12 Speed Road Cassette and Chain Comparison: Ultegra R8100 vs Force XG-1270

Quick and simple side-by-side comparison between two different 12 speed cassettes. The Ultegra R8100 is the second-tier road cassette from Shimano, while the Force XG-1270 is also the second-tier road cassette from SRAM. Being at the same grade makes it a fairer comparison, although I think the SRAM cassette costs more than the Shimano cassette.

For detailed information on each of the cassettes, check out their individual pages through the links above!

SRAM 10-36T cassette on the left, with the largest sprocket in black, and others in nickel chrome. 

Shimano 11-34T cassette on the right, with sand blast finish on all the sprockets. Looks very different!

SRAM cassette uses a pinned construction to link all the 12 sprockets together, while the Shimano cassette uses aluminium spiders and loose sprockets.

One way to check if the cassettes are cross compatible is to check the spacing between the sprockets. If they are similar, at least we know that the rear derailleur can shift the chain across the sprockets consistently.

Of course, there are other factors such as the sprocket thickness, teeth profile, the type of chain, the rear derailleur exact movements, but if the spacing don't match, no point checking all the others.

Spacing between sprockets on the Shimano cassette is about 1.8 mm.

Similar 1.8 mm spacing on the SRAM cassette as well. 

With a similar spacing between the sprockets, it might be possible to swap a Shimano cassette for a SRAM cassette, or vice versa. Only by testing it out on the actual bike would it be possible to know how well it works.

SRAM cassette is lightweight at 310 grams, for a relatively large 10-36T gear combination.

Shimano cassette is heavier at 341 grams. But I think it is cheaper as well.

The 12 speed chains are also different. SRAM has its own AXS Flattop 12 speed chain, which has larger rollers that makes it incompatible to many cassettes and chain rings. I made a detailed comparison and study of the Flattop chain, you can check out the measurements in the other post.

Comparison between a Shimano 11 speed (not 12 speed) and the SRAM AXS Flattop 12 speed chain.

One thing I wanted to test was whether I can use a Shimano 12 speed chain on the SRAM 12 speed cassette. If that is possible, I can theoretically widen the gear range of a Shimano 12 speed road drivetrain from 11-34T (max) to 10-36T, which is a big increase from 309% to 360%.

Seems that the Shimano CN-M9100 12 speed chain can rest nicely on the SRAM 12 speed cassette!

Side by side comparison of the 12 speed chains.

Another view of the chains. Different plate shapes, plate thickness, roller sizes, etc.

I didn't do any deeper comparison of the cassettes and chains, as I didn't see anything else worth comparing. Check out the individual posts for details on each of the components.

Fnhon Ultegra Di2 12 Speed: Assembly Part 2

Here is the second part of this bike build, the Fnhon Ultegra Di2 12 speed drop bar folding bike. As explained in the earlier posts, there are a few problems that had to be solved for this build to be possible.

1) Custom Di2 battery mount.

2) Short derailleur cage for the Ultegra Di2 RD-R8150 rear derailleur.

3) Narrow wide chain ring that is compatible to Shimano 12 speed chain AND Shimano 4 arm road crankset.

Here is the completed build!

Ultegra Di2 shifters ST-R8170 with good ergonomics.

Fnhon Ultegra Di2 12 Speed: Assembly Part 1

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.

Fnhon Ultegra Di2 12 Speed: 12 Speed Cassette, Chain and Chain Ring

After solving the issue of the Di2 battery mount on the Fnhon frame, and modifying the Ultegra R8150 rear derailleur cage to a shorter version, I am almost ready to start assembling the bike.

The drivetrain and shifting components on the Fnhon Ultegra Di2 12 speed folding bike are mostly new, except for the Ultegra R8000 crank arms which will be carried over from the Dahon MuSP. I did not get a new Ultegra R8100 crankset to match the rest of the Ultegra R8100/R8150 groupset, as I only need the crank arms and not the chain rings. Therefore, it is more than good enough to reuse the R8000 crank arms on the new setup.

Let's start with the cassette. A 12 speed road cassette is needed for the Ultegra Di2 12 speed setup, and I can choose between a 11-30T cassette or a 11-34T cassette. On the Specialized Aethos and Focus Paralane, which have front double drivetrains and are dedicated road bikes, I chose the 11-30T cassette for its tighter gear spacing.

However, for this new Ultegra Di2 setup on the Fnhon, it will be a 1x12 speed front single setup. Therefore, the gear range will be decided by the range of the cassette, while the chain ring will shift this gear range higher or lower. I decided to use the wider range 11-34T cassette on the Fnhon Ultegra Di2 12 speed folding bike.

