Author Topic: AbsoluteBLACK sub-compact chainrings  (Read 2029 times)

AbsoluteBLACK sub-compact chainrings
« on: December 23, 2018, 05:43:31 pm »
With bigger ranges available from rear derailleurs I've been mulling over the idea of a sub-compact (super-compact) to replace the triple I've used throughout my audax career but they are all seem to be limited in some respects - either lowest gear not low enough, or too expensive, or require a non-standard BB.  I've trialled an ersatz version using inner and middle positions of a triple crankset (the old 130/74BCD kind) and found a 44/28 front 11-32 rear (10speed) was not too far from where I wanted to be in terms of total range, but the chainguard on the outer position wasn't pretty, the chainline was not quite right, and some of the jumps are bit big.
Anyway I was talking gearing with someone at the AUK reunion who mentioned that it is now possible to get a smaller number of teeth on a 110BCD (the newer 4-arm asymmetric kind) by going OVAL :o
So I went out on a limb and used the best of the Black Friday deals to get an R7000 chainset and a set of 46/30 rings to fit it.   What with one thing and another I didn't get to try it out until yesterday, but first impressions are quite positive.  I did one of my regular loops, with a couple of stops to faff, no PBs on any of the hills, but overall time was pretty good (for me) and I formed the (unproveable) impression that the lactic build-up was slightly less pronounced than with similar cadence/similar effort on round rings.

More to come when I've tried them out on longer rides.

Re: AbsoluteBLACK sub-compact chainrings
« Reply #1 on: December 24, 2018, 06:53:23 am »
I use an AbsoluteBlack oval ring on my 1x bike. The biggest thing that struck me when I first started using it was that it felt no different than a round ring. Whether it helps on the steep off-road climbs I wouldn’t be able to tell, but it certainly doesn’t hinder me.

Re: AbsoluteBLACK sub-compact chainrings
« Reply #2 on: December 30, 2018, 09:08:56 am »
Just been for my first ride since fitting absolute black oval sub compact.  Bike is trek domain with Di2.
Removal of the old rings was really easy as was fitting the new rings.  I saw on one website that they had managed to fit the rings without removing the crank.  This is not possible with the subcompact rings. you do need to remove the cranks.

I took the opportunity to fit a new chain.

Rolling out of the drive I felt no difference.  Changing was fine.  Dropped the chain on one up change.  I was in the 11 cog at the back and changing from small to big the chain went too far.  I will adjust the limit screw and maybe drop the derailleur 0.5mm as I was perhaps a little large on my settings.

Climbing my local hill with a reasonable 12% section which i use as a measure the sub compact did what i wanted and gave the equivalent of another gear.  On my way back i had no problems with my limited sprinting!

I have an incline on the way back on which i like to practise keeping the legs turning circles whilst still maintaining a good power.  This definitely felt easier.

The oddest feeling was on spinning backwards when I really felt the ovality of the chainrings.

At the moment I would give them 10/10 and my setting up 9/10.

Re: AbsoluteBLACK sub-compact chainrings
« Reply #3 on: May 15, 2019, 12:55:01 pm »
More to come when I've tried them out on longer rides.

After a frustrating period when a ghastly creaking noise seemed to make an appearance with these (turned out to the BB, not cranks or rings after all), and the tweakage necessary to eliminate overshifting shifting on the up change, I'm now happy enough to take them out on BCM600 this weekend.  Just wish my legs were as well prepared...

More to come.

jiberjaber

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Re: AbsoluteBLACK sub-compact chainrings
« Reply #4 on: May 15, 2019, 02:15:45 pm »
Point of note for anyone searching / viewing in the future.

Absolute Black 46/30 rings fitted to Ultegra crank. After a year of use, creaking on power stroke.

After replacing BB etc finally traced it to symptoms only happening in outer 46t ring, silent in 30t inner ring. 

Remedied by removal of rings and a good clean of the spacers and crank spider holes. 

The way the spacers machined into the rings are constructed is that they allow a void which collects dirt (gravel dust mostly) over time - quite a lot in my case!  Once cleaned and refitted - good as new!
Regards,

Joergen

Re: AbsoluteBLACK sub-compact chainrings
« Reply #5 on: August 08, 2019, 05:13:16 pm »
30 t inner is an awesome thing to know about.  :thumbsup:
Does not play well with others

Re: AbsoluteBLACK sub-compact chainrings
« Reply #6 on: November 05, 2019, 02:34:30 pm »
I love the low gears but do find that they slip occasionally - once every few hours. 
It feels a bit like riding on worn chainrings.

