Shimano Ultegra Di2 vs SRAM Force AXS (12-speed) Groupset

By : Mr Mamil
Updated :

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Shimano Ultegra Di2 vs SRAM Force AXS Groupsets
Shimano Ultegra Di2 vs SRAM Force AXS Groupsets

The Shimano Ultegra Di2 (R8100) and SRAM Force AXS are arguably the most popular electronic groupset models. They sit in the mid-range, above the entry-level Shimano 105 and SRAM Rival AXS, and below the top of line, Shimano Dura-Ace and SRAM Red AXS.

The Ultegra Di2 and Force AXS have all the features of the Dura-Ace and Red AXS groupsets but at a more affordable price. 

Both groupsets have their advantages and disadvantages. In many cases, cyclists chose them based on personal preferences, or in sometimes, availability.

Many key differences between the Shimano Ultegra Di2 and SRAM Force AXS aren’t obvious. This article takes a closer look at all the features and specifications and breaks them down to help you decide the best fit for your needs. 

Key takeaways

The 12-speed Shimano Ultegra Di2 and SRAM Force AXS groupsets are mid/high-tiered electronic shifting groupsets for serious cyclists.

Both have all the features and functions of the top-of-the-line Dura-Ace Di2 and Red AXS, but they are available at a much lower price range. The main difference is the materials used, hence a slightly heavier weight.

ComparisonShimano Ultegra Di2SRAM Force AXS
LaunchedSeptember 2021April 2019
Total weight2,800g to 2,900g2,500g to 2,900g
ShiftingSemi-wirelessFull wireless
Disc brakesYesYes
Rim brakesYesYes
Pricing$2,400 to $2,500$2,400 to $2,500
Overview of Shimano Ultegra Di2 vs SRAM Force AXS groupsets comparison

Brake levers and shifters

Shimano Ultegra Di2 vs SRAM Force AXS Brake Levers
Shimano Ultegra Di2 vs SRAM Force AXS Brake Levers and Shifters
ComparisonShimano Ultegra Di2SRAM Force AXS
Model no.ST-R8170-R/LED-FRC-D1
Disc brakeAvailableAvailable
Rim brakeAvailableAvailable
Batteries (each lever)CR1632CR2032
Lever materialAluminumThermoplastic
Hood buttonYesNo
Cable ports21
Brake caliper mountFlat mountFlat mount
Weight (each lever)379g414g
Price (USD)$537$602
Shimano Ultegra Di2 vs SRAM Force AXS brake levers and shifters comparison

Shimano redesigned the Ultegra Di2 brake levers compared to its predecessor (R8070). The ServoWave technology, already available in GRX and XTR/XT range is now available on the Ultegra.

According to Shimano;

When you pull a ServoWave brake lever, initial pad travel is fast, so little lever movement is needed to bring the pads into contact with the rotor.

The power multiplication factor then increases rapidly at the pad-to-rim contact so more of the lever stroke is used to apply greater braking power with improved control.

Shimano ServoWave Technology

Each brake lever uses a CR1632 battery which Shimano claims lasts up to 2 years. There are two Di2 cable ports on each brake lever, but they’re not needed if it’s set up as wireless shifting.

The SRAM Force AXS brake levers look slightly chunkier than the Shimano Ultegra Di2 levers. This has been the case from the 11s SRAM Red disc brake levers as SRAM uses a larger hydraulic master cylinder in the hoods.

Each brake lever uses a CR2032 battery which SRAM claims lasts up to 2 years, depending on the shifting frequency. The battery levels can be checked using the LED indicator via the SRAM AXS app.

Similarities

  • Wireless shifting. Shimano Ultegra Di2 can be configured wireless (default option) or wired (requires additional cables and Junction A). SRAM Force AXS is a fully wireless setup.
  • Coin battery powered. Shimano Ultegra Di2 uses one CR1632 battery per lever, while SRAM Force AXS uses CR2032 battery.
  • Cable ports. Shimano Ultegra Di2 lever has two cable ports for a wired setup and sprint shifters. SRAM Force AXS has a single cable port for Blips (SRAM).
  • Lever reach adjustment refers to the distance between the drop bar grip to the brake lever. Shimano Ultegra Di2 and SRAM Force AXS support it.
  • Free stroke adjustment is available for both. This refers to the point in the brake levers’ stroke where the brake pads come into contact with the rotor. SRAM refers to this as the Contact Point Adjustment.

