Fnhon Ultegra Di2 12 Speed: Ultegra R8100 Crankset and new Kickstand

Final post for the Fnhon Ultegra Di2 12 speed folding bike! In the previous post I prepared the Ascent Cirrus Elite carbon wheelset for use on this bike. Due to the change of wheel size from 451 to 406, the gear ratio has been reduced by approximately 10%.

As the gear ratio should be carefully chosen to match the usage and rider's abilities, any significant change in the gear range will affect the suitability of the gearing. The previous gear range was 30 - 92 gear inches, which is ideal for climbing and relatively fast rides on the road.

However, changing the wheel size from 451 to 406 will cause this gear range to decrease to 27 - 84 gear inches, which does not have sufficient top speed for road riding.

Therefore, the easiest solution is to increase the chain ring size to compensate for the smaller wheel size. A Stone 46T narrow wide chain ring was used, and this will be changed to a larger 50T chain ring.

Stone 50T narrow wide chain ring. Weighs 118 grams, which is 20 grams more than the 46T version.

Compatible to Shimano 12 speed chains, and also the Shimano 4 arm road crankset BCD.

Close up look at the narrow wide teeth, for good chain retention. Chamfered teeth to reduce driving noise.

New 50T chain ring installed on the Ultegra R8100 crankarm! Along with my iconic coloured chain ring bolts.

Alongside the left crankarm

Right side crank arm with 50T chain ring weighs 480 grams

Left crank arm with crank arm fixing bolt weighs 195 grams

Total crankset weight is 675 grams, which is decent. This is the same Ultegra R8100 crankset that was on the Focus Paralane. After I disassembled that bike, I reused the components across a few of my other bikes. Now, the Fnhon Ultegra Di2 12 speed bike has a full Ultegra R8100 groupset.

After swapping from 451 to the smaller 406 wheelset, the kickstand does not work so well any more. The kickstand length is important, as it determines how much the bike tilts when parked. It is related to the wheel size, as a larger wheel diameter means that the axle height of the bike is higher.

With smaller 406 wheels and previous kickstand (optimized for 451 wheels), the bike angle is too straight when parked. This causes it to tilt over very easily.

I ordered a shorter kickstand to replace the original kickstand.

Original kickstand for 451 wheels weighs 158 grams

New shorter kickstand for 406 wheels weighs a bit less at 152 grams

With the correct kickstand, the bike leans to the side a bit more, which is what I wanted. Too little or too much tilt makes the bike unstable.

New shorter kickstand also helps to create a bit more clearance with the rear rotor when put up.

There is little space to fit a kickstand between the rear rotor and the rear wheel spokes.

With the new kickstand installed successfully, the modification of the Fnhon Ultegra Di2 12 speed folding bike is completed! Below are the pictures of the bike in its final state (I think). It has evolved a lot over the years, starting from a 11 speed flat handlebar setup with XTR Di2 components, to its current drop bar setup with 12 speed Ultegra Di2.

Ascent Cirrus Elite front wheel with new Panaracer Minits tires and Ashima Ai2 rotor!

5 mm adapter added to push out the rotor, from the Birdy position to the standard position.

Same setup for the rear wheel, but with a smaller 140 mm diameter rotor.

Shimano Ultegra R8100 crank arm, with Stone 50T narrow wide chain ring.

Here is the refreshed drivetrain! Matte grey rims and crank arms give a different look. The rear derailleur has a custom short cage to have more ground and tire clearance.

Full bike view with high profile carbon rims but smaller 406 wheel size.

Previous setup with larger 451 wheels but low profile rims. I like both even though they give off different vibes.

All the components you see here are high end stuff!

Saved 200+ grams with these upgrades. Now the bike weight (excluding pedals and kickstand) is just 9 kg! Just slightly more than the flat handlebar Fnhon DB11 setup.

Extra pictures of the bike out for test rides. Here is the giant pumpkin at Elementum, near Buona Vista.

