From the outside, the 12-speed Shimano 105 Di2 and Ultegra groupsets Di2 look very similar. They have the same shape, design, and technologies, but the price difference can be up to 3x for some components.
I’ll share my thoughts and experience of riding the Ultegra Di2 in the past 12 months. This will help you to decide which is best for you.
Key takeaways
In the past ten years, I’ve ridden the Shimano 11-speed mechanical and electronic groupsets. After moving to a disc brake bike in 2020, I’ve also owned both 11 and 12-speed Shimano Ultegra Di2 groupsets.
Here are my thoughts and key takeaways.
- Go for Shimano Ultegra Di2 if you’re a serious cyclist, doing at least 3-4 rides weekly. Expect to pay ~25% more for components that have higher manufacturing quality and lighter materials.
- Go for Shimano 105 Di2 if you’re on a tight budget and still want to experience what electronic shifting can offer: speed and precision with minimal maintenance. It offers a good balance of performance, reliability, and value. It has a broader range of gears up to 11-36T for the steepest gradients.
To be honest, you won’t be missing out much by going with the Shimano 105 Di2, except for the Servo Wave technology. In that case, you can consider upgrading the brake levers to Ultegra.
In the following sections, I’ll break down each component and discuss their differences in terms of features, weight, and price.
| Comparison | Shimano 105 Di2 | Shimano Ultegra Di2 |
|---|---|---|
| Series | R7100 | R8100 |
| Speed | 12 | 12 |
| Launched | June 2022 | August 2021 |
| Rim brake | No | Yes |
| Disc brake | Yes | Yes |
| Semi-wireless shifting | Yes | Yes |
| Power meter crankset | No | Yes |
| Price (USD) | $1,900 to $2,000 | $2,400 to $2,500 |
Groupset weight
The total weight for a semi-wireless setup (two cables) with a 50/34T front chainring and 11-34T cassette;
- Shimano Ultegra Di2: 2,374g
- Shimano 105 Di2: 2,562g
The Ultegra is ~200g lighter than the 105 Di2 groupset but costs ~25% more. The difference can be reduced using a hybrid Ultegra + 105 to get the best of both worlds. Several riders in my local group do this with a combination below or anything in between, depending on your preferences.
- Shimano 105 – front and rear derailleurs, disc rotor
- Shimano Ultegra – brake levers/shifters, brake calipers, crankset, cassette
Here’s a breakdown of all the individual components’ weight.
| Component | Shimano 105 Di2 | Shimano Ultegra Di2 |
|---|---|---|
| Disc brake levers/shifters (pair) | 423g | 391g |
| Disc brake calipers (pair) | 246g | 246g |
| Disc rotor (pair) | 256g | 236g |
| Rim brake levers/shifters (pair) | n/a | 295g |
| Rim brake calipers (pair) | n/a | 362g |
| Front derailleur | 142g | 116g |
| Rear derailleur | 302g | 262g |
| Crankset (50-34T) | 754g | 700g |
| Cassette (11-34T) | 361g | 345g |
| Battery | 53g | 53g |
| Cables (each) | 12.5g | 12.5g |
Brake levers and shifters
Both levers have the same ergonomic design and functionalities. They support wireless shifting and have 16.4mm of lever reach adjustment. That’s where the similarities end.
There are six differences in functionalities between them.
- Servo Wave is a Shimano mountain bike brake lever technology recently introduced to the 12-speed and GRX groupsets. Servo Wave increases the brake lever’s leverage by reducing the distance it needs to be pulled before the brake pads contact the rotor. The 105 does not have the Servo Wave, unlike the Ultegra and Dura-Ace brake levers.
- Hood button. There is no third button on top of the hood, unlike the Ultegra and Dura-Ace brake levers.
- Di2 cable ports. The 105 brake levers have only one Di2 port vs. two for Ultegra.
- Battery size. The 105 brake levers require 2x 1632 batteries each vs. 1x 1632 battery each in the Ultegra levers.