I actually had a Dura-Ace CS-R9200 11-34T 12 speed cassette as a spare, but decided not to use it on this bike. Instead, I decided to get a new Ultegra CS-R8100 11-34T 12 speed cassette, to match the rest of the components and also to do a comparison with the Dura-Ace cassette.

Dura-Ace vs Ultegra 11-34T 12 speed cassettes.

Birdy AXS: Chain Length, Freehub Grease and QR Axle Changes

Final post on the Birdy AXS 12 Speed folding bike! At least for now, until some new project or ideas pop into my head.

Throughout the whole upgrading process from the stock 9 speed Birdy City, I have learnt a lot about the Birdy folding bike. Especially for the folding design, where it is different from any other bike.

There were a few issues which were not fully resolved earlier, but they have now been fixed. 3 of the problems have been highlighted below, along with how I solved them.

First issue was the chain length on the Birdy drivetrain. As I transplanted the SRAM AXS 12 speed drivetrain from the Fnhon DB12 folding bike, I reused the existing chain as the mileage was quite low.

However, the chain stay length of the Birdy is longer at 430 mm, compared to the 400 mm of the Fnhon DB12. Therefore, using the same chain length with the same cassette and chain ring, on a longer chain stay, makes the rear derailleur cage stretch out too much.

At the largest sprocket (lowest gear), the rear derailleur cage is very stretched out and looks over the limit.

Birdy AXS: Introduction to Birdy City (Drivetrain Overview)

Here is a new folding bike for me to modify! It is the new Birdy City by Pacific Cycles, which is the entry level spec for Gen 3 Birdy folding bikes. Although there are many different component grades, all of them have the same frameset. Therefore, if I plan to change everything on the bike, might as well get the entry level model to save some money.

Many years ago, I tried the Birdy when it first came to Singapore, and I was very impressed with the suspension. However, I have never bought the bike as it was quite expensive compared to other folding bike options, plus the folded package always seemed awkward to me.

By chance, I happened to see a great offer by Mighty Velo, which had a good discount on some of the Birdy bikes. There was also an offer by Qoo10, which meant that when I combined the offers, there was a discount of more than SGD 700. This created a pretty irresistible deal, which is why I finally decided to buy the bike.

What's nice is that we can specify the colour of the bike frame for every spec, since the bike shop only assembles the chosen frame with the chosen component spec when you order it. It only takes a few days for them to queue and build up your bike, so the wait time is not a problem.

There are so many nice colours to choose from, but I finally chose this sky blue which looks really nice. In fact it looks very similar to the shade of blue used by Shimano.

Before I remove and modify any components on the stock Birdy City, I will first study it closely, and also do some test riding. This is to allow me to compare the ride feel and performance before and after the upgrades.

Completely stock Birdy City setup with 1x9 speed Sora.

Campagnolo Ekar: Bottom Bracket and Chain

As shown in the previous post about the Campagnolo Ekar crankset, the unique construction means that it will only be compatible to a Campagnolo bottom bracket. These are one of the many unique features of this Campagnolo Ekar gravel groupset.

A Campagnolo bottom bracket is needed to match the Ekar crankset. A standard BSA threaded bottom bracket is chosen to match the bike frame.

At first glance this bottom bracket looks the same as other outboard bottom brackets.

Specialized Aethos: Assembly Part 2 with Dura-Ace Di2 12 Speed Components

With the bottom bracket issue settled, now I can continue to assemble the Specialized Aethos. For the components, I am mostly using the Dura-Ace R9270 components which were previously installed on the Focus Paralane. I decided to use the Dura-Ace components on this Aethos, while I will install a new set of Ultegra 12 speed components on the Focus Paralane instead.

Dura-Ace Di2 RD-R9250 12 speed rear derailleur.

Tungsten All Weather Wax Lube and Chain Preparation

I have been reading a lot on bicycle chain lubrication, and it is quite fascinating to learn how the different chain lubes have such big effects on the chain efficiency and durability.

For my "dry" weather bikes, such as the Cervelo Aspero gravel bike and the other folding bikes, I have been using the Prolink chain lube since a long time ago. Not sure why I chose it, but it has worked well so far.

As for the wet weather bikes, such as the chain drive version of the Fabike C3 and the most recent Focus Paralane, I have been using the KMC EPT chain, which is extremely rust resistant. For that chain, I used Finish Line wet lube, which is water resistant and does not get washed away by rain. However, the wet lube does pick up quite a bit of dirt that makes the chain dirty easily.

