The launch of 105 Di2 sees Shimano following in the footsteps of SRAM, which launched Rival eTap AXS as its third-tier groupset, positioned below Force and Red, in April 2021. Both brands appear to have abandoned mechanical options.
Here, we will directly compare the features of the two groupsets.
Wireless vs semi-wireless
Shimano’s 105 Di2 follows its Ultegra and Dura-Ace siblings in that it is semi-wireless.
This sees the shifters communicate wirelessly to the rear derailleur, which is the brains of the system. The rear derailleur is wired to the front derailleur and a central battery, typically housed inside the seatpost.
We believe Shimano uses the same motor internals in 105 Di2 as Ultegra Di2 and Dura-Ace Di2, but we are waiting on confirmation from the brand.
SRAM’s eTap AXS platform, on the other hand, is fully wireless. The wireless shifters pair to the front and rear derailleurs, both of which feature removable and chargeable batteries.
SRAM says Rival eTap AXS’ electronic performance is identical to Force and Red because it uses the same motors, chips and antennas.
Both 105 Di2 and Rival eTap AXS feature 12-speeds.
Shimano typically opts for more conventional gear ratios, starting with an 11-tooth smallest cog, however it has made some interesting decisions on 105 Di2.
SRAM, alternatively, utilises a smaller 10-tooth starting cog to provide a wider range.
Shimano 105 Di2’s crankset is offered in a compact 50/34t and 52/36t, as is also the case with Ultegra.
There isn’t a 53/39t option anymore and if you’d like to run a racier 54/40t ratio, you’ll need to stump up for Dura-Ace.
Rival eTap AXS is available in 48/35t and 46/33t (and 43/30t in Rival Wide). It is not available in 50/37t, which is only an option for Force and Red.
Unlike any of Shimano’s road groupsets, Rival is also offered in a single-chainring option in a 46- or 40-tooth configuration.
SRAM also produces a gravel XPLR version of Rival eTap AXS and its single-chainring options range from 38, 40, 42, 44 and 46 teeth.
SRAM’s Rival chainset is of full-alloy construction and uses the brand’s DUB bottom bracket standard.
Both 105 Di2 and Rival eTap AXS feature 12-speed cassettes, but the brands differ with their ratio methodology.
Shimano’s 105 Di2 differs from Ultegra Di2 and Dura-Ace Di2 in that the cassette sizes offered are of a larger range – 11-34t and 11-36t.
By contrast, both Ultegra R8100 and Dura-Ace R9200 are offered in 11-30t and 11-34t. The cage of the 105 R7150 is longer and officially isn’t compatible with anything less than a 34-tooth.
SRAM differs in its methodology by using a 10-tooth smallest cog to provide a greater overall range of gears.
The brand uses its own XDR freehub standard to attach its cassettes, because they are not compatible with a HG freehub. Rival’s cassette options include 10-30t and 10-36t.
Shimano’s 105 Di2 shifter is identical to Ultegra Di2 and Dura-Ace Di2 in shape, with its shrouded design. Each shifter contains two separate buttons to operate the front and rear derailleur upshifts and downshifts.
On its semi-wireless 12-speed groupsets, Shimano claims the front shifting has been sped up by 45 per cent and the rear shifting by 58 per cent, compared to the previous-generation Di2 groupsets.
The 105 Di2 shifters are heavier than Ultegra Di2 and Dura-Ace Di2 because the lever blades are made from alloy rather than carbon.
SRAM Rival eTap AXS uses identical shifting logic to Force and Red – click the right-hand shifter button for a harder gear or the left-hand button for an easier gear, or both together to shift the front derailleur.
The Rival shifters are smaller in profile than Force or Red, perhaps signifying the way future Force and Red shifters are going to go.
They also forgo the two additional ports to carry additional satellite shifters and the material choice for the blades is aluminium in place of carbon.
Both 105 Di2 and Rival eTap AXS feature disc brake systems inspired by their spendier counterparts, but with a couple of features omitted.
