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Discussion Starter · #1 ·
Apparently Shimano has launched the GRX groupset without a 1x-specific Di2 option. Per my understanding, the RX815 Di2 STI levers pair with front and rear derailleurs. I want to run Di2 levers in a 1x11 configuration. Will the system permit this, and if so what is the most affordable way to go about getting the groupset I need?

The 1x12 SRAM Force Etap AXS is really appealing and would be my go-to, but I can't justify the additional cost. $1650 is a bit beyond me. I'm looking at disc groupsets only.

I do know electronic shifting is in my future. I rode a Di2 Ultegra-equipped bike for a week and it was just incredible.
 

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GRX will work as you desire- They even make a left brake lever without shifter guts.
The limitation is gearing. The largest 11 speed cassette that Shimano makes is an 11-42.

I guess you could also use an XTR derailleur and someone else's cassette. Like an E Thirteen cassette?
 

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Discussion Starter · #5 ·
GRX will work as you desire- They even make a left brake lever without shifter guts.
The limitation is gearing. The largest 11 speed cassette that Shimano makes is an 11-42.

I guess you could also use an XTR derailleur and someone else's cassette. Like an E Thirteen cassette?
I need about 300-350% range. The lowest gear ratio I need is ~1.25. So there are options. I climbed Mt. Mitchell on my gravel bike using nothing less than 1.25 gear ratio at a cadence of around 80.
 

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Discussion Starter · #6 ·
GRX will work as you desire- They even make a left brake lever without shifter guts.
The limitation is gearing. The largest 11 speed cassette that Shimano makes is an 11-42.

I guess you could also use an XTR derailleur and someone else's cassette. Like an E Thirteen cassette?
I guess, in the absence of a clear-cut 1x Di2 groupset, what exact parts do I have to get? I'm a fair novice to Di2.

Will the right shifter control both upshifts and downshifts of the rear derailleur? In addition to the rear derailleur and right shifter, what other pieces are needed? Is there a simple grouppo somewhere that will finish off the required parts?
 

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Couple things:
  1. Force price you show doesn't include chain, cassette, or crankset/rings
  2. No other cassettes are available for AXS so you have to use SRAM
  3. Only wolftooth currently has a chainring that will work with AXS 12 speed and that is for Easton Cranksets so you'll probably have to run the Force crankset
  4. Max cog on AXS RD is 33T, limiting your options on front ring size
  5. Max cog on GRX is a 42T giving you more options down the road
  6. Cassettes for the GRX system are going to be WAY cheaper than AXS. I believe the Force AXS cassette is $185 vs an Ultegra 11-35 at like $65 bucks.

To do a GRX Di2 1x system you'll need the following:
  1. Right and Left shifters (there isn't another shifter with the same ergonomics that isn't Di2)
  2. Wiring for handle bars (JC130 in the correct length)
  3. Wire from front junction box to bottom bracket junction box
  4. Wire from BB box to battery
  5. Wire from BB box to RD
  6. Di2 Battery
  7. Di2 seatpost battery insert (zipp makes a nice one for 27.2 seatposts)
  8. Di2 junction box for under the stem (unless you run one inside your bar end)
  9. Di2 Junction box for around the bottom bracket
  10. 1x Crankset of your choice
    Chain
  11. 1x Chainring

Once all connected the system will let you program it to have the buttons do what you want. Use the charging block for di2 to connect to a windows computer with the usb plug. Plug the other end into your junction box like your charging. Then download the E-TUBE software and you can program from there. .

I have a XTR Di2 RD running 1X on my CX race bike with RS785 front di2 shifters. I have it set up so both buttons on the left shifter move the RD to the right (harder gears) and both buttons on the right move the RD to the left (easier gears). This is great with gloved and/or cold hands when racing cx so you don't hit the wrong button.

AXS is appealing and I'm looking into it as well, but all that additional cost for having 12 speeds and a 10T is totally not worth it. With the GRX you could also use ethirteen or many other types of cassettes set up for 11 speed to get that 10T cog. I'm sure those companies will come out with 12 speed versions soon enough but even then you're still stuck with a max 33T cog in the back and I don't think that is good for a 1x system. The one bad thing is that GRX isn't going to be available for another month or more if you're trying to build a bike now that sucks.
 

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Discussion Starter · #8 ·
To do a GRX Di2 1x system you'll need the following:
  1. Right and Left shifters (there isn't another shifter with the same ergonomics that isn't Di2)
  2. Wiring for handle bars (JC130 in the correct length)
  3. Wire from front junction box to bottom bracket junction box
  4. Wire from BB box to battery
  5. Wire from BB box to RD
  6. Di2 Battery
  7. Di2 seatpost battery insert (zipp makes a nice one for 27.2 seatposts)
  8. Di2 junction box for under the stem (unless you run one inside your bar end)
  9. Di2 Junction box for around the bottom bracket
  10. 1x Crankset of your choice
    Chain
  11. 1x Chainring

Once all connected the system will let you program it to have the buttons do what you want, HOWEVER, you either need the PCE1 to program it OR you need the EUW111 or similar to use your phone or ipad to connect wirelessly to program the buttons. Other option is to take it to a shop and they can program it how you want.

