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Technical FAQ: Flying with Di2, combining components, and more

This week, Lennard Zinn answers readers' questions about flying with Di2 components, mixing parts, and more

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Traveling with Di2

Dear Lennard,
Will I be able to ship my Di2 battery on the airlines when I travel? Do I leave the battery on the bike in the shipping box, remove it from the bike and leave it in the shipping box, or carry it with me in my carry-on luggage?
— Rich

Dear Rich,
I talked to a Shimano spokesman, who said:

The TSA suggests you carry the battery in your carry-on bags if possible. This is easily done on a bike with an external Di2 battery. In the case of an internal battery it is OK to keep the battery on the bike, but TSA recommends disconnecting the battery. So disconnect your E-Tube wires at the rear derailleur, front derailleur and front junction. This will keep the battery isolated and not in use, saving your charge and protecting your components.

And for those Campagnolo EPS users, you should install the shutoff magnet in the Power Unit when traveling with the bike and leave the Power Unit on. The battery is not removable and is part of the bike once the bike is built.
― Lennard

Using Di2 with SRAM

Dear Lennard,
I’m weeks away from getting a new tandem frame. It will be Di2 powered. My question is: would SRAM’s new 11-speed WiFli 11-32 cogset be compatible with an Ultegra 6800 Di2 rear derailleur?
— Baxter

Dear Baxter,
The answer is yes, with some modifications. Both are 11-speed units and are designed with the same cog spacing, but the cog size is the issue.

The Ultegra 6870 rear derailleur’s maximum tooth capacity is 28 teeth. So in order to get it to shift onto that 32-tooth cog, you need to increase its capacity somehow. There are a number of ways to do this.

One is to use a longer rear derailleur hanger on the dropout to get the derailleur to drop down far enough to clear the largest cog.

Another method is to max out the b-screw adjustment (possibly in combination with the longer derailleur hanger as well) to get the derailleur to swing back far enough to clear the largest cog. It may require taking the b-screw out and putting it in from the opposite direction so the b-screw’s head contacts the tab on the derailleur hanger.

Finally, the most elegant solution is to use a longer jockey wheel cage on the derailleur. You can buy an Ultegra 6800 GS long-cage triple rear derailleur and interchange its jockey wheel cage with the one on your 6870 Di2 rear derailleur. That cage is compatible with 32 teeth on the large cog. You’ll still be left with a perfectly functional cable-actuated Ultegra 6800 11-speed rear derailleur when you’re done, in addition to your long-cage 6870 Di2 rear derailleur. There are also aftermarket solutions to get more gear capacity; check out Ian’s comment below, who had written me months ago about a similar issue.

I’m using Dura-Ace Di2 with Dura-Ace 50/34 compact chainrings and XTR 11-36 rear cassette with the K-Edge long cage, designed to let you use Di2 on a mountain bike. It has worked flawlessly and is a brilliant solution for heavy and/or loaded and/or weaker riders in the hills.
— Ian

― Lennard

Derailleur hanger lengths

Dear Lennard,
One thing that never seems to be discussed on questions about big gears in the back is the length of the derailleur hanger. Different frames have different length hangers. I can run a 12-32 on the back of my 2004 Trek 5200 with no problem using Shimano 6500 long cage derailleur. On my 2008 Trek 5.5 Madone, even with a long-cage MTB derailleur, a 28-tooth is the largest that I can run. The difference is the derailleur hanger length. I have not been able to find a source of a longer derailleur hanger to fit my 5500 frame. I am 66 years old and need all the low gears I can get in hilly terrain.
— Phillip

Dear Phillip,
Whenever I’m looking for a weird derailleur hanger, I start by looking at Wheels Manufacturing; maybe you’ll find one there.
― Lennard

Mixing, matching

Dear Lennard,
I wanted to comment on mixing brands/categories of gears/shifting components.

My lovely wife needed lower gears for the hills here in Western Oregon. I created a Frankenbike by fitting her road bike with a Shimano XTR MTB rear derailleur and a SRAM 990 MTB cluster. Since she likes gear indicators, she is using Shimano Sora shifters. These shift the XTR quite well and do a great job with the Campy Record front derailleur she is using to shift a 50/34 Campy Record road compact crankset. The shifting both front and back took some fine-tuning, but has performed well for over 10,000 kilometers. This gives her a 1:1 lowest gear ratio and lets her climb the 12-18 percent grades around us with comparative ease.

Keep up the fine work helping us backyard bike mechanics keep on tinkering.
— Henry

Dear Lennard,
I am getting geared up for the ’cross season, which is just around the corner here in Alaska, and was wondering if a setup like below will work?

SRAM Red 22 hydro shifters
SRAM XX1 or XO type 2 rear derailleur
SRAM X-glide 1190 cassette

What I really want is to run a rear derailleur with a clutch and hydraulic disc brakes, both of which are recent improvements that I feel will make the CX bike run much smoother. I’m just not sure if all those pieces play well together.
— John

Dear John,
I’m afraid that won’t work.

XX1 and new X01 11-speed MTB rear derailleurs use X-Actuation. That’s the communication between the rear derailleur and shifter, related to cable pull.

For 10-speed MTB, SRAM uses Exact Actuation, which is also used on SRAM 10-speed road. This is also used on SRAM 11-speed road.

Don’t confuse actuation ratio with the number of gears. An 11-speed Exact Actuation shifter shouldn’t be used on a 10-speed Exact Actuation system.

To answer your question, an XX1 X-Actuation rear derailleur isn’t compatible with an 11-speed road Exact Actuation shifter.
― Lennard

Dear Lennard,
I’ve been looking at upgrading my bike (Specialized Secteur Expert Disc Compact) from the mechanical Avid BB7 discs to the SRAM S-700 Hydraulic Disc Brakes. I’m trying to figure out if the new SRAM shifters/brake levers will work with my existing Shimano 105 front and rear derailleurs (10-speed), or if I would have to replace the derailleurs as well.
— Harris

Dear Harris,
No, you will have to get SRAM derailleurs; the cable pull is different from Shimano. You won’t need a new cogset because the S-700 levers are 10-speed compatible.

You could perhaps try that Shimano front derailleur; you might get away with it, but I wouldn’t bet on it. The rear derailleur definitely will not work.
― Lennard