- Shifter battery level indicator. There is a LED on the 105 levers to indicate the coin battery levels. Press two shift buttons for 0.5s, and the LED will light up.
- Rim brake. The 12-speed Shimano 105 was launched as a disc brake-only groupset compared to the Ultegra, which still has a rim-brake option.
| Comparison | Shimano 105 Di2 | Shimano Ultegra Di2 |
|---|---|---|
| Disc brake | Available | Available |
| Rim brake | Not available | Available |
| Model no. | ST-R7170-R/L | ST-R8170-R/L |
| Servo Wave | No | Yes |
| Coin batteries | 2x 1632 | 1x 1632 |
| Coin battery indicator | Yes | No |
| Hood button | No | Yes |
| Di2 ports | 1 | 2 |
| Brake levers weight | 423g (pair) | 391g (pair) |
| Brake levers price (USD) | $570 | $910 |
| Where to buy | Amazon Competitive Cyclist Wiggle | Amazon Competitive Cyclist Wiggle |
Mr. Mamil’s take: Consider upgrading to the Ultegra levers for the Servo Wave feature that provides better braking modulation and performance.
Rear derailleurs
Both rear derailleurs use the Shimano Shadow Technology, first introduced in the 11-speed groupsets. With the Shadow Technology, the rear derailleur has a low profile design at the top gear position (smallest cog) for a quieter drivetrain.
| Comparison | Shimano 105 Di2 | Shimano Ultegra Di2 |
|---|---|---|
| Model no. | RD-R7150 | RD-R8150 |
| Shadow Technology | Yes | Yes |
| Rear derailleur weight | 302g | 262g |
| Rear derailleur price (USD) | $280 | $410 |
| Where to buy | Competitive Cyclist | Competitive Cyclist Wiggle |
Minimum and maximum cog sizes
The 105 rear derailleur has a longer cage design to accommodate up to a 36T cassette compared to 34T on the Ultegra.
The table below shows the difference between each rear derailleur’s minimum and maximum cog sizes.
The B-gap settings for these cassettes are also different. An incorrectly set B-gap will lead to degraded shifting performance.
| Comparison | Shimano 105 Di2 | Shimano Ultegra Di2 |
|---|---|---|
| Min. small cog | 11T | 11T |
| Max. small cog | 11T | 14T |
| Min. big cog | 34T | 30T |
| Max. big cog | 36T | 34T |
Mr. Mamil’s take: The 105 rear derailleur is sufficient for most of us. It’s cheaper and can handle a larger cassette size (11-36T).
More reading : Shimano 105 vs. Ultegra vs. Dura-Ace Cassettes
Front derailleurs
Both front derailleurs have the same functionalities but differ in shape and weight.
The 105 front derailleur body is bigger, similar to the 11-speed Ultegra. The 12-speed Ultegra front derailleur has a slimmer design, smaller frontal area (33% less than its predecessor), and lower weight.
The 105 front derailleur is 26g heavier with the different materials used for the screws and plates.
| Comparison | Shimano 105 Di2 | Shimano Ultegra Di2 |
|---|---|---|
| Model no. | FD-R7150 | FD-R8150 |
| Front derailleur weight | 142g | 116g |
| Front derailleur price (USD) | $153 | $260 |
| Where to buy | Amazon Competitive Cyclist | Competitive Cyclist Wiggle |
Mr. Mamil’s take: The 105 front derailleur is more than sufficient. You can save up to $100 for other upgrades with a 27g weight penalty.
Groupsets comparison
Cranksets
Shimano introduced the 160mm crankarm length for the 105 cranksets, a similar move when it launched the Dura-Ace and Ultegra groupsets earlier.
The 105 and Ultegra 12-speed cranksets are available in five crankarm lengths: 160mm, 165mm, 170mm, 172.5mm, and 175mm.
