn’t help, fine on the bike stand but as soon as it was on the road under pressure the chain jumped again. It was the first Jockey wheel causing the problem. It was flopping around. Installed two new wheels and after a short test ride all seems well.
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