# Shimano Ultegra Di2 R8050 can't shift into smallest 2 cogs when in small chainring



## aclinjury (Sep 12, 2011)

Ok when in small chainring upfront, Di2 prevents the shift into the 2 smallest cogs. Now I've read that Shimano will prevent this shifting if the difference in teeth between the front chainrings is greater than 14. So that means any crankset combo of 50/34 or 52/36 will be prevented by the system to allow the shifting into the 2 smallest cogs in the back. Crankset of 53/39 will allow this sort of shifting.

That's my understanding. Now I have a 52/36 crankset, which has a 16-tooth difference, so I'm prevented from shifting into 2 smallest cogs. I googled, and some say the solution is to go into E-tube app and set my crankset to 53/39, and I did that. But I'm still prevented from going into the 2 smallest cogs.

My shifting scheme right now is "manual" (ie, no sync or semi-sync)

So what am I doing wrong here? Am I not programming things right in E-tube app?


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## cxwrench (Nov 9, 2004)

I haven't gotten into this at all yet but wouldn't it just be easier to just not use the 2 smallest cogs when in the small ring? They're kind of useless and you're better off shifting up to the big ring before you get there.


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## Marc (Jan 23, 2005)

This is the new gear change logic in E-Tube, only for the R8000 parts. The lockout is based on your gearing both crank and cassette...and there honestly appears to be no reason or sense behind it. Play with other crank/cluster settings and you should be able to get it unlocked.




cxwrench said:


> I haven't gotten into this at all yet but wouldn't it just be easier to just not use the 2 smallest cogs when in the small ring? They're kind of useless and you're better off shifting up to the big ring before you get there.


Except if you're the sort that sizes the chain in the small/small, then it is f'ing annoying


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## Steve B. (Jun 26, 2004)

When using the E-Tube app, you can see that there are some crank/cogset combos that allow full use of the range on the cassette. You can then set the system up to that crank & cassette as it really doesn't matter in operation.

Only thing affected would be if you are displaying ring/tooth on the Di2 section of a Garmin or Wahoo, then what the display is showing you is not actually what combo you are in. 

In practice you could also enable Synchro. That would then double shift to the big ring and next appropriate gear on the cassette.


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## aclinjury (Sep 12, 2011)

cxwrench said:


> I haven't gotten into this at all yet but wouldn't it just be easier to just not use the 2 smallest cogs when in the small ring? They're kind of useless and you're better off shifting up to the big ring before you get there.


well yes you right, but my question was also a bit academic too.


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## aclinjury (Sep 12, 2011)

Steve B. said:


> *When using the E-Tube app, you can see that there are some crank/cogset combos that allow full use of the range on the cassette*. You can then set the system up to that crank & cassette as it really doesn't matter in operation.
> 
> Only thing affected would be if you are displaying ring/tooth on the Di2 section of a Garmin or Wahoo, then what the display is showing you is not actually what combo you are in.
> 
> In practice you could also enable Synchro. That would then double shift to the big ring and next appropriate gear on the cassette.


learn me some, where do I see this screen in the app? I go into Shift Mode and get to choose crankset/cassette combo here. Then I'm taken to the next screen showing S1,S2. But I don't see any screen indicating that I'm able to use the full range of cassette while in small chainring.


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## cxwrench (Nov 9, 2004)

aclinjury said:


> well yes you right, but my question was also a bit academic too.


I know some guys have tricked it into working, I thought it involved what you did (telling the computer you have 53/39). I'll look into it when I get some time today.


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## Steve B. (Jun 26, 2004)

aclinjury said:


> learn me some, where do I see this screen in the app? I go into Shift Mode and get to choose crankset/cassette combo here. Then I'm taken to the next screen showing S1,S2. But I don't see any screen indicating that I'm able to use the full range of cassette while in small chainring.


Play around with different cranks and cassettes. I think the 53/39 as example, will let you use at least the 2nd smallest cog with certain cassettes.

