105 “upgrade” question

Equipment
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Hello All. I had a question about going from 105 mechanical (with hydraulic disc brakes) to 105 di2.

I have a ‘21 Trek Emonda and I’m trying to figure out the most cost-effective way to upgrade to DI2.

I asked the guys at my local bike shop and they were going to re-search it and get back to me and they kind of dropped the ball so I figured I would ask here where the real experts are.

Is it cheaper to buy a complete package or should I get each piece individually since I don’t need an entire group set?

Also, I’ve gotten conflicting information about my brakes if I need to change them out or not.

Any thoughts?

Any useful information is greatly appreciated. TIA

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  • What exactly are you planning to reuse?

I ask because the change from mechanical to Di2 along with the 11-speed to 12-speed requirement means that nearly everything group related has to be change. At best, I think you could reuse the disc brake calipers and rotors, but everything else would seem to need to be replaced.

With that much changing, trying to be frugal with bottom end of the brakes seems like minimal gain to me. That in mind and not even looking at prices, I have to imagine that a full group purchase will beat out piecing it together unless you get very picky with sales and such for individual pieces.

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11-speed? Buy used and piece it up, keep your calipers.

12-speed? Kit all the way.

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  • He mentioned:
  • So 12-speed is the answer since 105 Di2 never existed until the R7100 one just introduced as 12-speed.
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Dang, I can’t read!

Thanks for that catch.

EDIT: OP, you might be able to score an 11-speed set-up on the cheap, and keep a lot of the grouppo you already have. Ultegra and DA Di2 have remote ports and top-buttons that 12-speed 105 doesn’t.

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  • Taking a different swing at this, it might be worth a look at the older Ultegra Di2 11-speed group. I have no idea what’s out there, but since that is the old group and only 11-speed, you might be able to find it cheaper.

  • Couple that with the fact that sticking to 11-speed actually allows you to keep far more of your current group (Crankset, Cassette, Chain and brakes that you mention) it could be the least expensive way to get Di2 on your current build.

  • BINGO! I was writing the same as you were doing your edit apparently :smiley: :+1:
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To answer this question, you just have to shop around. I’ve gotten tremendous deals on groupsets over the years by shopping the lowest price on every part from multiple vendors plus ebay and piecing it together.

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I was thinking of keeping cranks and calipers but I see your point.

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That’s actually a great idea

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That’s where I get nervous. I’m worried I’m gonna find a “great deal” that has a piece missing I’m unaware of that ends up costing my a ton just to get separately. Never bought a group set before and definitely never an electronic one so I’d hate to come up a component short

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You can definitely use the cranks….I am still running an 11 spd crank with my 12 spd Di2 and have had zero issues.

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You’ll have to shop around. And don’t neglect to check Ultegra prices, as they might be on sale for similar price as the 105.

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And if it were. me I’d run an Ultegra cassette (Hyperglide+) and a DA chain, which I’ve found last longer and don’t really cost much extra.

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Doubt you’ll save any money anyway. Even if you did, why go through all that hassle just to have old brakes?

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Okay all, thanks for your advice. I happened to find a complete (no cranks) ultegra setup for $860. Is that a decent price?

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What would call a good price? I have an Ultegra set for $860 thst I can pull the trigger on.

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I have no idea. Google is your friend. My best deals usually come from Europe (to the US).

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May be cheaper to find a used 11 speed Ultegra than a 12 105. Could reuse the rotors and calipers, crank and cassette/chain. Would just need shifters, battery( and the trek mount), junction boxes and wiring.