Tech & Wearables

Technical FAQ: Mixing cranks on gravel bikes

One reader asks about using a Campy crank on a Shimano drivetrain, while another reader inquires about mixing in a Wolftooth component.

Dear Lennard,
I want to put a front derailleur and Campy H11 52/36 crank on my Ibis Hakka MX gravel bike. It has Shimano Di2 Ultegra Shifters and XT Rear derailleur. I am hoping to put on a Di2 front derailleur and get a T47 BB from Argonaut and get it wired up and programmed. My mechanic does not think it works to have a Campy H11 crank on a Shimano drivetrain, but I am thinking it’s just a crank. What is the diff? I like the Campy cranks and have had great success with them in the past so I want to try that if I can. They used to make Fulcrum cranks for Shimano drivetrains so just curious why the mechanic does not think this will work.
— Jonas

Dear Jonas,
It’s not going to work, and that’s not due to whether the crank is Campy or Shimano (or Fulcrum); it’s because of the chainring sizes.

While neither Shimano nor Campagnolo will recommend mixing and matching their components with each other, that crank will work fine with a Shimano Di2 road front derailleur, with particular emphasis on “road.” Though the H11 crank has a slightly wider chain line for disc-brake dropout spacing, that would not be an impediment to it working with current 11-speed Di2 road front derailleurs. The chainrings would be plenty stiff to handle Di2’s shifting power.

The problem is, you’ve got a Di2 MTB (XT) rear derailleur, and it will not work with a Di2 road front derailleur. Shimano’s road and MTB Di2 derailleurs will both work with either road or MTB Di2 shifters, but you cannot mix and match the derailleurs on the bike. Both derailleurs have to be either road or MTB; a Di2 MTB rear derailleur will not work with a Di2 road front derailleur, or vice versa. Since that Campy crank has road chainring sizes, an XT or XTR Di2 front derailleur will not work with it. In order to use that crank on your Hakka MX with an Ultegra Di2 front derailleur, you would have to also switch the rear derailleur to Ultegra or Dura-Ace Di2.
― Lennard

Dear Lennard,
I am in the process of figuring a drivetrain for a drop bar mountain/gravel bike. I am considering the Shimano GRX 812 derailleur and 1X system. I see riders using a WolfTooth to get an 11-46 cassette or greater out of this.

I would like to get the gearing low with a 32T chainring. Can I use a Deore XT M8000 crank with this? Would I have to go to a White Industries crank or something else? (I thought I saw someone use a SRAM, but I am unsure.)

Thank you for your insights!
—Don

Dear Don,
I wonder what you mean by a mountain/gravel bike. I assume you mean that you might use as big a tire as 29 x 2.25” on it, whereas 700 x 45C is about as big as one normally associates with gravel tires.

There are a number of things to consider here. One is that the Shimano GRX 812 rear derailleur is only rated to a max rear cog of 42T and total cassette range (gear capacity) of 31 teeth (42-11=31). While it’s possible that the 812 could handle a 46T on your bike, there is no guarantee of that. Bikes vary in length and angle of the derailleur hanger as well as bottom bracket height, all of which affect the max cog capacity of the rear derailleur.

The Shimano GRX 810 rear derailleur has a higher total gear capacity, namely 40 teeth. Unlike the 812, however, it is designed for a 2 X 11 drivetrain, and that high gear capacity is related to taking up chain slack when shifting the front chainrings, not to being able to get its upper jockey wheel under a bigger rear cog. Its max rear cog rating is only 34 teeth, while its max difference in front chainring sizes is 17 teeth. The 40-tooth gear capacity is arrived at by subtracting the smallest cog from the biggest one and adding the chainring difference: 34-11+17=40.

When you talk about Wolf Tooth, I assume you are talking about taking the 17T and 19T cogs out of your cassette, replacing them with a single 18T cog, and putting a Wolf Tooth GC large cog behind the cog stack. First of all, for Shimano 11-speed, Wolf Tooth’s largest is 45T, not 46T. You could, of course, just use a Deore XT 11-46T cassette and not have the bigger jump in cog size by replacing the 17T and 19T cogs with an 18T cog.

Since you mention Wolf Tooth, if the 812 derailleur attached to your derailleur hanger doesn’t handle the 46T (or 45T) cog, you can get its RoadLink derailleur hanger extender or GoatLink 11 to increase the cog size it can handle.

As for using a Deore XT M8000 crank, you want to make sure you don’t get a Boost-compatible crank, distinguished by a “B” in the product code. The chainline on the Shimano FC-M8000-B1, which is designed for Boost (12 X 148mm rear end) has a chainline of 53mm. Assuming you have a disc-brake gravel bike, the chainline for its 12 X 142mm rear end (or a 135mm quick-release rear end, which is the same hub spacing) is 47mm for road/gravel (based on best shift/chain performance) and 49-50mm for MTB (based on ensuring that the chain clears the rear tire).

The Shimano FC-M8000-1 crank has a chainline of 50.4mm and should work fine for you. If you really are going to use up to a 2.25” (57mm) tire width, you will want that MTB crank’s chainline, whereas if you are only going up to 42 or 45mm tire width, you could use a road crank with a 47mm chainline.
― Lennard


Lennard Zinn, our longtime technical writer, joined VeloNews in 1987. He is also a custom frame builder (www.zinncycles.com) and purveyor of non-custom huge bikes (bikeclydesdale.com), a former U.S. national team rider, co-author of “The Haywire Heart,” and author of many bicycle books including “Zinn and the Art of Road Bike Maintenance,” “DVD, as well as “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.” He holds a bachelor’s in physics from Colorado College.

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