104bcd sram xx1 eagle chainring offset

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simoncx
Posts: 161
Joined: Sun Nov 15, 2009 12:27 am

by simoncx

Anyone have a 34t sram 104bcd eagle ring and know the offset, in the pics online it looks like it's offset more then the 32t which I have but cant find any info on the offset?

grover
Posts: 1178
Joined: Mon Jul 26, 2004 1:06 pm

by grover

The 104bcd rings are all zero offset. They're just flat. The offset for the rings that aren't direct mount will come from the spider.

by Weenie


simoncx
Posts: 161
Joined: Sun Nov 15, 2009 12:27 am

by simoncx

Thats what I thought at first but laid on a flat surface the sram (quarq) eagle 32t ring has about 2mm offset compared to a wolf tooth 32/34t or AB 32t and from the looks of the pics online the eagle 34t is definitely not zero offset either. This is the chainring I am talking about https://www.quarq.com/product/sram-x-sy ... chainring/

grover
Posts: 1178
Joined: Mon Jul 26, 2004 1:06 pm

by grover

Interesting.

There's only one SKU for each ring size and SRAM don't list an offset. My initial theory would be that the chain can contact the tips of the quarq spider with the smallest ring they make (32T?). So they build in some offset so it doesn't hit, which they then need to build into all the sizes so that the chainline is consistent.

Consider their 1x road rings. They are all offset to bring the chainline narrower over the top of the spider. No other manufacturers (WT or AB etc) do this so you end up with a wider chainline.

What's the problem you're trying to solve?

simoncx
Posts: 161
Joined: Sun Nov 15, 2009 12:27 am

by simoncx

grover wrote:
Tue Mar 26, 2019 4:13 am
Interesting.

There's only one SKU for each ring size and SRAM don't list an offset. My initial theory would be that the chain can contact the tips of the quarq spider with the smallest ring they make (32T?). So they build in some offset so it doesn't hit, which they then need to build into all the sizes so that the chainline is consistent.

Consider their 1x road rings. They are all offset to bring the chainline narrower over the top of the spider. No other manufacturers (WT or AB etc) do this so you end up with a wider chainline.

What's the problem you're trying to solve?
I'm trying to replace my wolftooth (34t) on my quarq but would prefer if it had some inward offset so it gives me a better chainline when in the upper part of the cassette. Swapping cranks with a 6mm dm ring the chainline is spot on but on the quarq with wolftooth it seems its outward 2-3mm by looking at the chainstay, so I'm hoping if the 34t eagle ring is about the same offset as the 32t it should make the same chainline as dm ring. I guess I'll order the eagle 34t and see if it has alittle inward offset like the 32t.

sqber
Posts: 32
Joined: Sun Dec 21, 2008 12:51 am
Location: Tallinn
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by sqber

Why not use some spacers/washers between the ring and spider? During winter, I used my Quarq Boost crankset on a CX bike, which is not boost. I added 3mm of spacers to bring the chainring back inwards. You may need to buy new longer bolts, though.

by Weenie


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