Gear shifting problem

[Vincent]

Hello guys.

I have a question.

Now I have 2 wheels. One is Easton EC90SL carbon clincher and the other is Mavic's cheap one.( can't remember its name sry)

The mavic wheels are for my indoor trainer and the Easton is for a ride.
The problem is gear shifting troubles.

My bike is Cervelo S5 and the drive train is Ultelgra 6770 Di2 (electric one)
And the cassettes for Easton is Ultegra 6700 12-28 and the other cassettes for Mavic (which is for the trainer) is 105 12-25.
And of course, the derailleurs are set to Easton wheels (12-28)
So whenever I train with my trainer I always experience shifting troubles.

Here's my question.

Because of that, I'm going to buy same two 12-25 sprockets for the 2 wheels to prevent the shifting troubles.
Will this way be a solution ?

Thanks a lot in advance

[Joe_W]

Unless the hubs you put them on are also the same: no. The exact spot where the cassette begins / ends does matter, which depends on the hub. The difference might be subtle, but it is there.
Doesn't the Di2 have an automatic adjustment function?