illjustride

Going to go with the shimano grx Di2. I'm wondering what specific parts I would need. I am getting rear grx di2 derailleur. But does the GRX hoods come with a battery? Do I get that separate? Shimano offers an E-Tube kit, do I need this? I am running a 1x11 setup so just trying to figure out if I can just get specific parts to make it work.

wsteve464

Battery is separate, e tubes also, plan on 4-5 of them around $ 20 each, You will need a Juction A/charge port, either in the end of the handle bars or the mtb kind mounted to the handle bars, a 3 or 4 way junction to connect the RD, Batt to the front end. I have probably forgotten something.

Steve B.

First HUGE/BIG suggestion is do some research on YT as to how the systems work and what parts are required. From what I'm seeing

1) The very first BIG question is does your frame have internal cable routing ? and is it Di2 compliant ?. All the components - shifter, front junction box/display, battery and rear derailer connect via E-Tube cables, that have a connector that needs to be able to pass thru openings in the frame. Some frames have internal mechanical cable routing but do not have openings that can allow the E-Tube connector to fit thru. I just recently used a Dremel tool to enlarge openings in my Specialized frame that were designed for mechanical cable housing, so the E-Tube connector would route internal. Not for the faint of heart (aluminum frame). Some frames that do not have internal routing can use the external wire system. They make kits that hide the wires on the exterior of the frame. Personally, If my frame did not have a method of routing cables internally, I would not go Di2.

2) There's a single battery that powers the whole system. That battery can either go external on a mount at the bottle cage, internal in a shim inside the seat post, or in a shim inside the fork steerer. The fork method requires some parts to change out the compression plug (carbon steerer) or Star Nut (aluminum steerer), plus a new stem cap that allows the cable to exit. If the battery goes to the seat post you need to determine the route. That may mean removing the bottom bracket to route the cable up. Some frames have a removable cover on the bottom of the b-bracket to allow internal mechanical cables to be changed. My Specialized (mt. bike) had this and I used the route a dropper post would use, needing to Dremel the opening a bit.

3) Than you can talk about components.
- GRX 1X shifters. The left lever doea not have a switch for shifting.
- H-Bar display SC-MT800, serves as a 3 port junction and replaces the A Junction. has BT. About as cheap as the A junction that mounts under the stem .
- Battery, plus shim
- Rear derailer.
- 3 Cables. I used 1600mmm cables from the h-bar mounted display unit, ran both cables internally to the battery and rear derailer. It was a good length (and is the longest they make). The shifter cable is whatever length fits, add some extra hide under the bar tape, use a string to measure all cable lengths.
- Probably a new 1X crank and b-bracket
- Assuming you use the existing cassette and chain.

tyrion

Here's a video of a guy putting together a Di2 1x bike.

mr_bill

First, Di2 can be routed internally or externally.

Second, this dealers manual will answer your questions as to what you need, and also if you feel comfortable doing this yourself.

Otherwise, work with a LBS to verify parts and do the install.

https://si.shimano.com/#/en/iDM/RX81...C_INSTALLATION

-mr. bill

Sy Reene

This is why we all love cycling.. the purity and essence of the engineering involved!

Steve B.

Having just installed a new XT Di2 system on an existing 1X mt. bike, it's all kind of fresh.

Is it harder to install and get right than mechanical ?, maybe, but only because its "different". I did Di2 2-1/2 years ago on a road bike, haven't touched it since.

But I was sorely tempted to say "leave it as 2X, gravel bikes work better as 2X". LOL

illjustride

Thanks for the feedback. The frame I am using is a Hakka MX which is designed for Di2. As for parts, I have handlebars that can mount the new Shimano junction A in the handlebar end and that seems like a cleaner way to go. I can run junction B in the bottom bracket area I suppose. As for the battery the Hakka MX has a spot to put it on the downtube. I'll do my homework before I purchase anything right now. I want to make sure I get all the cables and wiring I need. For the 1X GRX shifter. I noticed it was designed differently and ergonomically doesn't look like the rear shifter. Would I be able to get the front GRX shifter and not run a wire to it for now.

wsteve464

Just buy the shifters for 2x and leave the front unconnected. Or get the front shifter for a dropper post

illjustride

Thanks, my thinking exactly. I'd like for the levers to be identical. Plus I can use it if I want to get a dropper post.

wsteve464

The dropper lever is different than the one for shifting.

This thread has pics of the dropper shifter

https://www.bikeforums.net/cyclocros...per-lever.html

illjustride

UPDATE:

Everything is coming together in terms of parts. I just received my frameset Hakka MX, and my handlebars, stem and seat post. I ordered the parts for the Di2 setup without the cables for now. This includes junction A (RS910), junction B (JC-41), and internal battery BT-DN110A-1. Before I get the cables I want to measure everything first with string as what @Steve B. had mentioned and also visit my local bike shop to talk with them about the proper cable length. As for the bar end junction A RS910, I am wondering If I really need the expensive Y-Split rooting cable (EW-JC130). Again, I am running this setup 1x but with my left front GRX shifter, I purchased I can use for something else. Can anyone recommend going with the Y-Split rooting cable or can this be done without? I know Shimano recommends it with the bar end junction.

mr_bill

If I understand your question:

If you want to use the buttons on both the left shifter and right shifter to shift the rear derailleur, you need the Y-split.

If you don’t want to run a signal cable to one of your shifters (so it’s only a brake lever, the switches are non-functional), you should be able to run straight wire to the shifter you wish to connect to the bar end junction A and then straight wire to the wireless unit or junction B.

-mr. bill

illjustride

Thanks for the help. Where would the EW-WU111 wireless come in? Would you use this for from Junction A to the JC 130 to this WU111 and then to the junction box B? This way I can fully utilize the Di2 system connecting it with my computer, phone, etc? https://bike.shimano.com/en-EU/produ.../EW-WU111.html

mr_bill

The wireless unit has to be outside the frame. Typically just outside where the wire goes from the junction to the downtube. Advantage for your setup is it can replace an inline junction tube for a wee bit of money, so to connect both shifters you can go with one of the cheaper Y-splits to connect both them. (If you don’t put either an inline or a wireless, Murphy says you risk popping the connector near the bottom bracket if you pull the handlebars during service, which is a PITA.)

In addition to the app, there are several bike computers that will interface with it. Allows you to see gear selection (meh, also significant indicator lag) but probably more importantly check battery status. (Since you are running 1x, you won’t get the heads up of the front derailleur refusing to shift at low battery, and the blinky lights are both a pain and easy to miss.)

-mr. bill