Shimano Di2 shifting chain prob.

[Angus McCoatup]

Words of wisdom please. I have Ultegra 6800 Di2. Had from new, done 2000km dry miles, never crashed or dropped or otherwise damaged. Worked perfectly from new, not modified in ay way. Kept well maintained, cleaned regularly. Love it and has shifted like a dream since new. Lately however, when in either of the lowest gears on the cassette (nearest the hub just to be clear), it throws the chain from the big chain ring to the small ring. Have followed instructional vids and have adjusted the front mech as per the spec. Can not find an obvious cause, no point where the chain is catching or similar prob. It worked perfectly in all gears since new and I really want to get this sorted. Any help v. much appreciated.

Many thanks.

A Mc C

 

[Slioch]

Is your chain worn and needs replacing?

Following video shows what to look for...


And here's a cheap chain stretch measuring tool...
https://www.ebay.co.uk/itm/Bicycle-...853119&hash=item23a6712f93:g:mCQAAOSwpF1bWpM~

 

[Yellow Saddle]

Is your chain worn and needs replacing?

Following video shows what to look for...


And here's a cheap chain stretch measuring tool...
https://www.ebay.co.uk/itm/Bicycle-...853119&hash=item23a6712f93:g:mCQAAOSwpF1bWpM~

Chain wear never manifests as erratic gear shifting.

 

[Yellow Saddle]

Words of wisdom please. I have Ultegra 6800 Di2. Had from new, done 2000km dry miles, never crashed or dropped or otherwise damaged. Worked perfectly from new, not modified in ay way. Kept well maintained, cleaned regularly. Love it and has shifted like a dream since new. Lately however, when in either of the lowest gears on the cassette (nearest the hub just to be clear), it throws the chain from the big chain ring to the small ring. Have followed instructional vids and have adjusted the front mech as per the spec. Can not find an obvious cause, no point where the chain is catching or similar prob. It worked perfectly in all gears since new and I really want to get this sorted. Any help v. much appreciated.

Many thanks.

A Mc C

It sounds to me as if an anti-cross chaining mode has kicked in. This prevents you from using big/big and small/small. It is a software feature.

 

[derrick]

Words of wisdom please. I have Ultegra 6800 Di2. Had from new, done 2000km dry miles, never crashed or dropped or otherwise damaged. Worked perfectly from new, not modified in ay way. Kept well maintained, cleaned regularly. Love it and has shifted like a dream since new. Lately however, when in either of the lowest gears on the cassette (nearest the hub just to be clear), it throws the chain from the big chain ring to the small ring. Have followed instructional vids and have adjusted the front mech as per the spec. Can not find an obvious cause, no point where the chain is catching or similar prob. It worked perfectly in all gears since new and I really want to get this sorted. Any help v. much appreciated.

Many thanks.

A Mc C

Worn chain and chainring.

 

[Yellow Saddle]

Worn chain and chainring.

How would that work?

 

[Slioch]

Chain wear never manifests as erratic gear shifting.

Chain wear may be a factor, and is something I would always check if I started getting erratic gear shifting.

One of my bikes did develop erratic shifting and, when I checked the chain, it was close to 1% wear. I fitted a new chain, didn't fiddle with anything else, and the problem was solved. I appreciate that this wasn't Di2 though.

I agree that the problem may be caused by a number of other factors, but you need to go through a process of triage to rule out the more obvious causes first, before getting onto the more technical ones?

 

[Vantage]

Worn chains/sprockets/chain rings causes a multitude of problems, but changing gear without input from the rider isn't one of them.

 

[Gary E]

Have you upgraded the firmware on your Di2 system? There are a number of threads if you do a quick Google search that say this is a feature of the software that prevents cross-chaining. Can't say I've noticed it on mine but maybe I'm just changing myself before Di2 intervenes.

 

[Yellow Saddle]

Chain wear may be a factor, and is something I would always check if I started getting erratic gear shifting.

One of my bikes did develop erratic shifting and, when I checked the chain, it was close to 1% wear. I fitted a new chain, didn't fiddle with anything else, and the problem was solved. I appreciate that this wasn't Di2 though.

I agree that the problem may be caused by a number of other factors, but you need to go through a process of triage to rule out the more obvious causes first, before getting onto the more technical ones?

Don't misunderstand me. Chainwear is NEVER responsible for erratic shifting. One uncontrolled anecdotal example doesn't prove it. Once you understand how a worn chain and worn sprockets and/or new sprockets interact, you'll understand why.

There is no may or maybe in this issue.

 

[derrick]

How would that work?

It falling of the big front ring. Quite simple.

 

[derrick]

Don't misunderstand me. Chainwear is NEVER responsible for erratic shifting. One uncontrolled anecdotal example doesn't prove it. Once you understand how a worn chain and worn sprockets and/or new sprockets interact, you'll understand why.

There is no may or maybe in this issue.

Its not eratic shifting.

 

[derrick]

It sounds to me as if an anti-cross chaining mode has kicked in. This prevents you from using big/big and small/small. It is a software feature.

Anti cross chaing cannot kick in. It needs to be programed.

 

[Gary E]

Anti cross chaing cannot kick in. It needs to be programed.

You're right, it's not likely to just reprogram itself, but here are several posts online where people have reported that, after a firmware update, the anti-cross chaining is the default setting. That's why I asked if he'd updated his firmware.

 

[derrick]

You're right, it's not likely to just reprogram itself, but here are several posts online where people have reported that, after a firmware update, the anti-cross chaining is the default setting. That's why I asked if he'd updated his firmware.

But he did mention nothing done apart from cleaning, But thats interesting what you say. i have never come across a firmware update that could do that, i will look out for that as i look after a lot of Di2 bikes,