Set it, load/save it and try it.


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## aclinjury (Sep 12, 2011)

Steve B. said:


> Play around with different cranks and cassettes. I think the 53/39 as example, will let you use at least the 2nd smallest cog with certain cassettes.
> 
> Set it, load/save it and try it.


ok I finally figured it out. I can now shift to the smallest cog

The Shimano E-tube app is damn non-intuitive. But basically I went into "Shift Mode" and set the crankset to 53/39 and 11-25 cassette, and choose "no set gear position". And intuitively, I thought that was all there needed to be done. Nope. I then had to "download bike settings to file" and this will save the settings to a file. Then I had to do a "upload settings from file" and pick the file I just saved. Boom, that worked. What a non-intuitive app that E-tube is! 

Anyway, I've decided to revert back to my original settings, ie., let system prevents shifting into 2 smallest cogs because I don't see any reason to use the 2 smallest cogs when in the small chainring

However, I now have a copy of the "settings file" of the 53/39 & 11/25 cassette that I can load up to the bike anytime should I ever want to shift into the smallest cog for whatever reason.


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## sgc (Jun 22, 2013)

If you have a look at this thread 
http://forums.roadbikereview.com/components-wrenching/9150-rear-derailleur-chain-362605.html

It gives details on how to get the system to recognise the 11T and 12T cogs when on the small ring

regards


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## aclinjury (Sep 12, 2011)

Marc said:


> This is the new gear change logic in E-Tube, only for the R8000 parts. The lockout is based on your gearing both crank and cassette...and there honestly appears to be no reason or sense behind it. Play with other crank/cluster settings and you should be able to get it unlocked.
> 
> 
> 
> *Except if you're the sort that sizes the chain in the small/small*, then it is f'ing annoying


Marc & CX,

this is what I've just found on my bike Di2 setup (which was orginally done by the LBS mech).

The LBS mech had originally set my Di2 system up for use with a 52/36 crankset, which means that Di2 system was preventing the use of the 2 smallest cogs. He set up my Di2 system like this first.

Then he went to measure and cut my chain, with the chain sitting in the 3rd smallest cog (i.e, he couldn't have used small/small to size up the chain due to Di2 system preventing it). 

So.... when I did go to "trick the E-tube app" (see my above post) to allow me to shift into small/small, well guess what?? the chain is now too looong (by 2 links it seemed) for small/small combo. At this point, I was thinking, oh hmm should cut down the chain. But then I thought if I cut down the chain to make it fit in small/small, and now if i'm in the big/big combo, then chain would be a tad short (but still working) and thus this would put more tension on the chain, right. And I think CX has said that he favors using the chain as long as possible, am I right CX? 

After some pondering, I believe the whole logic behind Shimano E-tube app does make sense! Shimano wants you to use the longest possible chain length in big/big and to get this longest possible chain length, they would necessarily need to prevent you from shifting into smallest/smallest combo. So that was why I went back to the original setup.

edit:
I notice that new Di2 8050 rear deraileur (and probably same for the Di2 9050) has LESS ability to take up chain slack then compared to other Shimano non-Di2 derailleur. If you look the 8050 derailleur, it doesn't go back all the way like other non-Di2 derailleurs can. Shimano must have designed it like this on purpose and then use Di2 programming to limit which gear combo you can shift into, thus by doing this artifical limit (eg, no small/small for certain crankset), you can effective use a longer chain length WITHOUT needing to design a derailleur to take up the chain slack when in small/small (because you're prevented from doing that). I believe the previous generation Di2 6850/9050 series did not prevent this small/small combo and their rear derailleurs were designed to take up more chain slack, am I right? I don't have not used the Di2 6850/9050 series so I cannot confirm, just speculating, maybe somebody can confirm this this if they have both generations Di2.


