On Test: Rotor Q-ring Chainrings

 Elliptical chain rings are not a new invention, Shimano touted their 'Bio-pace' rings in the early 90's and they are still the butt of most cyclists jokes to this day. They were flawed, but the understanding as to why has only come to light in the past few years, thanks to companies like Rotor. Unfortunately Rotor have the unenviable task of trying to convince people that their idea actually works - when they have all heard about how "Oval chain rings don't work because Shimano tried it and if they can't get it right how can a small company from Spain hope to?"

Let's start by looking at the point of an Oval chain ring. To do this you need to understand 'dead spots' in a bicycles' drivetrain. This is a bit of a misnomer as the drivetrain components (chain rings and cassette) are round and as such cannot 'pulse' or produce a dead spot themselves, the dead spot comes from how we power the drivetrain which means looking at the crank arms.
I think 'dead spot' is a bit of an inaccurate term and will use the term 'dead phase' from now on - let me explain. When the crank arms are in the vertical position it is nigh on impossible for you to put any power through the drivetrain, as opposed to the horizontal position where you can put a large amount of force through it (see diagram above)
To overcome this we could do two things, either make the cranks longer at the vertical in an effort to get more leverage (therefore power) into the system (a mechanical nightmare I would think) OR make the chain rings oval to give us the leverage to overcome this 'dead phase' or loss of power production.

So how did Shimano get it so wrong? Well I admire them for trying I really do, but the system was flawed because the ellipse was oriented in the wrong plane with the smallest part of the chain ring being in the horizontal position when the cranks were oriented to the vertical, effectively accentuating the power loss rather than promoting power gain through the dead phase of the cranks. It was also fixed in one position.

 Rotor have addressed the issues that Bio-pace had by switching the largest portion of the 'egg' to coincide with the cranks at the vertical position stretching the chain and giving you the torque to get you through the dead phase, but they didn't stop there, they have also given you the option to either advance or retard the timing at which you reach the power point of the chain rings.
 Feel like you're reaching it to early? Switch it. Feel like your reaching it to late? Switch it again. You have the option to play with five positions, three on one side of the chain ring, two on the other, hence the outer ring runs two chain drop pins. Rotor tag the option to find your ultimate position OCP or Optimum Chainring Position and they advise you ride at least 500km (200km on a MTB) following a four phase adaption process before making changes and formulating opinions.

So what are they like? I was keen to try them and allured by the promises of extra wattage and power (4.1% power and 9.1% less lactate - can you even measure this?!) but was aware that there may be a placebo initially because of the packaging claims. You need to take care to order the correct BCD for the cranks you are running (130mm for my five arm Ultegra).

Fitting was quite easy, you still need the 1-3mm gap to the front mech, you just measure it from the tallest point of the chain ring (about when the crankarms are horizontal - see pic above). One of the most asked questions I get is "Are they both oval?" Yes the inner ring is oval too, but I have heard of people running a standard round ring on the inside.

Once fitted and chain ring bolts torqued, they look the business (in my opinion) I love the way they pulse when you spin the cranks, it gives the bike a real 'pro' look. Rotor now advise that you take your first 500km at a steady pace to allow your mind and body to adapt to the rings, so don't whack them on mid-way into a season and expect good results, in fact you may get just the opposite as these rings will work parts of your leg that round ones don't - smash these poor muscles before they are trained and you'll go backwards quickly and may even injure yourself, IGNORE THIS AT YOUR PERIL!! because I can honestly say that I haven't since a kid had pain in my calf muscles, but after two spins on these chaps I was in bits! I took this as a good thing though, I was using muscles I hadn't before and making my legs stronger.

The weird thing about these rings when you first try them is that they don't feel like they are oval at all, they feel smoother to turn than a set of rounds do!  The finish of the rings is top dollar with some lovely etched logos and they have lasted well - I have now done well over 800km on these rings now and they still look box fresh.  I am still running them in the suggested position three and find this suits my style of riding best.

It's not been all smooth running though, the shifting quality of the rings isn't a patch on a set of Shimano's finest - some of this can be put down to their ovalness - but the pick up and drop-off from small to big just isn't crisp enough and I've had some bad chain drops when under 'full beans'

I also think these rings aren't for everyone. If you have spent years developing the perfect spin - or you spin a high cadence, stick with round rings - these won't help you. But if you want a 'perfect spin' and don't want to spend years perfecting it or you turn a big gear at a low cadence (like I do) I think you'll get on with these rings a treat, buy some! (Rotor give you the option to do a 30 day free trial)

Overall these rings really highlight the dead phase in a set of round rings and I really notice it when switching back to my MTB, but now I know it's there (and you really do with flat pedals) I can adapt my pedaling to suit, something I'd never have thought of prior to the Q-rings. Good stuff.