From Zero Friction Cycling, I came across this new type of drip on wax lube, which is almost as efficient as the full molten wax dip, and yet is easier to apply as it is a drip on type.

Which is why I decided to get this Tungsten All Weather Wax Lube to test it out for myself and see if it is really as good as it says.

Here it is! Let's give it a try and see how it goes.

Focus Paralane: 2x11 Speed Drivetrain Installation

As a commuting bike, the Focus Paralane is nearly perfect, as it is a fast road bike with high end components. However, since I use it a a road bike for group rides as well, I find that the gear range is not quite enough. This is most apparent when riding down slope, as the highest gear (Front 40T and rear 11T) is 98 gear inches, which is not enough when riding fast down the slopes.

Therefore, if I am using it as a road bike for group rides as well, I need more gear range. There is already a wide 11-36T cassette on this bike, so I cannot use a wider range cassette without sacrificing the close gear steps. Best way is to install a front double system with two chain rings, to get the wider gear range and yet with close gear steps.

When I installed the Dura-Ace R9100 crank arms onto this bike, the chain rings were kept aside. Now, what I need to do is to just reinstall the chain rings onto the Dura-Ace crank arms.

Before that, I needed to check if this frame can accommodate a front derailleur properly. The stock Curana fenders had a cutout to avoid interference with the front derailleur, so with the SKS mudguards, there might be some issue.

Attaching the Dura-Ace FD-R9250 Di2 Front Derailleur to the front derailleur mount to check it out.

United Trifold: Chain Tensioner from Bottom Bracket (Unsuccessful)

After changing to the 10 speed drivetrain as shown in the previous post, the United Trifold does not have any issue during riding. However, folding becomes a problem due to the short cage of the Saint rear derailleur, which creates a lot of chain slack when folded.

Therefore, I did more research to find out how to maintain tension on the chain when a trifold is folded.

There are additional chain guides that can be added to a trifold, so that it helps to tension the chain when it is folded. As shown below in the example, it wraps the chain around the chain ring, so that the chain takes a longer path from the chain ring to the rear derailleur when folded. This prevents the chain from becoming too slack.

Example showing how the additional chain guide around the chain ring will route and tension the chain when the trifold is folded.

Here is one example of the chain guide, which will be sandwiched between the bottom bracket and the frame.

It is made of a stamped piece of aluminium, and needs special shaping to avoid interference.

Weighs 38 grams

Thickness of the chain guide is around 3.1 mm. In this case it will act as the spacer of the drive side bottom bracket.

Unfortunately, I found that this chain guide interferes with the crank arm.

Apparently the bend on the chain guide is designed to avoid the crank arm shape on square taper cranksets, not the chunky Shimano Hollowtech crank arms.

No way to make it work in this case. I will not sacrifice the crankset for this chain guide.

On to Plan B. There is another chain guide which serves the same purpose, but it is designed differently. Let's see if it works.

Example of the alternate chain guide, shown on another bike. It is designed to avoid the chain stay and crank arms when folded.

Here is how it looks. Angles can be adjusted individually at the pivot points.

This part will be sandwiched underneath the drive side bottom bracket adapter, and also wrap around the bottom bracket shell.

In addition to the bolt, there is an additional pin to prevent rotation of the arm. Seems that angle adjustment is not possible after all.

This chain guide is a bit heavier at 60 grams.

The part that will rest under the bottom bracket adapter is about 2.4 mm thick.

The thickest part of this chain guide is 10 mm for extra stiffness.

Distance from centre of bottom bracket to the roller (which contacts the chain) is about 123 mm. This distance limits the size of the chain ring that you can use.

Internal diameter of the chain guide is 35 mm, which is slightly larger than the thread diameter of the English threaded BC 1.37" x 24 TPI bottom bracket threads.

Unfortunately, another interference problem. This chain guide does not fit the bottom bracket shell on the United Trifold.

This chain guide is designed to wrap around the bottom bracket, but it is too small for the bottom bracket shell on the United Trifold.

From my analysis, this chain guide is designed to fit around trifold with steel frames. The bottom bracket shell on a steel frame has relatively thin walls, as there is no need to make it thick for strength.

However, the United Trifold is an aluminium frame, which means it has an aluminium bottom bracket shell. Thus, the walls on the aluminium bottom bracket shell are thicker, and the outer diameter is too big for this chain guide. Yet another difference on this frame that causes problems with aftermarket modifications. If I try to grind away the interference on the chain guide, I think it will just break off as the material becomes too thin.

