Di2 problem

DougalG

Re: Problems with Rear Mechs
by DougalG » Wed Jun 06, 2018 17:40 pm

Hi! I’ve just bought an s-works sl6 disc. Great bike ...

There is however something strange about the Di2 gear shifting : I cannot use all 22 gears.

Now the bike shop tells me that this is no surprise because the disc causes the wheel to be wider and as a consequence not all gears can be ‘reached’. In fact, 6 of the gears cannot be used. As a single example the 2 smallest gears at the rear cannot be driven by the smallest front gear/sprocket.

Does anyone have any experience of this??

Dougal

shirley_basso

That's normal I think with synchro shift. Can't go small small or big big. Disc may exacerbate the problem as you see.

StillGoing

As above, Di2 synchro shifting is designed to prevent you going into gears that would stress the chain line and in effect be wasted watts. It will allow you to go big ring and into the all but the two largest sprockets and small ring and but the last 3 smallest sprockets. You need E-Tube to program the synchro shifting to let it know what size chain rings and cassette that you're using. It then works out the optimum up and down changes on the cassette.

DougalG

Reassurance is gold. Many thanks to both of you!

Dave_P1

Just to note, it has nothing to do with that fact you're running disc brakes. If you turned off syncro shift then all gears should be available

StillGoing

Dave_P1 wrote:

Just to note, it has nothing to do with that fact you're running disc brakes. If you turned off syncro shift then all gears should be available

Not with Ultegra Di2 R8050/70. It is designed to prevent cross chaining which may damage the rear derailleur due to it being mounted further in.

• Restrictions on gear position can be disabled via the Customize menu in E-TUBE PROJECT. (Restrictions cannot be disabled for 52–36T or 50–34T.)

DougalG

Does it make a difference, in terms of the cross chaining issue, that I’m using the Dura Ace variation rather than the Ultegra ?

shirley_basso

Pretty sure it doesn't.

StillGoing

DougalG wrote:

Does it make a difference, in terms of the cross chaining issue, that I’m using the Dura Ace variation rather than the Ultegra ?

No the Ultegra and Dura Ace versions operate exactly the same and perform to the same standard. The only difference between them is the materials used, Dura Ace being lighter.

964cup

philthy3 wrote:

• Restrictions on gear position can be disabled via the Customize menu in E-TUBE PROJECT. (Restrictions cannot be disabled for 52–36T or 50–34T.)

IME, DA9150 locks out small ring and two smallest cogs only (with synchro shift off); everything else is available up to and including 50x32 (although you can feel the stress on the chainline). But you can lie to it and tell it you're running 53/39 when you aren't, If you have some compulsive desire to knacker your drive train by riding in 34x11 for some odd reason.

StillGoing

964Cup wrote:

philthy3 wrote:

• Restrictions on gear position can be disabled via the Customize menu in E-TUBE PROJECT. (Restrictions cannot be disabled for 52–36T or 50–34T.)

IME, DA9150 locks out small ring and two smallest cogs only (with synchro shift off); everything else is available up to and including 50x32 (although you can feel the stress on the chainline). But you can lie to it and tell it you're running 53/39 when you aren't, If you have some compulsive desire to knacker your drive train by riding in 34x11 for some odd reason.

Why would you want to lie to it? The idea of synchronised shifting is to change gears automatically on the rear for the front chainring that you're in, giving you the closest ratio to the combination you've just changed from. Say big ring 52 and 26 on a hill and change down to the 28 whereby the front changes down to the 36 small ring and the rear changes up to the 19 on the cassette. Fooling it cocks all that up and makes synchro shifting a waste of time and money.

webboo

Does that not feel a bit weird like your gears have been possessed.

paulwood

No, after a few weeks it feels completely natural, so much so that going back to a manual group set seems really strange having to use both levers when changing the front ring.

StillGoing

paulwood wrote:

No, after a few weeks it feels completely natural, so much so that going back to a manual group set seems really strange having to use both levers when changing the front ring.

Completely agree. I was very anti electronic groupsets until forced down the route due to a medical condition. Now, I wish I'd done it sooner. It just makes sense and less rushed getting the necessary changes in.

Livewire

I find Semi Synchro Shift works best once you get used to it, I want to know exactly when the chain jumps up/down on the front chainrings and with Fully synchronised you can sometimes get caught out.

Semi Synchro works like a charm.