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I now ride Bianchi Aria with 105 mechanical groupset and I want to upgrade my drivetrain and go to electronic shifting because I'm sick of messing with the cables every month or two. Still, I also think I wanna go for SRAM (force or probably RED if I'm not greedy) instead of Shimano for a couple of reasons: because I find the charging and true wireless system more convenient compared to obsolete wires and non-replaceable battery of Shimano.

I realize that I'm not only going to have to buy a new groupset, but I also going to have to change a few of my other components as well.

It's gonna be the bottom bracket to match an SRAM crankset and a rear hub to XDR.

And my first question is: Didn't I miss anything?

Second question: According to this official website and my own eyes, the bottom bracket is now “Shimano SM-BB72-41B”. Will I be able to install the SRAM crankset in that BB with the help of adapters?

Third question: Is it possible to upgrade it gradually? For example, install a crankset first and make it work with an 11-speed chain and cassette. And then probably spend another thousand or two for an SRAM upgrade kit?

And the fourth and the most important question: Am I overcomplicating things?

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    Why do you need to "mess with the cables every month or two"? Mine (also Shimano, different groups) don't need any adjustments for an entire season or more.
    – Zeus
    Aug 16, 2022 at 9:11
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    As for question 2, if you look at the "frame" section, you see it's a normal PF86 shell. So to make SRAM cranks work you buy the applicable PF86 bb, i.e. the Dub PF86 bb.
    – Nathan Knutson
    Aug 16, 2022 at 9:41

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First question: having to mess with cables every month or two is not normal. I would recommend investigating that first. If you still have the stock wheels, you can just replace the freehub body, no need to replace the whole hub (the part that attaches to the cassette).

Second question: the bottom bracket will also need to be changed, but that's a minor cost compared to the rest of the transmission. Even if it were compatible, it's also a wear item, so if you haven't changed it yet, it won't do any harm to replace it when changing the crankset.

Otherwise, for your third question: better to upgrade everything in one operation. Installing the crankset first is probably the only thing that you can do "before the rest", but there are some issues with that. Shimano uses bigger cassettes/chainrings than SRAM. Recent SRAM cassettes use a 10-tooth small sprocket (vs 11-tooth for Shimano), which allows them to use smaller chainrings to keep the same ratios. Because of that,

  • the 105 front derailleur won't work "optimally" (the front derailleur cage is designed in function of the dimensions of the chainrings).
  • the ratios will be lower, so it will have an impact on your speed (SRAM cranksets are almost matching Shimano gravel cranksets).
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    I'm not even sure the crankset could be installed on its own. SRAM 12 speed road is designed to work with the flat top chain. I wouldn't be confident of it working in an 11 speed setup
    – Andy P
    Aug 16, 2022 at 9:52

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