As described in detail in the previous post, where the new GRX ST-RX815 hydraulic Di2 shifters were introduced, I will now install it onto the Cervelo Aspero gravel bike. The bike currently has the Dura-Ace ST-R9170 hydraulic Di2 road shifters, which are good for road riding but not so ideal for gravel riding.
GRX ST-RX815 hydraulic Di2 shifters. Lots of small but measurable differences compared to the road shifters.
My plan is to replace just the shifters, leaving the rest of the hydraulic hose in place. The idea is to cut away the existing insert and olive, and just install a new insert and olive. The hose will be slightly shorter by about 1.5 cm, but there is enough slack in the hose length not to be an issue.
It was a nightmare to thread all the hydraulic hose and Di2 wires through the PRO Vibe Aero Superlight handlebar previously, so I don't want to do it again. Therefore, reusing the hydraulic hose is the smart choice in this case.
Gathered all my tools for hydraulic bleeding. This was before I got the new TL-BT001/002/003 hydraulic bleeding tools which have been improved in many areas.
After removing the bar tape, I need to loosen this connecting bolt on the shifter.
Note that once you loosen the connecting bolt, the hydraulic fluid will be free to flow out. I'm not worried about the hose end, as the brake caliper end is sealed, and the fluid cannot flow out from the cut hose.
However, the shifter side will have fluid leaking out, as there is a reservoir full of fluid in the shifter. If the lever is pressed, the hydraulic fluid will squirt out. My suggestion is to point the shifter downwards, such that the open end is pointing upwards.
My immediate concern would be to fix the new shifter, and settle the removed shifter later on. I will need to drain the fluid out of the old shifter, before I store it. Else all the fluid will leak out during storage, making a mess of the whole shifter.
Anyway, that is for later, as I need to connect the new GRX shifter after I disconnect the old Dura-Ace shifter.
Once the connecting bolt is loosened, the existing hose can be pulled out of the shifter by hand. The old compressed olive can be seen on the hose.
Since the olive can't be pulled off or reused, it will be removed by cutting the hose. Use a proper hose cutter to make sure the end is flat as shown.
During cutting of the hose, a few drops of hydraulic fluid will drip out, so make sure to wrap the area with a cloth to avoid a mess. Also, if you have not already done so, make sure the brake pads and rotors have been removed from the bike, to avoid hydraulic fluid getting on it later during the bleeding process. They need to be off the bike anyway for the yellow bleeding block to be installed.
Press the insert into the hose by hand, and push it in fully using a proper insert tool. Make sure to use the silver coloured insert for BH90 hose.
Once the insert is inserted properly, put on the connecting bolt and a new olive.
The next step is to push the hose into the shifter, taking care to ensure that the hose is fully inserted, and the olive is seated properly and not tilted. Then, tightening the connecting bolt till the appropriate torque, and the whole system is connected! Take care not to over-tighten the connecting bolt or the shifter may crack.
Once the system is connected, it is time to bleed the system. There is fluid in the hose and the brake caliper, but none in the shifter. Therefore, all the air needs to be pushed out of the system, and filled with hydraulic fluid. For Shimano brakes, mineral oil is used. The bleeding cup will be connected to the top of the shifter.
Filling up the syringe with mineral oil, and connecting it to the brake caliper.
I will not go through the whole bleeding procedure, but it is difficult to perform by just one person, unless you are experienced. A handlebar holder helps a lot to prevent the handlebar from turning during the bleeding process.
During the shifter swap, I also noticed that the clamp band is different, as shown below.
Regular plated steel clamp band on the left (used in GRX and all road shifters), and the titanium clamp band, used only in Dura-Ace shifters.
The titanium clamp band on the right is slightly thicker, although the cutouts are also larger.
Steel clamp band weighs 12 grams each...
...while the titanium clamp band is only 6 grams each. Half the weight! But it is only 6 grams difference per shifter, not that significant unless you are chasing every gram.
Both sides of the shifters need to be replaced, so it took some time and work to complete. It is actually a lot of work to ensure that the bleeding is done properly, with firm and equal braking performance on both sides. Leave it to the mechanics at the shop if you are not sure!
Good ergonomics for 1-finger braking. The tall hood provides a "wall" to prevent the hand from sliding off the front.
Another angle showing how the tall hood allows the hand stay on the shifter securely. Also note the additional Di2 button at the side of the hood, which will be activated by the inside of the thumb.
Strong ribs enable the hand to remain in place over bumpy terrain, preventing the hand from slipping forward or to the side. Best used with gloves to prevent abrasion on the hands.
Fresh bar tape wrapped on the handlebar, after the shifter positions have been confirmed with an actual riding test.
Still not used to the unusual looking shape of the GRX Di2 shifters. But the ergonomics work really well.
View of the shifter from the inside. I really like the new placement of the additional Di2 button.
Testing out the new GRX shifter on some proper gravel trails.
I am really pleased with the new GRX Di2 shifters, they feel so much more secure over bumpy gravel trails. Ergonomics are spot on as well, and I like the ability to use 1-finger braking effectively while riding on the hoods. For more details, please check out the previous post where I shared the details of the new GRX Di2 shifters.
With these new GRX Di2 shifters, the Cervelo Aspero is now a proper gravel bike, with most components optimized for proper gravel riding, instead of having some compromises for road riding.
If you haven't tried these new GRX shifters for gravel riding, I highly suggest you give it a go, to see the improvement over the usual road shifters.
GRX Di2 shifters attracting bees!
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