Thursday, December 18, 2014

Merida Scultura 5000 - Ultegra 6800 Crankset (Compact 50/34T)

Continuing from the previous post about the upgrade to Dura-Ace 9000 BB and chain, in this post I will write about the upgrade to the crankset.

The Merida Scultura 5000 (and many other 2014 Merida road bikes) come with the Shimano non-series 11 speed crankset, FC-RS500. This is an affordable 11 speed crankset that is quite a bit cheaper than the Ultegra or Shimano 105 cranksets. By using this lower cost non-series crankset, the bike OEMs will be able to lower the price of their bikes.

Stock crankset, the non-series Shimano 11 speed road crankset, FC-RS500.

11 speed compatible, and in compact gear combination of 50/34T.

The machined chainring cutouts and the black finishing is actually quite attractive, and makes it easy to match the appearance of almost any bike frame.

Weight of left crankarm + crank bolt is 249 grams.

Weight of right crankarm + chainrings is 546 grams.

Together, the FC-RS500 non-series crankset weighs 796 grams (some rounding off error).

Now, this non-series crankset actually performs quite well and I have no complaints about it. Shifting is fine and it also looks quite good. With a crankset weight of 796 grams it is actually not very heavy for this grade of crankset.

The Merida Scultura 5000 comes with some Ultegra 6800 components, and it is my wish to have a complete Ultegra 6800 groupset on the bike. This means swapping out some components for Ultegra 6800 components, and the crankset is one of them. One of the components which had already been changed to Ultegra is the cassette, which was upgraded a while ago.

By upgrading the crankset to the Ultegra 6800 crankset, the expected differences are lower weight, better shifting, stiffer crankset and better appearance.

Ultegra 6800 crankset!

Same compact 50/34T chainrings, length of 170mm.

One thing to note is that for newer cranksets (Dura-Ace 9000, Ultegra 6800 and Shimano 105 5800), the crank arm fixing bolt is now longer than those on older cranksets. This is to improve the thread engagement of the crank arm fixing bolt onto the spindle, so that there is less chance of it dropping off or stripping the thread. Another reason is to allow the left crankarm to be tightened onto the spindle even if a BB spacer is placed under the right side BB cup.

Same serration profile for old and new crank arm fixing bolt

The new crank arm fixing bolt on the right can be seen to have twice as many threads as the previous version.

One thing that I really like about this new Ultegra 6800 crankset is that it looks really good. The matte/glossy grey anodised finishing looks very high end, and I think it looks even better than the chrome + black finishing of the Dura-Ace 9000 crankset.

Another big difference is the 4 arm design, which is radically different from previous generations of 5 arm crank designs. At first it may seem weird if you are not used to it, but after seeing this 4 arm design for a couple of years, I actually find it quite special, and it helps to identify the groupset series on the bike.

Ultegra 6800 crankset with the iconic 4 arm design

11 speed compatible, also compact 50/34T chainrings. Both standard 53/39T and compact 50/34T cranksets share the same crankarm, with the same BCD.

Outer chainring is made of 2 parts bonded together, as you can see from the picture here. The outer layer with the chainring teeth is bonded to the inner layer which creates this hollow outer chainring.

Some shifting ramps and pins on the inside of the outer chainring to improve shifting.

34T inner chainring made of aluminium

The crankarm is also made of 2 pieces bonded together. In fact you can still see some sort of hardened epoxy oozing out near the 4 arm area.

Lots of codes and numbers for identifying the part and batch of this production

No I did not cut open my Ultegra crankarm. This cut-away sample is from the display at Shimano Cycling World, showing the hollow crankarm and its two piece crankarm construction.

Hollow crankarm of Dura-Ace 9000, with even thinner walls for lighter weight.

Left crankarm + crank arm fixing bolt weighs 197 grams.

Right crankarm + chainrings weigh 480 grams.

Together, the full Ultegra 6800 compact crankset (170mm) weighs 677 grams.

The weight of the Ultegra 6800 crankset is 677 grams, while the non-series RS500 crankset weighs 796 grams. This gives a weight reduction of 119 grams by changing the crankset.

