Saturday, March 13, 2021

Shimano Ultegra R8000 vs Non-Series RS510 Crankset

If you are looking for an inexpensive road 11 speed crankset, you can consider this Shimano non-series FC-RS510 crankset. Being non-series, it is a more budget friendly version that will cost less than the higher end 105, Ultegra or Dura-Ace versions. Tiagra is a 10 speed groupset so it will technically not be compatible to 11 speed drivetrains.

Some bike brands mix and match groupset components, in order to save some costs on the final full bike. For example, my Merida Scultura 5000 came with an Ultegra groupset, but it is not actually a full Ultegra groupset. The less conspicuous components such as the cassette and chain was 105 level, while the crankset was a non series RS500 crankset as well.

Let's see what are the main differences between a non-series crankset and those from a better groupset.

As a non-series crankset, it cannot look better than one from a higher grade. Therefore, the design and surface finishing will be simpler. The second important reason is to reduce the cost of production, as a simpler surface treatment will be cheaper to produce, and also easier to produce in higher quantity.

Plain black painting on the RS510 crank arm, while the Ultegra crank arm has two-tone anodising.

Higher end crank arms use the Hollowtech construction, with a hollow crank arm that saves weight over a solid or carved out crank arm. The hollow crank arm is made by either one piece forging, or by making two separate parts that are bonded together. Either one of these methods are a lot more expensive than just basic forging, found on the RS510 crankset.

RS510 has a solid crank arm with the back carved out to save a bit of weight, while the Ultegra crank arm is hollow, made by bonding the front and back pieces together.

Finally, with the simpler appearance and construction, lastly comes the weight difference. The weight difference is a byproduct of the product design and manufacturing method, but it conveniently serves as a differentiation between different grades as well. The engineers do not purposely design it to be heavy, it just happens that a simpler construction is heavier in weight.

One of the key objective of having a hollow crank arm is to lower weight, as top level components need to have low weight in order to sell well. It may sound crude but it is true, all top level cyclists or serious enthusiasts are obsessed with reducing the weight on their bikes.

As for normal cyclists who place more emphasis on basic functionality and cost, a lower priced crankset translates to a lower priced bike, although it will be a bit heavier than a high end bike.

RS510 right crank arm weighs 406 grams

Ultegra R8000 right crank arm weighs 325 grams, about 81 grams lesser.

RS510 left crank arm weighs 258 grams

Ultegra R8000 left crank arm weighs 194 grams, about 64 grams lighter.

The weight difference of the crank arms is 145 grams, which is massive in terms of crankset weight. This does not include the weight difference of the chain rings, which I think might make the difference even bigger.

In summary, the simpler appearance and construction of the RS510 crankset results in a higher weight, which finally translates to lower cost for the non-series crankset.

Performance wise, the non-series crankset will probably work just as well, apart from the extra weight that it adds to the bicycle.


  1. Excellent review. Exactly what I was looking for.

  2. Wouldn't the stiffness make a difference too? Maybe that is hard to measure though.

    1. There is probably a difference in stiffness, but hard to quantify.

  3. Also one very important thing:
    chainrings are not compatible

  4. are their chainring interchageble?

  5. I have the 510 on my gravel bike and looking to convert to a 1x.

    I know the BCD is 110 but can't tell if a standard 110 BCD narrow/wide ring will fit or if its one of the slight offset types?

    If a standard 110 chainring wont fit would something like the GRX one fit?


    1. You need to get a Shimano 110 BCD, 4 arm type of chain ring. Something like the older road 9000/6800/5800 series, as what I have used before.

    2. Thanks for the help and advice. I cant seem to find that particular Wolftooth chainring on that link as they only seem to offer the Ultegra (newer) version and the GRX one now so not sure where to go with that now as the fitment looks different.

    3. You can use the type for newer R8000 crankset on RS510. Just that there will be a cutout where it is not needed on RS510.

    4. Hi,

      Before I answer you I would like to say thank you for this blog post which deals with a material that nobody talks about and yet allows you to use a good cheap product. Also note that the difference with the 105, Ultegra and Dura Ace road cranksets is the Q factor, it is 150 for the RS510 (vs 145 for the others), like the Tiagra and Sora, which is nicer for weak knees and/or gravel (GRX is 151).

      Then I can tell you about my experience to switch to mono on 110 BCD 4 arms Shimano's cranksets. There are others solutions in addition to those given above to have a mono (and narrow wide) chainring. The most popular one here in France is the SPECIALITES TA ONE X 110 mm. The manufacturer even announces that the chainring is slightly shifted inwards to adapt the chainline to single chainring. I used it succesfully with efficiency on a 5800 crankset. It comes in 38, 40, 42 and 44 teeth. Beware, there is another version, SPECIALITES TA ONE X110 GRX, the BCD 110 of the GRX is not compatible with the 110 road Shimano if I understood correctly !

      I bought a used STONE chainring and put it on a RS510 crankset (I even got the plastic cover from the original large RS510 chainring to re-cut covers for the new single chainring), and it's fine. On the other hand, in new, I only found it on a forbidden site:

      Enjoy !

      P.S : here are the links for the two chainring SPECIALITES TA :
      -the good one :,denture,38-dts

      - the one for GRX only :,denture,38-dts

    5. Thanks for sharing. The RS510 crankset matches well with the Stone narrow wide chain rings as well.

    6. @tylsteve

      I discovered your blog today by stumbling upon this article, I didn't see that you had already dealt with the subject of this tray, sorry! As I said, I too have mounted STONE on the RS510, it works great!

      But I'm going to catch up, I really want to read what's on your blog!

      Have a nice day!

  6. Nice, thanks a lot for the effort

  7. this RS510 comes on the new Giant Defy Advanced 1 and i'm wondering if you could swap out the crankset for a the full GRX 810 2x?

  8. You could, but you will need to change to the GRX front derailleur as well.
    1st reason is that the chain line for the GRX crankset is 2.5 mm further out.
    2nd reason is that the 105 road FD is not compatible to the smaller 48/31T chain rings of the GRX crankset.

  9. Hi, thanks for this. Really helpful. My 2023 Giant Defy 1 (105Di2) can with this crankset. Any reason I cant swap it out for the 105 Di2 12 speed crankset?

    1. I believe the Crankset on your bike should be the 12 speed version FC-RS520. You can swap it for the 105 version FC-R7100. The 105 version has hollow crank arms and will be lighter.

  10. Could I use 52T RS510 chainring with Tiagra being everything else? I know Tiagra also has 52T chainring in it's line up, but RS510 chainring is only available here, in India.

  11. Can I use stages Ultegra R8000 left crank arm with right rs-510?
    I wonder if the distance between the pedal attachment points on the crank arms would be identical

  12. should be ok. I think the Q factor is the same, so it should be symmetrical.