Caliwild

OK, I'm thinking of upgrading my 1x GRX group to a 1x GRX di2. As far as I can tell, all I would have to upgrade is the right shifter, the rear derailleur, and then get the battery and wiring... Am I missing something? Thanks in advance...

lasauge 

Yep, you got it. Shifter, 'A' junction box (you need this for the battery charging port), battery, derailer, and wires to go between those 4 parts - and probably a 'B' junction and wire unless you do something out of the ordinary with your battery to avoid needing it. And grommets to go on the wires where they enter/exit the frame - Santa Cruz should offer these.

grolby

A B junction isn’t strictly needed, without it you would need to run a wire from the battery to junction A and another from junction A to the derailleur. If you do just a right lever, this is easy enough, all available A junction boxes have at least 3 ports. The downside is the wires would be very long (and depending on bike size the longest available wire might not be long enough) and you give up some flexibility for future changes or additions to the system.

SoSmellyAir

May I ask why? For 1/4 s faster shifts?

Caliwild

Less maintenance. All my road bikes with di2 shift perfectly after thousand of miles. The same can't be said of mechanical shifting, where the cables stretch. Trust me, I was a skeptic until I tried di2.

Steve B.

Shimano makes a device for their off road groups called the SCMT800. Its a h-bar mounted display unit that also has 3 - E-tube ports, a battery port and a BT connection built in. You can use this to send 2 E-Tube cables to the battery and a R derailer as well as R shifter. Also has a useful battery status display as well as gear indicator.

SoSmellyAir

This is an excellent reason. I was once stranded after my RD cable snapped. From then on I resolved to replace shift cables every other year.

Caliwild

Ooh, I like that... I hadn't seen that before. Thanks, I may just end up using that...

Steve B.

It saves you the added expense of a WU111 BT unit plus short cable.

msu2001la

I'd love to see "after" photos if you go through with this.
I have a 3 year old GRX 1x bike and am thinking of doing the same. Was debating SRAM AXS just because it seems more simple to install, but hadn't thought about the idea of GRX 1x only needing the right shifter, and keeping the existing left.

bike_tom

I believe GRX is the only remaining Shimano Di2 groupset that is still fully wired. Dura Ace, Ultegra, and the new 105 use wireless shifters. Given that GRX was introduced in 2019, an update would seem likely sooner rather than later. If this is a "nice to have" upgrade, you might consider waiting a bit to see what comes out this year. Depends on the value one places on reducing wires/cables. Just a thought.

Caliwild

Funny you just posted that... one of my buddies just said the same thing. Might not be a bad idea to hold off for a few months.

BMW1150

Since this a electronic vs mechanical thread I like to pose this question. Anyone have any thoughts/concerns of using electronic shifting and the impact dirt and gravel roads would have on longevity? Long time mt.biker and I see the abuse my bike takes compare to my road bike. Trying to decide on SRAM or go with GRX.

SoSmellyAir

I don't have an e-shifting bike, but it seems that cable and housings are more susceptible to ingress of moisture and/or fine dirt than signal wires, which can be completely sealed.

Regarding electronic groupsets, Shimano has a single battery under the seat post which requires wiring to the derailleur(s), whereas SRAM has one battery per derailleur. The former system seems more weatherproof, while the latter allows easier installation and replacement.

BMW1150

Thanks, makes sense. You raised some good points.

Steve B.

Di2 and Sram elec work better on a mt. bike then a road bike, IMO. Mostly impervious to dirt and mud. So an even better reason to go this route if the bike gets dirty. Only concern I see is trashing the rear derailer, they are expensive to replace.

BMW1150

Interesting, you think just the opposite. Appreciate the input.