Absolute Black 46/30 on Ultegra - chainline issues?

Watches with interest, as thinking about getting some sub-compact rings

I have a GRX chainset on my CX bike so will swap across with the stock Shimano rings, which should achieve a 5mm outboard chainline shift, will see if the little tinkles and clunks go away.

For what it's worth after less than 100km on the 46/30 setup, I'm think a bigger gap at the front would be better. The GRX chainrings are 48/31 so can test that theory.

Is it on the small or big ring?

not quite your issue (and just my experience) but i switched back to Shimano rings after trying Absolute black for about 1000km - never shifted as cleanly and definitely more noisy. I didn't check chainline TBF

Also intrigued. I had no idea these existed until a month or so back. Am I right in thinking that you basically have to run either 46/30 or 48/32, but you can't mix and match?

Is it on the small or big ring?

Both. I could understand it just in the wee ring (Shimano advise against these combos anyway) but not in the big ring.

never shifted as cleanly and definitely more noisy

Generally I like them, in fact the shifting on my road bike is probably better than the standard Shimano rings! AB do recommend Dura Ace chains for some reason, wonder if it's a noise thing (I'm using a £50 YBN chain that got good reviews).

Am I right in thinking that you basically have to run either 46/30 or 48/32, but you can’t mix and match?

Yes, exactly this. The bolt arrangements to fit smaller chainrings require specific threading etc. on the smallest ring. Hence also the 2.5mm offset.

@13thfloormonk any chance of a link to those, I can't seem to find them anywhere. Thanks.

I think these rings have a 2.5mm offset inboard

Worth trying a 2.5mm spacer on the bottom bracket to offset that? They're only pence.

Then there would be insufficient NDS crank/axle overlap.

@bazz here you go

https://absoluteblack.cc/oval-road-chainrings-30-46-and-32-48-for-110-4bcd/

Just select 46 + 30 + bolts.

Or if you want to visit one of the finest bike shops in Scotland and ogle some boutique Ti and carbon framesets then I got mine at Synergy Cycles in Auchterarder.

Worth trying a 2.5mm spacer on the bottom bracket to offset that? They’re only pence.

I do miss the old system of being able to swap spacers around! Wouldn't want to risk it as sillyoldman says, would leave 2.5mm less axle in NDS crank 😬

It occurred to me that the Wipperman reusable split link has deeper side plates than normal split links, so will swap it for the stock YBN split link, and then will try the GRX cranks with 'normal' Shimano rings, which will be 5mm further out in total.

Sadly that would leave me with 100km old chainrings and Ultegra cranks, so keep your eyes on the classifieds! 😉

Thanks @13thfloormonk unfortunately being at the farthest end of England i fear a visit to Synergy cycles is unlikely!

No help other than to say it *can* work:

I have 46/30 AB rings on 105 (11 speed) on a 130mm OLN, 405mm chainstay road bike. Other than the FD being very finicky to set up (the rings are really a little too far in-board for the FD) they work perfectly. I guess my smalles (11T) sprocket will be roughly where your 2nd smallest sprocket is (due to 5mm OLN difference) and it doesn't have any problems.

I also have a set of 46/30 BikinnGreen round rings on ultegara (11 speed). They're even more in-board (perhaps -5mm chainline) so FD set up is even harder, but they also work fine on an 11 speed setup with 142mm rear and 418mm chainstays after hours fettling the FD. No problems at the cassette/RD end though.

TBH I'll probably go Middleburn R02 next time as the chainline is easier to deal with for the FD.

Sadly that would leave me with 100km old chainrings and Ultegra cranks, so keep your eyes on the classifieds!

Dibbs!

Thanks @mcbyker that's good info.

I think the chainstays on the gravel bike are closer to 440mm so that will improve the chainline. Overall it will certainly be better than your 142mm setup.

Still leaves me a bit stumped, will swap the quick link and if that doesn't work will experiment with the GRX rings and cranks.

IHN - noted 😎

@mcbyker - would a GRX front mech solve your front mech finickiness?

@scottroutes no, the AB chainrings are closer to the seat tube than normal i.e. smaller chainline....GRX chailine is wider than 43.5 road standard, I belive. So GRX FD would actually be worse 🙁

@mcbyker I should have asked - what chain(s) are you running?

I measured chain width and my YBN is no wider than stated width of a Dura Ace (AB's recommended chain).

I had a look in the stand, in big ring when backpedaling the chain definitely catches on the next biggest sprocket, but there's no obvious catch when forward pedalling. Quick link isn't catching either, so one way or another I think I'll be swapping chainset. There's perhaps some other quirk of geometry (or flex in a skinny steel frame?) which is causing it.

Hi @13thfloormonk - just wondering how you got on with the 46/30 absolutes. I've put a 34T inner oval on my ultegra cranks, but it's not enough of a difference. I'm off to the alps in June, and suspect i should fess up, admit I'm not as strong as i was, go 46/30 and potentially enjoy the climbs

Riding a 50/34 - 34/11 at the moment

I sold them ☹️

Never actually caused any issue but my OCD couldn't live with it. Re-fitted stock GRX cranks with 48/31 and never looked back.

I think some time after there was a thread on here about certain Shimano cassettes that might have demonstrated a similar issue, but it was too long after the fact to be sure it was the cause of my odd noises...