Differences

  • Shift buttons. There are three shift buttons on the Shimano Ultegra Di2 levers compared to one on the SRAM Force AXS. The buttons are fully customizable according to your preferences through the Shimano E-Tube App or SRAM AXS mobile app.
  • Material. Shimano Ultegra Di2 brake levers are made of aluminum vs Long-fiber-reinforced thermoplastic (LFRT) for SRAM Force AXS. The shifter buttons are made out of plastic.
  • Weight. Shimano Ultegra is around 35g lighter (levers, brake caliper, brake hose).
  • Tactile feel. The Shimano shift buttons feel lighter compared to the more tactile SRAM buttons.

Rear derailleurs

Shimano Ultegra Di2 vs SRAM Force AXS Rear Derailleurs
Shimano Ultegra Di2 vs SRAM Force AXS Rear Derailleurs
ComparisonShimano Ultegra Di2SRAM Force AXS
Model no.RD-R8150RD-FRC-E-D1
Weight262g330g
Price (USD)$410$648
Max. cog size34T33T, 36T
Cage materialAluminumAluminum
Pulley bearingsSteelSteel
Shimano Ultegra Di2 vs SRAM Force AXS rear derailleurs comparison

The Shimano Ultegra Di2 rear derailleur sport the same design as the 105 Di2 and Dura-Ace Di2 models. It uses the Shimano Shadow design, which places the rear derailleur in a low-profile design that provides aerodynamic benefits and lessens the chances of damage in a crash.

The rear derailleur also acts as the hub of the Di2 system, holding the charging port, LED indicators, and function button for configurations. The aluminum derailleur cage supports cassette sizes up to 34T.

The SRAM Force AXS rear derailleur is noticeably bigger as it needs to accommodate the battery. There are two variants available, short cage (max 33T) or medium cage (max 36T).

SRAM uses its Orbit technology (only available in Force and Red AXS) to keep the chain under tension and ensure smooth shifting.

According to SRAM;

Orbit technology is an innovative new form of derailleur motion control. It utilizes silicon fluid as part of an elegant and ultra-lightweight damper system.

Compared to a standard friction clutch system, Orbit technology places no additional resistance on the rear derailleur’s spring when under slow or light movement. This means easier shifting and rear wheel removal. And while riding the fluid damper reduces chain bounce.

SRAM’s Orbit Technology

Similarities

  • Long cage. The rear derailleurs can be considered long cages and support a maximum cog size of 34T (Shimano) and 36T (SRAM).
  • Cage material. The rear derailleur cages are made from aluminum with steel pulley wheel bearings.

Differences

  • 1X compatibility is supported by the SRAM Force AXS.
  • Weight. SRAM Force AXS rear derailleur is significantly heavier (+68g) than Shimano Ultegra Di2. This is partly due to the SRAM battery, which weighs 26g alone.
More reading : How to Get the Most Out of Shimano Di2 Features

Front derailleurs

Shimano Ultegra Di2 vs SRAM Force AXS Front Derailleurs
Shimano Ultegra Di2 vs SRAM Force AXS front derailleurs
ComparisonShimano Ultegra Di2 SRAM Force AXS
Model no.FD-R8150FD-FRC-E-D1
Weight112g177g
Price (USD)$260$418
Shimano Ultegra Di2 vs SRAM Force AXS front derailleurs

Shimano has completely redesigned the Ultegra Di2 front derailleur to be lower profile and slimmer than its predecessor (R8070)

The SRAM Force AXS front derailleur is bigger as it needs to accommodate the battery. It’s heavier (+55g) than the Shimano Ultegra Di2. This is partly due to the battery, which weighs 26g.

