Our sponsored World Champs XC racer switched over to Cannondale recently, and she quickly needed some new wheels for her Cannondale "Ai" Scalpel. Ai stands for Asymmetric Integration and means the rear wheel has a specific 6mm dish (to the non drive side). More on that in a moment.
She rides Project 321 hubs, and the beauty of the system is that standard hubs can be used, along with standard rims. From the wheel perspective, we have to build to a specific offset.
Cannondale says the offset shifts the rear hub and drivetrain 6mm to the right, enabling super short chainstays without any of the usual compromises and a rear wheel that is dramatically stiffer and stronger because the spoke tension and angles are equal on both sides.
We say close to equal in most cases, very close. It is important to note that this approach negates the benefits of asymmetric rims. So if you are building an Ai wheel, stick with a centre drilled rim (for the rear at least).
The new Cannondale Ai HollowGram chainring spider also moves the chainrings 6mm to the right, balancing the system and maintaining perfect chain-line, shifting and pedal Q-factor. This very simple approach enables:
- The shortest chainstays on the market, for incredible traction, stiffness and agility.
- Up to 60% increase in rear wheel stiffness (claimed by Cannondale).
- Dual chainring compatibility with super short stays.
- Better mud clearance.
- Better tyre clearance with the chain and front derailleur.
Note how the dotted line runs down centrally between the hub flanges (on the Ai dished rear wheel in the illustration above).
To make this happen, Cannondale moved its entire right drive-side outboard by 6mm. Calling this its Asymmetric Integration (Ai) drivetrain, the chainstays are asymmetrical. In the case of the Scalpel, this requires a standard 142x12mm rear wheel to be redished 6mm to the left (no Boost here - we need to save as much weight as possible).
The "free" upside of this approach is a very close to evenly dished rear wheel (it all depends on what hub you are using) for a stronger wheel with less and more even lateral flex characteristics.
The downside is that off-the-shelf wheels or your old wheels are not usable on an Ai bike without a redish, or potentially a reposke. But hey, better than having to buy a whole new wheelset ... or is it.
As experienced wheel builders, we can adjust a stock build or hand build from scratch to make sure your new (or old wheels) will fit an Ai Cannondale.
Get in contact if you have a Cannondale Ai bike, and need some new wheels, or perhaps think your older wheelset might work well in your new Ai bike. It's what we do.