With all the problems solved as described in the earlier posts, the assembly of the new Fnhon Ultegra Di2 12 speed can now begin! I usually wait until all the required parts are available before I start building, instead of building half way and then waiting for the rest of the parts.
First step is to install the new Ultegra R8100 11-34T cassette onto the wheelset. This is the same custom built wheelset by Ascent Bikes, and with the same Panaracer Minits Lite tires as used previously.
Ultegra R8100 11-34T 12 speed cassette installed!
Using the new XTR MT900 rotors, same as the ones which I am using on the Focus Paralane.
New shifters are needed for this drop bar bike, as the 12 speed Di2 system requires 12 speed hydraulic Di2 shifters. I am using Dura-Ace ST-R9270 on both the Specialized Aethos and the Focus Paralane, but there is no need for Dura-Ace here.
There are ergonomic improvements going from the Ultegra 11 speed ST-R8070 to the Ultegra 12 speed ST-R8170. On the other hand, between Dura-Ace and Ultegra, the shifters are virtually identical in terms of function and ergonomics. Therefore, the Ultegra Di2 ST-R8170 shifters are the smart choice.
I got the Ultegra ST-R8170 shifters as a standalone component, instead of being bundled with the brake calipers which is more common.
One thing to take note if you buy these hydraulic shifters without the brake calipers, is that the connecting bolts are not included. These bolts are needed to connect the hydraulic hose to the shifter and also the brake caliper side. I had spares from previous projects so it is not a problem for me.
The main reason why I did not get the bundled set is because I won't need the Ultegra BR-R8170 hydraulic brake calipers anyway, since the Fnhon frame cannot use Flat Mount brake calipers. Previously the Fnhon was using XTR BR-M9100 brake calipers, but those have been transferred over to the Birdy AXS 12 speed, along with the XTR BL-M9120 brake levers.
Since I still like the direct hose connection (compared to banjo type) on the XTR M9100 brake calipers, I had to get another set for this Fnhon Ultegra Di2 12 speed folding bike. This means that the Ultegra ST-R8170 shifters will be paired to the XTR BR-M9100 brake calipers. Officially they are not listed as compatible, but there is no issue with pairing these as the shifter is able to displace enough oil volume to activate the 2 piston brake caliper properly. Not sure if a 4 piston brake caliper would still be compatible though.
Assembly is straightforward since I had already anticipated and cleared the problems earlier on. Let's check out the pictures of the nearly-completed bike!
Brand new 1x12 speed drivetrain! Only the Ultegra R8000 crank arms are reused from the Dahon MuSP.
New 46T narrow wide chain ring from Stone, that is compatible to Shimano 12 speed chains AND also Shimano road 110 mm BCD crank arms.
XTR M9100 hydraulic brake calipers, mounted on the front fork using a IS to PM adapter. Rotor is 160 mm diameter.
Using a similar IS to PM adapter, but with a 140 mm rotor at the rear.
There are actually IS mount to Flat Mount adapters, but they are not compatible to all bikes, and it seems difficult to adjust the caliper position. The rotor diameter is restricted to front 180 mm and rear 160 mm as well, so can't use it for this bike.
Here is the custom designed and 3D printed Di2 battery holder! Lots of slots to enable the ideal cable tie positions.
Single Di2 wire exits from the bottom of the battery holder and is routed towards the rear derailleur.
Here is how the full bike looks, before putting on the bar tape.
The outward folding handlepost and Controltech stem are transferred over from the Dahon MuSP, as they are ideal for a drop bar folding bike. The Dahon MuSP has been converted to a 1x9 speed flat handlebar folding bike, and so it uses another handlepost and handlebar.
Using the portrait mode and stage lighting effect on the iPhone to highlight the Ultegra Di2 shifters.
These shifters have great ergonomics, improved from the previous 11 speed version.
In the next post I will show the full component specifications and weight of the Fnhon Ultegra Di2 12 speed drop bar folding bike. For now, let's look at the gear ratios available with this new drivetrain.
Previously, my drop bar folding bike was the Dahon MuSP, with 1x11 speed Ultegra Di2. It uses a 11-30T cassette with a 46T chain ring, giving a gear range of 33.7 to 92 gear inches.
Now, with the new 12 speed Ultegra Di2 drivetrain, the cassette has been changed to a 11-34T 12 speed cassette. The difference is merely the addition of a 34T sprocket at the low side, with all the other 11 sprocket sizes remaining the same.
Combined with a similarly sized 46T chain ring, the gear range at the top end remains the same as what is intended, as I don't need more top speed. What I gain is actually just an additional low gear of 29.8 gear inches, courtesy of the additional 34T sprocket.
New gear range of the Fnhon Ultegra Di2 12 speed is 29.8 to 92 gear inches.
With the additional low gear, this bike will enable the rider to climb slopes more easily, which was one of the drawbacks of the previous setup. It is rather unstable to pedal while standing up on a folding bike, due to the additional flex in the frame and different geometry, when compared to a road bike. Therefore, the lower gear enables climbing even when seated which is a benefit.
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