Di2 Internal Battery and Retrofit

Dragonfly Pro Di2 Integration Seat Lug with Internal Cable


Calfee Di2 Internal Battery and Wiring System

If you would like Calfee to retrofit your frame, please complete the Calfee Di2 Order Form and review our protocol for Sending Your Frame for Repair.


Calfee Design offers an elegant solution for electronic shifting systems.  This proprietary internal battery and wiring system is available on all Calfee models and also as a retrofit on most frames.  Click here for a product summary.  Click here for Calfee Internal Battery and Wiring System pricing.

This product has already generated tremendous excitement in the cycling public, the cycling press and even among framebuilders; please consider the very recent evaluations by cyclingnews.com and VeloNews (including a video).  Our solution has also impressed Shimano; we recently retrofit Wayne Stetina’s 2011 HTC – High Road S-Works Tarmac SL3.  Wayne is Vice President of the bicycle division of Shimano America.  In addition to installing our battery and modified harness, we modified Wayne’s SL3 to accept internal wiring, removed non-essential external cable stops and applied a fresh matte clear coat.  He shares his thoughts and findings here, in this May, 2011 interview.  You can enjoy photos of Wayne’s bike with our Di2 product here in the All Hail the Black Market blog.  We similarly optimized a very special Trek Madone for Steve Blick, Oakley’s Sports Marketing Manager.  It was discovered and photographed at the 2011 Tour of California.  Enjoy the coverage here.  We even earned the opportunity to outfit HTC – High Road who enjoyed our product in the 2011 Tour de France.

The innovation starts with a custom battery system housed inside the seatpost.  We machine an aluminum sleeve that is bonded to the inside of the seatpost and serves to anchor our removable battery.  A circlip acts as a stop and retains the battery in the aluminum sleeve.  Remove the circlip and the battery is freed.  Our battery can be fit in seatposts of any size as we fabricate composite shims to take up any space between the aluminum sleeve that retains the battery and the inner wall of the seatpost.  We are also able to fit our battery in aero posts; in some cases, we will use foam instead of our aluminum housing to secure the battery in the post.

How do you charge our internal battery?  For Dura Ace Di2, we now offer the Calfee Dura Ace adapter cable; this accessory is an adapter that plugs into our existing charger and is compatible with the DA Di2 internal wiring harness.  Simply unplug either your front or rear DA Di2 derailleur and plug our charger into the wiring harness.  Our charger returns power to our battery through the DA internal wiring harness.  You no longer need to remove the seat post to recharge our battery.  This product in immediately available and is compatible with any Calfee DA Di2 installs, past or present.  The Calfee Dura Ace adapter cable will add only $45 to our system’s published retail pricing.  Click here for more information and a description of additional charging options.  Click here for Calfee Internal Battery and Wiring System pricing.

Ultegra Di2 customers cannot use the Calfee Dura Ace charger adapter (or like adapter) owing to differences in how the Dura Ace and Ultegra wiring harnesses manage signal and power transmission.  Ultegra clients need only remove the seatpost from the frame to charge our battery.  Ultegra clients interested in an external charging solution will enjoy the Calfee PowerPost; we install our battery in an ENVE seatpost, drill a small hole just below the seat clamp on the front of the post, and install an electrical port.  This port will receive our battery as well as any number of Calfee electronic accessories.  Click here for more information and a description of additional charging options.  Click here for Calfee Internal Battery and Wiring System pricing.

The Calfee solution is 8% lighter and significantly longer lasting than Shimano’s product.  In fact, field testing reveals that our battery will last between 2500 and 10,000 miles, depending on temperature and how often the front derailleur is made to move the chain between rings.  At a minimum, that is 2 to 3 times longer lasting than the Shimano battery.  Conveniently, Shimano’s inline battery life indicator displays our battery’s status.  You may charge our battery as often as you like; you needn’t discharge it completely before returning it to the charger that we provide.  You will do no damage to our battery either way.  Our battery can be completely depleted and recharged hundreds of times before its ability to hold a complete charge begins to slowly diminish.

The Calfee Di2 Internal Battery and Wiring System eliminates the need for cable ties, adhesives and external mounts, improving the bikes form and enhancing its aerodynamic function.  To achieve fully internal routing for the electronic shift cables, Calfee makes the necessary modifications to the wiring harness, battery, seat post and frame.  If you would like Calfee to retrofit your carbon frame, please complete the Calfee Di2 Order Form and review our protocol for Sending Your Frame for Repair.

Calfee Design has extensive experience repairing carbon fiber frames. This is critical in building/retrofitting carbon frames not necessarily designed for internal routing. Calfee amends the frame as needed, including the creation of access holes, at no detriment to the structural integrity of the frame. Proper repair and reinforcement is imperative to preserve ride quality and guarantee strength of the frame after the required changes have been made to the original structure.

Frames retrofitted to work with an internal Shimano Di2 system cannot readily be swapped between traditional shifting and electronic. However, modifications can be made in the future to remove the retrofit features and allow for traditional cables.

Currently, any make or model of carbon fiber frame is eligible for Calfee’s Di2 retrofit. Internal routing for SRM power meters is also available. There may be a few frames that are not compatible with an internal Di2 system, though none have been identified at this time. The retrofit package is priced to start at $700. Pricing includes the required frame modifications, our custom battery, battery charger, installation of the wiring harness and basic paint touch-ups. You can provide the internal wiring harness which we’ll modify (no charge) or you can purchase the harness from Calfee for an additional $250. The process requires approximately 3 weeks for completion.  If you would like Calfee to retrofit your carbon frame, please complete the Calfee Di2 Order Form and review our protocol for Sending Your Frame for Repair.

For more information, please contact:

Michael Moore




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