Chainring offset

[ILoveEnriqueAli]

Hi

I recently fitted a Surly 32t stainless steel chain ring to a Shimano Deore XT 737 crankset with the proprietary inner and outer chainrings.

Upon trying to index my front mech, I noticed that the chain was falling between the inner and middle chain rings due to a larger gap than between my middle and outer chainrings. When I chatted to a friend, he said that Shimano chain rings have an offset from the crank bolts to the teeth line.

I am looking to buy some chain ring spacers to correct this.

Does anyone know the offset of Shimano chainrings and therefore what size spacers I would need? Or has anyone else solved the same problem?

Thanks very much,
Max

 

[marc two tone]

Re:

The type of compatibility can be a 'depends what you have' thing about it.

The remedy is to faff about to get it right. I solved this issue myself a week ago on my own bike, where the narrower 9sp chain feel between middle and inner.
Alloy rings can be slender like specialites or chunky like falcon and talon.

My solution was simply to fit the narrow brass washers that deore DX and the LX early models came with. 1.2mm ??? Washers.. Is it....anyway all good now, shifts without chainsuck.
Let us know how you get on.

 

[ILoveEnriqueAli]

Re:

Thanks for the reply and advice!

That's kind of what I was leaning towards anyway ahaha. I'm going to order 5 of both 1.2mm and 2mm spacers I think and have a play. Just SJS charges £1 per spacer... so I was hoping someone would have exact numbers, but not the end of the world to have extra washers!

I'll let you know how it goes.

 

[Splatter Paint]

Re:

Can you measure what offset you've currently got and go from there?

 

[ILoveEnriqueAli]

Re:

I'm heading to my LBS later to use their calipers so I have a better idea of what I'm dealing with

 

[legrandefromage]

I wouldn't have said that there is any specific offset. It may just be that your stainless chairing is thinner than the original.

Mind the gap!

 

[ILoveEnriqueAli]

I wouldn't have said that there is any specific offset. It may just be that your stainless chairing is thinner than the original.

Mind the gap!

Looking at the profile of my removed 32t Shimano chainring, you can see that the bolt holes are offset from the teeth considerably; the arms of the bolt holes are curved away from the teeth themselves. So there is definitely offset!

Conversely, my Surly chainring's mounts are in direct line with the teeth

 

[legrandefromage]

There is no 'offset', the only Shimano rings that have a specific offset were ones for the odd spiders such as STX and ST-RC where one ring would bolt to another.

Have a look, here is your chainset with the rings, the teeth are in line as is every other aluminium chainring from any manufacturer.

http://velobase.com/ViewComponent.aspx? ... e&Enum=115

Your Surly chainring is much thinner so by using it you are effectively moving the chainline over, you still need spacers but only to put your skinny chainring back to where it should be

 

[FluffyChicken]

Re:

Measure it off the bike.
Lay them flat (front side down), you can directly compare.
look for a none ramped and shaped pin on the Shimano.

On granny rings this was a problem and that was Pre Ramped pins., steel always needed longer spacers then Alu. it was part of the instructions in some things (BiuzzSaw?).
eBay should have the spacers cheaper for that sort of thickness.

 

[ILoveEnriqueAli]

Re:

Yep, my bad completely, no offset from what I can see. I could've sworn that my chainrings had that profile and it matched what my friend said.

However, upon returning home from work, I checked my chain rings and there is no offset. It must just be a thin chain ring as you say.

I'm hoping that the 1.2mm spacers will do it from the looks of things. I will let you guys no either way!