Sunday, July 7, 2024

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.

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