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Cervelo P-Series Di2 conversion, cable length, other parts?
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I’m looking to convert a 61cm P-Series from 105 to Di2 - I have all the derailleurs, battery and shifters, but still need the cables and battery attachment. For the front I’m guessing the old 5-port junction box is correct and wires out from there? Should I use the Bluetooth adaptor (i have the right battery). Does anyone know the required cable lengths? Anything else I need to know? Unfortunately I can't find any kind of manual for the bike from Cervelo...
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [_Nickel_] [ In reply to ]
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You should measure for the wire lengths.
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [_Nickel_] [ In reply to ]
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_Nickel_ wrote:
I’m looking to convert a 61cm P-Series from 105 to Di2 - I have all the derailleurs, battery and shifters, but still need the cables and battery attachment. For the front I’m guessing the old 5-port junction box is correct and wires out from there? Should I use the Bluetooth adaptor (i have the right battery). Does anyone know the required cable lengths? Anything else I need to know? Unfortunately I can't find any kind of manual for the bike from Cervelo...

As Jim recommends, measure your frame and bars for the proper cable lengths. You need to account for access and add extra length where it makes sense.

Depending on your base bar and extension set up you can get a much cleaner install using the RS910 bar end style 2 port junction A combined with junction b’s as it is hard to hide the 5 port or 3 port junction A’s anywhere.

The BTLE D-Fly may or may not be useful for you. I like it on Di2 road bike installs so I can use the brifters buttons to control my garmin edge screens. It also can send battery level info to the same head unit. Otherwise I usually don’t find myself reprogramming shifting options very often. I also suspect the D-Fly draws down the battery quicker as my newer Di2 installs need to be recharged a lot more often than my older systems did.
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [SummitAK] [ In reply to ]
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I measured the frame but I guess my problem is that im not quite sure how much to add. For example I would have gotten a 500mm cable for the RD to junction in front of the BB, but Giant fro example recommends a 750mm cable for a slightly shorter chainstay in the Trinity according to page 18 of their manual - is that much really necessary?
https://wiki.geant.org/...103449196&api=v2
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [_Nickel_] [ In reply to ]
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500mm is way too short for the rear derailleur.

You need to be able to pull several inches of the wire outside the bottom bracket so you can connect it to the B junction.

I would typically use 600mm or 650mm, whatever is available.
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [_Nickel_] [ In reply to ]
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FYI, Shimano recommend you measure the length from point to point, choose the next size up and add 50mm to make sure the wire is not too short. For example:

If the measured length is 325mm, the next size up is 350 and the correct wire length would be 350 + 50 = 400mm.

Generally speaking prefer slightly too long wires over short ones. You can usually hide excess wire in the frame :)

BetterShifting.com - Di2 help and guides| BetterShifting Instagram | Terry's Instagram
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [_Nickel_] [ In reply to ]
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I have a 61 cm 2017 P3 that I just fit up with Di2 this past spring. I have the battery in the seat post and an internal junction B above the bottom bracket which accepts the FD (300mm), RD (650mm) battery (250mm) and a long 1200 that runs up to the external junction A that I mounted at the front of the stem with a K-edge bracket. I have a wireless unit but haven't put it in yet as I also want to change out the external junction A to an internal to clean up the front a bit so everything is completely hidden but I haven't had the time. I could have gone shorter on the 1200 but I bought as a set and that's what came with it and it's easy enough to hide in the frame cavity like someone said.
Last edited by: jond81: Jan 14, 21 3:50
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [jond81] [ In reply to ]
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I just did this exact thing on my 61cm P-series. You can see a couple photos of the front end after the conversion in the thread below. I used a 5 port junction box and put it under the stem, attaching it with a zip tie around the stem. The four port junction box went behind the bottom bracket, there is an access panel for that. The manual that came with your P-series has the di2 routing diagram for the bike.

https://forum.slowtwitch.com/...s!_P7024521/?page=-1


You will need the seatpost battery holder, front derailleur di2 guide and rear derailleur di2 wire guide. I bought mine from mybikeshop.com. Part numbers are below.
Cervelo Seatpost Internal Battery Mount - MT-BINT-SP
Cervelo E-Wire Open Grommet - GR-BEC-OPEN
Cervelo Dropout Open Grommet - GR-DRPOUT-GUIDE


I used the tool this guy made to pull the di2 wires. It was easy to make and it worked great.
https://www.youtube.com/...Dase_vpBE&t=239s


I would also get the Shimano TL-EW02 E-tube wiring plug tool, it is cheap and makes things a bit easier to connect/disconnect.


