# Semi-Synchro and Synchro-Shift together?



## kestrel242 (May 14, 2010)

I just started playing with Synchro and Semi-Synchro shift on my DI2 setup. I don't see any compelling reason that the two modes must be mutually exclusive. Is there some way to have both functions active together?


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## fronesis (Jan 22, 2014)

kestrel242 said:


> I just started playing with Synchro and Semi-Synchro shift on my DI2 setup. I don't see any compelling reason that the two modes must be mutually exclusive. Is there some way to have both functions active together?


Short answer: no; it's either one or the other.

Longer answer: full synchro _mostly includes _all of what semi-synchro does. That is, when the system, while in full synchro, decides to shift up front it will offset at the rear the same way that semi-synchro does. In addition, while in full synchro you are free to shift the FD manually on your own, whenever you wish. The one thing "missing" from full synchro is that when you shift the FD on your own while in full, there is no offset at the back.


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## Steve B. (Jun 26, 2004)

I'm actually not that clear on how useful semi mode is in use. I understand that when you manually shift the FD the system figures out where you were in terms of gear inches, (or whatever) and moves the RD to the next "harder" gear. I think.

Full Syncro makes sense especially if you set it up to the desired shift points. Thus if you are in the small ring and running down the cogset (11-23 in this case), rather then use the 11 after the 12, you set it up to go big ring and up to the 17 cog. Or wherever you set it. Or you stay in the big ring to the 21 cog, then the next shift to an "easier " cog goes small ring and R down to the 14. That makes sense to me and thus full essentially means you don't "need" the left shifter.


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## fronesis (Jan 22, 2014)

Steve B. said:


> I'm actually not that clear on how useful semi mode is in function I understand that when you manually shift the FD the system figures out where you were in terms of gear inches, (or whatever) and moves the RD to the next "harder" gear. I think.


Semi-synchro is NOT that smart. It's not doing any sort of calculations. The "semi-synchro" mode is really just one function: whenever the rider manually shifts the FD, the system automatically moves the RD the other direction (as an offset) by 1–3 cogs. The amount the RD moves is chosen in the settings. 

But this means the overall effect on gearing will depend on both _how many_ cogs the person chooses in settings for the RD offset and _when _the rider shifts. For example, if you shift to the big ring while still in a relatively large cog in back and you have the offset set at 3, then this is going to be very different than if you are in the middle of the cassette with the offset at 1.


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## Marc (Jan 23, 2005)

Steve B. said:


> I'm actually not that clear on how useful semi mode is in use. I understand that when you manually shift the FD the system figures out where you were in terms of gear inches, (or whatever) and moves the RD to the next "harder" gear. I think.
> 
> Full Syncro makes sense especially if you set it up to the desired shift points. Thus if you are in the small ring and running down the cogset (11-23 in this case), rather then use the 11 after the 12, you set it up to go big ring and up to the 17 cog. Or wherever you set it. Or you stay in the big ring to the 21 cog, then the next shift to an "easier " cog goes small ring and R down to the 14. That makes sense to me and thus full essentially means you don't "need" the left shifter.


Full-synch....You don't even need buttons to control the FD. Can paddle-shifting similar to SRAM....but only at preset shift-pints for the FD dump....multi-shift allows for sequential gearing, but again you only have the preset FD shift.

Semi-synch. You need to control the FD....but with multi-shift in the back you can get a sequentially smaller gear wherever you are in the cassette and whenever.


Semi ends up being much more flexible, as the FD shift takes longer and can occur at awkward times in the middle of a climb for example. Whereas Full is "simpler"-although odds are if you spent the $$$ on Di2 you probably already know when to operate an FD and why.


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## fronesis (Jan 22, 2014)

Marc said:


> -although odds are if you spent the $$$ on Di2 you probably already know when to operate an FD and why.


+1

I'm something of a tech geek and I thought it was cool to have the synchro shift options. I played with them a lot for a few hundred miles. 

And then I went back to manual all the way. I don't really see myself ever tempted to use the synchro features. 

