Originally Posted by
Andy_K
For instance, I love indexed shifting. I would hate to go back to friction shifting (except maybe on the front derailleur). But with indexed shifting, when something goes wrong (and, granted, it often does) I can easily fix it, usually without even stopping the bike. With electronic shifting, it sounds like the system is designed to be able to adjust itself, and that's fantastic. You could probably go years without having to worry about it. But when it breaks is it going to be something I can fix, or am I going to be dropping $500 for a replacement part?
To the extent that something actually breaks and is not just out of adjustment, no, you probably will not be able to fix it and will have to buy a replacement part... just like you would a part on your indexing system.
I.e.: If your STI brake/shifter goes south, you'll probably have to replace it (unless it's Campy...); same with Di2. Di2 might even be a bit more serviceable, where you can order a replacement lever with the shift buttons rather than just a mechanical brake lever, no shifter guts.
If you crash and mangle your rear der, I'm not sure of too many you could actually service with replacement parts -- you're replacing the entire derailleur whether traditional or Di2. Cost is higher for the electronic shifting components...
But if you're just talking adjustment, you can do the same kind of rear der trim on electronic stuff that you can do on mechanical stuff, while riding, from the cockpit. No front der adjustment as it keys off the RD, unless there's an issue with the limit screws. ...in which case you are getting off the bike to futz with whether you have mechanical or electronic shifting.