Cranksets

Shimano Ultegra Di2 vs SRAM Force AXS Cranksets
Shimano Ultegra Di2 vs SRAM Force AXS Cranksets
ComparisonShimano Ultegra Di2SRAM Force AXS
Model no.FC-R8100FC-FRC-D1
Chainring options50-34T, 52-36T46/33T, 48/35T
BCD110mm107mm, Direct mount
Crankarm materialAluminumCarbon
Crankarm lengths160, 165, 170, 172.5, 175mm165, 167.5, 170, 172.5, 175, 177.5mm
Axle diameter24mm29mm
Chainline44.5mm45, 51mm (wide)
PowermeterOptionalOptional
Weight700g (50/34)724g (46/33T)
Price (USD)$315$461
Shimano Ultegra Di2 vs SRAM Force AXS cranksets comparison

Shimano stuck with the traditional compact (50/34T) and semi-compact (52/36T) when they moved to 12s. However, there is no longer a 53/39T (standard) chainring with the Ultegra 12s crankset.

The Shimano 11s chainrings are incompatible with the 12s crankset, although they both have the same BCD. The difference lies in the placement of the 4 arms. Compared to its predecessor, the Ultegra 12s crankarm is available from 160mm to 175mm.

SRAM employs the X-Range Gearing for all its 12s groupsets. The SRAM Force AXS cranksets are available in 46/33T or 48/35T combinations. 

There is a power meter upgrade variant for the SRAM Force AXS cranksets. The chainrings and crankarms remain, while the 107mm BCD spider is swapped with the SRAM AXS power meter spider (PM-AXS-SPDR-D1).

Similarities

  • Crankarm material. Both are made from aluminum.
  • Power meter option. By swapping the spider, the SRAM Force AXS crankset can be upgraded to a power meter. For Shimano, a new crankset is required (FC-R8100P).

Differences

  • Chainring combination. The Shimano Ultegra Di2 is available in 50/34T (compact) and 52-36T (semi-compact). The chainring sizes for SRAM Force AXS are slightly smaller at 46/33T or 48/35T.
  • BCD. Shimano uses a 110mm BCD, and SRAM uses a 107mm BCD. The SRAM crankset also supports a Direct Mount chainring to lower the overall weight. 
  • Bottom bracket compatibility. Shimano crankset uses a 24mm steel axle. SRAM uses a 29mm steel axle and is only compatible with SRAM DUB bottom brackets.
  • Crankarm lengths. Shimano crankarms are available in 160, 165, 170, 172.5, and 175mm lengths. SRAM is available from 165 to 175mm, in 2.5mm increments.
More reading : How to Decide Between Compact vs Standard Crankset

Gear ratios

One of the biggest differences between the Shimano SRAM 12-speed groupset is the gear ratios.

SRAM’s X-Range Gearing has a wider gearing range and tighter jumps between cogs than Shimano. This makes it more versatile and easier to maintain the same cadence after a gear shift.

  • High gear. SRAM has the highest gear ratio at 4.8 using a 48/35T front chainring and 10T rear cog, followed by Shimano (4.73) with a 52/36T front chainring and an 11T rear cog.
  • Low gear. SRAM has the lowest gear ratio at 0.92 using a 46/33T front chainring and 36T rear cog. The lowest gear ratio for Shimano is 1.00 with 50/34T front chainring and 34T rear cog.

The table below shows the possible gearing setup for Shimano Ultegra Di2 vs SRAM Force AXS.

Front chainringRear cogShimano gear ratioSRAM gear ratio
50114.55
34360.94
52114.73
36361.00
46104.60
33301.10
33360.92
48104.80
35301.17
35360.97
50114.55
34341.00
52114.73
36341.06
Shimano Ultegra Di2 vs SRAM Force AXS gear ratios comparison

Chains

ComparisonShimano Ultegra Di2SRAM Force AXS
ModelCN-M8100CN-FRC-D1
Links116, 126114, 120
Weight254g259g
MaterialSteelSteel
Outer plates finishGrayNickel
Inner plates finishChromeChrome
Pin designSolidSolid
Price (USD)$46$50
Shimano Ultegra Di2 vs SRAM Force AXS chain comparison

Shimano Ultegra and SRAM Force AXS chains are steel and have a solid pin design.

The Shimano Ultegra chains are available in 116 and 126 links. It’s the same chain as the Shimano XT mountain bike range.