I should also note that after putting about 8,000 or so miles on Di2, the ONLY time I've ever managed to make a shifting mistake on a di2 bike was when I was in synchro mode and stupidly shifted the FD while basically stopped at a light – chain got jammed up. As I say, this was a dumb shift, but regular di2 would have been fine with it...it was the attempted offset in the rear that caused the problem...


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## kestrel242 (May 14, 2010)

fronesis said:


> Short answer: no; it's either one or the other.


Ok, thanks for the direct answer. That's unfortunate.



> Longer answer: full synchro _mostly includes _all of what semi-synchro does. That is, when the system, while in full synchro, decides to shift up front it will offset at the rear the same way that semi-synchro does. In addition, while in full synchro you are free to shift the FD manually on your own, whenever you wish. The one thing "missing" from full synchro is that when you shift the FD on your own while in full, there is no offset at the back.


I see them as very different concepts. One moderates the jump in gear ratio when you manually shift the FD, and the other lets you avoid cross chaining and makes it possible to use the right shifter to access your entire gear ratio range without using the left shifter. It should be feasible to integrate the two. However, given that Shimano has dictated it otherwise and I don't have the resources to hack the logic to do something else, it is what it is.


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## fronesis (Jan 22, 2014)

kestrel242 said:


> I see them as very different concepts. *One moderates the jump in gear ratio* when you manually shift the FD, and *the other lets you avoid cross chaining and makes it possible to use the right shifter to access your entire gear ratio range* without using the left shifter. It should be feasible to integrate the two.


Hmmm...for what it's worth, two further thoughts from me:

1. You describe semi-synchro as moderating the gear ratio jump, and that's totally fair (it does that) but for the record, full synchro ALSO does that. So if the main aspect of semi-synchro for you is the moderated gear jump, then you don't lose that with full synchro.

2. One thing you may have noticed, but perhaps others aren't aware: full synchro doesn't really AVOID cross-chaining all that much. On a bike with a normal compact double (50/34) and a relatively standard 11–28 cassette, the full synchro will keep you in the big ring all the way to the 25 cog in back. (You can't change this in settings). 

Compared to the way I normally shift my bike manually, the full synchro actually encourages and insists on a greater degree of cross-chaining. Yes, it won't let you shift into the 50, 28 combo, and it won't let you get anywhere near the smallest cogs while in the small ring up front, but when I ride with full synchro ON I have MORE cross-chaining than with it off.


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## Steve B. (Jun 26, 2004)

fronesis said:


> Hmmm...for what it's worth, two further thoughts from me:
> 
> 1. You describe semi-synchro as moderating the gear ratio jump, and that's totally fair (it does that) but for the record, full synchro ALSO does that. So if the main aspect of semi-synchro for you is the moderated gear jump, then you don't lose that with full synchro.
> 
> ...


As I understand it, there's a setting called "gear position control" which can be put in "do not set" mode and which allows true cross chaining - small/small, big/big.

Not sure if it's allowed in any of the syncro modes. 

And curious as to why you cannot change the shift points, I thought you had the ability to set where the shift up to big ring happens in terms of which cog you are in, as well as shift down. I'm a newbie at this, so any help appreciated.


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## fronesis (Jan 22, 2014)

Steve B. said:


> As I understand it, there's a setting called "gear position control" which can be put in "do not set" mode and which allows true cross chaining - small/small, big/big.


I was speaking specifically about synchro modes. In manual modes, small/small and big/big are both accessible. And with auto-trim, they both work fine. 

I've read about the system locking out certain cogs on the newest dura ace Di2, but I'm running 6870 so I don't know about that.



> And curious as to why you cannot change the shift points, I thought you had the ability to set where the shift up to big ring happens in terms of which cog you are in, as well as shift down. I'm a newbie at this, so any help appreciated.


The eTube software DOES have settings to change shift points, but if you tell it you have a 50/34 chainset and an 11–28 cassette (which is what I actually have), then the option to choose to shift down to the small ring earlier is NOT available. At least, it wasn't available the last time I tried to do it, about 4 months ago. It's possible that newer firmware has given more options here, but as of early this past fall, you had very few options.


