Tuesday, January 10, 2017

Shimano Dura-Ace 7900 vs Shimano Dura-Ace 9000: Crankset

I recently got the Dura-Ace 7900 crankset from the Rodalink online store at a great deal. This gives me a chance to make a detailed comparison between the Dura-Ace 7900 crankset and the Dura-Ace 9000 crankset.

First of all, the 7900 crankset is designed for 2x10 speed drivetrains, while the 9000 crankset is for 2x11 speed. Strictly speaking, these cranksets are not cross compatible as the front shifting performance will not be ideal. However, many people have used these cranksets interchangeably across 10 and 11 speed drivetrains with no major issues.

What I have for comparison is a Dura-Ace 7900 crankset, with 53/39T and 165mm crank arm length. As for the Dura-Ace 9000 crankset, it is 50/34T, with 170mm crank arm length. As such, the total weight comparison is not the most accurate as the specifications are slightly different.

Dura-Ace 7900 crankset, with 5 arm design and 130mm PCD.

Dura-Ace 9000 crankset, with an asymmetrical 4 arm design, and a 110mm PCD

Super polished 7900 outer chain ring, together with dark grey matte anodising.

Polished silver and black anodising on 9000 chain ring. Black inner chain ring with a silver band.

7900 crankset, with surprisingly few shifting pins and ramps. Another look at the silver inner chain ring teeth.

9000 crankset, with more shifting pins. All black inner chain ring.

Inner view of the 7900 crankset with 39T chain ring

Inner view of the 9000 crankset, with 34T chain ring

7900 crank arm with rounded edges, hollow forged in one piece.

9000 crank arm is wider and has a more rectangular cross section. Bonded from two separate pieces.

Left side crank arm comparison. The 9000 crank arm is significantly larger in terms of width.

Another look, comparing the rounded edges of the 7900 crank arm with the sharper edges of the 9000 crank arm.

7900 left side crank arm has the logo facing the right side up when the crank arm is facing to the back, while the 9000 crank arm is the other way round.

7900 crank arm with a hollow and open 5 arm profile

9000 crank arm with a hollow but closed 4 arm profile

Weight of 165mm left side 7900 crank arm

Weight of 170mm left side 9000 crank arm. If I'm not wrong, this weight will be the same as the 165mm length, as the arm is the same, just that the pedal hole is drilled at a slightly different place.

Right side crank arm of 7900, 319 grams  

53/39T chain rings of 7900, 145 grams 


Right side crank arm of 9000, 306 grams. Lighter than 7900.

50/34T chain rings of 9000. Lighter mainly due to smaller size.

Comparing the arm construction of 7900 (left) vs 9000 (right)

Side by side view of 7900 vs 9000 right side crank arms

Right side of the 7900 crankset with 53/39T chain rings and 165mm crank arm length weighs 465 grams.

Right side of the 9000 crankset with 50/34T chain rings and 170mm crank arm length is lighter at 440 grams. The lower weight is from the smaller chain rings and also lighter crank arm.

Total 7900 crankset weight is 643 grams

9000 crankset weight is even lower at 615 grams

Side by side comparison of the different chain rings. Note that there are many cosmetic and construction differences.

Final picture for crankset comparison. Both the 5 arm and the 4 arm designs are iconic and special in their own ways.

Other than the difference colour schemes, there are also major differences in how the crank arms are made, and how different parts of the crankset are constructed. Both are lightweight and look extremely high end, with exceptional surface finishing and high quality manufacturing.

18 comments:

  1. Thanks for the write up. Very informative.

    ReplyDelete
  2. Hi there.
    My name is Hakim and hope you could help me with this.
    I’m currently using dura ace 7900 crankset and would like to purchase an upgrade kit for R7000/R8000 (without the crank)
    Is the crankset compatible with R7000/R8000 ?
    With budget in mind, is it advisable?
    Thank you for your time Sir.

    ReplyDelete
    Replies
    1. This 7900 crankset is for 10 speed, which is different from R7000/R8000 which is 11 speed. The chain width is different and so is the front derailleur. The crankset is not 100% compatible, and so you will experience sub-optimal front shifting performance.

      Delete
  3. Hello. Thank you for review, very usefull and detailed. Do you think they have same q-factor, so potentially (irrespective of estetics) I can use 9000 left crank with powermeter on my 7900 crankset?

    Cheers,
    Marat

    ReplyDelete
  4. Hello, my name is James.
    Last week my 7900 crankset (177.5mm 39-53) completely snapped and broke right where the pedal screws in. This happened while riding up a slight incline and I was pushing hard on the pedals. The crankset is 8 years old and was never damaged in any way, and always kept in immaculate condition. This break was a manufacturing defect, and my local bike shop is sending it back to Shimano for evaluation.
    Question: Can I use a 9000 Crankset to replace my broken 7900 Crankset even though the 9000 is for 11-speed, and the 7900 is for 10-speed? Is the 9000 sprocket spacing too narrow for the 7900 chain? Any recommendations without changing everything over to 11-speed?

    ReplyDelete
    Replies
    1. It will work although not 100% compatible, as the spacing between the front chain rings is closer on the 11 speed crankset. You will likely get some chain rubbing at cross chain conditions and shifting may also be affected.

      Delete
  5. I have some spare 7900 front and rear derailleur and 7900 cassette which I plan to use on my next build but instead of getting an all dura ace set-up I am planning to use 10-speed Shimano Ultegra for all the other missing parts that I do not have yet.
    Question: Would the Dura Ace and Ultegra parts synch? Any Advice?

    ReplyDelete
    Replies
    1. As long as they are the same number of speeds, Dura-Ace and Ultegra will be compatible.

      Delete
  6. Hello, I am looking at buying a Dura-ace 7900 crankset 50/34 to use with my Dura-ace 7800 drivetrain. Will there be any compatibility issues as I read the 7900 cranks work ONLY WITH CN7900 chain?

    ReplyDelete
  7. Hello, I am looking at buying a Dura-ace 7900 crankset 50/34 to use with my Dura-ace 7800 drivetrain. Will there be any compatibility issues as I read the 7900 cranks work ONLY WITH CN7900 chain?

    ReplyDelete
  8. I can find DA 9000 left Stages arms more readily than 7900 versions, can I mount a 9000 left arm with a power meter onto my 7900 crankset?

    ReplyDelete
    Replies
    1. Should be ok, just make sure the left and right crankarm lengths are the same.

      Delete
  9. I have a 7900 Dura Ace set up a need a new rear derailer,what new version can I get in a Dura Ace.

    ReplyDelete
  10. What can I replace my 7900 rear derailer Dura Ace. I still wanna keep it with DuraAce?

    ReplyDelete
    Replies
    1. There is no more 10 speed Dura-Ace, so you need to get the same RD-7900.
      Other compatible 10 speed RD are Ultegra RD-6700, 105 RD-5700.

      Delete
  11. Thanks, helpful. I hab the Same Question!

    ReplyDelete

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