Technical FAQ: Shifting setup, Di2 troubleshooting, and more

Lennard answers questions about shifting, ranging from troubleshooting Di2 to equipping a road bike with a single-chainring drivetrain

Dear Lennard,
I am building a new Trek Emonda with Ultegra 10-speed shifters and drivetrain. The shifters are aligned for internal (under the bar tape) cable routing, and the frame likewise is set up for internally-routed cables. I need to put inline barrel adjusters in for the shifter cables, but find the only cable stop in my setup is at the cable port in the downtube.

Can you recommend a commercially-available inline adjuster that will work with my setup without placing the adjuster at that cable port, and thus sparing the frame and downtube unnecessary wear and rubbing?
― Joe

Dear Joe,
Yes, there are a number of inline cable barrel adjusters available that can be placed anywhere on the cable, rather than at the cable stop. Here are some from Jagwire, SRAM, and Shimano.
― Lennard

Dear Lennard,
I have Shimano Ultegra 6770 Di2 on one of my bikes. The shifting worked flawlessly for about 5,000km, then in my wisdom, I decided to get the rear derailleur reprogrammed so I could do multiple shifts with one touch of the button.

Ever since the reprogramming, the front derailleur will throw the chain off of the big ring on upshifts.

I have rechecked the installation of the front derailleur, and it is installed as per the Shimano manual, but I cannot get the outer plate of the front derailleur within the 0.5-1mm of chain clearance that Shimano calls for in the manual. The outer plate is 3mm away from the chain and the top adjusting bolt is just touching its landing. I cannot get the outer plate any closer to the chain, and this 3mm clearance is letting the chain drop off the outside of the big chainring.

I did put the rear derailleur back to the original shift pattern, but that did not cure the problem.

Is there any way that the reprogramming of the rear derailleur has somehow affected the programming of the front derailleur?

If so, how do I correct the front shifting problem?
― Bryan

Dear Bryan,
I doubt reprogramming the rear derailleur could have done that to your front derailleur. It sounds to me like the high-gear limit is just not properly adjusted.

You don’t mention the high-gear limit screw (unless that is what you mean by “adjusting screw”). Have you adjusted it to prevent the cage from moving outboard so far?

Its rotation direction is clockwise to move the cage outward, and counterclockwise to move it inward (which is what you want it to do); note that this is the opposite direction of how the high-limit screw works on a cable-actuated front derailleur.
― Lennard

Dear Lennard,
Thank you so much for responding!

Sorry for the using the wrong terminology (adjusting screw); I did mean the high-gear limit screw. You are correct in your description of how the high-gear limit screw works. The screw works mechanically by moving the front cage farther away from the frame, it does not “limit” or stop the outward adjustment of the cage like most mechanical shift systems do.

I can actually remove the limit screw and the derailleur will still not adjust (inward) closer to the outer chainring; my screw is set so that it just has tension on it, negating the possibility of the screw falling out.

Since I wrote to you, I contacted both Shimano USA and Shimano Canada, and both said that any programming alteration to the rear derailleur will not affect the front derailleur. That was good news!

What I have done to cure the problem was squeeze the two plates of the front derailleur closer together. That has brought the outer guide plate closer to the outside of the chain when it is on the big ring.

In hindsight, I do remember the chain jamming on a front, and multiple rear, upshift shortly after I had the rear derailleur reprogrammed. The chain jammed between the front derailleur and the large chainring, and maybe when this occurred, the front derailleur plates splayed out? It is also possible that I blamed the programming on the front derailleur problem because it was the last thing I altered before encountering this problem.

I have intended on measuring the distance between the two plates of the front derailleur of my Dura-Ace-equipped bike and compare it with the Ultegra-equipped bike I was having problems with, but since squeezing the two plates together, I have not thrown a chain in over 1,000km this year … and I have forgotten to take the measurement. Probably because I have been riding so much!

I really do appreciate your response and am a longtime reader of all your tech columns, so please keep up the good work.
― Bryan

Dear Bryan,
Glad to hear you solved it! Your theory of the cage having gotten bent when you jammed the chain makes sense.
― Lennard

Dear Lennard,
Reading your last few answers about drivetrain compatibility, I thought I’d ask you about an idea I’ve had for awhile: Would it be possible to make a 1X road drivetrain by combining SRAM X1 (or X01, or XX1) and CX1?

You could use the (10-42) cassette, derailleur, and chain from X1 with a 46-tooth chainring and shifters/brake levers from CX1 (plus, of course, a custom rear wheel with the correct cassette body).

Using these parts, a gear ratio (chainring/cassette) of 1.10-4.60 ― this isn’t far off of a compact and an 11-32 cassette at 1.06-4.55 …

I understand that there might be a slight discrepancy in the cable pull required for the shifter/derailleur combo, and thought that might be sortable by replacing the internal barrel of the CX1 shift lever with a modified/custom version (or just using a friction shifter).

A plus of this system would also be the ability to easily change the gearing ratios of the entire bike for CX/horrible hills/similar by only changing a single chainring.

Obviously it wouldn’t work for racing because of the large jumps, but for a do-it-all bike … ?
― Sam

Dear Sam,
All SRAM 11-speed road shifters are interchangeable with SRAM Force CX1 shifters. You know this because you can run CX1 as a hydraulic-disc-brake setup with a pair of Force CX1 hydraulic levers, or you can use it with cable-actuated brakes with the stripped left lever devoid of shifting internals and any right SRAM 11-speed road shifter.

Furthermore, all SRAM road shifters are compatible with all SRAM MTB rear derailleurs, except 11-speed ones.

So, the group you are proposing would not shift properly, because the shifter and rear derailleur are not compatible. You seem to understand this, but the reality of changing the guts of the shifter so it would work like a SRAM 1X11 shifter would be a massive project.

You would of course have a rear disc hub, and presumably you’d be running this as a disc-brake bike. To do it with hydraulic disc brakes, you’d need the SRAM CX1 hydraulic levers, whose shifting would be incompatible with an XX1 or X1 or X01 rear derailleur. And there is no such thing as a replaceable “internal barrel” for SRAM road or CX1 shifters. To design and build new 11-speed internals and interchange them into the CX1 lever would be a task well beyond that of any but a very detail-oriented machinist with a lot of time to devote to this project.

If you were to run it with cable-actuated brakes, then you could just use old-school brake levers without shifting internals, and you could use a frictional bar-end shifter. But shifting 11 cogs with such narrow spaces between them would be touchy to do just by feel on a frictional lever; frictional shifting was much more realistic in the days of six-speed cogsets with wider chains and cog spacings.

I guess I’m getting caught up in the specifics of how you would do this rather than of the opportunity you are envisioning. In answer to that, yes, this setup would offer a lot of versatility. But since it would not be feasible to do it, it will remain a pipe dream for the time being.
― Lennard