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My understanding is that 7/8/9/10 chainring spacing is the same.

I have a Shimano Claris double/2x8-speed that I want to upgrade to a triple front, but using a 10-speed crank. I’ve acquired a Shimano Tigara 3x10 front derailleur/mech, triple/3x8 left brifter, and will run a 10-speed chain. I may have a cage length issue, but otherwise will this work?

But also, let’s settle this, since I’ve looked this up a bunch, and it leads to much more complex discussions and a lot of noise. Do 7/8/9/10-speed cranks all have the same spacing? Then what about 11 and 12?

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  • Another way to put it - "since Tiagra 10 speed is the same as normal 11 speed ratios in the rear, did Shimano also fiddle the front ? "
    – Criggie ♦
    Commented Feb 20, 2022 at 4:10
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    One of the muddling factors is chainring spacing is a combination of the thickness of the spider tabs, the stock thickness of the chainring, and the offset (if any) of the tooth centerline on the chainring. So for example since some generations/models of Shimano cranks have chainrings with a lot of offset and many don't have any, the answer can depend on what exact problem you're trying to solve (a chainring/crank compatibility question versus a crank/shifter one for example).
    – Nathan Knutson
    Commented Feb 21, 2022 at 4:20

2 Answers 2

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There is often confusion about so-called '10 speed chainrings' and '11 speed chainrings'- but there are no such things as all derailleur chainrings are suitable for all systems from 3 to 11 speed. However some '10 speed' and '11 speed' cranks place their chainrings slightly closer together, but this isn't usually critical.

http://www.cornant.uk/info/cranks.html

Note that 11speed chainrings are supplied as a timed pair by most manufacturers to enable reliable shifting with the flat chain profile.

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    Why would different spacing not matter for indexing?
    – BBaysinger
    Commented Feb 20, 2022 at 13:04
  • Because narrow chain can't fall between widely spaced chainrings and the chain wouldn't rub against close spaced large ring on small-small combination. Wait...
    – ojs
    Commented Feb 20, 2022 at 13:18
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    @BBaysinger The front derailleur is a blunt instrument that simply smashes the chain from one ring to the other with very little precision. There is generally enough adjustment of minimum and maximum position that a small difference in ring spacing isn't relevant. The chain can only fall between the two rings if the chainring bolts are loose or washers have been added where they shouldn't be.
    – Noise
    Commented Feb 20, 2022 at 16:21
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    @ojs noone uses the small-small combination. On 11sp road it is generally impossible, and simply wears parts fast on other systems.
    – Noise
    Commented Feb 20, 2022 at 16:22
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    @ojs Shimano Di2 doesn't even allow that combination anymore because the chain gets caught by the pickup pins on the large chainring on a short chainstay road bike. Even on SRAM 22 it can still foul the chainring.
    – Noise
    Commented Feb 21, 2022 at 13:30
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"My understanding is that 7/8/9/10 chainring spacing is the same." - NO!

The chain will fall between chainrings, almost all the time.

Another problem you will have is, rear derailleur pulleys. If you have a 8 speed rear derailleur, that won't work with 10 speed. 10 speed chain is much narrower. But you can replace pulleys.

You will be using 3x10 crankset, 8 speed rear derailleur, 10 speed front derailleur and 3x8 brifters, right?

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  • Everything is 3x8 except the crankset which is 3x10.
    – BBaysinger
    Commented Dec 21, 2022 at 21:23

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