chain "skates" on little ring??

dieselgeezer

Hi,
Can anyone shed some light on the following problem?
10 speed set-up with FSA compact chainset (rings marked 9/10 speed). Quite often when going from big ring to little ring with rear sprocket on 21 or 23 (12 -25 cassette) the chain drops off the big ring but doesn't engage properly with the little ring, it seems to hover above it. You can still turn the pedals but you aren't going anywhere. Have tried various adjustments on the front mech but no success.
Any tips ?

keef66

Is it possible that your chain's too short?

Does it happen when on smaller sprockets at the back?

dieselgeezer

Nope, only happens when the chain is on the 21,23 or 25 (but never have it on the 50 x 25 to begin with).

keef66

Well that eliminates the chain length theory. ( I actually meant to say is it too long?)

Suggests instead it's to do with chainline / alignment of the front mech.

Is the front mech cage absolutely parallel to the chainring when it's over the small ring?

Have you tried adjusting the lower limit screw to allow the cage to move a gnat's whisker further inwards when dropping to the small ring??

Monty Dog

I agree, likely to be front mech alignment / stop screw adjustment

dieselgeezer

Think I've sorted it by even more bending in of the leading edge of the outer plate of the front mech. Time will tell!
Thanks for your input.

Berk Bonebonce

You are not giving the chain time enough to engage with the teeth on the small chainring before turning the pedals under load. You get this with compact chainsets where there is a big jump between chainring sizes. It is not the gears it is you.

Tom Butcher

I've had this on an FSA chainset - googling suggested it wasn't an unknown problem with that model of chainset. That said maybe if I'd searched for skating and Shimano or Campag I'd have found similar tales.

cq20

I had the same problem with my Campag Xenon compact chainset. It was intermittient but when it did happen I was always in the middle of the rear cogs. For other reasons, I changed the FD but the problem was still there and still infrequent. Never solved it, but it hasn't happened on my new Campag equipped bike.

Berk Bonebonce

It is not rocket science. If you change from big to small chainring and put force on the pedals before the chain fully engages with the teeth on the small ring, the chain will 'skate'.

This problem will disappear when you learn how to ride a bike.

Tom Butcher

Sorry but that's nonsense - I've been riding bikes for years, campag and shimano, never experienced this skating except with the FSA chainset that came on my time trial bike. A bit of googling it shows it is a recognised problem with at least some FSA chainsets.

cq20

... and a bit more googling will show it happens on some Campag.

Oh all of these people who can't ride bikes properly :roll:

.. but I must have suddenly learned how to ride a bike since I got my new bike as I no longer have this problem

Berk Bonebonce

And do you people also have rear mechs that do not seem to shift properly when you are standing on the pedals going up a steep hill?

Tom Butcher

Yeah so you've never had a chainset prone to it therefore it isn't a problem - must be rider error - ffs.

rolf_f

I get this on my Campagnolo Centaur and Record mechs. As the Record one started out fine and only manifested itself around the time I would expect to adjust for cable stretch, I can only assume that I used to know how to ride a bike properly but, with practice, have got worse

The bloke who built my bike was surprised when I asked him for advice on this. He did suggest thinner chain oil might encourage that bit quicker a shift so I might give that a go. Plus also micro adjustments on the limit screw.

Not found much on google on this for Campag so any links to make up for my poor Googling would be much appreciated!