At the old Bukit Timah Railway Station.

Fnhon Ultegra Di2 12 Speed: Ascent Cirrus Elite Birdy Wheelset with Ashima Rotors

Two more blog posts to finish writing about the upgrade of the Fnhon Ultegra Di2 12 speed folding bike. The bike itself is already very good, however I decided to transfer some components from another bike over to this Fnhon bike. After all, we can't let a good carbon wheelset go to waste.

When I changed the wheelset on the Birdy AXS 12 speed to the Suncord 4 spoke carbon wheelset, the Ascent Cirrus Elite carbon wheelset was taken off the Birdy. Although the Ascent Cirrus Elite wheelset was meant to be a Birdy-specific wheelset, I realized that it can be fitted to normal folding bikes with the clever use of an adapter.

With an offset adapter for 6 bolt rotors, the brake rotor position on the Birdy-specific hub can be adjusted to match that of a normal front hub. That is the adapter that I will use to fit this Ascent Cirrus Elite wheelset (Birdy-specific rotor position) onto the Fnhon bike (standard 100 mm front OLD).

Note that the Fnhon was previously using a lightweight aluminium wheelset in 451 size, which was inherited from the original Fnhon DB12 in flat handlebar. This is the exact same Fnhon Tornado frame that was used to build the Fnhon Ultegra Di2 12 speed with a 3 way swap.

Now, the wheel size will be reduced to 406, since the Ascent Cirrus Elite wheelset is of a smaller 406 size instead of 451.

Ascent Cirrus Elite carbon wheelset in 406 size, with new tires and inner tubes ready to go.

New Panaracer Minits Lite tires in 32-406 size, exactly the same as what I am using on the Birdy AXS 12 speed.

A normal butyl inner tube weighs 104 grams...

...but a lightweight TPU inner tube only weighs 25 grams!

Ashima Ai2 super lightweight rotors! More holes than material on it. These have a diameter of 160 mm and 140 mm.

Here is the small adapter which is 5 mm thick, used to push the rotor position 5 mm outwards to make it compatible to normal bikes.

Adapter goes in between the rotor and the hub, to be fixed with a longer rotor bolt.

I used these black titanium bolts which needs to be longer than usual, due to the adapter. Bolt heads are rather big but still fits.

Rotor bolts cannot be too long either, or it will interfere with the hub shell or spokes.

Adapter sandwiched between the hub rotor mounting and the 6 bolt rotor. The rotor position is now at the standard position, instead of being 5 mm inwards as found on a Birdy.

Tires, inner tube, rotors all mounted!

Lightweight rotor ready to be tested

Ascent Cirrus Elite 406 carbon wheelset ready for installation onto the Fnhon Ultegra Di2 12 speed folding bike.

Since I was removing the old 451 wheelset and installing the new 406 wheelset, I decided to do a weight comparison as well. Not a completely fair comparison as some of the components are different, but it is an accurate representation of the weight difference due to this wheelset change.

451 aluminium rear wheel including tire, inner tube, rotor, weighs 1092 grams.

451 aluminium front wheel including tire, inner tube, rotor, weighs 970 grams.

406 carbon rear wheel including tire, inner tube, rotor, weighs 936 grams.

406 carbon front wheel including tire, inner tube, rotor, weighs 844 grams.

Overall, changing from the aluminium to the carbon wheelset (including change of tires, inner tube, rotors) saves 282 grams, which is pretty significant.

The wheel size is also reduced from 451 to 406, which means a reduction in overall gear ratio. That will be addressed separately through the drivetrain.

406 carbon wheelset on the left, 451 aluminium wheelset on the right. Big difference in rim profile and also overall diameter.

Ultegra CS-R8100 11-34T 12 speed cassette installed!

There is no issue converting the Ascent Cirrus Elite carbon wheelset from Birdy usage to general folding bike usage, all it takes is the small rotor adapter and some rotor bolts.

