Slack-tight Slack-tight - Problem with New Crankset?

[Jezston]

Finally got all the bits I need together (minus front brake, that can come later) for my new fixed/track build. Was going to do this with a friend, but that fell through so pottered over to the friendly LBS to assemble the bike.

Bottom bracket and crankset attached, rear sprocket and lockring on frame, chain split and attached.

Problem straight away. The chain is going slack at some points and tight at other points in the rotation of the cranks. LBS thinks there's something wrong with the chainring or spider.

Pain as I bought the chainset over a month ago, so returning it is going to be an issue, especially after I noticed that they didn't package it too well and there are minor scuffs on the cranks.

Before I get myself into a return/re-return headache, is there anything else it could be I should investigate?

 

[RecordAceFromNew]

There is ALWAYS a tight spot. The question is whether there is too much. See this.

 

[Jezston]

Its pretty massive. At tight spot the chain barely moves. At loose spot its got about 2 inches of play.

 

[RecordAceFromNew]

Its pretty massive. At tight spot the chain barely moves. At loose spot its got about 2 inches of play.

If the chainset is not one piece you could follow Sheldon's guide on how to centre the ring.

 

[sidevalve]

Didn't get an older biopace chainring by mistake did you ?

 

[RecordAceFromNew]

Didn't get an older biopace chainring by mistake did you ?

I very much doubt it, it is because it takes only around 1mm* of ring offset to get 2 inches of vertical play the OP said he is experiencing.

* very roughly speaking +/-1mm of ring offset will effectively affect chain length requirement by 4mm, which will give rise to over 2" of vertical play halfway at the chainstay

 

[Jezston]

It's a brand new Stronglight Track 2000 chainset if that matters - definitely not an old biopace chainset!

Just read sheldon's guide - that gives hope as yes it's a separate chainring and crankset. Seems this might be a common thing with new SS cranksets? Or if it's not perfect from the off, should I be sending it back?