Therefore, both the existing solutions for a trifold chain guide does not fit on this bike, due to crankset or frame interference. I need to keep searching for solutions...

Fnhon DB12: Installation of SRAM eTap AXS

With all the new 12 speed components in place, it is now time to assemble them onto the Fnhon folding bike! This is an ambitious modification, where there is no existing bike to take reference from. Also, I would not know if everything was going to work, until I actually install them. And this is why I took on this challenge, as it is new to me, and allows me to learn many new things.

All the new components needed for the 12 speed AXS drivetrain conversion!

Force AXS 10-36T 12 speed cassette, mounted on the XDR freehub body.

Force AXS 12 speed Flattop chain

Force AXS wireless rear derailleur, rated for up to 36T cassettes.

GX AXS wireless shifter, taken from the MTB side to be used on this flat handlebar bike.

New 44T Wolf Tooth narrow wide chain ring, with a revised teeth profile to work with the Flattop chain that has larger chain rollers. I will be using the same Shimano Ultegra 6800 crankset.

New bottom bracket from Ascent Bikes. Not necessary for this 12 speed modification, but I took the chance to try out this new bottom bracket.

Before I could install the new 12 speed components, I had to remove all the existing 11 speed Di2 components. During removal of these components, I found it liberating, as I no longer need to attach a battery to the seat post, nor run Di2 wires along the handlebar and frame.

All these Di2 components can be removed!

Existing Di2 handlebar setup, with a display (Junction A), a Di2 switch and wires running around.

It felt good to remove all these wires and Di2 parts from the bike, as the handlebar looks so much neater. One thing I would miss is the Di2 gear display, which shows me the selected gear and also the battery level. Technically this can be done by pairing the AXS system with a Garmin head unit, much like the Di2 version, but this would require a Garmin to be added to the folding bike, which I think is not necessary.

After installing the wheelset, now with the 10-36T 12 speed cassette, next is to install the Force AXS wireless rear derailleur. As there are no wires or cables, I just had to secure it on the hanger, that's all! Extremely easy and convenient to do.

To optimize the shifting performance, the guide pulley of the rear derailleur should be adjusted to the recommended distance from the cassette sprocket. In this case, I need to set it to 5 mm.

A tool is helpfully supplied together with the rear derailleur, for setting the distance. You could also do it with a ruler.

Using the printed markings, adjust the B-tension bolt on the rear derailleur, to adjust the distance as required.

Chain length would be pretty important as well. In this case, I plan to keep the chain as long as feasible, to reduce chain tension, so I did not follow the recommendations.

Only 4 links left, as I made the chain as long as possible (without chain slack), instead of as short as possible (without overstretching the rear derailleur). This is possible only because it is a front single drivetrain, where the rear derailleur cage has extra chain capacity.

Using the full chain weight + box (299 grams) minus off the remaining chain + box (47 grams), gives the actual chain weight that is on the bike as 252 grams.

Comparing the stock clamp band with the third-party adapter (I-Spec EV type).

On the I-Spec EV brake lever, this nut needs to be installed onto the clamp band first. The shifter will then be attached to it.

Some problem with tool access, making it difficult to tighten the bolt at certain positions.

Handlebar looks clean with only one clamp band per side. I added loctite to the bolt to prevent self-loosening.

Final shifter position, after multiple trials and adjustments.

Lastly, the rear derailleur position will need some fine-tuning, to align the guide pulley with the sprocket. On the previous Di2, this was done by pressing the function button on Junction A, to enter adjustment mode.

On this AXS system, it is done by holding the function button on the shifter, and pressing the upshift or downshift button for small adjustments in either direction. Off the bike this can be done with one hand. However, it is nearly impossible to do adjustments while riding, as my fingers cannot press both the function button and shifting button simultaneously.

Instructions for adjusting the rear derailleur position, from the shifter side.

Additional function to shift the rear derailleur without a shifter!

While fiddling with the AXS system, I found that if I pressed the rear derailleur function button once, it would shift the rear derailleur outwards by one gear. A double press shifts it inwards by one gear. I thought this was brilliant, as it can ensure that I can still set my rear derailleur to a preferred "single speed" gear to get home, in the event that the shifter runs out of battery or gets damaged.

In the next post, I will share the final setup on this Fnhon folding bike, along with many more close up pictures. Did I manage to reduce any weight by changing to this wireless 12 speed drivetrain?