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[Closed] Direct mount chainrings - offset vs. boost?

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[#11845893]

Am a bit behind the times with chainring tech!

I'm running a 36tooth oval narrow wide chainring on my Superfly.

I want to go down to 32 tooth for bikepacking duties.

It's a 2x chainset so I've spaced the existing chainring towards the wheel using chainring spacers but would prefer something which was already offset.

I see 'BOOST' chainrings available, but to my mind these would be offset out the way to allow for the wider hub?

Otherwise, if a chainring is advertised as 'offset' is it safe to assume it will be offset towards the wheel?

Ta


 
Posted : 16/04/2021 12:16 pm
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Yeah the offset is inwards
6mm offset = non boost 142mm
3mm offset = Boost 148mm
0mm offset = Superboost 157mm

For Sram DM chainrings anyway, not sure about others.


 
Posted : 16/04/2021 12:39 pm
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I thought offset only applied to direct mount chainrings. I've never seen 104bcd advertised with specific offset.

If your current cranks are fine I'd just stick with the spacers and get a new 104. They tend to be cheaper than direct mount too.


 
Posted : 16/04/2021 12:41 pm
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Direct mount just seems easier to find! Will check bolt circle and see if I can find an oval 32 in my bolt pattern.

I think Wiggle are listing BOOST chainrings as non-Boost, e.g. the Blackspire Snaggletooth with 3mm offset only comes in a BOOST option but the Wiggle listing refers to it as non-Boost.

Sounds like I could run it anyway, on the basis that I want the 3mm offset


 
Posted : 16/04/2021 12:55 pm
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Boost chainrings are designed to increase chainline anyhow, not decrease it ,so opposite of what you want


 
Posted : 16/04/2021 3:12 pm
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There is a good discussion of chainline in relation to non-direct mount chainsets by One-Up here.


 
Posted : 16/04/2021 5:42 pm
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+1

'offset' relates to direct mount chainrings, and it sound like you have a spider + chainring.

If so then just space the chainring so it's lined up to the middle of the cassette, or better still slightly inboard/closer to the frame. Chainrings - in the traditional sense - have no 'offset'. They are just chainrings.


 
Posted : 16/04/2021 8:05 pm
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Yeah, I currently have a spider, but it's a direct mount spider so I fancied taking advantage and getting a direct mount chainring.

HOWEVER I've just found a conventional 4-bolt 94BCD Absolute Black chainring in stock which incorporates a 2.5mm inboard offset anyway due to funky bolt holes, so win win.

Thanks folks


 
Posted : 16/04/2021 9:05 pm