The SRAM Force AXS chains are available in 114 and 120 links. They have a nickel outer and chrome inner plate finish. It uses a Flattop design which, according to SRAM, is quieter and more durable.

According to SRAM;

To gain a wider gear range with smaller gearing steps, the chain has to get narrower. With Flattop, we’ve added material on the flat side of the chain plates to strengthen every link. 

Flattop chains feature longer wearing large diameter rollers that help deliver the same drivetrain efficiency as our 11-speed drivetrains. All of these technologies together have enabled us to engineer a narrower 12-speed chain that lasts 36% longer than our 11-speed chains.

SRAM
More reading : When to Replace A Bike Chain?

Cassettes

Shimano Ultegra Di2 vs SRAM Force AXS Cassettes
Shimano Ultegra Di2 vs SRAM Force AXS Cassettes
ComparisonShimano Ultegra Di2SRAM Force AXS
ModelCS-R8100-12CS-XG-1270-D1
Sizes11-30T (291g)
11-34T (345g)
10-28T (222g)
10-30T (236g)
10-33T (266g)
10-36T (310g)
Price$112$195
Shimano Ultegra Di2 vs SRAM Force AXS cassettes comparison

The Shimano Ultegra 12-speed cassette is available in two sizes; 11-30T and 11-34T. It uses the newer Hyperglide+ (HG+) technology, where the tooth profile matches the chain for faster shifting, both up and down the cassette, especially under load.

SRAM Force AXS cassettes are available in four sizes; 10-28T, 10-30T, 10-33T, and 10-36T. This caters to both serious cyclists, racers and also everyday cyclists.

The cassette is a single piece; with four cogs CNC machined out of a single block of steel and eight individually pinned cogs. SRAM Force AXS cassettes before 2021 have a black finish compared to the current nickel-chrome finish.

More reading : Shimano 105 vs Ultegra vs Dura-Ace Cassettes

Brake rotors

Shimano Ultegra Di2 vs SRAM Force AXS Centerlock Rotors 160mm
Shimano Ultegra Di2 vs SRAM Force AXS Centerline Rotors
ComparisonShimano UltegraSRAM PacelineSRAM Centerline
Model no.RT-CL800RT-PLN-A1RT-CLX-R-A1
Mount typeCenterlockCenterlock, 6-boltCenterlock, 6-bolt
Weight (140mm)95g137g108g
Weight (160mm)113g157g135g
Price – 140mm (USD)$61$54$113
Price – 160mm (USD)$61$54$113
Shimano Ultegra Di2 vs SRAM Force AXS rotors comparison

Shimano Ultegra and SRAM Force rotors are available in 140mm and 160mm sizes.

SRAM offers two rotor choices;

  • Paceline. Cheaper but heavier.
  • Centerline. Lighter but 2x more expensive.

Both Paceline and Centerline rotors are available in either Centerlock or 6-bolt. Shimano rotors are only Centerlock.

Shimano used the same brake rotors from their mountain bike lineup, the RT-MT800, when launching the 12-speed Ultegra groupset in September 2021. In June 2022, Shimano introduced a new disc rotor, the RT-CL800, as part of the Ultegra R8100 series.

More reading : Centerlock vs 6-bolt Disc Brake Rotors

Brake pads

The Shimano Ultegra comes with Shimano’s latest, fifth-generation organic (resin) brake pads, L05A-RF. Older models such as L03A-RF (organic), L02A-RF (organic), or L04C-MF (metallic) are compatible with the disc brake calipers as they all have the same shape. 

The SRAM Force AXS comes with an organic brake pad with steel plating. There are other alternatives, such as organic compounds with aluminum plating or metallic compounds with steel plating.

More reading : Resin vs Metal Disc Brake Pads Comparison

Batteries

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.

The weighs 52g and has a capacity of 500 mAh. It takes around 1.5 to 2 hours for a full charge and can last for around 2,500 to 3,000km per charge.

SRAM uses one battery each for the front and rear derailleurs. Each battery weighs 24g and can last up to 1,000km per charge for the rear battery, which sees more usage.

The advantage of SRAM is that the batteries are easily interchangeable should any battery run flat. It takes around 60 minutes for a full charge.

More reading : How to Check Shimano Di2 Battery Levels