12-speed Ultegra 81xx Di2 install and (first) use impressions
 

After 14000kms and time to replace the second cassette on my SL7, I decided to strip off the 11-speed 80xx series Di2 and go for 12-speed. I contemplated Dura-Ace for about a minute and then decided to buy Ultegra. I’ve had a few DA parts here and there over the years, but Ultegra has always served me well, and the dollars/euros were more important than the grams.

Install: It was easy, considering the frame (aero type road with all hosing hidden…no cables up front certainly helped!).
(1) Plugged the RD into the battery, slapped it on the charger for about an hour.
(2) Prepped the bike by removing the crank, the BB, and all of the 11-speed Di2 bits.
(3) Plugged in the FD, and toggled the Bluetooth connectivity mode so I could use my phone to “talk” to it; created a bike profile in the E-Tube app, and then paired the shifters (R then L, but it probably doesn’t matter) to the system.
(4) Started hanging parts.

• installed the rear brake caliper, which came filled and with a 1700mm hose which I ran through the frame and left the free end hanging out of the headset
• installed the front brake caliper, came with a 1000m hose, to the fork
• installed the fork, and set the brake hoses, per the manual, then installed the handlebar (internally routed aero bar), then hooked up the shifter levers which were also filled.
• tested brakes, no bleeding required, firmed up on the third pull on both ends once the pads were advanced to the rotors.
• replaced BB and crank, then installed derailleurs, chain (had to add 2 links due to larger rear cassette and larger jockey wheels on the RD); adjusted everything, took about 5 minutes using the app.

(5) Set up SynchroShifting, where the system just shifts the front based on the shift points I set, so all I do in practice is shift the rear.

Today, went for a ride. Initial impressions…
(1) the system shifts much faster than the prior gen 11-speed. It is not noticeable on normal up/down shifts, it is a stark improvement when the Synchro shifting has to shift the rear and front as I go up/down the range.
(2) the new brake calipers are a massive improvement over the prior gen. The set back Shimano claims they added must work, because I never heard them after releasing the levers, and the engagement is incredibly fast, predictable, and easily modulated.

My only lingering question is to wonder when Shimano will add 12-spd to the GRX line and bring these new brakes over.

The use of TerryDi2C’s great website (bettershifting.com) made hunting for specific directions a much simpler task than reading the Shimano DMs once I was into the install.

Short update. I live in Belgium, and it rains frequently here from October to March, and a little less frequently from April to September. So the bike is gonna see rain...and yesterday was the first rainy ride. Noticeably, the brakes were much quieter once the bike was good and wet. The brakes also seemed (this is purely perception I am sure) a bit more confidence inspiring because of the improved threshold modulation over the previous generation hydro brake system from Shimano. And yes, having ridden on SRAM hydro discs, these are amazingly better, IMO (again, probably just perception, but they work really well). The brakes alone are reason enough for me to be happy with my choices here.

Nice! I'll be installing my own R8100 soon!

...after I install some more light in the shed so that I can actually work on my bike ;)

Hey TerryDi2C, did you get the light in your shed? Curious your impressions.

I have to agree with you on the brakes. Shimano brakes are just better. I recently got a new Domane with the eTap AXS and I find the brakes to be the weak point. I am so used to Shimano brakes and I find these just not a solid. Again, could be that I am just used to the Shimano brakes. I am currently updating my Emonda ALR with eTap AXS, but staying with the Shimano rim brake, so I picked up some new Ultegra 8100 brakes which allow for a better fit on the 28mm tires I run. Never was a fan of the SRAM rim brakes.

Hah, yep! I'll build my bike sunday or early next week :)
There's A LOT of light in the shed now
https://cimg0.ibsrv.net/gimg/bikefor...9ea930cb89.jpg
https://cimg1.ibsrv.net/gimg/bikefor...b9ce933839.jpg

Metallic or resin pads?
My 2018 Ultegra Di2 Synapse came with metallic pads and I spent 2 1/2 years hating the battle of the squeal. No matter what I did the squeal always came back. Got a gravel bike with resin pads and was incredulous; no squeal. Put resin pads on the other bike and couldn’t be happier.
Wondering if my experience is typical.

I've not had too many issues with the noise, my issue was with perceived softness when I went to brake. It just did not feel as grippy and solid even though I used the same pad manufacturer. I was just not a fan

This is interesting to me, since 11sp Di2 does not shift well in Synchro and Semi-Synchro modes, in my opinion. On my bike, in those modes, the bike seems like it first shifts the FD, then after a very brief lag it will shift the RD. It sort of upsets my cadence twice, rather than smoothing it out. Consequently, I don't use those modes.

Squeal is a function of pad and rotor interaction in my experience. Braking may be "noisier" with metallic pads, but squeal is not normal if the pads and rotor are clean and free of contaminants. Metallic pads make more noise when braking than resin, but squeal is definitely not a normal noise.

Exactly this. I still use full syncro on my 11-speed Di2 bikes, but I pay close attention to the shift points because it always seems to happen right when I don't want it to happen. It's worse when down shifting than up shifting in my experience...but it is barely noticeable on the 12-speed.

Exactly, because a downshift (on the FD) can happen so quickly that the RD can't keep up.

I suspect the system doesn't generate enough torque to quickly (and simultaneously) shift both the FD and RD...But it sounds like they've worked that out in 12sp, from your post. Good to know.