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## Steve B. (Jun 26, 2004)

fronesis said:


> I was speaking specifically about synchro modes. In manual modes, small/small and big/big are both accessible. And with auto-trim, they both work fine.
> 
> I've read about the system locking out certain cogs on the newest dura ace Di2, but I'm running 6870 so I don't know about that.
> 
> ...


Well in a week or so in installing an 8050 upgrade group, I’ll tell you then.


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## fronesis (Jan 22, 2014)

Steve B. said:


> Well in a week or so in installing an 8050 upgrade group, I’ll tell you then.


Excellent - please do. 

8070 is top of my upgrade list!


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## Marc (Jan 23, 2005)

fronesis said:


> I was speaking specifically about synchro modes. In manual modes, small/small and big/big are both accessible. And with auto-trim, they both work fine.
> 
> I've read about the system locking out certain cogs on the newest dura ace Di2, but I'm running 6870 so I don't know about that.
> 
> ...


Odd. With an 11-32 and a "50/34" I have full access to shift points just fine. Ofc, what Di2 thinks is the gearing is irrelevant. I have a 46/30 crankset and select "50/34" and it doesn't know the difference. Select a 53/39 and have full access to everything/. Only thing that gets hinkied is Garmin's "Gears" readout of gear ratios and tooth counts.


8050's RD is pretty much the same as 6870's except for the cross-chain lockout option and the 11-34 cassette listing. Put an 8050-0GS Di2 RD on my Bigfoot rig this afternoon.




Steve B. said:


> Well in a week or so in installing an 8050 upgrade group, I’ll tell you then.


FYI:

A) The E-tube port is an inch or two further away from the dropout than on 6870, so cable clack is needed

B) Check the Dealer Manual I think Page 44. There's a "fork" on the mount tab that needs angled right on the dropout.


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## Steve B. (Jun 26, 2004)

Marc said:


> FYI:
> 
> A) The E-tube port is an inch or two further away from the dropout than on 6870, so cable clack is needed
> 
> B) Check the Dealer Manual I think Page 44. There's a "fork" on the mount tab that needs angled right on the dropout.[/COLOR]


Good to know, thx


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## kestrel242 (May 14, 2010)

fronesis said:


> Hmmm...for what it's worth, two further thoughts from me:
> 
> 1. You describe semi-synchro as moderating the gear ratio jump, and that's totally fair (it does that) but for the record, full synchro ALSO does that. So if the main aspect of semi-synchro for you is the moderated gear jump, then you don't lose that with full synchro.


That's not what I'm experiencing. When I use the left shifter to request an FD shift in semi-synchro, I get two gears from the RD as well (as we concur, moderating the gear ratio jump). However in full-synchro, when I use the left shifter to request an FD shift, there is no corresponding shift in the RD. 



> 2. One thing you may have noticed, but perhaps others aren't aware: full synchro doesn't really AVOID cross-chaining all that much. On a bike with a normal compact double (50/34) and a relatively standard 11–28 cassette, the full synchro will keep you in the big ring all the way to the 25 cog in back. (You can't change this in settings).
> 
> Compared to the way I normally shift my bike manually, the full synchro actually encourages and insists on a greater degree of cross-chaining. Yes, it won't let you shift into the 50, 28 combo, and it won't let you get anywhere near the smallest cogs while in the small ring up front, but when I ride with full synchro ON I have MORE cross-chaining than with it off.


You might be mistaken about how the E-tube interface works. It's true that you can't easily swipe the full range. However, the reason for that is that the software is restricting how many gears does the RD move in a synchro shift. You have to keep the start and finish RD gears close together (no more than perhaps 3-4 gears apart). If you shuffle side-to-side down the ratio matrix you should be able to set nearly any combination you want with the caveat that the RD must start and finish within so many gears, and you can only define one downshift crossover point and one upshift crossover point.

