Spin Doctor Tech Tip – Shimano Dura-Ace Di2 Electronic Shift System
February 16, 2010 57 Comments
So you’ve won the lottery and your first big purchase is Shimano’s new electronic Dura-Ace Di2 drivetrain.
Before you install it, BE ADVISED that your ego may be put in jeopardy. Yes, the new Di2 components are so slick that your bike, once Di2 adorned, will be smarter than you. Push a button and you have perfect shifts every time. The front derailleur will automatically trim itself to eliminate cross chain rubbing, and the rear derailleur disconnects its motor when you lay the bike down. The system will even tell you when the battery is low or if there’s a malfunction. Plus the battery lasts 1000 KM and will recharge in only 90 minutes.
Like we said, this stuff is SWEET!
Even better, Dura-Ace Di2 meets the “clock on the VCR” standard. If you can program the clock on your VCR, installation of Di2 will be a snap. The components come with good, clear installation and set-up instructions plus Shimano has an even better online tutorial, http://di2certified.shimano.com. That site features both a how-to video and an interactive installation and operation lesson.
But there are a few small subtleties that, if missed, can short circuit Di2’s marvelous performance.
Be aware of these issues:
• Do not touch the cable connector terminal/contacts. The system is great but can malfunction if the contacts are fouled.
• The RD-7970 rear derailleur will accommodate cassette cogs as large as 27 teeth, no bigger. Do not be tempted to install the new Dura-Ace 7900 11-28 cassette; it will hang up.
• Be sure to remove the battery when installing the derailleurs or repositioning them. The motors in the derailleurs are powerful enough to break or badly pinch a finger.
• If you are installing the FD-7970 front derailleur on a braze-on mount, be sure to use the provided small stainless steel patch to protect your frame. The FD-7970 uses a “support bolt” that screws against the frame to orient the cage relative to the crank. The support bolt will damage the frame if you have failed to attach the protector.
• The wiring harness comes with a plastic tool (TL-EW01) to plug the wiring harness electrical connectors into the brake levers/shifters. It is also to be used to disconnect any of Di2’s electrical connectors. Use the tool! Do not pull connectors apart.
• The ST-7970 brake levers/shifters have additional terminals for auxiliary shifter buttons. If you are not going to use them, seal them from the weather by installing the provided dummy plugs.
• The new CN-7900 chain is asymmetrical and shifts great when correctly oriented. Install it so that the non-perforated outer plate (engraved with Shimano & Dura-Ace logos) is on the outside.
• When properly assembled the Di2 system is extremely waterproof, but individual components require special care when cleaning:
- Do not soak components in degreaser. This may damage critical seals.
- Shimano recommends cleaning components with a rag soaked in mild degreaser. Do not use a spray or brush, as they can damage the seals.
- The articulated joints & pivots of the Di2 front and rear derailleurs are connected to the internal servo motors. Lubricating these pivots may damage seals and expose the motor to contamination.
- Maintenance of the pulley can be done in the same way as with a conventional derailleur.
So what was the test rig here in our office to learn all about Dura-Ace Di2? None other than our very own 2010 Scattante CFR Pro Shimano Dura-Ace Di2 Road Bike (seen here in our Technical Support area). Featuring our brand new sub-1000g CFR-A3 Frame, with BB30 crankset, this is definitely a worthy ride upon which to hang a complete Dura-Ace Di2 drivetrain.