Previously, I had also changed out the BB from the Tiagra BB to the Dura-Ace 9000 BB, which saved 26 grams. Together, changing the crankset and BB from RS500 + Tiagra BB to the new Ultegra 6800 crankset + Dura-Ace 9000 BB saved 145 grams.

Comparing the appearance of the non-series RS500 crankset with the Ultegra 6800 crankset.

Yet another picture of the great looking Ultegra 6800 crankset

Recent new components that have been installed on the Merida road bike. 

Installed the Ultegra crankset into the new Dura-Ace 9000 BB

Another look at the Ultegra crankset and Dura-Ace BB

No need to re-adjust the FD position, as the size of the chainring is still the same.

Re-installed my favourite PD-A530 SPD pedals onto the new Ultegra crankset

View of the drivetrain side of the crankset

Full view of the bike with the new Ultegra 6800 crankset!

I think the new crankset matches the bike frame and the rest of the components really well. The new Ultegra crankset is also lower in weight than the original RS500 crankset. As for shifting performance, it feels the same before and after the change. For a comparison with the previous generation of Ultegra 6700 10 speed crankset, you can check out this post.

On the other hand, the improved stiffness of the crankarm can be felt when I perform a static loading test. How I do it is to point the crankarm downwards at the 6 o'clock position, and step on the pedal to provide a loading force. The crankarm will deflect inwards and this can be seen quite easily if there is any flex.

When I perform this test on the RS500 crankset, there is a noticeable deflection of a few millimeters inwards. When I tried it on the Ultegra 6800 crankset, there is almost no deflection at all. This difference in stiffness can be seen visually and also felt through the feet.

So far, with the weight reduction from the Selle Italia SLR Kit Carbonio Flow saddle (save 215 grams) and also from this new crankset and BB (save 145 grams), there is a weight saving of 360 grams over the stock set up.

There are still some components which are not of the Ultegra groupset yet, so there are more changes to come!


  1. Thank you for your blog post. I just received a mail-ordered Mekk Pinerolo AL2.5 that was advertised to have a 105 crank. When it showed up, it had the RS500 and I was a little bummed. I called the company and they gave me a $20 gift card and refunded my $20 shipping charge. I am encouraged to hear you say that "...this non-series crankset actually performs quite well and I have no complaints about it. Shifting is fine and it also looks quite good. With a crankset weight of 796 grams it is actually not very heavy for this grade of crankset." My biggest concern is the shifting performance compared to the 105. This is my first road bike and most of the components are 105. The brakes are Tiagra. I still feel like I got a good deal because I got an nice frame with mostly good components for under a grand. Thanks again.

  2. Wouldn't changing the wheelset would have been more beneficial in terms of weight, seeing that even your front wheel has 32 spokes?
    However I for myself can not say how much stiffness helps over loosing weight (if those would be compared), for example when driving up a hill. Would it for example be more worth to go from let's say Tiagra -> Ultegra drivetrain (if weight would stay the same), or would it be better so save a certain amount (how much?) weight, when going up a hill (under whatever other conditions)? Is there some information on this somewhere?
    Overall, many people say the cheapest highest gain can be gotten from good tires (reduction in rolling resistance helps a lot), but at least for you, as you already have Schwalbe One, they are already very good.

    1. Well if you continue reading, you will find that I also changed out my wheelset later on and saved a lot of weight.

  3. Hi, did you have to buy the new fixing bolt separately, or did it come with the Ultegra 6800 crankset?

    1. The longer fixing bolt comes with the crankset.

  4. Hi there,

    Would you allow me to borrow one of the images from this article to use on Very happy to link to your blog in exchange.

    If so, shoot me an email at: matthew DOT loveridge AT immediate DOT co DOT uk


    1. Hi Matthew, go ahead, just link it to my blog. By the way, what article will it be used for? Please drop me a link when it is published, thanks.

    2. Thank you so much! It's about Shimano cranks, I'll send you a link when it's live.


    3. Hello again, you may already have seen it, but here's the article. Thanks again for giving permission!


  5. Hi there, I have the same idea of replacing my FC-RS500 to a 6800 Ultegra crankset. Did you have to readjust the front derailleur or anything after the change? Many thanks!

    1. If the chain ring size is the same, no need to adjust the FD height. But there will be some differences in the chain line, so the FD cable tension and limit screws will likely need to be adjusted.


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