In my case, I'm running an 11-40 XTR cassette on my bike, which isn't on the list at all, but by cross referencing the interface to an appropriate gear ratio calculator, I was able to set it up so that cross chaining with the right shifter is impossible, and the change in ratio is modest. (inducing a cross chain with the left shifter is still perfectly feasible)

My complaint is that I can have full syncro add some intelligence to how the right shifter works, but I can't at the same time have semi-synchro add some intelligence to how the left shifter works. I think that's a missed opportunity.


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## Steve B. (Jun 26, 2004)

Is anybody running an 8050 or equiv. DA group and funding the 2nd smallest cog is locked out, regardless of Gear Position Control being set to off ?.


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## fronesis (Jan 22, 2014)

kestrel242 said:


> That's not what I'm experiencing. When I use the left shifter to request an FD shift in semi-synchro, I get two gears from the RD as well (as we concur, moderating the gear ratio jump). However in full-synchro, when I use the left shifter to request an FD shift, there is no corresponding shift in the RD.


No, what you describe is accurate, but not what I was saying (or at least trying to say) was different:

There are two different points, both apply to what happens when you are in FULL synchro:
1. If you shift the RD until the point at which the full synchro system decides to move the FD, then at the moment of the FD shift, the system will also offset the RD.

2. However, if you simply click the FD button manually, you get no offset. 

As for setting the point at which the full synchro decides to shift in front, it may be that there are more options now in the settings, or it may be that you have more options that I'm seeing because you have an 11–40 cassette.

As I stated before, if I tell eTube I have a 50/34 up front and an 11–28 in back (which is what I have), then it will NOT allow me to choose anything but the 25 cog as the shift point for the move from the small to big ring. 

I'm sure I could trick it (by telling it I have a combo of gears I don't have) and it may be that the new firmware has altered this. I'll need to check, but with it pouring down rain outside, I haven't really been looking at the bike.


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## Steve B. (Jun 26, 2004)

There are options but the system will only let you shift to the next available combination when moving up or down. There are limits as described here:

"To ensure rider comfort when using Synchronized shift, the cells may only be moved within aset range, which is established according to the following rules.

Synchronized shifting outward
‧ Synchro shift point RD gear position ≧ Shift end point RD gear position
‧ Settable range for the Shift end point shall extend to the gear position with a gear
ratio one step lower than that of the Synchro shift point.

(Example) If the Synchro shift point is 2.40, the Shift end point can be moved down to
the gear position with the gear ratio 2.26.

Synchronized shifting inward
‧ Synchro shift point RD gear position ≦ Shift end point RD gear position
‧ Settable range for the Shift end point shall extend to the gear position with a gear
ratio one step higher than that of the Synchro shift point.

(Example) If the Synchro shift point is 2.08, the Shift end point can be moved up to the
gear position with the gear ratio 2.12."

The system in theory allows a maximum cog move of 6 cogs, but only 4 in semi mode. I'm not sure if that means you can configure a move from a 34/12 to a 50/17, as I would be when using a 34/50 and 11-23. That would be a great automatic move. Likewise I'd love to use a 50/21 to a 34/15 which is the next logical move if doing it manually. 

Time will tell if the system allows it.


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## kestrel242 (May 14, 2010)

Steve B. said:


> The system in theory allows a maximum cog move of 6 cogs, but only 4 in semi mode. I'm not sure if that means you can configure a move from a 34/12 to a 50/17, as I would be when using a 34/50 and 11-23. That would be a great automatic move. Likewise I'd love to use a 50/21 to a 34/15 which is the next logical move if doing it manually.
> 
> Time will tell if the system allows it.


That's essentially what I'm doing on mine. You should have no trouble.


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## kestrel242 (May 14, 2010)

fronesis said:


> No, what you describe is accurate, but not what I was saying (or at least trying to say) was different:
> 
> There are two different points, both apply to what happens when you are in FULL synchro:
> 1. If you shift the RD until the point at which the full synchro system decides to move the FD, then at the moment of the FD shift, the system will also offset the RD.
> ...


Nah, the 11-40 isn't supported by the software at all. In fact neither is the HG800 11-34, which is meant to be to used on road/gravel bikes.


