Well Cannondale introduced this for a number of there bikes.
What is Ai (asymmetric stays)? Well put simply it is the drivetrain being moved 6mm to the right meaning the stays are no longer symmetric. This has the effect of changing the dish by 6mm. So wheels built for a bike with symmetric stays cannot be used in a bike with Ai. It is not possible to redish wheels either to acco.adte this standard as spoke lengths will be 1mm off. I wont do it other may but it's a mistake as its building potential problems for the wheel.
The upside is tensions are more even.
All disc brake wheels I build with the BORG DX hubs can be built for the AI standard. I can rebuild wheels built for symmetric stays with new spokes of the correct length for th AI standard. Some hubs may not be suitable due to there geometry but most rear hubs are suitable.
Ai bikes are all 12m TA.
I do dispute cannondale claim that radial and lateral wheel stifness increased by using Ai. Making spoke tensions even does not increase wheel stiffness. Lateral stiffnes is actually reduced by a couple of percent due to reduction in the left side bracing angle. The left side bracing angle contributed more to lateral stiffnes than the right side. That geometry and cant be argued with. Radial stiffness will be reduced as the right spoke bracing angle is increased. So the upto 60% claim in cookoo land territory. There is a weak link between tension balance and radial and lateral stiffness but since disc brake wheels have good tension balance to begin with the improvement of evening the tensions is very limited. In principle you can increase the loads required to detension spokes (often confused with stifness) but have tou tried loading a wheel till the spokes detension on Borg wheel. Not easy. So as with all thing take the marketing with a pinch of salt. However Cannondale use it and if you like there bikes using this design feature you need compatible wheels. The Cycle Clinic builds great wheels for these bikes.
From cannondale's website
The heart of the Scalpel-Si and F-Si System Integration is the all-new, Ai, asymmetrically offset rear triangle and drivetrain. The offset shifts the rear hub and drivetrain 6mm to the right, delivering 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 then integrate this with our new Ai HollowGram spider, which moves the chainrings an equal 6mm to the right, balancing the system and maintaining perfect chain-line, shifting performance and Q-factor. This elegantly simple approach - Ai - enables us to have our cake and eat it too. The extra space created by shifting the drivetrain outboard enables us to have:
- The shortest chainstays on the market, for incredible traction,
- Stiffness and agility.
- Up to 60% increase in rear wheel stiffness.
- Dual chainring compatibility with super short stays.
- Tons of mud clearance.
- Ample tire clearance with the chain and front derailleur.
It started being used in 2017. Cannondale dont state on there website which model use this design feature. There catalogues do. The Cycle Clinic are not Cannondale dealers so it is not easy for us to identify which models have this feature. Before ordering please ensure your bike has Ai,this is best done with Cannondale or knowledgeable Cannondale dealer.
In the 2019 catalogue the SuperX, Jekyell 29 and 27.5, Scalpel SE and Scalpel Si used Ai. However there maybe other models too.
I have been stung once before with an american customer ordering wheels for Ai then using them briefly and returning them because they did not fit his bike. His credit card company forced a refund (I was going to refund anyway but no one like being forced to do something). Therefore it is important you check first. I like customers who trust me if they do I can help them.