Sunday, October 9, 2016

Shimano Ultegra 6800 vs Shimano 105 5800: Crankset

The two most popular road groupsets are Shimano Ultegra and Shimano 105, and this is largely due to the value and performance that these two groupsets have.

Ultegra is the second tier road component, just below the top end Dura-Ace. It has 90% of the function and performance of Dura-Ace, and yet cost half the price. It is a great buy for those who value performance and are willing to spend a bit more than average.

As for Shimano 105, it is the third tier road groupset, just below Ultegra and above Tiagra. This is probably the most popular and common groupset for road bikes in most countries. With performance that is probably 70-80% of Dura-Ace, and at one-third the price of Dura-Ace, it is great value. It weighs a bit more than Ultegra, mainly due to higher usage of steel as compared to aluminium for Ultegra. It is perfect for those who want to experience high end technology but are on a tighter budget.

This time, I will compare the crankset of Ultegra 6800 and Shimano 105 5800, both of which are 2x11 speed road cranksets. Let's take a look at their physical differences and similarities before comparing the technical differences.

In order to make a more thorough comparison, I removed the chainrings from the crank arms and compared them separately.

Ultegra has a dark grey finishing, while 105 has a black finishing. Both will match well with most bikes. From far, these look similar, except for the size and shape of the logo.

The back of the crankarms also look similar, with not many obvious differences.

The Ultegra crankarm (top) has a chamfered edge, while the 105 crankarm (bottom) has a more rounded edge.

The 4 arm area of the crankarms have more differences. The 4 arm area of the Ultegra crankarm on the left is bonded together front to back, while the 105 crankarm on the right side is one piece with a hollow area.

Another view showing the difference. The Ultegra crankarm has a joint line, while the 105 crankarm on the right does not. By making the crankarm in one piece, it eliminates the bonding process and lowers the production cost of the 105 crankset.

For more information on the Ultegra 6800 crankset, check out these other two comparisons.
Ultegra 6800 vs Ultegra 6700: Crankset
Dura-Ace 9000 vs Ultegra 6800: Crankset

Ultegra 6800 right crankarm weighs 331 grams...

...105 right crankarm weighs 340 grams. A 9 gram difference, not that much.

As for the left side crankarm, one interesting difference I noted is the direction of the logo printing. The Ultegra logo looks upright when the crankarm faces forward, while the 105 logo looks upright when the crankarm faces to the rear.

The 105 crankarm on the right side looks a bit slimmer at the middle portion.

Ultegra left crank arm plus crank arm fixing bolt weighs 201 grams...

...105 left crank arm plus crank arm fixing bolt weighs almost the same at 205 grams.

Inner 36T chainring of the Ultegra crankset weighs 34 grams...

...inner 36T chainring of the 105 crankset weighs 37 grams. Almost the same.

Ultegra chainring on the left has an aluminium shell bonded to the outside of the teeth, while the 105 chainring teeth is one piece with the outer shell.

105 chainring on top is basically made up of an aluminium shell, which ends in the gear teeth at the edges. Ultegra chainring teeth and the shell are made separately and bonded together.

Big differences when viewed from the back. Ultegra chainring has the original Hollowglide chainring construction, which is made up of a ring of gear teeth, bonded on both sides by the outer shell and inner shell, which makes it hollow and yet lightweight and rigid.
Shimano 105 chainring is a lower cost version, with an outer aluminium shell + teeth on the outside, and a composite structure on the inside for strength and rigidity. 

Closer look at the differences in chainring construction. 105 chainring on the right side with composite material and lots of ribs. Gives the rigidity of a Hollowglide construction but at lower cost.

A closer look at the injection molded ribbed design at the back of the 105 large chainring.

Weight of Ultegra 52T outer chainring is 121 grams...

52T 105 5800 Outer Chainring weighs 164 grams, a substantial increase over the Ultegra.

Ultegra uses the lightweight aluminium chainring bolts which weigh only 5 grams in total

105 has the more standard steel chainring bolts which weigh a bit more at 12 grams.

Ultegra FC-6800 52/36T: 692 grams
105 FC-5800 52/36T: 758 grams

Main differences:
1) Weight (105 is 66 grams more than Ultegra, for 52/36T spec)
2) Cost (105 is about 1/3 cheaper than Ultegra)
3) Hollowglide outer chainring construction
4) Chainring bolt material (steel vs aluminium)
5) Construction of right side crank arm (4 arm area)
6) Surface finishing

In my opinion, the differences between these crankarms are mainly cosmetic, with lower cost construction methods used for the lower priced 105 crankset. Every component of the Ultegra crankset weighs just a bit lighter than the 105 crankset, which all adds up to give the total weight difference. Otherwise, the performance should be similar, which makes the 105 crankset great value as it is affordable and yet works well.


  1. Thanks for posting such a detailed comparison! I've installed both on different bikes and they really are quite beautifully made.

  2. Thank you for this. It makes me think saving $100+ when buying a left only power meter (with crankarm) by getting the 105 version over the 6800 worth it. Even though I have a 6800 crankset.

  3. Is it possible to install FC-5800 52/36 chainrings on a FC-6800 50/34 crankset?

    1. Not too sure, as the interface shape between the chain ring and the crank arm may be different. Best to get the correct series to match.

  4. Thank you for this! I just destroyed my Ultegra 6800 cranks after 4,041 miles and 27 months. The epoxy came loose on the crank arm and are no longer usable. Having 105 on two other bikes, I have decided to replace the Ultegra cranks with 105 5800. The weight difference is negligible and the cost of replacement chainrings is cheaper.

  5. Hi do you know if you can use a ultegra 8000 crankset with a 6800 front derailleur? It's on a giant trinity. Thanks

    1. Both are for road 11 speed so it will be ok.

  6. i have a dahon jetstream p8 no disc i am thinking of making it the lightest ever. im a little confused on the size of the front wheel and back wheel. is the front 74 or 100? and the rear is 130? Thanks ! im currently going to use a small scale to weight all the original factory parts too!

    1. Better measure the actual width of the hubs as the Jetstream is somewhat different from the more standard models such as Vitesse, Speed, etc.

  7. Great post, thank you. Is there any reason why I couldn't swap in a 105 crank arm w/ a power meter on an Ultegra crank with the same size spec (170)?

    1. You can, there will be no problem, except for the appearance which does not match.

  8. Hi can i use this cranksets for dahon vybe d7

    1. Yes you can, but you also need to change the bottom bracket to the Hollowtech type. 68 mm width, English threaded, road type.

  9. Hi can i use this cranksets for dahon vybe d7

  10. Good review. Would the 8000 chainrings fit on 7000 cranks then? Thanks.

    1. Not so sure, but even if it fits the joint area will not match well. Just use the correct chain ring to match the crank arm.

    2. Note that even within the Ultegra 11sp series, 6800 vs 8000, the chainrings ARE NOT interchangeable. One arm of the spider has a countoured contact surface where the chainring mates up. That single contour will prevent you from running a 6800 small ring on an r8000 spider. Lots of material out there will tell you parts are interchangeable but sadly that is not the case.

  11. Hi! Can i use this build with my giant expressway 2? Thanks

  12. Hi,

    Since stocks are limited, can I swap my FC5800 50T with a FC6800 50T?
    Will the crank spider match cosmetically?

    1. It will probably fit but not match in appearance, as the shape and colour is different.