Shimano no longer offers the standard chainring size (53/39T) for all 12-speed groupsets. There are two chainring options for 105 and Ultegra.
Important note: The crankarms have a four-arm attachment, similar to the previous generations. However, the 11 and 12-speed chainrings are not cross-compatible due to the arms’ location.
| Chainring size | Shimano 105 Di2 | Shimano Ultegra Di2 |
|---|---|---|
| 50/34T | Yes | Yes |
| 52/36T | Yes | Yes |
| 53/39T | not available | not available |
| Where to buy | Amazon Competitive Cyclist | Amazon Competitive Cyclist |
More reading : Which Power Meter Fits A Shimano Crankset?
Chains
The 12-speed 105 and Ultegra chains are the same Shimano 12-speed mountain bike chains. The XT is renamed Ultegra, and SLX is renamed 105.
Both chains are the same. They’re made from steel with a gray outer plate coating and a hollow design.
The main difference is the coating on the inner plates and pins.
- Sil-Tec coating on 105 inner chain plates.
- Chrome coating on Ultegra’s pins.
| Comparison | Shimano 105 Di2 | Shimano Ultegra Di2 |
|---|---|---|
| Model | CN-M7100 | CN-M8100 |
| Links | 116, 126 | 116, 126 |
| Chain weight (116) | 254g | 254g |
| Chain material | Steel | Steel |
| Outer plates coating | Gray | Gray |
| Inner plates coating | Sil-Tec | Chrome |
| Rollers coating | None | None |
| Pins coating | None | Chrome |
| Pin design | Solid | Solid |
| Chain price (USD) | $43 | $46 |
| Where to buy | Amazon Competitive Cyclist Wiggle | Amazon Competitive Cyclist Wiggle |
Mr. Mamil’s take: Both 105 and Ultegra chains are similar in price and weight. Both are equal in my eyes, so it’s up to you.
More reading : How to Wax A Bicycle Chain
Cassettes
With all its 12-speed groupsets, Shimano has streamlined the cassette sizes. There are three differences between the 105 and Ultegra cassettes.
Cassette sizes
105 cassette sizes start from 11-34T and Ultegra from 11-30T. The 11-36T cassette is a non-7100 series cassette.
| Cassette size | Shimano 105 Di2 | Shimano Ultegra Di2 |
|---|---|---|
| 11-30T | not available | Yes (CS-R8100-12) |
| 11-34T | Yes (CS-R7101-12) | Yes (CS-R8100-12) |
| 11-36T | Yes (CS-HG710-12) | not available |
| Cassette price (USD) | $66 | $112 |
| Where to buy | Amazon Wiggle | Amazon Competitive Cyclist Wiggle |
Shimano Hyperglide+ vs. Hyperglide
The 105 cassette uses the older Hyperglide (HG) technology vs. the newer Hyperglide+ (HG+) on the Ultegra.
- Hyperglide+ (HG+) is a specific cog tooth profile to match the chain for faster shifting, both up and down the cassette, especially under load.
- Hyperglide (HG) is similar, but only for shifting up to a larger cog.
Spider arm design
Both cassettes use an aluminum spider arm.
- 105 cassette has one spider arm, connecting the largest five cogs for 11-34T (21, 24, 37, 30, 34) and 11-36T (21, 24, 28, 32, 36).
- Ultegra cassette has two spider arms for the largest six and seven cogs for 11-30T and 11-34T, respectively.
Mr. Mamil’s take: This depends on your circumstances. If you need a larger cassette (11-36T), the only choice is the 105 cassette. If you’re riding an 11-30T or 11-34T, I’d suggest paying more for the Ultegra cassette. The Hyperglide+ technology makes a big difference in shifting performance and how the shift feels.
More reading : How to Shift Gears Correctly
Disc brakes
Brake calipers
Both brake calipers have the same design with a 10% wider brake pad clearance and easier access to the bleed port.
