The following is my how-to to fully internalize Di2 on the 2010 S3 frame. This is not as simple as I wanted it to be and requires electronic soldering skills (there over 25 26 gauge wire connections to solder). My original plan was to drill/dremel the frame opening so that it can use the Di2 internal wire kit as is but I decided against doing anything to the frame and concentrate on customizing the Di2 wiring instead - $200 wire kit < $4500 frame. Sucks that all the opens are just a hair too small for the Di2 connectors. Here is the Pre-Di2 pic:
Notice the shift cables routing around the stem and into the top tube. This actually was a big pain as I was rubbing against them when out of the saddle.
After about 6hrs and 30 solder connections I fired it up and everything worked 100%. Not sure if it was skill or luck but I was quite skeptical that everything would work right off the bat. Most of the time was spent checking and double/triple checking everything to ensure that my plan would work. Overall, it was an interesting project but not sure if it was worth the time and effort spent? If I was to do it again I may just internalize the battery. I have done many hours of Internet searching, reading and thinking on the best implementation so here is my recipe on fully internalizing Di2 on a 2010 S3: Here is the completed ride:
No more cables routed around the stem. Instead, the main control wire is split and routed down the existing ICS-3 holes and tied to the rear brake cable. The grommets are from the Di2 internal wire kit and made a nice cover for the openings.
The Di2 status device is mounted on the right side of the stem.
Here is the RD entering the back of the chainstay.
Thanks Cervelo for the super large opening and bottom bracket area as I was able to tuck everyhing back into the frame without much effort even after wrapping everything in shrink tubing.
Things needed and where to get:
- Di2 components (obviously)a. Shifters (ST-7970)b. Front wire kit (SM-EW79)c. RD/FD (RD-7970/FD-7970)d. Internal short wire kit (EW-7973-1) I got components from ebay seller melfren and internal wire kit from amazon.com
- TEnergy 7.4 1200mAH lipo stick battery and TEnergy universal smart charger for lipo Got these from Amazon – Battery superstore
- Model Power 2 conductor wire 26AWG (#2302) Got from local model train store
- Any 18-20 AWG power wire Used old power supply line for PC harddrives
- Heat shrink tubing for 24AWG, 20AWG and 3AWG wire Got from local model train store as home depot/lowes does not have anything this small
- Mini Tamya male plugThere should be a plug that comes with the charger. If not, any model RC store
- Soft styrofoam padding (type used in insulation) Home Depot
- Electronic solder gun and rosin core solder Radioshack
- (Optional) Third hand tool with magnifying glass. My eyes are not what they used to be? Radioshack
Technically speaking, you can use any 26AWG and 20AWG wire you like. It can even be built using single strands from Radioshack (24AWG only). I went with the Model Power stuff because it is a cleaner install. Also, do not skimp on the heat shrink tubing as this not only insulates but adds strength to the connections. I double up on the shrink tubing. Used 24AWG for each lead and 3AWG for the entire connection
Integrating battery in seat tube (appetizers)I determine putting battery inside the seat tube is simpler than inside the seat post then using the seat post like a cap. The reason is that the battery will slide out (due to gravity) and into the seat tube over time. The entire battery holder extends about 2” from the top of the seat tube so that I can remove it easily after the seat post is removed.
- Cut and shape the foam so that it securely fits inside the seat tube of the frame and stops at the water bottle cage top bolt with 2” extending from the top of the tube.
- Measure the length of the seat post that is inserted in the frame and from the top of the foam mark that length + 2”.
- Trim from the top to the mark so that it fits into the seat post
- Cut out a section to fit the battery and connectors starting at the top.
- Cut a channel from the bottom of the battery section to the bottom of the foam. This is for the wires.
Splicing wires and routing in frame (main course)
- Remove existing derailleur wire guide at bottom bracket and ICS3 liners.
- Cut power wire that connects the Di2 battery holder to the main Di2 junction device
- Splice in the Mini Tamya connector and 20AWG wire (long enough to be unplug at top of seat tube)
- Route power wires from top of seat to hole at bottom bracket
- Solder to power leads from Di2 bracket
- Cut all Di2 FD, RD and down tube wires about 2” from main junction connection side
- Measure and splice in wiring to FD and RD cable from FD and RD points to bottom bracket hole
- Route FD and RD cables thru frame and recombine the main junction connectors
- Measure and cut the 26 gauge wire the length of the down tube. Make 3 sections
- Take 1 section and split the wire so there are 2 individual wires
- Take 1 of the individual wires and combine with other wire to make one 3 lead wire.
- Cut the wire from internal wire kit labeled “Junction 1” about 2” from the end that connects to the front status box. You are essentially replacing the original Di2 downtube wire with 2 separate wires (a 3 lead and a 2 lead wires) routing them thru the ICS3 holes. Splice 3 leads to 1 wire and splice the other 2 leads to the other wire. Make sure to keep track of the leads.
- Route each wire thru frame using existing ICS3 FD/RD holes and recombine it with the connector at the bottom
Making connections (dessert)
- Connect up system and test
- Put battery and wires into foam channel and insert into seat tube until it stops and about 2” extends from top
- Replace seat post
- Push connectors and wires into hole and secure junction to bottom bracket. Thanks Cervelo for once for having a large hole at the bottom bracket.
Here are some pics during the project:
Here is the main Di2 connection block with the battery connection cut that is mounted to the bottom bracket. Unlike other pictures that I have seen there are only 2 leads here (which makes sense).
Here is the RD wire cut. Notice that there are 4 leads here. Both the FD and RD have 4 leads and the main wire has 5 leads.
Here is a full test prior to install.