vinuneuro

Anyone know if Di2 will work with 46/30?

TimothyH

@Marcus_Ti is running it.

He should be along any second.

Marcus_Ti

Yuppers it works. A few things to know/be aware of:

A) That FD needs to be mounted pretty low, same as a CX crank. Be aware if you're using a frame with a riveted on braze

B) You'll probably want a chain catcher, even though it is Di2. You'll also probably want the mid-cage rear anyway just for the extra chain-wrap capacity, nvm whatever largest cog you figure you'll run.

C) Shimano never made their Ultegra and Di2 RD/FD with a 46/30 in mind. Heck E-Tube and Di2 doesn't even have the option in their software to tell Di2 what your gearing is. It only really matter WRT having your Garmin read out your gear ratio numbers, otherwise you'd never notice.

LOL. Helps being bored at work on a Friday night, still riding in/out from work even though we've been hammered with rain last 3 days.

vinuneuro

Is braze-on a deal breaker?

Aside from gear ratio number, Garmin won't be able to tell accurately show the cog position as well? And I guess synchro shift is out as well since the firmware doesn't support these ratios?

Are these caveats the same for 48/32?

Thanks for your help.

Marcus_Ti

RE: Gear numerology...

What you do is lie to Di2 about what you crank gears are. It honestly doesn't matter much, aside from the Garmin readout IRL, aside from implications for multi-shifting (number of gears you can multishift gets locked out for lord knows what reason on 52/36). I use "50/34", because all the multi-shift capabilities are fully unlocked (unlike 52/36) and the 16T delta means the gear ratio readout in E-Tube is consistently wrong to my equipment (rather than inconsistently wrong)....making setting up synchro-shift points easier.

The same caveats apply to ANY crankset gearing that is not: 53/39, 50/34, or 52/36. AKA only roadie gearings that Shimano sells themselves. IIRC. Those are the only 3 gears the roadie derailleurs recognize in E-Tube, and that data is forwarded to any computer head-unit that displays Di2 gearing info....presumably if you use MTB Di2 FD/RD you'd see the MTB gearings Shimano sells. Cog position reads as correct, but any data field that shows a tooth count or ratio will be wrong. Synchro-shift doesn't care about your gearing, although the multi-shift does get capped as mentioned before in 52/36 to two gears instead of 3.

Same rules for 48/32 or any non-Shimano crank gearing you contrive.

NOTE: The R785 (AKA "old") hydraulic Di2 brifters are agnostic WRT XTR Di2 (MTB) or Ultegra/Dura-Ace (roadie Di2). I *suspect* that agnosticism will cease with the new Ultegra/Dura-Ace parts for 2017, as their caliper and disc brifters are roadie tiered and branded (unlike "R785" which was neither tiered nor branded, the lever read "SHIMANO" rather than "ULTEGRA"). IIRC, the XTR RD has a clutch on it which would be nice for rough roads-but you need to use the XTR FD as well.


RE: Braze-on

Best advice I have is be careful. Maybe I'm a worrying mother-hen much...but I can imagine say a roadie frame with a fixed braze too high (seen posts about it being a problem for eTap SRAM....story for another time). Best and safest thing to do is use a frame with a clamp-on. Shimano's SM-AD67 clamp mount is cheap and dirt easy to get aligned and simple/stupid to add a K-Edge chain catcher too.


Oh and just because...bike porn, back from days when it was sunny and warm before monsoon season hit:

That crankset is IRD's Defiant 46/30 sq taper crankset using Shimano's UN-55 BB. Got the crank on ebay for 50% off retail and the BB on sale for $15USD.

vinuneuro

Hey Marcus, sorry for the belated reply. Thanks for the detailed post, this is very helpful. I may hit you up again for some help when I switch to Di2. I'd like to see what happens with Ultegra 8050 Di2 which looks like it'll be released soon and if more 46/30 cranksets hit the market.

Nice setup.

Marcus_Ti

Thanks.

FYI in every year passed...from the time of the new Ultegra Di2 announcement, to retail channel availability....was 8-12 months. Shimano never has been able to keep up with OEM demand for coming model year to have any spares for retail channels. Maybe this year will be different, never know. You might be waiting for a while.

vinuneuro

It's on chainreaction which gives me hope, but like you say, never know. I think people have been waiting for 9170 Di2 to actually hit stock for a while now.

r8050 | Chain Reaction Cycles

Cyclist0108

It does, at least in my case. I am using it with a WI 46/30T, originally with an 11-32T cassette.

As an experiment, I just put a SRAM 11-36T cassette on my off-road wheelset, and it works with that, too, so my lowest gear is 30/36 front/back.

vinuneuro

@Marcus_Ti, @wgscott, @TimothyH and anyone else with Di2 sub-compact expereince. As I get closer to making the switch to Di2, new question arises. Since the e-tube software doesn't support anything smaller than 50/34, how will Syncro Shift work correctly?

Cyclist0108

@vinuneuro

I've never tried syncro shifting. I just have it set up as default electronic shifting, since that is what I am used to thinking about.

The implication from the above is that unless Shimano's software has your gearing explicitly as an option, it won't get the shift pattern correct, unless it coincidently matches some other canned option. I really don't know the software, so I will leave the rest to someone who does.

I do agree with the OP that having an "expert mode" where you could put in whatever gearing suits you would be ideal, but since Shimano offers neither 46/30T road chainrings nor 11-36T cassettes, I wouldn't hold my breath.

