ROTOR’s latest Qarbon Qrings are lightweight and rigid elliptical front chainrings, sometimes referred to as ‘oval’. They are part-carbon in construction and come in a variety of sizes for the outer front chainring.
“Qarbon is designed to work with all 9, 10 and 11-speed drivetrains. It is available in 110 BCD and offers 3 versions: 53, 52 and 50 teeth. Qarbon can be combined with any 110 BCD inner ROTOR 5 arm chainring. These do not fit the Shimano 4 bolt 110 BCD.” Source: velotechservices.co.uk
I looked at the Qarbon 53T and a non-Qarbo 38T, I think, inner.
Positives: Some cyclists, including myself, believe that elliptical chainrings reduce deadspots in their pedal stroke and either increase power or decrease the effort to get a given level of power. They are said to reduce knee problems.
The theory behind this can be simplified to “the ellipse ensures that a greater portion of the pedal stroke is spent around the point where your pedal stroke is most powerful”.
When combined with the MAS spider (shown in the image) the number of fitting positions are doubled from 5 to 10 by adding half-positions.
The marketing blurb says they are 8% lighter and 20% stiffer. I’m sure that’s true. They also claim use by “70% of the pro peloton”.
They are very simple to fit, requiring an allen key/wrench or two. If you have a pointy/armed/spider-shaped spider (!) then you can often wiggle the smaller chainring over it without having to remove the drive side spider.
ROTOR dealers should normally offer a 30-day money-back guarantee. If you buy them and don’t like them you return them for a refund. You can’t get fairer than that. The first time I bought some, the dealer even fitted them and adjusted the derailleur for free. Nice!
Negatives: Whilst the rings themselves are easy to fit, getting the front derailleur positioned ‘just right’ for optimal shifting takes a little longer. In reality you will most likely lose a gear or two where the chain rubs too much on the front mechanism. Not the end of the world as those are the gears where your chain is twisted the most anyway.
It is not obvious which setting to use. Is it 1, 2, 3, 4 or 5? Until recently the initial ROTOR recommendation has been ‘3’. Or change it by experimentation and I seem to remember that on TT bikes ‘4’ was said to be worth a go too. This seemed quite unscientific to me despite the experimentation involved!
Note: The ROTOR MAS spider needs to be removed in order to fit the smaller chainring. But that just requires a large allen key/wrench and even I found it simple to change.
Comments: I have used Q-Rings for several years and have been happy so doing. Usually I preferred to use only the larger, more expensive, chainring and keeping the smaller/inner circular one for occasional forays into the hills. Mainly this was for the reason that the smaller circular chainring seemed to give me an extra half a gear over the oval at the very low end – especially when I needed it on a particular local PB-testing route. I only had them on my TT bike and really I used them because it did seem to make my stroke smoother and my position more comfortable accordingly – I didn’t really use them for reasons of ‘extra power’ per se but presumed there would be some immeasurable benefit there somewhere.
However, as part of a wider look at the entire ROTOR MAS spider and the INpower axle-based power meter I have gone through somewhat of a revelation. The Inpower software very quickly told me that I should use setting 5 by working out my Optimum Chainring Angle (OCA) and consequent Optimum Chainring Position (OCP – see image above). With a new setting of OCP=5 I *IMMEDIATELY* set a series of personal power-duration “PBs” up local hills. The efforts were markedly better (several %) than previous efforts over the previous 6 months. And these efforts were all done without much recent bike training and whilst run-fatigued. I am 99% sure the data was correct as I had 2 power meters.
These benefits were mostly demonstrated in this test on the inner, non-Qarbon Qring chainring. Indeed the MAS spider was also able to let me choose half positions eg position 4.5 or 5.5. I’m still working on fine tuning that.
The benefit on the outer should be the same, as the effect of the ovals is the same I am told.
To complicate matters I believe the older ROTOR QXL Qrings have a different type of oval which may suit more extreme positions (like my TT position) even more. I will realise in 4 years time that I should have got one of those probably! Sigh.
Conclusions and Recommendations:
It seems I’ve got it wrong over the last few years … big time.
My recommendation to you is to give them a try. Remember the money-back guarantee. You really have nothing to lose.
For me it is clear that I need to keep using the repositioned big Qring and start using the smaller Qring again.
It also seems very sensible for me to say to you that you really need to get the position correct to achieve the benefit, otherwise you might be wasting your time. But I can’t see how you would get the position right without either one of the newer INpower power meters or, perhaps, by inferring data from a wattbike session (Polar View – angle of peak force).
If you want to go down this route nag your dealer for a quick go with a ROTOR power meter on one of their bikes with a PC next to the trainer for a quick 5 minute test. That’s all it really needs. I would suggest that intuitively it seems that the further away from positon 3 (ie OCP=1 or OCP=5) you are tested at for optimal positioning then the greater the benefit is likely to be. That seems to be the case for me.
Unless you are after every last micro-watt of power and weight, I don’t think you need to go for one of the Qarbon, part-carbon rings. The regular non-carbon ones will be pretty much exactly the same in terms of changes to pedal stroke dynamics. They might flex a bit more , especially >=53T, but they are cheaper.
Alternatives: There are many others such as from B-Labs and Wolf. The elliptical chainring was invented decades ago.
Detailed Review: A look at the INpower 3D+ Power Meter, the MAS Spider and Qarbon Qrings.
Price (rrp) At £170 they are not cheap. You should be able to get them from any ROTOR dealer such as Sigma Sport.
Disclaimer: I think the ROTOR distributor has given me these to keep. I’ll have to check. I bought all my other ROTOR Qrings – just failed to optimise them properly :-(. Personally I couldn’t justify the cost of the Carbon rings BUT I would, have and will now continue to use ROTOR’s Metal-only Qrings when performance is important to me.