Chainring Problem

[JPBoothy]

I mentioned my current problem in the 'what have you fettled today' section but I think that was the wrong place so I'll try again here.. I have just replaced my 36t OEM Inner chainring with an FSA part but something us not quite right. They are both labelled as 10spd but the chain seems to slip on the new one. I have had a close look and it is as if the teeth don't protrude far enough through the chain links causing it to slip. The chain is also new but is a Shimano Tiagra chain not an FSA. The new ring appeared to be lighter in weight and I'm now wondering if it was possibly a bit thinner too. If so, then it was not noticeable enough to warrant the use of spacers IMO.. Would that make a difference to the way the chain meshes with the teeth on the ring? The finish of it was also more like what I'd expect of an outer ring than an inner (Gloss paint with branding etc..) but whether that makes any difference I honestly don't know.

Any ideas folks?

 

[fossyant]

Photos of both sides of the chain ring ?

 

[weareHKR]

As above... ☝

 

[twentysix by twentyfive]

If so, then it was not noticeable enough to warrant the use of spacers IMO.

I'm lost with this sentence

 

[JPBoothy]

I'm lost with this sentence

Sorry, I meant that if the new part was thinner 'than the original' then the difference did not appear to be enough to warrant me using packers/shims when mounting it on the legs of the crank spider so as to bring it back in line with the center of the chain. Any clearer?

 

[JPBoothy]

Photos of both sides of the chain ring ?

Here goes but, I never have much success when trying to attach photos.

 

[T4tomo]

a new chain-ring will often slip on a worn chain, but you've fitted a new chain. The FSA / Shimano thing doesn't matter. and all 10-spd set up ?

I'm mystified

 

[twentysix by twentyfive]

Sorry, I meant that if the new part was thinner 'than the original' then the difference did not appear to be enough for me to use packers/shims when mounting it on the spider to bring it out to the same chainline position as that of the original. Any clearer?

Thanks - yes indeed. 10 isn't that much thinner to be an issue in that case

I use an easy "measure". If you can't pull the chain (using your fingers) up very far off the big chainring at the horizontal point on the ring then the chain is good (as is your chainring). If you can pull it up a bit too much you have a problem. Unless the front ring is badly and fairly obviously worn it's a quick and easy test without pfaff. I guess there is a bit of "by eye" that needs "calibrating". Experience is good for that. Check it out and post a pic.......

 

[twentysix by twentyfive]

Here goes but, I never have much success when trying to attach photos. View attachment 582625

View attachment 582610

Why do you feel you need to change the ring? The old one looks fine to me.

 

[T4tomo]

just a thought, have you got it right way round, the tooth profiles are sometime subtly different leading and trailing

 

[Mike_P]

..and is the chain on the right way, some have defined outer sides. If in doubt it's usually the side that has branding etc on it that goes on the outside.

 

[fossyant]

The cassette isn't worn is it. A new chain will slip on a worn cassette. Very rare for chains to skip on chainrings.

That new FSA looks correct in that it is an inner ring. Outer rings have shift ramps and pins.

 

[Deleted member 1258]

just a thought, have you got it right way round, the tooth profiles are sometime subtly different leading and trailing

Thats what I was thinking, the old chain ring looks like its still got miles in it.

 

[JPBoothy]

a new chain-ring will often slip on a worn chain, but you've fitted a new chain. The FSA / Shimano thing doesn't matter. and all 10-spd set up ?

I'm mystified

Yes it is a new Shimano 10 spd chain with branding (HG etc.. ) facing out.

 

[Randomnerd]

Might be an old cassette?