AXS is appealing and I'm looking into it as well, but all that additional cost for having 12 speeds and a 10T is totally not worth it. With the GRX you could also use ethirteen or many other types of cassettes set up for 11 speed to get that 10T cog. I'm sure those companies will come out with 12 speed versions soon enough but even then you're still stuck with a max 33T cog in the back and I don't think that is good for a 1x system. The one bad thing is that GRX isn't going to be available for another month or more if you're trying to build a bike now that sucks.
Awesome info, exactly what I was looking for. Also I fully agree that the AXS pricing isn't worth it after looking into it a bit more. The wait isn't a problem with me, I've got a month to research until I get started on the build. That may be a good thing or a bad thing :)
 

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I updated my post with more info on how to program di2 without the wireless or the service tool. You can use the charging block. BCR2 I believe.


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Why do you have to use Sram only cassettes with AXS? I believe that any 12 spd cassette would work, even $80 SunRace 12 spd cassettes.
The spacing for the roller of the chain is different so it won't work. You can use an eagle RD and chain and then use a different 12 sod cassette but the flat top chain doesn't fit any other cassettes including the 12 spd eagle one.

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Discussion Starter · #13 ·
So now that you guys have been so helpful with figuring out 1x configurations, I pulled the trigger on a 2x system :) Why not?

I need the stuff now, so waiting for GRX stuff to show up wasn't an option. I pulled the trigger on a $1270 (after tax) SRAM Red eTap groupset from Universal Cycles:

https://www.universalcycles.com/shopping/product_details.php?id=91235

This ended up being just as cheap as any other electronic disc groupset I could have gotten (Shimano Ultegra Di2), without the clutter of Di2 cables and stuff. I really like the cable-free way SRAM does things.

Am I correct in understanding that the only difference between SRAM Red eTap and SRAM Red eTap AXS is that AXS comes with an app while the normal eTap doesn't? I just need traditional shifting, so I don't care about the app.
 

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Well a few differences I guess.

Red etap is 11 speed | AXS is 12 speed
Red etap is not programmable | AXS is programmable
Red etap is supposed to be a little slower reacting than AXS but reviews are it is negligible
Red etap has less clearance for wide tires on the front derailleur (5mm less width on tire)

That is about it. Cassettes are going to be a crap ton cheaper for the 11 speed if so that is a plus for sure.
 

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Discussion Starter · #15 ·
Well a few differences I guess.

Red etap is 11 speed | AXS is 12 speed
Red etap is not programmable | AXS is programmable
Red etap is supposed to be a little slower reacting than AXS but reviews are it is negligible
Red etap has less clearance for wide tires on the front derailleur (5mm less width on tire)

That is about it. Cassettes are going to be a crap ton cheaper for the 11 speed if so that is a plus for sure.
Thanks for that! The biggie for me is that eTap is electronic, easy to adjust, and self-adjusting. Otherwise my derailleurs always seem to be getting out of tune.

Tire clearance, open cycles says you can still run up to 40mm tires. Seems like a lot. I just want to fit a 32mm at some point, I hope that works.

11-speed is all I need. What's one more cog if it costs so much more.

Looking forward to it!
 

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Great info here!
Also looking to lose the cables and go 1x on my ti gravel bike in the near future. I am looking at this kit (minus the front mech) as to what I would need. I would rather go with the new GRX di2, but not yet sure how the pricing will compare. I am OK with an XT or XTR 11/42 cassette for most of the riding I do. Will report back when parts become available and I can figure this all out.

https://mybikeshop.com/products/shi...MIxIqjz-CR4wIVEZSzCh34QAefEAQYAyABEgIqMPD_BwE
 

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Just following up here. I’m riding gravel in Steamboat Springs Colorado this weekend and I’ve realized that 1x just ain’t going to cut it.

Within 1 minute of leaving for my ride I spun out a 40/11 but I also needed the 40/42 I had on there to climb some of the roads I was riding. There were also multiple times I spun out on rolling pavement and gravel that I would have been pedaling with a 2x. I figure I need to be able to pedal while putting decent power down up to about 33-34 mph. But I also need to be able to climb at around 4mph with how steep some of the Jeep roads are. I could get this with a 9 or 10 tooth cog but the jumps in the cassette would be so huge I know I wouldn’t like it. On CX and MTB you’re not pedaling fire road or pavement down hills and the climbing I don’t notice the jumps as much. But an hour long road climb I definitely notice the cadence jumps. Anyway I’m going 2x on my new build.


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Just following up here. I'm riding gravel in Steamboat Springs Colorado this weekend and I've realized that 1x just ain't going to cut it.

Within 1 minute of leaving for my ride I spun out a 40/11 but I also needed the 40/42 I had on there to climb some of the roads I was riding. There were also multiple times I spun out on rolling pavement and gravel that I would have been pedaling with a 2x. I figure I need to be able to pedal while putting decent power down up to about 33-34 mph. But I also need to be able to climb at around 4mph with how steep some of the Jeep roads are. I could get this with a 9 or 10 tooth cog but the jumps in the cassette would be so huge I know I wouldn't like it. On CX and MTB you're not pedaling fire road or pavement down hills and the climbing I don't notice the jumps as much. But an hour long road climb I definitely notice the cadence jumps. Anyway I'm going 2x on my new build.

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Was also thinking that a straight up 1x could limit road riding and climbing. For this same reason, I am also considering 2x with a di2 rear and just a cable front mech to save on cost. Does anyone ride di2 rear only and normal front mix?
 
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