Probably the new Shimano gravel chainset has made them obsolete, if your aim is lower gears rather than oval magic.

Re: AbsoluteBLACK sub-compact chainrings
« Reply #7 on: November 05, 2019, 07:26:52 pm »
It's hard to see why making a chainring oval would allow it to be smaller (in terms of number of teeth), because ovals have both low spots and high spots. On the face of it, a circle of the same radius as the low spots would always be smaller (but, if the low spot is half-way between two arms, the radius might be too small to accommodate the BCD).

Didn't I read somewhere that AbsoluteBLACK also make small, round chainrings, just by doing a better job of designing the BCD into the circle? I don't have much faith in the oval business, because it's been "invented" and then debunked about once a decade since the days of Starley, but more-compact rings sound interesting.

Re: AbsoluteBLACK sub-compact chainrings
« Reply #8 on: November 05, 2019, 08:01:47 pm »
Shimano 4 arm chainring bolt holes aren't 90 degrees to each other, they're more like an X, so an O shaped chainring fits nicely.

Karla

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Re: AbsoluteBLACK sub-compact chainrings
« Reply #9 on: November 06, 2019, 12:50:22 pm »
Probably the new Shimano gravel chainset has made them obsolete, if your aim is lower gears rather than oval magic.

Indeed: the GRX600 46/30 double will set you back about £85 for the entire chainset, which is almost exactly the same as you'll pay for a pair of AbsoluteBlack rings. 

Re: AbsoluteBLACK sub-compact chainrings
« Reply #10 on: November 06, 2019, 01:00:50 pm »
GRX has 2.5mm wider chainline and a 5mm wider Q-factor, which may put some people off, and pushes the limits of non-GRX front mechs.

Re: AbsoluteBLACK sub-compact chainrings
« Reply #11 on: November 06, 2019, 03:22:39 pm »
I continue to love my absolute black.  I have no idea if it is the size or the oval nature.  i just find that I can pedal more smoothly for longer up steep hills.  I will always take a placebo!!

tedshred

  • AKA: Dirk - Let me see those hands
Re: AbsoluteBLACK sub-compact chainrings
« Reply #12 on: November 11, 2019, 02:24:35 pm »
On the back of a conversation with jiberjaber on Saturday evening, I have looked into the AB rings a bit further.

They appeal for my gravelly bike because you can never have enough gearing and I could use an ultegra power meter (of which I have a spare but I don't have one for Praxis) if I added them to an ultegra spider.

I am running Praxis Zayante 48-32 chainrings and a shimano 11-34 cassette on ultegra RX derailleurs.  I know the RD will take an 11-36 with no faff and an 11-40 with minimal faff. 

32/36 will give me the same ratio as 30/34.  That said, I could go full on and have 30/40 which would get even me up most things even with big tyres - if I didn't fall over due to lack of momentum.

What to do ?  The cheaper option is to buy a cassette.  Is the option of a 30 tooth chainring worth the additional expense ?  Is it worth it just because 11-40 will look a bit OTT ?

As for the GRX, the ultegra level chainset is 48/31 which seems a bit useless, never mind any chainline issues.  Had they been available when I built the bike, I might have gone for a GRX groupset.
The pleasure of pain endured
To purify our misfit ways

Re: AbsoluteBLACK sub-compact chainrings
« Reply #13 on: November 11, 2019, 02:53:08 pm »
You can use the Ultegra power meter with the GRX right spider - the splines are the same.

The only real difference between the 610 and 800 is weight, because it uses Tiagra-style C-section cranks. You lose half of that extra weight when you swap the left crank.

(My 165mm RX610 46/30 is 535g drive side, 271g NDS)

tedshred

  • AKA: Dirk - Let me see those hands
Re: AbsoluteBLACK sub-compact chainrings
« Reply #14 on: November 11, 2019, 03:32:09 pm »
Interesting.

Zayante 48/32 is supposed to be about 712g.

Ultegra 6800 50/34 is about 677g but I am unsure what difference the AB rings make to weight - you can also buy AB rings for the Zayante of course.  The weight is pretty marginal.  It is the performance I want to keep up.

What derailleurs are you running with the GRX ?
The pleasure of pain endured
To purify our misfit ways