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## aclinjury (Sep 12, 2011)

sgc said:


> If you have a look at this thread
> http://forums.roadbikereview.com/components-wrenching/9150-rear-derailleur-chain-362605.html
> 
> It gives details on how to get the system to recognise the 11T and 12T cogs when on the small ring
> ...


yes I pretty much tried it exactly like what was discussed in that thread:
1. set crankset to 53/39
2. set cassette to 11/25
3. set gear option to "No set gear"

And I thought that was it and it should have worked. But apparently it didn't. I had to do the extra steps of saving/loading the settings file like I describe previously.

But good to know anyway.


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## sgc (Jun 22, 2013)

I used a laptop interface as opposed to the etube app, perhaps that is the difference and the extra requirement to save/load the file?


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## aclinjury (Sep 12, 2011)

sgc said:


> I used a laptop interface as opposed to the etube app, perhaps that is the difference and the extra requirement to save/load the file?


hmm could be. Or maybe I somehow didn't "save" or "upload" to the bike, although I see no such option to ask me if I wanted to save/upload to bike. Nothing. Thus, I assumed everything was gonna work after disconnecting from Bluetooth in the E-tube app. But then I went to check on the bike shifting, nothing! No change. After some head scratching and mucking, I found that I had to do the whole save/load procedures like I described above to work. Boom! 

the E-tube app could have been better designed to be more idiot-proof for folks like me, IMO!

edit:
Well I discovered I was at fault for not saving the settings to the bike when asked to by the Etube app. So... yep, it was user's error! Didn't have to muck with upload/save like I have stated earlier in my post a few up. Sorry for blaming Shimano when it was the operator


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## tlg (May 11, 2011)

aclinjury said:


> edit:
> I notice that new Di2 8050 rear deraileur (and probably same for the Di2 9050) has LESS ability to take up chain slack then compared to other Shimano non-Di2 derailleur. If you look the 8050 derailleur, it doesn't go back all the way like other non-Di2 derailleurs can. Shimano must have designed it like this on purpose and then use Di2 programming to limit which gear combo you can shift into, thus by doing this artifical limit (eg, no small/small for certain crankset), you can effective use a longer chain length WITHOUT needing to design a derailleur to take up the chain slack when in small/small (because you're prevented from doing that). I believe the previous generation Di2 6850/9050 series did not prevent this small/small combo and their rear derailleurs were designed to take up more chain slack, am I right? I don't have not used the Di2 6850/9050 series so I cannot confirm, just speculating, maybe somebody can confirm this this if they have both generations Di2.


I think you're correct! I'm working on a new 9150 install. Had it all finished up last night. Sized and installed the chain. I used the small-small method... cause that's that sh!t and always works. I went to shift into big-big and almost tore the friggin RD off! Chain is too short! WTF

Luckily I had another chain. Sized and installed that using the shimano big-big method. (didn't break the chain, just marked it). But using this method, in the small-small combo the chain is slack and the RD can't take it up. Figured I'm doing something majorly wrong and can't figure what it could possibly be. But if the system won't let you use the smaller cogs, that makes sense. 

Have to tinker some more tonight and look at it closer.


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## aclinjury (Sep 12, 2011)

tlg said:


> I think you're correct! I'm working on a new 9150 install. Had it all finished up last night. Sized and installed the chain. I used the small-small method... cause that's that sh!t and always works. I went to shift into big-big and almost tore the friggin RD off! Chain is too short! WTF
> 
> Luckily I had another chain. Sized and installed that using the shimano big-big method. (didn't break the chain, just marked it). But using this method, in the small-small combo the chain is slack and the RD can't take it up. Figured I'm doing something majorly wrong and can't figure what it could possibly be. But if the system won't let you use the smaller cogs, that makes sense.
> 
> Have to tinker some more tonight and look at it closer.


yep, that's exactly what I have eventually figured it out.

And to be honest, by NOT sizing using the "small-small" method, may be better in here because it allows more chain slack when you're in big-big. And besides, nobody ever should use small-small combo, so there is really no point sizing it for small-small (versus sizing for large-large where people actually do use it sometimes).