In the next post I will show the wheelset on the bike, along with some other changes to address the change of gear ratio due to the smaller 406 wheelset.

Rotor Offset Adapter: 6 Bolt Ashima Rotor on 6 Bolt Hub

Previously I wrote about the special adapter which is used to install a 6 bolt rotor on a Birdy-spec Centerlock hub. The adapter was 5 mm taller to account for the rotor position offset.

Now, what if you want to use a Birdy-spec 6 bolt hub on a standard front fork with standard rotor position? Since the Birdy front hub has the rotor position offset 5 mm inwards, it will not be compatible to standard front forks.

With the adapter shown below, when installed on a Birdy front hub, it pushes the rotor outwards by 5 mm, which will put it at the standard position for standard bikes.

6 bolt adapter used to offset the rotor by 5 mm outwards

Note that the adapter set also comes with 2x 5 mm spacers, with an internal diameter of 12 mm. This is because this adapter set is actually meant for MTB thru axle front wheels, to modify older 100 mm OLD front wheels to be compatible with newer Boost front forks with 110 mm OLD.

6 bolt adapter is about 5 mm thick as required.

Weight is just 5 grams as it is made of aluminium

A longer rotor bolt is needed, since there is now an additional 5 mm thickness from the adapter. I got a few different longer bolts to try out to see which is more suitable.

Standard Shimano rotor bolt on the left, longer rotor bolt on the right came with the adapter set.

Shimano steel rotor bolts weigh 12 grams for a set of 6.

Longer rotor bolts weigh 18 grams. Made of steel as well.

Titanium longer bolt on the left, compared to the standard Shimano rotor bolt.

I didn't realize that the titanium bolt head diameter was larger, it may not fit on the rotor.

Set of 6 longer titanium rotor bolts weigh just 11 grams

The reason I got this 6 bolt rotor adapter set is because I want to install the Birdy-spec Ascent Cirrus Elite carbon wheelset onto the Fnhon Ultegra Di2 12 speed folding bike. I had previously modified the Birdy AXS 12 speed to use the awesome looking Suncord 4 spoke carbon wheelset, and the Ascent wheelset is now available to be used on another bike.

Since the Ascent Cirrus Elite carbon wheelset has a 6 bolt hub, that will mean that I need 6 bolt rotors as well. I could reuse the Shimano RT66 6 bolt rotors, but I decided to try something new and lighter. That is how I ended up buying a new set of Ashima Ai2 lightweight rotors.

Pair of Ashima Ai2 super lightweight rotors! The smaller 140 mm rotor is for the rear of the Fnhon Ultegra Di2.

The Ashima rotors come with its own set of rotor bolts as well, of the standard short variety.

Both the 160 mm and 140 mm rotors side by side. There is more empty space than rotor!

160 mm rotor with narrow spider arms. It is important to install the rotor in the correct direction to ensure that it is loaded in the stronger orientation.

160 mm rotor weighs only 74 grams, as compared to 112 grams for the Shimano RT66.

140 mm rotor shown here. The cutouts at the brake pad contact area are so big that I'm not sure if the braking will be effective, or it will end up shredding the brake pads.

140 mm rotor weighs just 65 grams! The Dura-Ace CL900 140 mm rotor weighs 95 grams without lock ring.

6 bolt rotor adapter to be used with the Ashima 6 bolt rotor.

Adapter to be used under the rotor, to push it outwards by 5 mm.

4 different rotor bolts. Left is the longer titanium bolt with large bolt head; middle 2 are the stock Shimano (black) and Ashima (silver) bolts; right side is the longer bolt that came with the adapter set.

Here is how the 4 different bolts look on the rotor. Seems that the bigger bolt head on the titanium rotor bolt is still compatible.

In the blog posts for the Fnhon Ultegra Di2 12 speed bike, I will show in more detail the installation of the rotor and the adapter.