By Jim Weaver, Service Manager, Fit Werx, Waitsfield, VT.
For several years Cervelo used Magura hydraulic rim brakes on their P3 and P5 time trial/triathlon bikes. These brakes provide outstanding braking, with excellent modulation and minimal hand effort – hallmarks of hydraulic brakes. Shimano produces base bar brake levers that incorporate buttons for the Di2 electronic shifting system. This combination of brake lever and shifting buttons on a TT bike is a great application of the electronic shifting technology, allowing shifting when riding with your hands on the aero base bar, such as when climbing, braking or turning, without having to move your hand from the base bar to the aero extensions.
Over the past few years, we have had a couple of owners of such bikes who wanted to get the advantages of this shifting added to their Magura brake levers but, unfortunately, the hydraulic Magura brake is not compatible with Shimano’s TT brake /shift button combination lever. Some research showed a couple of solutions that involved some rather complicated disassembly and rewiring of the shifting buttons while another solution makes use of buttons from a Cateye computer that has long been out of production. All the solutions seemed unduly difficult or unavailable and I had been using a different solution outlined in a previous article (https://fitwerx.com/di2-tttri-shifters-and-hydraulic-brakes-you-can-have-it-all). In this solution we used Shimano’s Di2 climbing buttons to allow electronic shifting from the brake lever position on Cervelos equipped with Magura hydraulic rim brakes. While this solution certainly provided Di2 shifting at the desired location (at the brake levers), the climbing buttons hung below the aerobar and would interfere with the brake lever unless the levers were adjusted just right. The installation was not easy either. The cable attached to the climbing shifter is not long enough to reach from the end of the aero base bar back to the cockpit junction box and required splicing the cable from the shifter to a separate E-Tube cable so that it would be long enough to reach from the brake levers to the junction box. Splicing these cables was a VERY tedious process that required patience, a steady hand, and an exceeding sharp blade (keep bandages handy!).
I was recently confronted with not one, but two requests for the same modification to new Cervelo P3’s with Magura brakes. Given that I was not completely satisfied with my previous solution, I started working on a quality alternative. The new solution involves the use, and destruction, of a pair of Shimano’s Ultegra 6870 TT Brake Levers with integrated Di2 buttons.
The first step of the process is to extricate the shift buttons off the integrated brake levers. As I was going to need to clamp the lever assembly in a vice, I had to remove all of the internal parts, leaving only the empty shell. Then, carefully clamping the brake lever in a vice, and using a hacksaw, I slowly cut the shift button portion off of the brake levers. This is not a task to be rushed. Careful trimming and grinding on our bench sander and with various files left me with the shift button portion only. Once removed, I reassembled the internals of the shift buttons, being particularly careful to align the sets of springs, one inside the other, that will prevent the buttons from working if misaligned. The resulting button assembly was then epoxied to the Magura brake levers. After a bit of trimming of the hardened epoxy with various small files, and painting with black paint, the result is a fairly neat and clean installation that adds Di2 shifting capability to the Magura hydraulic TT levers.
The primary benefit of this solution is that the buttons no longer potentially interferes with the brake lever operation as it had been and it is more stable overall. Installation is also easier as the cable from the shifter is more than long enough to reach the cockpit junction box with ease, no tedious cable splicing is needed, and excess cable can easily be stuffed up into the base bar. From a cost standpoint, the parts needed for my original solution, using the climbing shifters, was $250, while the cost of the Di2 brake lever set is $390.00. However, while the parts are more costly, the end result is better, and saves the indefinite cost of frayed nerves and possibly ruined cables by trying to splice cables together.
If you have a Di2 equipped TT bike with Magura hydraulic brake, or are considering conversion to Di2 and want to keep your Magura brakes, we feel we now have a good, no compromises solution to the dilemma. A solution that allows you to keep those great brakes while getting the convenient Di2 shifting to boot.
With locations outside of New York City in Ridgefield Park, NJ; in Peabody and Lexington, MA; and near Burlington and Stowe, VT in Waitsfield, Fit Werx technicians have installed and worked on Shimano Di2 and Campagnolo EPS electronic shift systems since their inception. Contact us if we can supply parts and be of service.