Jimbop
I'm pondering whether to treat myself to Di2 and have a mix of Di2 components in mind. I have a few questions if anyone happens to know the answers.

1) GRX RX815 Di2 shifters. I think you can have remote shifters but I'm not clear on how the ports on the shifters work. Ideally I'd like to have the bar end junction box for easy charging and neat cabling (I'm not a fan of the under stem junction box). In my ideal scenario I'd have it setup so I could have shifters on quick release aero bars (Redshift) and be able to unplug them for easy fitting/removal, perhaps taping up the ends of the cables when the bars are off the bike. Is this possible?

2) FD-R8050 Di2 front mech because I want to keep my existing R8000 crankset with PM. I run 38mm off-road but might want to go wider in the future. If I had to switch to the GRX crankset I'd lose my PM, which would suck. Are there any tyre clearance limitations with this front mech?

3) RD-RX805 Di2 rear mech because I think the design looks cleaner than the GRX RX815 Di2 rear mech but I'd be interested if anyone knows any pros or cons of either?
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harryleesbr
All your answers can be found here

https://di2center.com/



Jimbop wrote:
I'm pondering whether to treat myself to Di2 and have a mix of Di2 components in mind. I have a few questions if anyone happens to know the answers.

1) GRX RX815 Di2 shifters. I think you can have remote shifters but I'm not clear on how the ports on the shifters work. Ideally I'd like to have the bar end junction box for easy charging and neat cabling (I'm not a fan of the under stem junction box). In my ideal scenario I'd have it setup so I could have shifters on quick release aero bars (Redshift) and be able to unplug them for easy fitting/removal, perhaps taping up the ends of the cables when the bars are off the bike. Is this possible?

2) FD-R8050 Di2 front mech because I want to keep my existing R8000 crankset with PM. I run 38mm off-road but might want to go wider in the future. If I had to switch to the GRX crankset I'd lose my PM, which would suck. Are there any tyre clearance limitations with this front mech?

3) RD-RX805 Di2 rear mech because I think the design looks cleaner than the GRX RX815 Di2 rear mech but I'd be interested if anyone knows any pros or cons of either?
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Terry_BetterShifting
Jimbop wrote:
I'm pondering whether to treat myself to Di2 and have a mix of Di2 components in mind. I have a few questions if anyone happens to know the answers.

1) GRX RX815 Di2 shifters. I think you can have remote shifters but I'm not clear on how the ports on the shifters work. Ideally I'd like to have the bar end junction box for easy charging and neat cabling (I'm not a fan of the under stem junction box). In my ideal scenario I'd have it setup so I could have shifters on quick release aero bars (Redshift) and be able to unplug them for easy fitting/removal, perhaps taping up the ends of the cables when the bars are off the bike. Is this possible?


Sure - you can unplug shifters as you see fit. Each shifter has two ports, so you'll have two spare ports to plug other components into. You may be able to fit an SM-JC41 internal Junction B in your quick release aero bars and plug  your aero bar shifters into that. Then you would only have to connect the aero bar SM-JC41 whenever to fit the aero bar 🙂.
Di2 itself does not really care how it is connected, as long as it is. Shimano will recommend you use the EW-JC130 Y-splitter, but you don't have to. Have a look at this video for an alternative: 



Jimbop wrote:

2) FD-R8050 Di2 front mech because I want to keep my existing R8000 crankset with PM. I run 38mm off-road but might want to go wider in the future. If I had to switch to the GRX crankset I'd lose my PM, which would suck. Are there any tyre clearance limitations with this front mech?
[/quote[

You *may* be able to fit the GRX FD if you really have to. On WW a user posted a similar question: https://weightweenies.starbike.com/forum/viewtopic.php?f=4&t=161815&p=1574786&hilit=grx&sid=24a549d63182c195f1199900f118625d#p1574786


3) RD-RX805 Di2 rear mech because I think the design looks cleaner than the GRX RX815 Di2 rear mech but I'd be interested if anyone knows any pros or cons of either?

I think they're quite similar. I haven't used either, but Shimano claim that the GRX model was built to can take more of a beating than the RD-RX805. It's also 7g heavier, so they could be right. The RD-RX805 isn't really meant to be knocked around or impacted by rocks 😃.
The specs are very similar:
https://bike.shimano.com/en-EU/product/component/grx-di2/RD-RX815.html
https://bike.shimano.com/en-EU/product/component/ultegra-rx/RD-RX805-GS.html

-Terry
(I run Di2center 😉)
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Jimbop



Sure - you can unplug shifters as you see fit. Each shifter has two ports, so you'll have two spare ports to plug other components into. You may be able to fit an SM-JC41 internal Junction B in your quick release aero bars and plug  your aero bar shifters into that. Then you would only have to connect the aero bar SM-JC41 whenever to fit the aero bar 🙂.
Di2 itself does not really care how it is connected, as long as it is. Shimano will recommend you use the EW-JC130 Y-splitter, but you don't have to. Have a look at this video for an alternative: 

I think they're quite similar. I haven't used either, but Shimano claim that the GRX model was built to can take more of a beating than the RD-RX805. It's also 7g heavier, so they could be right. The RD-RX805 isn't really meant to be knocked around or impacted by rocks 😃.
The specs are very similar:
https://bike.shimano.com/en-EU/product/component/grx-di2/RD-RX815.html
https://bike.shimano.com/en-EU/product/component/ultegra-rx/RD-RX805-GS.html

-Terry
(I run Di2center 😉)


thanks so much Terry! I did checkout Di2center and whilst there is a heck of a lot of info over there my questions are pretty specific and I couldn’t find the answers nor a forum but I mightn’t have looked hard enough.

for the aero bar setup would there just be a wire coming out of the bar tape that I would connect to the junction box on the aero bar? I can’t quite imagine what it would look like. Wish they would bring out wireless Di2 already even if it still had a central battery so that the cockpit wiring could be eliminated. 

I’ll check out the weightweenies link re the front mech - didn’t realise that was a possibility. Does the R8000 Di2 mech result in less tyre clearance than the mechanical version? I’ll check but I don’t think I have a clearance issue now but I don’t know how the di2 version differs. 

if I go for it then I’ll go for the GRX rear mech for the reason you mentioned. I read somewhere today that it was more robust. 

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Terry_BetterShifting
hmm, good question regarding the wire..
An inline junction exists (EW-JC200), but in my opinion it is still too 'bulky' to fit under the bar tape. Personally I would just plug in / unplug the electric wire at the shifter and then run the temporary electric wire along the handlebars - but it depends on how often you use the aero bars.

I'll think about this some more, tonight ;-).

You can use both GRX and road derailleurs on the same bike by the way (they are both road "category"). Using MTB and road/GRX (derailleurs) on the same bike won't work. You can use any shifter you'd like though (up to 6 shifters).
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