As far as di2 wire lengths go, I don't remember what lengths I used. I know my seat tube to battery wire is a bit short - i.e it works, but if I pull out the seatpoost it pulls out the di2 wire because it is too short.


Hope this helps. Let me know if you have any other questions.
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [jond81] [ In reply to ]
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jond81 wrote:
I have a 61 cm 2017 P3 that I just fit up with Di2 this past spring. I have the battery in the seat post and an internal junction B above the bottom bracket which accepts the FD (300mm), RD (650mm) battery (250mm) and a long 1200 that runs up to the external junction A that I mounted at the front of the stem with a K-edge bracket. I have a wireless unit but haven't put it in yet as I also want to change out the external junction A to an internal to clean up the front a bit so everything is completely hidden but I haven't had the time. I could have gone shorter on the 1200 but I bought as a set and that's what came with it and it's easy enough to hide in the frame cavity like someone said.

I did not realize there is an internal 5 port junction A?

If there is a 5 port internal junction A where would you hide it on a P series?

I ask as I'd like to clean-up the di2 wires on my P series as well

Thanks!
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [Adub] [ In reply to ]
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [jimatbeyond] [ In reply to ]
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Thanks for the link. Where would you mount this on a P series frame?
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [Adub] [ In reply to ]
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Adub wrote:


Thanks for the link. Where would you mount this on a P series frame?

So that's just a two port that would be mounted at the near end of one aero bar extension. I believe all internal A's are two port and the external has the option of 5 port or 3 port. As far as I know there isn't an internal 5 port. If you want to use the internal A (again, only 2 ports) there are a couple different wiring methods to keep it clean/internal if you have a path between the bar extensions. It usually involves the 3 wire piece (EW-JC130-MM) and a 4 port internal junction B, both kept somewhere in the base bar cavity. I have a very simple Profile Design T2 Wing base bar and PD Sonic Ergo aerobars so to keep it 100% concealed from the aero bars into the base bar I'd need to drill a small hole between the two and feed it in, then I'd have one wire from the base bar (taped with the brake cable to hide) to the wireless unit in that little cavity at the top tube of the frame.
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [Adub] [ In reply to ]
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Adub wrote:

Thanks for the link. Where would you mount this on a P series frame?


You wouldn't mount it on the frame.

You would mount it in your aero bar.
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Re: Cervelo P-Series Di2 conversion, cable length, other parts? [jond81] [ In reply to ]
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jond81 wrote:
Adub wrote:


Thanks for the link. Where would you mount this on a P series frame?


So that's just a two port that would be mounted at the near end of one aero bar extension. I believe all internal A's are two port and the external has the option of 5 port or 3 port. As far as I know there isn't an internal 5 port. If you want to use the internal A (again, only 2 ports) there are a couple different wiring methods to keep it clean/internal if you have a path between the bar extensions. It usually involves the 3 wire piece (EW-JC130-MM) and a 4 port internal junction B, both kept somewhere in the base bar cavity. I have a very simple Profile Design T2 Wing base bar and PD Sonic Ergo aerobars so to keep it 100% concealed from the aero bars into the base bar I'd need to drill a small hole between the two and feed it in, then I'd have one wire from the base bar (taped with the brake cable to hide) to the wireless unit in that little cavity at the top tube of the frame.

Yeah, the internal EW-RS910 is two ports.
The below-the-stem SM-EW90-A has 3, SM-EW90-B has 5 ports.. The displays (SC-MT800 / SC-M9051 have three ports).

As far as I'm concerned the way to go is indeed using one or two junction Bs in your base bar (SM-JC41). They're really quite small and can go almost anywhere.

BetterShifting.com - Di2 help and guides| BetterShifting Instagram | Terry's Instagram
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