Shifters: better ergonomics
The shapes of both the mechanical and electronic shifters have changed. They are now more similar to one another than ever before. The mechanical shifters are slimmed down and rounded, doing away with the previous generation’s fairly blocked shape.
The hood is now a dual compound with softer rubber where hands rest most often. The new 9000 shifters offer the same 10mm of reach adjustment as before, but getting to the adjuster bolt is much easier. Installing cables is also much easier, something mechanics will appreciate.
The lever throw, or stroke, is a third less for a given shift and begins more outboard and finishes with the lever closer to vertical than before. This means that the shift occurs where a rider’s hands are at their strongest.
Brakes: designed for wider rims
The new brakes are compatible with current Shimano offerings. So if you’re looking for a brake upgrade, you can bolt on the 9000 brakes with no problems. The newest Shimano stoppers are designed around 23mm rims and will handle widths up to 28mm with an aftermarket pad that is a bit thinner. Previous brakes were designed for 21mm rims.
Braking power and modulation are both improved and during a brief spin on the bike (riding aluminum rims), the braking felt incredible. The brakes are extremely powerful and the modulation is fantastic.
The brakes now have three pivots, two rotating on bearings and the third on a bushing. The anchor bolt is no longer a pivot and Shimano claims that making all the arms shorter decreases friction in the system.
Shimano will also offer a direct-mount brake for use on time trial and aero road bikes. There is also have a quick release that splices into the brake housing, handy for many aerodynamic bikes (or possibly for use on cyclocross bikes with cantilever brakes).
Cables: new coating
New cables for both shifting and braking also help the group. Priced comparably to current cables, the new offerings have a polymer coating to reduce friction by a claimed 10 percent. Shimano’s Wayne Stetina also pointed out that as the polymer is worn off it doesn’t gum up the housing, “unlike another popular high-end cable set on the market.”
Derailleurs: lighter action
New styling cues are used throughout the group. While the new rear derailleur has an updated look, the front derailleur is a departure for Shimano. Its most striking feature is the extended arm for the cable anchor bolt on the front derailleur. Thanks to it, the overall force required to shift is greatly decreased.
Shimano’s design goal with the new 9000 series was to recapture the light action of Shimano’s venerated (my favorite) 7800 group that was lost in the 7900 group. Shifting the new group while it’s in a workstand shows that Shimano has been successful. On the road, thanks to the smaller shifter body, excellent ergonomics and light action, the group delivers exceptionally fast shifting. Front shifting in particular is phenomenal. The amount of force required is reduced, especially at the end of the now-shortened lever throw.
Unfortunately there is no backwards compatibility with the 9000 group. The amount of cable pull for the rear shifting is somewhere between current Shimano road and current Shimano mountain derailleurs. So you can’t buy the new derailleurs and use your current shifters, nor can you buy only the new shifters.