[Closed] Chainring offset

Park Tool has just put up a very informative video. Get your Vernier caliper out!

So far as I understand it 6mm offset is 'old fashioned' standard and 3mm offset is for a boost frame ie newer and betterer as we're all led to believe.

Nutshell, it’s Boost and non-Boost as the chainlines  are different because the chainring has a different location from the centreline.   There’s a lot more silliness due to crank designs, but Boost/non Boost and use what the crank mfr says for B.B. spacers is the simple version.

Thanks guys. I think I get it.

One more question. Would it be possible to use a shimano chain ring with the sram eagle gear?

Apologies if that's a stupid question. New to this.

You can't use a shimano bolt pattern chainring on SRAM cranks if thats what you mean?

The new eagle chainrings seems to wear better and are a quieter than the normal thick thin rings.

As above, for a non-boost frame you want the 6mm offset. The 3mm offset is for a boost frame and hub where the cassette is 3mm further out. If you use a 3mm chainring then you will struggle to reach the largest sprockets.

The eagle GX is only available as srams direct mount as far as I am aware so shimano wont fit. It is possible to get 104 bcd spiders for sram chainsets to let you use a 104bcd chainring, make sure you get the right one with the correct offset. Something like a GXP 1x10 one should be fine. A boost one will put the chain too far out and a 2x10 one will also not be optimal and put it a mm or two further out.

I have just picked up a 1x10 sram spider to do exactly this and fit a 104bcd oval ring as the sram eagle oval rings are eye wateringly expensive. Works components have just stopped doing their 6mm offset sram ovals and I refuse to touch anything from a certain other make (UK based) after a recent experience.

Ok thanks, I think I'll stump up the extra for the eagle chainring then. At least I know it will work.

Thanks for the advice.