110 BCD but not?

[ishaw]

So, I bought some cranks ages ago and stashed them away. They are modern, but the appeal was that they were marked up as 110 BCD so a retro MTB ring size (or modern road I guess).

However I got them out of the stash today to see what rings I had that would fit them, I should have paid more attention when buying as they are 4 arm, not 5 so none of my old style retro rings are going to work

What is this whichcraft, non 110 BCD, 110 BCD? How can a 4 arm spider be 110 BCD? I'm confused? I will say that the 4 arms aren't evenly spaced, so even if some of the spacing is 110 BCD, some aren't.

That's confusing, wasn't like this back in the day until compact, then 104, but at least you knew what was what.

 

[dyna-ti]

Might be helpful, or at least a starting position.
https://www.sheldonbrown.com/cribsheet-bcd.html#fouruneven
Good old Sheldon Brown, what a legacy, what a resource that man created.

 

[primo]

sounds like an asymmetric bcd, are they FSA cranks by any chance?

 

[ishaw]

They are FSA, though Shimano and SRAM also make them it seems, and none seem to use the same spacing where it isn't 110 BCD. Why, why why?????

 

[legrandefromage]

I have noticed many rings come with little extra bits of metal so you can't interchange brands until the grinder has had a word

 

[primo]

They are FSA, though Shimano and SRAM also make them it seems, and none seem to use the same spacing where it isn't 110 BCD. Why, why why?????

that's correct Shimano's 4x110 abs bcd does differ slightly to FSA's, which FSA chainset do you have as I can likely source a chainring for you..

 

[ishaw]

that's correct Shimano's 4x110 abs bcd does differ slightly to FSA's, which FSA chainset do you have as I can likely source a chainring for you..

Thanks. It's the k-force carbon ones. I was hoping I could swap out the double rings for a narrow wide and use on my gravel bike in place of the apex 1, just because.

Narrow wide rings seem plentiful and cheap in almost all other bcds except this new 110, whether Shimano, FSA or SRAM.

 

[Woz]

It's a damn silly nightmare out there now. Not to mention the odd off-set bolt trick they have dreamt up.

Patience with this issue ran out a long time ago.

 

[primo]

Thanks. It's the k-force carbon ones. I was hoping I could swap out the double rings for a narrow wide and use on my gravel bike in place of the apex 1, just because.

Narrow wide rings seem plentiful and cheap in almost all other bcds except this new 110, whether Shimano, FSA or SRAM.

k-force uses its own specific outer chainring sadly, no current option for a 1x chainring in the FSA range that's compatible unless you have the K-force modular chainset... post up an image and I will confirm.

 

[ishaw]

Bummer. Pretty sure it's not modular as the spider is integrated with the arm iirc. I'll check tomorrow.

I thought about swapping with my road set which are older but proper 110 BCD but that's bb30 so not compatible with my gravel frame which is a threaded BB.

Pretty sure when I bought them the seller had a narrow wide ring, but he wouldn't sell me it as he was not happy they went for less than he wanted.