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Road Gear

Tech FAQ: Test riding and diagnosing EPS aero shifters

Lennard Zinn test rode the EPS aero-bar shifters and brake levers and shares what he learned, including diagnosing and adjusting the system

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Editor’s Note: Lennard Zinn’s regular column is devoted to addressing readers’ technical questions about bikes, their care, and how we as riders can use them as comfortably and efficiently as possible. This week, Zinn calls an audible and brings you in-depth diagnostic advice for Campagnolo’s EPS electronic drivetrain and his first-ride thoughts the new EPS aero shifter. Readers can send brief technical questions directly to Zinn.

MARINA DEL REY, California (VN) — After riding the Campagnolo Electronic Power Shift (EPS) aero-bar shifters and brake levers from Marina del Rey on roads skirting LAX, I came away with a new understanding of the EPS system in general. The system worked great, and, fortunately, mine was a bit out of adjustment, so I learned how to diagnose and adjust it.

The super-short chainstays on a time trial/triathlon bike pose a challenge for silent and rub-free operation with any drivetrain due to the extreme chain angles, and EPS is no exception. The EPS front derailleur automatically trims its position as you shift through the rear cogs, but the range of adjustment to avoid chain rub on the front derailleur in cross gears is much narrower on a TT bike like this than on a standard road bike, and I repeated the procedure a couple of times to optimize it. Even if you can eliminate derailleur rub, however, when in extreme cross gears on a bike with such short chainstays, the chain is going to rub the big chainring when in the small-small combination, and it will make noise entering and leaving the tooth on top and bottom of the chainring in the big-big combination.

My only criticism of the EPS TT/Tri system is the same one I have for Shimano’s Di2 TT/Tri shifters, namely that there are two shift buttons on the left base bar brake lever. With either Di2 or EPS, the buttons on the left base bar brake lever can be accidentally operated to shift to a chainring you don’t want.

On Di2, the levers are close together, facing inboard, and when climbing out of the saddle and pulling on the base bars, it’s not hard to bump the shifter and suddenly end up with the chain on the big chainring when you least want it. The close-together Di2 buttons can also be confused when brain dead due to hypoxia. With EPS, the buttons are at least well-separated, one being on the top and one on the inboard side, so the confusion aspect is less of a concern. However, I did accidentally bump the side button once when pedaling hard out of a corner, and the chain suddenly dropped to the inner chainring when I was going hard in a big gear.

You don’t need two buttons for the front derailleur, because the only choice when shifting is to go to the other chainring. So why not just have one button, and have it on the top, where you can’t accidentally hit it? The downside of making a shifting mistake on the front derailleur is much greater than accidentally shifting the wrong direction in the rear, and going to a single button should minimize mistakes. Of course, Campagnolo would have to abandon its philosophy of “One Lever, One Action” to effect this change.

Bullet/Bora comparison

Besides price (TBA), the differences between the 815-gram Bullet Ultra crankset and the 795-gram Bora Ultra crankset are many. First, the Bora arms and spider are hollow and the Bullet arms and spider have foam cores. The Bora has an Ultra-Torque bottom bracket with a titanium axle and a left-handed thread titanium fixing screw (left-hand threaded to prevent using it — and galling the threads — in a UT crank not designed for it). The Ti spindle and bolt result in a 40-gram weight reduction over steel Ultra-Torque bottom brackets. The Bullet has a full-length-axle Power Torque bottom bracket. Bora bottom brackets will have CULT top-quality ceramic ball bearings and super-hard, polished, corrosion-resistant Cronitect steel races for a nine-fold increased lifetime when lubricated with only light oil. Bullet bottom brackets have greased USBTM ceramic ball bearings with standard steel races. Campagnolo will offer Bullet chainrings in 34-50, 36-52 and 39-53 combinations, while Boras will not have a compact option and will come 39-53, 42-54 and 42-55 rings. Both cranks will come in 170, 172.5 and 175mm lengths and will feature XPSSTM chainring profiling, featuring eight up-shift zones and two down-shift zones of the chainring.

All Campagnolo EPS control components, including the circuit boards themselves, are 100-percent waterproof and built to operate in any weather condition. They comply with the international IP67 standard; they can be submerged in water to a one-meter depth without leakage.


One stand-out feature of each EPS TT/Tri aerobar lever is the “Switch Mode” button right under the lever. To adjust an out-of-tune derailleur, simply shift to the big/big gear combination and then hold both mode buttons down for six seconds until the indicator light glows blue on the side of the EPS interface — a small box that on a TT/Tri bike is strapped to one of the aero bar extensions. Besides having a status indicator light, the EPS interface translates analog voltage inputs from the shift levers into digital commands for the Digital Tech Intelligence (DTI) Power Unit.

To adjust the derailleurs once the LED on the EPS interface glows blue, shift to the second-smallest cog and bump the rear shift lever either up or down, depending on which way the jockey wheels need to go to line up under the cog for the chain to run silently. Each bump of the lever in this adjustment mode moves the jockey wheels laterally 0.2mm — similar to a single click of a cable barrel adjuster. Once adjusted correctly, hit the right mode button once to memorize the adjustment. Then shift to the second largest cog (while still on the big chainring). Again, bump the right shifter up or down as needed to center the jockey wheels under the cog and silence the chain. Once adjusted properly, hit the right mode button again.

While still in the adjustment mode (LED on interface glowing blue), set the front derailleur adjustment. First, shift to the small chainring and largest cog. Holding the left shift lever up or down gradually drives the inner front derailleur cage plate away from or toward the chain. Adjust it so that there is about 1mm of clearance between the chain and the inner cage plate in the small/big combination, and hit the left mode button once to memorize the adjustment. That is all there is to do for front derailleur adjustment. No adjustment needs to be made on the big chainring. This is about the quickest and easiest front derailleur adjustment I know of — no limit screws, cable tension adjustments, etc.

You can fine-tune these adjustments as well, even while riding. For instance, if you get a wheel change in a race and the shifting is off or if, after you’ve performed the front and rear adjustments, shifting is sluggish or noisy in between a pair of cogs somewhere in the cogset, for instance, hold only the right mode button down for six seconds. The LED on the EPS interface will now glow pink. Bump the right shifter up or down (which moves the rear derailleur in or out 0.2mm with each bump) until the issue is resolved. Then tap the right mode button again to memorize the adjustment. Similarly, if there is chain rub in, say, the big-big combination after you’ve completed the front derailleur adjustment procedure, hold only the left mode button down for six seconds until the LED on the EPS interface glows pink. Bump the left shifter up or down (which moves the front derailleur out or in) until the rub is gone. Then tap the left mode button again to memorize the adjustment.

Unlike Shimano, Campagnolo does not offer a software interface for dealers to buy to diagnose problems in the electronic shifting system. Instead, in the interest of simplicity, ease and convenience, all diagnostics are built into the Power Unit that also encloses the battery. While the presence of sophisticated circuit boards and indicator LEDs in the Digital Tech Intelligence (DTI) Power Unit precludes aftermarket EPS batteries integrated into seatposts (as Calfee and others do for Shimano Di2 batteries), it does make it possible for the user to perform all diagnostics and electronic adjustments out on the road.

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