> As I stated before, if I tell eTube I have a 50/34 up front and an 11–28 in back (which is what I have), then it will NOT allow me to choose anything but the 25 cog as the shift point for the move from the small to big ring.
> 
> I'm sure I could trick it (by telling it I have a combo of gears I don't have) and it may be that the new firmware has altered this. I'll need to check, but with it pouring down rain outside, I haven't really been looking at the bike.


I just checked the setup on the 11-28 and it works the same. You should be able to do it. Apparently the key is what Steve B pointed out that the start and end points have to be within a gear ratio delta of 1.0 (or at least *think* they have a delta of 1.0


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## Marc (Jan 23, 2005)

kestrel242 said:


> Nah, the 11-40 isn't supported by the software at all. In fact neither is the HG800 11-34, which is meant to be to used on road/gravel bikes.
> 
> 
> I just checked the setup on the 11-28 and it works the same. You should be able to do it. Apparently the key is what Steve B pointed out that the start and end points have to be within a gear ratio delta of 1.0 (or at least *think* they have a delta of 1.0



The cassette choice is based on the RD part number. If you're not seeing the newer gen cogsets, I'll guess you aren't using the new-for-2017 Di2 parts. Same way the crankset gear choice locks out based on road vs MTB HTII parts based on what FD-line you use.


And aside from Garmin's "Gears" readout...what Di2 think the gearing is matters not at all IRL.


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## fronesis (Jan 22, 2014)

Please help me out with full synchro settings. 

After a bit of a debacle, I've now updated the firmware on all my devices, precisely so I could check these setting, since Kestrel persuasively argued that it was do-able. 

I can SELECT all sorts of gear points when creating a settings file, but the end result is always a file with an "!" icon added to it. And I'm unable to drag that file into one of the slots. 

I've tried a dozen different arrangements, and the only ones it accepts are when the big to little FD shift point is chose at either the largest cog or the second to largest. 

I'm making sure not to violate any other rules as specified by SteveB: my gear ratio jumps are small, etc. 

I don't get it.

EDIT: Just to add, I've now confirmed this in the eTube setting on the Windows app. That app just lets you drag the FD down shift point with the cursor, but the ONLY options are 1st gear and 2nd gear (28 or 25); you can't drag it lower than that.

In the iOS eTube app I can choose those gears when creating a custom configuration, but it will not let me use that configuration. 

I'm really at a loss as to how others are getting this to work.


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## fronesis (Jan 22, 2014)

In case it's not clear, here's what I'm talking about. The first image is the custom full synchro map I've created. It's simple, reasonable, and doesn't violate any Shimano rules. The second image is what you get when you save that map, and the ! means it can't be used.
















I get the same results when using eTube on both iOS and Windows 10. 
I have also tried saying I have a 53/39 or a 52/36 up front, and I've tried 11–32, 12–23 and everything in between at back.

No matter what I try there is one hard and fast rule: I cannot set a FD downshift that occurs in anything other than the largest or second-to-largest cog.

My only guesses now are:

1. Some people are using older firmware than I, and it's allowed for them but not for me?

2. Perhaps people are creating the setting file but not actually adding it?


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## kestrel242 (May 14, 2010)

Marc said:


> The cassette choice is based on the RD part number. If you're not seeing the newer gen cogsets, I'll guess you aren't using the new-for-2017 Di2 parts. Same way the crankset gear choice locks out based on road vs MTB HTII parts based on what FD-line you use.


What? So my last gen Ultegra won't include the HG800 because ... it's a last gen derailleur and this is a current-gen cassette? Wow, that's like having a old pump that doesn't work on 29ers. It doesn't even make any sense, a firmware update should bring it in line.

Whatever, sounds like Shimano thinks they're Apple or something.


> And aside from Garmin's "Gears" readout...what Di2 think the gearing is matters not at all IRL.


Naturally.


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## kestrel242 (May 14, 2010)

fronesis said:


> No matter what I try there is one hard and fast rule: I cannot set a FD downshift that occurs in anything other than the largest or second-to-largest cog.


