105 Di2 vs. Ultegra Mechanical (a detailed comparison that took one sleepless night)

This post compares the advantages and disadvantages of Shimano’s 105 Di2 and Ultegra’s mechanical series in relation to one another.

The Advantages of 105 Di2

  • Affordable Electronic Shifting

105 Di2 is more expensive than Ultegra’s mechanical options, but it’s much cheaper than Ultegra Di2’s set.

For example, the 105 R7150 Di2 derailleur is about USD 180 (depending on the retailer) whereas the Ultegra RD-R8150 Di2 is about USD 350.

The next table compares the prices of 105 Di2, Ultegra’s 11-speed mechanical set, and Ultegra Di2. (As already said, the prices vary. Those are averages calculated by analyzing the online stores).  

Rear Derailleurs

Group setModelSpeedsPrice
105R7150 Di212USD 180
Ultegra MechanicalRD-R800011USD 90
Ultegra Di2R8150 Di212USD 350
  • 105 Di2’s rear derailleur is almost half the price of Ultegra Di2. Thus, if you want an affordable Di2 system, 105 wins.
  • Ultegra’s 11-speed R8000 derailleur offers the best value for money if one is willing to sacrifice the number of gears and doesn’t want electronic shifting.

Front derailleurs

Group setModelSpeedsPrice

105R7150 Di212USD 85
Ultegra MechanicalFD-R800011USD 40
Ultegra Di2R8050 Di212USD 170

Here we observe the same phenomenon – Ultegra Di 2 is two times more expensive than 105 Di2 which is two times more expensive than Ultegra’s mechanical option.


Group setModelSpeedsPrice

105DI2 STI ST-R717012USD 450-550 (pair)
Ultegra MechanicalST-R800011USD 375
Ultegra Di2ST-R817012USD 500-640

The price of the shifters is floating. The discrepancy between the three groups is much smaller when put in percentages.

  • All The Benefits of Electronic Shifting

In this comparison, it’s necessary to specify the advantages of electronic shifting over mechanical systems. Those would be:

  1. Low maintenance
  2. Fast shifting
  3. Fast adjustments
  4. Smoothness
  5. Sequential shifting
  6. Auto shifting
  7. No degradation of performance over time due to dirt or component wear

The Disadvantages of 105 Di2

  • Higher cost

At the end of the day, 105 Di2 is a relatively new groupset with e-shifters and thus it ends up costing more than an Ultegra mechanical setup. The price discrepancy could increase even more if one is willing to purchase second-hand mechanical parts.

If you’re on a budget, it’s recommended to save the extra money or invest it into components that make a bigger difference such as the wheels.

The mechanical shifting of Ultegra is supreme when the system is set correctly and most people would be pretty happy with it.

  • Batteries could be annoying

Some people don’t like the battery aspect of electronic shifting. If you want an analog setup that is not dependent on electricity and is therefore self-sustainable, e-shifting is not for you.

That said, the batteries last a long time. Just check their status via the app to see if they have to be charged. Always charge them before a long trip.

  • More difficult to repair

Electronic drivetrains are more sophisticated and thus they could be impossible to repair on the road.

Ultimately, nothing beats the simplicity of mechanical components when it comes to reliability.

This doesn’t mean that e-components aren’t sufficiently reliable. They are, but some people want a setup that can be maintained even in the wilderness.

  • Marginal benefit

If electronic shifting wasn’t offering an edge, the professionals wouldn’t use it. That said, most cyclists are not pros and our times are relevant only to us. If you don’t cycle for maximum performance, then you definitely don’t need the latest tech.

The Advantages of Ultegra Mechanical

  • Lighter

In general, mechanical components of the higher classes tend to be lighter.

The next table compares the weight of 105 Di2 and Ultegra 11-speed mechanical parts.

Group setPartModelWeightDifference
105RDR7150 Di2*302g51% in favor of Ultegra (102g)
105FD FD-R7150142g54% in favor of Ultegra (50g)
105ShiftersST-R7170 423g3.54% in favor of 105 (15g)
105CranksetFC-R7100 (50/34)754g11.8% in favor of Ultegra (80g)
UltegraCranksetFC-R8000 (50/34)674g
105CassetteHG710 (11-34)361g23.6% (69g) in favor of Ultegra**
UltegraCassetteCS-R8000 (11-32)292g

*It’s necessary to add the weight of the battery (53g) to the 105 Di2 group set.

**It’s normal for the Ultegra cassette to be light as it has one less sprocket and a smaller large cog.

Conclusions: An 11-speed Ultegra setup will save you about 300-350 grams. The difference isn’t substantial, but it isn’t exactly slim either.

  • Cheaper

As already mentioned, Ultegra’s 11-speed line can be acquired for less money than the new 105 Di2 group set.

  • Proven Reliability

Ultegra’s mechanical group sets are known to be of exceptional quality. As long as the units in question are in good shape, optimal performance should be expected.

  • Simpler

Mechanical groupsets have been here for a long time. They’re simple and efficient.

  • Repairable

If an electronic component goes down, the chances of repairing it in the wilderness are slim to none. Mechanical parts are easier to tinker with, although there are no guarantees that it will be possible to get them up and running after a major hit.

The Downsides of Ultegra Mechanical

  • Boring

Mechanical group sets are nice, but they have been around forever and aren’t always enough to trigger interest among enthusiasts.

In this particular comparison, the strongest point of Ultegra is its lower price. But if the price is the leading factor, then one can go for 105 mechanical and save even more money without experiencing a noticeable or any degree of underperformance.

On the other hand, if you’re willing to pay 1/3 to 1/2 more for 105 Di2, you will get an “exciting” drivetrain that uses top-of-the-line technology.

Enthusiasts tired of the same old tech will find 105 Di2 more appealing than the working but otherwise boring mechanical group sets.

When to choose 105 Di2?

105 Di2 is a good choice when:

  • You want a reliable electronic groupset at an affordable price.
  • You want every single edge that you can get to improve your performance.
  • You don’t mind spending the extra money.
  • You don’t mind occasionally charging batteries.
  • You like the simple and neat appearance of a drivetrain without gear cables.

Ultegra Mechanical is a good choice when:

  • You are on a limited budget and want a reliable group set that won’t let you down.
  • You don’t care about having the latest technology on your bike because you know that performance ultimately depends on your cycling ability rather than components.
  • You don’t want to deal with battery charging.
  • You want a lighter bike.

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