Presumably the mountain bike version would have more options, but maybe all of those are canned as well.

Good computer programming in part consists of allowing the end-user to do stuff the programmer doesn't anticipate. (It would also be nice if the program ran on OS X and Linux, and ideally was open-source, so someone could modify it.)

Marcus_Ti

Just lie to E-Tube. Seriously. It works fine. Lower than 46/30 you might run into actual geometry problems due to FD capacity.

Shimano has never made it clear if the seemingly arbitrary lockouts on gearing combinations in e-tube have any technical basis or not. All it seems to effect are the "Gears" fields on a Garmin. Set it to whatever crank and combo you want--I haven't noticed any difference in shifting performance.


FWIW the R8050 Di2 RD has some nice features that make it worth it. Also the R8070 Di2 brifters I believe are agnostic WRT MTB/RD derailleur support. Catch being the MTB RDs only support a 40T max IIRC...But the XT/XTR RD is clutched.





What is truly bizarre about it... Shimano has sold a 46/36 Hollowtech crankset for years for CX. It used to be called "CX50" and a non-tiered part, this year they dubbed it "Ultegra". AFAIK Shimano e-tube has no official support (it isn't listed in e-tube) for Shimano's own CX crankset...what is more Shimano is, and has been, an official sponsor of UCI CX where racers are using Shimano Di2 (and probably less ranked raced too)

Danny01

Sweet ride

vinuneuro

This will be a 8070/8050 2x setup. The rub is I want to use syncro-shift so that the front will automatically shift between the two rings when I get to the end of the cassette. But it looks like e-tube will let you customize shift points and which cog to shift to when it makes the front shift? In which case it should be ok. #firstworldproblems.

Btw there is an awesome product Fit Link from WickWerks that allows you to lower the FD if your braze on mount isn't low enough, and there's even a Di2 version. Specialized put a 48/32 on the last year of my gen frame and has continued to use 48/32 in the current Diverge, so I'm hoping it won't be necessary.

https://wickwerks.com/products/fit-link-adapter/

Marcus_Ti

E-tube lets you customize shift points...yes...(there's a but coming)


But, the 8000-gen Di2 has a few more arbitrary lockdowns than 6870. My pictured rig up top has changed a bit...due to a few oddball RD suicides (that I cannot explain nor can my LBS), there's now an 8050 mid-cage Di2 RD. Given winter, and the bike is in the freezing garage I haven't toyed exhaustively with it (only got it running for commuting....but the dinner-plate down shift in full-synchro seems fixed on the penultimate cassette cog.

2-multishifts on FD shift in semi-synchro is easy...there's a lockdown on what cranks get 2x multishifts and what cranks get the full 3x multishift.


Just remember to use the bracing set-screw on the FD...IIRC all Shimano FDs mech or Di2 have a bracing screws, but it is easily forgotten,

Cyclist0108

Who am I, chopped liver?

(I thought you were too.)

TimothyH

@vinuneuro,

Both @Marcus_Ti and Professor @wgscott are on the cutting edge of Di2 capability in terms of ultracompact and are going to be your authoritative source on this topic.

I don't use an ultra-compact crankset and actually put my system into sync/semi-sync mode only once to try it. I also don't use a Garmin or other gear display. I might go ultra-compact someday but not yet.


-Tim-

Marcus_Ti

LOL, old thread.


Damnit...Just got a 10% off code I could use to get an FSA SL-K 46/30 ($350 with BB), probably drop 300grams off my IRD Defiant.

TimothyH

That post was May 2017.

Steve B.

46/36 is one of the listed cranks in E-Tube, AFAIK, and as I’ve discovered only the current cranks and cassettes as listed on the site are going to be compatible “according to Shimano”. And as others have stated it’s really only an issue if you happen to desire a correct gear indication on a Garmin or similar device.

Cyclist0108

Woops.

Sorry. I just got back from a bike ride. I should wait before I play internet.

Marcus_Ti

46/36 doesn't show up here in the Etube app. All I have listed are 52/36, 52/38, 55/42, and 53/39. I have a 9070 FD-so maybe the D/A part blocks it out, if you're seeing it on your end.

Steve B.

More knowledgeable people can correct me if I have this wrong,

As per my recent experience setting up a new 8050 system and as others have stated, you can tell E-Tube that you have any cassette and any crank that’s listed in the system, then run something completely different.

One caveat is the 53/39 crank is the only listed crank that allows you to run in what they call Gear Position “Off” mode. Gear Position is a function that protects the R derailer from incorrect chain length and/or R derailer take up capacity. It’s really more important to mt. bike systems with their huge gearing ranges, but for some reason Shimano has it in the road groups as well. With Gear Position “Set”, which is a setting locked on with cranks other than 53/39, you cannot run the chain down to what they call the 10th and 11th cogs while in the small ring (11&12 on a 11-anything cassette). With Gear Position Off, you can run any cog with any ring. Another caveat is you need Gear Position to be Set to run either Synchro mode, but Manual mode works fine.

Edit: I just noticed that a 46/36 allows Gear Position to be off. That’s good.

And of course if you pick whatever useful cranks and cassettes to make the system run as you desire and the settings do not reflect what’s actually on the bike, a Garmin D-Fly screen will show incorrect ring and cogs, if that matters to you.

Steve B.

Here's a just taken screen shot of the E-Tube setting page for 8050, with 46/36 as an option.