As Shimano is the market leader when it comes to cranks, Rotor knew that making QXL chainrings to fit the S-company’s cranks was essential. Here you have an Inner Chainring.
Rotor has taken their Q-Ring concept to the next level. Their QXL Inner Chainring has increased ovality, 16% rather than 10%, for greater comfort and power transfer.
If these numbers mean nothing to you, you probably don’t have Rotor Q-Rings on your bike. That’s important, as Rotor believes that experienced Q-Ring users will benefit the most, and adapt the easiest, to QXL rings.
To give an example of how the ovality works, a nominal 53-tooth big ring is a virtual 49-tooth ring at the dead spot, and a virtual 57 at the moment of peak power.
The basic idea of Q-Rings, which is taken farther with QXL, is that since your body can’t produce equal power throughout the pedal stroke, it would be better to work with your body’s strengths and weaknesses to have a bigger gear where your legs are most powerful and a smaller gear where your legs are least powerful. This, btw, is the reverse of the much-maligned Shimano Bio-Pace system which came and went years ago, but has given non-round rings a bad name ever since.
Rotor sees these rings as ideal for racers and other folks who produce lots of power and pedal at higher cadences. The dead spot area offers more rest and the power stroke area more power. The result is you go faster with less effort.
The rings can even be tuned, which is why you see multiple bolt holes throughout the ring. There are five positions, which Rotor calls OCP5, for Optimum Chainring Position 5, so you can adjust the point of peak power and peak rest to perfectly mesh with your pedaling style. A guide comes with the ring to help you determine your perfect position.
The rings start out as solid 7075 aluminum plate and are CNC-machined into shape.
The rings are designed for both 110mm (compact) and 130mm (standard) bolt circle diameter five-arm spiders. 110mm rings come in 38 and 36. 130mm rings come in 41 and 44. In both cases, the size is limited by the spider. They are designed for 10- and 11-speed derailleur systems, though 9-speed should work as well. You can mate them to round, Q, and QXL inner rings.
This Shimano four-arm Rotor QXL Inner Chainring is extreme to make extreme climbing easier.