I see what you're saying. I just spent an hour trying to duplicate your intended map and couldn't make it work. My best guess is that's a bug in the software.


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## fronesis (Jan 22, 2014)

kestrel242 said:


> I see what you're saying. I just spent an hour trying to duplicate your intended map and couldn't make it work. My best guess is that's a bug in the software.


Thanks for taking the time! It wasn't for nothing, since now I'm slightly more confident that I'm not going crazy!!


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## Marc (Jan 23, 2005)

kestrel242 said:


> What? So my last gen Ultegra won't include the HG800 because ... it's a last gen derailleur and this is a current-gen cassette? Wow, that's like having a old pump that doesn't work on 29ers. It doesn't even make any sense, a firmware update should bring it in line.
> 
> Whatever, sounds like Shimano thinks they're Apple or something.
> 
> ...


E-tube really is like iTunes some days. The HG800 exceeds the tooth-count spec for 6870 (GS is 32T max)...so it probably will never show up. I plugged an 8050RD into my rig and 11-34 appeared right away.

I have yet to make sense of Shimano's arbitrary lockdowns of certain things based on cog tooth count. 6870 had it too. IIRC 52/36 only had 2 multishifts allowed whereas 53/39 and 50/34 had 3.


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## Steve B. (Jun 26, 2004)

Marc said:


> E-tube really is like iTunes some days. The HG800 exceeds the tooth-count spec for 6870 (GS is 32T max)...so it probably will never show up. I plugged an 8050RD into my rig and 11-34 appeared right away.
> 
> I have yet to make sense of Shimano's arbitrary lockdowns of certain things based on cog tooth count. 6870 had it too. IIRC 52/36 only had 2 multishifts allowed whereas 53/39 and 50/34 had 3.


Well, Shimano has always taken a Big Brother approach in terms of deciding what's best for the consumer, witness the whole line of cassettes starting at 11. Who actually needs that ?. 

I think with certain aspects of Di2 they are asserting that with the consumer having control of the number of chain links installed, that damage can occur if the R derailer cannot take up the chain in certain combo's, thus they limit the combo's to a safe range. 

They are essentially unable to trust the home installer to follow guidelines.


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## Steve B. (Jun 26, 2004)

OK, in middle of an 8050 upgrade install and very frustrated.

1) The iPhone app seemed useless, then I downloaded the PC app and connected via the battery BCR2

Here's the issues:

- No ability to set to manual shift mode, synchro or semi seem to be it
- No 11-23 cassette option, in any crank type.
- No indication of battery charge on app's
- How to set to Gear Position Control adjustment ability for Do Not Set ?, this would let me manually use the 12 cog in manual mode, which I can not configure.

I mean is Shimano kidding ?, this is Nanny State BS

Unhappy with this


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## fronesis (Jan 22, 2014)

Steve B. said:


> OK, in middle of an 8050 upgrade install and very frustrated.
> 
> 1) The iPhone app seemed useless, then I downloaded the PC app and connected via the battery BCR2
> 
> ...


As to the first issue: there is nothing to 'set' in manual mode, so the app doesn't deal with that. The app configures settings for semi and full-synchro, and then when on the bike you use the junction box to toggle between the 3 modes. So this one isn't an oversight on Shimano's part.

As for all the other stuff: I can't help you there! Like you, I'm growing disappointed with Shimano's implementation of the di2 firmware and software interfaces.


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## Marc (Jan 23, 2005)

Steve B. said:


> OK, in middle of an 8050 upgrade install and very frustrated.
> 
> 1) The iPhone app seemed useless, then I downloaded the PC app and connected via the battery BCR2
> 
> ...


1) Read the junction box manual.

2) The cassette option is honestly just fluff functionally, beyond the Garmin Gears field.

3) I don't think the app has ever had a battery status indicator

4) GPC is based on your crankset choice....for whatever reason.


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## Steve B. (Jun 26, 2004)

Marc said:


> 1) Read the junction box manual.
> 
> 2) The cassette option is honestly just fluff functionally, beyond the Garmin Gears field.
> 
> ...