The only difference between them is the weight. The 105 calipers are 74g/pair heavier.
| Comparison | Shimano 105 Di2 | Shimano Ultegra Di2 |
|---|---|---|
| Model no. | BR-R7170-F/R | BR-R8170-F/R |
| Front brake caliper weight | 157g | 120g |
| Rear brake caliper weight | 141g | 104g |
| Front brake caliper price (USD) | $82 | $88 |
| Rear brake caliper price (USD) | $76 | $83 |
| Where to buy | Amazon Competitive Cyclist Wiggle | Amazon Competitive Cyclist |
Mr. Mamil’s take: Both 105 and Ultegra brake calipers’ prices are almost identical but significantly different in weight. Consider upgrading to the Ultegra calipers.
More reading : How to Fix Sticky A Disc Brake Caliper
Brake rotors
Shimano used the same brake rotors from their mountain bike lineup, the RT-CL800 (Ultegra) and SM-RT70 (105). Both rotors are available in 140mm and 160mm sizes.
The difference between the 105 and Ultegra rotors lies in their design and cooling technologies. Both rotors are Centerlock, with the 105 rotors having six arms vs. four for Ultegra.
| Comparison | Shimano 105 Di2 | Shimano Ultegra Di2 |
|---|---|---|
| Model no. | SM-RT70 | RT-CL800 |
| 140mm rotor price weight | 121g | 95g |
| 160mm rotor price weight | 133g | 113g |
| ICE Technologies | Yes | Yes |
| ICE Freeza Technologies | No | Yes |
| 140mm rotor price (USD) | $46 | $61 |
| 160mm rotor price (USD) | $46 | $61 |
| Where to buy | Amazon Competitive Cyclist | Amazon Competitive Cyclist |
Cooling technologies
One of the common problems with disc brakes is excessive heat during long and/or hard braking. To overcome this, Shimano deploys two methods;
- ICE Technologies. Both rotors have the same 3-layer design (stainless steel/aluminum/stainless steel), which Shimano calls the ICE Technologies.
- Freeza. Only the Ultegra rotors have cooling fins for better heat dissipation, which Shimano calls the Freeza technology.
Mr. Mamil’s take: The MAMIL in me would consider upgrading to the Ultegra rotors for its sleeker look.
More reading : Shimano Dura-Ace vs. XTR Rotors Comparison
Brake pads
Both brake calipers have the new L05A-RF resin brake pads with cooling fins. Shimano’s fifth-generation resin brake pad has 50% better wear resistance than its predecessor, L03A.
The L05A and L03A are cross-compatible as they have the same shape and design. The difference lies in the resin materials.
More reading : Shimano L05A Brake Pad Alternatives Resin vs. Metal Disc Brake Pads Comparison
Shimano Di2 battery and cables
Shimano introduced a new battery (BT-DN300) for the 12-speed wireless groupsets.
There are three ports on the battery, with only two needed for a wireless setup. The third port will be used for a wired setup to connect the shifters via a junction box. Only two cables are needed for a semi-wireless setup of 12-speed Shimano groupsets,
- Battery to front derailleur
- Battery to rear derailleur
The cables are available from 150mm to 1000mm in 50mm increments and 200mm from 1000mm to 1600mm.
More reading : How to Charge Shimano Di2 Battery
Synchronized Shift and wireless connectivity
The 105 and Ulrtegra Di2 are similar in terms of software functionalities. Both have wireless connectivity over Bluetooth / ANT feature, support synchronized shift, and you can set up and configure them using Shimano’s E-Tube app.
Unlike the 11-speed Ultegra groupset, the 12-speed 105 and Ultegra Di2 do not allow you to lock out the smallest two cassette sprockets.
Alex Lee is the founder and editor-at-large of Mr. Mamil. Coming from a professional engineering background, he breaks down technical cycling nuances into an easy-to-understand and digestible format here.
He has been riding road bikes actively for the past 12 years and started racing competitively in the senior category during the summer recently.