Having said that, I'm still baffled why Shimano didn't desing their 8150/9150 RD to have the capacity to take up more slack though. Sure they didn't need to (due to their electronic control mechanism), but it wouldn't hurt to just design in more capacity to uptake more slack for those who want to use a bigger cassette like a 32t one (like the good old days of their mechanical groupsets).


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## tlg (May 11, 2011)

aclinjury said:


> yep, that's exactly what I have eventually figured it out.
> 
> And to be honest, by NOT sizing using the "small-small" method, may be better in here because it allows more chain slack when you're in big-big. And besides, nobody ever should use small-small combo, so there is really no point sizing it for small-small (versus sizing for large-large where people actually do use it sometimes).


Big big is only ok if you use a 30T cassette to size it. If you start with a 25T or 28T, you have to replace the chain to go to a larger cassette.
So tonight I'll be putting a 30T on to size the chain.

Sure, you shouldn't use small small. Nor big-big. But Shimano didn't lock out the big-big combo. And there's FAR more potential for bad things to happen there. If your chain is too short and you go big big, say goodbye to your RD. 
If your chain is too long and you go small small, it just droops.



> Having said that, I'm still baffled why Shimano didn't desing their 8150/9150 RD to have the capacity to take up more slack though. Sure they didn't need to (due to their electronic control mechanism), but it wouldn't hurt to just design in more capacity to uptake more slack for those who want to use a bigger cassette like a 32t one (like the good old days of their mechanical groupsets).


Yea I'm kinda surprised too. I kept hearing how the new system has a bigger range but in reality it doesn't.


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## LiquidCooled (Jun 9, 2017)

tlg said:


> Big big is only ok if you use a 30T cassette to size it. If you start with a 25T or 28T, you have to replace the chain to go to a larger cassette.
> So tonight I'll be putting a 30T on to size the chain.


What if you size it with a 28T, and add one extra link? Wouldn't that allow the use of a 30T at a later time without replacing the chain?


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## tlg (May 11, 2011)

LiquidCooled said:


> What if you size it with a 28T, and add one extra link? Wouldn't that allow the use of a 30T at a later time without replacing the chain?


Not sure if it'd take 1, 2, or 3. But I have a 30T so might as well just be safe and use it.


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## ultreia (Mar 11, 2010)

I tried to do this to unlock the latest two cogs. I couldn't because I can't set 11-25 cassette with R8050-GS. Do you know how to unlock?


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## cxwrench (Nov 9, 2004)

ultreia said:


> I tried to do this to unlock the latest two cogs. I couldn't because I can't set 11-25 cassette with R8050-GS. Do you know how to unlock?


Why would you want to? Shift to the big ring, don't cross chain small/small...makes no sense.


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## ultreia (Mar 11, 2010)

I want to have small/small... 
I know that makes no sense to this cross but I want to be able to do it... in cyclocross it is useful some times...


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## cxwrench (Nov 9, 2004)

ultreia said:


> I want to have small/small...
> I know that makes no sense to this cross but I want to be able to do it... in cyclocross it is useful some times...


:skep: Yeah...ok


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## bdaghisallo1 (Sep 25, 2007)

ultreia said:


> I tried to do this to unlock the latest two cogs. I couldn't because I can't set 11-25 cassette with R8050-GS. Do you know how to unlock?


Try unchecking the 'gear control' option in the E-Tube software.


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## ultreia (Mar 11, 2010)

It is solved now, the question is to have the new battery BT-DN110. Without this battery you can´t change the behaviour of the rear derailleur. After you set the configuration in a bike with that battery, then you can use the rear derailleur in any bike unlocked.

So the steps should be for a 8050-GS:

0. Verify you have a BT-DN110 where you are trying to unlock the rear derailleur 
1. set crankset to 53/39
2. set cassette to 11/28
3. set gear option to "No set gear"


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## Srode (Aug 19, 2012)

started new post instead of tacking on here


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