eyewannabike

I'm interested in a bike that has DI2 components but only a 10 speed cassette on the back. will it be possible to change it to an 11 speed without much hassle?

yankeefan

You'll need an 11 speed chain, 11 speed Di2 front and rear derailleurs , 11 speed crankset (can someone verify this? my understanding is that the spacing between chainrings is different to allow for a better chainline in the 11th cog) and the software to update your 10 speed shifters to 11 speed.

dave1442397

If you really want 11-speed Di2, you might be better off waiting for a bike that has it.

I kept an eye on ebay for months, and then two bikes that were perfect for me popped up on the same day. I ended up buying a demo bike at 30% off, with full Ultegra Di2 build, just what I wanted.

dvdslw

It's not really worth it at all to upgrade unless you need a new derailleur for some reason and already have 11 spd wheels, it just costs too much to justify having one more gear on the cassette. I have 10spd di2 with a 12/25 cassette and spend most of the time right in the middle and seldom switch down to the 12 unless I'm hauling ass down hill. I do feel the need for a higher gear so I've been looking at a 12/28 to help get me up hills without switching to the small ring up front. I would pay attention to where you are on the cassette 90% of your ride and the other 10% where you can improve maybe an extra cog will help but probably not.

khuon

If we are talking about 10-speed Ultegra Di2 (6770 series) then it is possible but it won't be cheap and simple and there are some pitfalls along the way. If we're talking about 10-speed Dura-Ace (7970 series) then it is not possible.

At the minimum, you will need to replace the cassette, chain and rear derailleur. You will also need to pay close attention to your firmware. It used to be possible to have an 11-speed Di2 component talk to a 10-speed Di2 component but then Shimano dropped support for mixing through a firmware update. So if you do this you will need to stay below a certain firmware version otherwise the system will go dead. The biggest challenge I'd say is ensuring that the entire system start out at a firmware revision that is below that cutoff version.

I'll second what others have said and advise that if you really want 11-speed then you should wait for an 11-speed bike to become available for you. Another option would of course be to upgrade the entire group. But you have to really want the bike for the frame... otherwise buying a new bike with 11-speed Di2 will likely be more cost-effective.