Technical FAQ: Shimano-Magura, Campagnolo-Shimano, and other mash-ups

Have a question for Lennard? Please email him at veloqna@comcast.net to be included in Technical FAQ.

Dear Lennard,
I read that Chris Froome uses Magura disc calipers with his Shimano brake levers to reduce brake rub because the pads retract further on the Maguras.

Does that really work?
—Pierre

Dear Pierre,
Yes, it does!

“Shigura” brakes are Shimano brake levers combined with Magura calipers; they have been used by some finicky riders on mountain bikes for a while. The motivation is to get the performance and modulation of the Magura brake and the ergonomics of the Shimano lever. Both systems are filled with mineral oil, which is what makes this combination possible. Contrast it with the big no-no of mixing mineral-oil brake components with ones that take DOT brake fluid, like SRAM or Formula.

Magura makes flat-mount calipers, so they can be used on road bikes. In addition to improved brake performance or increased pad retraction, there is another reason for this component mix, and that is fit on the chainstay. If a frame has a tight angle between the chainstay and seatstay, the seatstay can impinge on the space required for the rear flat-mount caliper. Shimano calipers are harder to fit into that space than are SRAM, Magura, or Campagnolo ones, but a SRAM caliper is incompatible with those others due to its DOT fluid; the mineral-oil seals will be compromised by DOT fluid.

Here is a Shimano lever we mixed with a Campagnolo caliper to fit into a tight seatstay/chainstay corner. Because Campagnolo partnered with Magura to develop its disc brake, the Campagnolo caliper takes Magura Royal Blood mineral oil and has the same magnetic pad-separation system as Magura (vs. the butterfly-spring pad separator of Shimano and SRAM). Since Campagnolo has a dedicated caliper for each size rotor, it doesn’t take an adaptor to switch from a 140mm to 160mm rotor and hence sits closer to the chainstay to fit into a tight space better.

On this bike, I replaced the Shimano GRX rear caliper with a Campagnolo Record one. The brake performance is great—if anything, it feels like an upgrade to me. I used a Campagnolo barb and olive on the caliper end and a Shimano barb on the lever end (the olive is already inside the lever and engages when you tighten the big sleeve nut). I filled the system with blue Magura Royal Blood, rather than pink Shimano brake oil. I’m so used to seeing pink fluid in the Shimano bleed funnel, and it was mind-boggling to see blue fluid in it.

BTW, we built this bike for an 86-year-old customer with a mixte (step-through) frame design and dropper post to make it easier for him to mount and dismount the bike.

So there’s another “Shimagnolo” mashup, except this one is a hydraulic brake! Other Shimagnolo setups are generally derailleur/shifter combos, and rim brakes allow mixing and matching, too.
― Lennard

Dear Lennard,
In your September 14 column, you advised Phil against getting a steel frame built for both rim and disc brakes – part of your reasoning was a limit of 28mm tire width for rim brakes. Is there some reason that you ruled out cantilever-brake posts for mini-V brakes or cantilever brakes? I am very happy with my rim brake steel frame rando bike, cantilever brakes and 32mm tires.

And fork selection was also part of your reasoning. Four years ago, I built up a light touring bike with rim brakes on front, disc on rear. I did not go out of my way to build it with that mix of brakes; in my case I simply already owned a good rim brake fork with cantilever brake posts and front rack mounting capability when I bought a titanium frame (Lynskey Backroad) that was built for disc brakes in the rear. Thus, it was simpler and cheaper for me to build it up with that mix of brakes. I use 37mm wide tires on that bike. My point is that if Phil wanted to run rear rim brakes on his custom build, if he could only find a disc fork, mixing brakes would certainly be an option.
— George

Dear George,
There’s nothing fundamentally wrong with that, other than brake performance in wet conditions. I had no fundamental complaints with cantilevers on cyclocross bikes before discs were accepted in that realm, and cantis and V-brakes on mountain bikes were also okay back in the day. I don’t think that you can compare their performance to good hydraulic disc brakes, however.
— Lennard

Dear Lennard,
Just a small detail I picked up in your great reply to Phil regarding the steel frameset in a previous column. You said the maximum tire he could go with was 28mm if he had rim brakes. That all depends on the brake and fork crown/seatstay clearance, of course. On my old-school Surly Cross-Check, I have cantilever brakes and gobs of tire clearance in the fork and seatstays. So, I run 32mm tires for the road. Maybe on a modern road racing frame, that would be the case, but you can definitely still get a rim brake fork with the right clearance if your mind is open.

I’m sure it was just an oversight on your part in the explanation but figured I’d point it out for clarification’s sake.
—Peter

Dear Peter,
Yes, it was an oversight. Thanks for catching it.
― Lennard

Dear Lennard,
My question revolves around the newly introduced Shimano Dura-Ace and Ultegra groupsets, specifically the decision to stick with an 11-tooth gear as the lowest numerical gear vs. going to 10 like SRAM. Obviously, a 54-11 is still not as big as the 50-10 from SRAM. Why didn’t Shimano go with a 10-tooth gear for their smallest gear? Friction differences between 54-11 setup vs. a 50-10? Other reasons?

Also, I’m thinking a 52/36 Shimano chainring with a SRAM 12-speed cassette and its 10-tooth smallest cog would be a very sweet setup to get a large gear (e.g., 52-10) and still benefit from not having too much cadence drop off between the gears with a 52-tooth chainring vs. 54. So, will the SRAM 12-speed cassette work with the new Dura-Ace and Ultegra 12-speed groupsets? Should the SRAM or Shimano chain be used? I’d love to get your feedback.
— Nigel

Dear Nigel,
The drivetrain friction is higher with a 10-tooth cog than with an 11-speed cog and a correspondingly larger chainring. This article about the differences between 1x and 2x drivetrains explains why.

No, a SRAM AXS 12-speed (road) cassette will not work with Dura-Ace and Ultegra 12-speed groupsets, or any other non-AXS drivetrain. That’s because the AXS chain has larger rollers than any other chain, so the AXS 12-speed cog profiles in the cassette don’t fit non-AXS chains.

Here’s the answer from Shimano:

“We selected 11T for the smallest sprocket considering all aspects including the gear ratio required for road racing, frequency of use, gear steps across the cassette, and efficiency of the drive system for faster speed. With the same gear ratio, combining larger gears can provide higher drive efficiency. This is especially beneficial for fast riding in racing situations. And of course, we won’t comment on cross-compatibility with SRAM components. But we can share the significant benefits of running Shimano road groups as a full system, particularly because of the Hyperglide+ shifting technology. When you introduce non-Shimano components to the drivetrain, you lose that shifting technology and that would be a shame because Hyperglide+ is a huge upgrade with these new groups. Here’s a little on that: Hyperglide+ offers fast, precise shifting without having to reduce the pedaling force when an instantaneous gear change is needed for breaking away or bridging across to a cyclist or group ahead. When compared to previous drivetrain generations, Hyperglide+ delivers exceptional shifts to smaller cogs, especially under maximum pedaling load. Whether you race or not, seamless gear shifting lets you concentrate on the ride, your effort, and the world around you.” — Shimano

― Lennard

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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.

Follow @lennardzinn on Twitter.