Yes, you guys are correct that you can set to manual in the A Junction. 

I could be crazy but I think the app’s are flaky as I’ve seen the ability to set to manual mode as well as setting gear position. If you set Synchro and semi off in app, you could then choose Gear Position to not set, thus gaining the ability to use the 2nd cog. 

I’m tinkering tomorrow. Can’t do it tonight. I put on a new Shimano 11spd chain and it doesn’t come with a connection pin (might have fell out of the box, who knows) So off to the LBS where I got a KMC 11spd Missing Link, only to discover that unlike any other (SRAM) type link, it needs a special tool to install. 

Good thing the weather sucks.


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## Steve B. (Jun 26, 2004)

OK, just read in the manual that Gear Position cannot be turned off if using a 34/50 crank.

Hmm.....


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## Steve B. (Jun 26, 2004)

Marc said:


> E-tube really is like iTunes some days. The HG800 exceeds the tooth-count spec for 6870 (GS is 32T max)...so it probably will never show up. I plugged an 8050RD into my rig and 11-34 appeared right away.
> 
> I have yet to make sense of Shimano's arbitrary lockdowns of certain things based on cog tooth count. 6870 had it too. IIRC 52/36 only had 2 multishifts allowed whereas 53/39 and 50/34 had 3.


Had a revelation last night that it matters not, in some respects, as to what cogset and crank the system is told you are using. 

I told my system I had a 53/39 crank as well as a 12/25 cogset, was then able to turn off Gear Position, which now lets me use any cog and any chainring. As well, it opens up the synchro setting moves somewhat, and you can play with that.


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## Steve B. (Jun 26, 2004)

The conundrum of cheating the Di2 system. 

1) Shimano has discontinued producing my favorite cassette, the 11-23 (they could not explain why), thus you have to cheat Di2 by telling it you are using a 12-25. Sucks as I like this cassette for flat Long Island riding as it has one tooth jumps from 11 to 19. It's still usable in Di2 (and available to buy), but see below.

2) If telling Di2 you have a 34/50 crank, the system will not allow access to the 2nd smallest cog, what Shimano calls the 10th cog. They state this is to prevent cross chaining, yet it's allowed on other cranks. They won't change this limitation. I asked. 

3) The results of the above are that you also need to lie about the crank, a 36/52 will allow access to the 10th cog.

4) When viewing the cog/crank gear locations on a Garmin or whatever, the readout is incorrect as to the Gear Combo. When you are in a 34/12 it's actually saying 36/13. Makes the whole point of getting this readout on your computer somewhat useless. This is a nit-pick somewhat, until you recall what the system costs. 

5) Shimano is truly being Big Brother with this and is yet again choosing what works for the masses and not allowing much in the way of customization.


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## Marc (Jan 23, 2005)

Steve B. said:


> The conundrum of cheating the Di2 system.
> 
> 1) Shimano has discontinued producing my favorite cassette, the 11-23 (they could not explain why), thus you have to cheat Di2 by telling it you are using a 12-25. Sucks as I like this cassette for flat Long Island riding as it has one tooth jumps from 11 to 19. It's still usable in Di2 (and available to buy), but see below.
> 
> ...



What is annoying about the Garmin readout...you can customise your gears in your Garmin itself and have them read correctly....BUT...it resets after every ride.


Also note that only the cog tooth count and ratio fields are effected....that cog position readouts still work fine.


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## Steve B. (Jun 26, 2004)

Marc said:


> What is annoying about the Garmin readout...you can customise your gears in your Garmin itself and have them read correctly....BUT...it resets after every ride.
> 
> 
> Also note that only the cog tooth count and ratio fields are effected....that cog position readouts still work fine.


Yes, I discovered that last night that the whenever the Garmin does it's BT connection with Di2, it grabs the configuration out of Di2, over-writing what you changed on Garmin. 

As well, Di2 does not keep it's BT running and at some point senses no connection and shuts down. Thus every ride you need to do a Garmin to Di2 manual connection. Maybe a good thing Di2 shuts off BT as it saves the battery.


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