A Really Brief History of Rotor
Rotor the company had its roots in Spain at the Aeronautic Engineering School in Madrid. Their Rotor cranks revolutionized the bike industry with its bold and innovative engineering. Some might be sad to know that this review is on the Rotor Q-Rings instead of the cranks. However, both are design with the same purpose in mind – to get rid of the pedalling dead zone.
What is wrong?
When a person is cycling, he will experience a loss of power when the pedals reach the 6 or 12 o’clock position. At these positions, the pedals are already at the minimum and maximum displacement from the fulcrum of power generator of the bike – the hips. When the pedals are at the 4 or 10 o’clock positions, there will be a better ability to load more driving force into the cranks.
The reason why it’s harder to pedal when the cranks are at the 12 and 6 o’ clock position is because the three essentials for a lever system, the fulcrum (bottom bracket), the load (chain) and the effort (pedals) are all in a vertical line. This means a much higher effort is needed to initiate movement. Apparently Rotor saw this and decided to make the “dead spot” faster by letting the crankarms pass through the positions easier by reducing the effective teeth count. Rotor claims their elliptical design factors in other variables such as leg and bike inertia into account.
In addition, the Q-Rings include various adjustments which riders can tune according their personal preference. These include the compensation of inertia into the pedalling stroke and preferences of when the point of maximum effective teeth comes into play. There are a total of 5 positions where you can change each chainring to (though only the middle three are officially marked with 1, 2 or 3 dots respectively), and you can put the chainrings at independent adjustment positions to the other Q-Rings.
While Ahmad at Cyclecraft fitted on the LX crankarms with the Rotor Q-Rings, he noted that the effective chainline was particularly important. The different bend at some of the frames’ chainstays, may not have enough clearance for the Q-Rings. But this can be easily rectified by using some spacers on the driveside of the bottom bracket.
Another major adjustment will be the front derailleur (FD) clamp height. You’d be out of luck if you were using an E-type FD. In all likelihood, your FD will have to be moved up by about 2 to 5mm higher than its current position, assuming your largest current chainring is 44T. In addition, should you be fitting the Q-Rings onto your bike by yourself, do pay attention to the inner cage plate clearance between the FD and the highest point of each Q-Ring – notably the middle ring. For the DIY folks, it would help to have a workstand for you to work your bike with – you already have one, don’t you? Rotate the cranks slowly and shift the chain slowly between them, and note the clearance. You wouldn’t want your new chainrings to rub your FD inner cage plate raw, or the other way round. Either way, it’s bad news; but rest assured that it can be worked around with no hitches. The set of 3 Q-Rings for mountain bikes come standard for the 104/64mm BCD in a combination of 44/34/24, and weigh only a scant 136g.
General Usage Notes
The first thing that struck me about the Q-Rings was the excellent shifting quality and its high quality CNC finish.
Some people might ask, why not get the Rotor RS4X crankset instead? Well, if you’re a weight-weenie or are a fairly lightweight person, you might want to know using the Q-Rings hardly add any weight to your current bike setup, while the Rotor crankset is heavier and is fairly complex to set up. And did I mention about cost? Do take note that the Q-Rings does NOT do away entirely with the dead spot, it only serves to vastly reduce it. If you want something that does the job better than the Q-Rings, then you might want to look at the RS4X crankset.
This should have been a general note, but the first time I pedalled slowly on the 24T granny Q-Ring on level ground, I could feel the difference it made right away within 5 meters. Having had some knee injuries years before, I was thoroughly floored at the way it did away with the “vacuum” while pedalling, especially when the crankarms were at about the 12 and 6 o’ clock positions.
For those who have had knee injuries or Patellofemoral Pain Syndrome (including CMP or Chondromalacia Patellae), you will be relief to know that your knees can be relieved of the usual stresses while wanting to ride longer or further, especially when riding offroad.
Being used to riding at high cadences, I was also very impressed with the gradually increasing acceleration of the cranks while pedalling. The effort needed to pass the crankarms through the TDC/BDC was so much lesser and the gradual increment and decrement of this load was so well thought out. The Q-Rings allow a naturally high cadence pedalling while riding on road. For off-road, it allows a reduction of required effort at the right phases of the pedalling motion to assist you to get more power for the same effort. Not forgetting the Patented OCP (Optimum Chainring Positioning) design offers independent adjustability within each individual chainring to suit a rider’s style.
The primary pitfall of the Q-Rings would be the cost. At over S$300 per set, it’s quite a bundle.
I didn’t ask for the manual when I had the Q-Rings installed on my bike, and it brought me to search for it online. No such luck though – it was unavailable for downloading from the main Rotor website. I did ask for it when I returned the review set, but the manual looks pretty scant for a product that I personally had some liking for during the testing period. (Edited 5th August 2006: the PDF file can be found on the Rotor USA website now)
Lewis mentioned to me that a rider may want to ride for over a long distance or long time to get used to the settings of the Q-Rings. So in a way, that may take up a long time to dial in your optimal personal settings for the chainrings.
And for loghoppers out there, there may be a slight concern in case of accidentally smashing the big ring into obstacles. You’d need to work out only an extra 1 cm or so under your BB when clearing obstacles.
All in all, some things can’t just be weighed by price alone. It’s probably like buying a BMW or a Kia – both will work, but the pricier item may work a lot better, despite having some quirks of its own. If you’ve have a problem or had reconstruction surgery at the knee(s), the Q-Rings may just magically transform your riding that you’ve taken for granted to the next level.
The Q-Rings are available for several categories of usage as listed below
Cross-country / Freeride
- 104mm BCD outer 44T
- 104mm BCD middle 34T
- 64mm BCD inner 24T
Cross-country, XTR 2003 dimensions (Available June ’06)
- 146mm BCD outer 45t
- 102mm BCD middle 33t
- 64mm BCD inner 23t
- 104mm BCD middle 38T (or Singlespeed, available June ’06)
- Shimano 130mm BCD 53/40T or 54T (Time Trial)
- Campagnolo 135mm BCD 53/41T
- Compact Crank 110mm BCD 50/36T
There are some slight issues, as listed in the official Rotor Bike website:
- Campagnolo Compact cranks: At this point in time, only the 41T inner road double chainring for Campagnolo will fit the new compact crank. If demand is sufficient, we will design a specific Q ring for these cranks.
- Stronglight compact cranks: A number of Stronglight compact cranks have been known to pose problems in installing Q-Rings because of carbon fiber reinforcements that interfere with the OCP ring behind the crank arm.
- FSA pre-2005 Carbon cranks: A ridge on the back of the crank arm on 2004 and earlier FSA carbon cranks prevents Q-Rings from being installed on these cranks.
- New Shimano Compact: Q-Rings will not fit the new 2006 Shimano compact road cranks.
- E-Type Derailleurs: Q Rings will not work with E-Type front derailleur.
[Edited on 8/8/06]
We got a few queries stating that the Q-rings are nothing more than the old Shimano Bio-pace rings in the 80’s. While we agree that the concept and form between the two seem very similar, they are distinctly different in a couple of ways.
The Bio-Pace chainrings have the maximum equivalent tooth size at the dead-spots, while the opposite is true for the Q-rings. This enables you to pass through the dead-spots quicker with less stress to your knees.
The Q-rings are elliptical while the Bio-pace and O.SYMETRIC chainrings are asymmetrical. The specific elliptical shape of the Q-rings allows a smooth uniform pedaling stroke with no sudden acceleration movement.
- The ROTOR patented OCP system enables you to customize the position of the Q-Rings to suit your own needs as mentioned in the review.