Like Ultegra and Dura-Ace, Shimano claims its 105 R7170 disc brakes offer 10 per cent greater clearance (compared to the previous-generation brakes) between the pad and rotor to alleviate any rubbing.
They also receive a separate bleed port, accessible from the side of the caliper, to make bleeding a more intuitive process. They continue to rely on mineral oil of Shimano’s own variety, but lack Servo Wave, a feature found on Ultegra and Dura-Ace.
Servo Wave introduces a non-linear relationship between the lever and pad travel, which is claimed to improve braking modulation.
The 105 R7170 brakes also feature Shimano’s free stroke adjustment, which was omitted from the outgoing R7000 series.
SRAM Rival eTap AXS’ disc brakes use the same two-piece caliper body found on Force and Red and rely on DOT fluid. It differs from its more expensive siblings as it doesn’t incorporate the brand’s Bleeding Edge technology, a specific bleed port that allows for quicker and easier bleeding.
There is also no contact point adjustment like on Force or Red, although reach adjustment is retained.
Neither 105 Di2 or Rival eTap AXS are available in a rim-brake configuration, unlike their more expensive counterparts.
Shimano continues to use its eTube iOS/Android/Windows app to pair the shifters and derailleurs together, as well as customising the shifting arrangement or adding in third-party devices, such as a Garmin.
SRAM continues to use its AIREA technology that allows the shifters and derailleurs to communicate, as well as BLE for smartphone app communication and ANT+ for connectivity to head units.
On both Shimano’s eTube and SRAM’s AXS iOS/Android app, you can customise the shifting controls to your preference.
While appearances are subjective, both 105 Di2 and Rival eTap AXS feature broadly similar design features to their spendier siblings.
105 Di2 incorporates the same shifter design as Ultegra and Dura-Ace, but loses the auxiliary button on the top of the hoods, as well as the ability to fit satellite shifters.
The 105 Di2 lever also lacks the ability to accept a Di2 wire, a feature found on Ultegra Di2 and Dura-Ace Di2 if you’d like to increase your battery life.
Rival, on the other hand, also broadly incorporates the design aesthetic of Force and Red, albeit with major revisions to its shifter.
The shifter is less bulbous than Force or Red, as they forgo the two additional ports that would be used for satellite shifters, as well as the braking contact point adjustment.
The hoods themselves also differ from Force and Red, with a liner grip pattern that mirrors the texturing on the gear shifter.
Shimano 105 Di2 is compatible with most frames and wheels, because the 12-speed cassette is backwards-compatible with existing HG-freehub bodies.
Your frame will need to feature internal routing between the derailleurs and the seatpost or seat tube area to house the battery.
SRAM Rival eTap AXS is compatible with a greater amount of frames than 105 Di2, because it’s fully wireless, so it could be run on externally routed frames.
However, you will need to ensure you have wheels with an XDR freehub body, which is less common than Shimano’s HG standard.
SRAM’s Rival eTap AXS is available now.
We are waiting to hear back from Shimano on specific availability of 105 Di2. We would expect it to follow Shimano’s usual availability trajectory, where it’s initially found on complete bikes, and it will later be available to buy separately.
SRAM’s Rival eTap AXS is also available as a gravel groupset as it comes in an XPLR and Wide option.
XPLR is a gravel-specific groupset with a 10-44t cassette and a corresponding rear derailleur to match.
Wide is a taller gearing for road and off-road use that utilises a smaller ratio on the chainset with a revised front derailleur.
Shimano’s 105 Di2 isn’t designed specifically to be used on gravel and Shimano has its GRX ecosystem for that purpose, which is 11-speed.
SRAM Rival eTap AXS has a power meter upgrade option, which is available on the complete chainset as original equipment or it can be upgraded. The Quarq DUB PWR unit offers single-sided power measurement and battery life is claimed to be one year.
Shimano has not launched a 105-series power meter, but the groupset will likely be supported by third-party power meter manufacturers in due course.
A complete 105 Di2 groupset is said to weigh 2,995g with a 50/34t chainset, 172.5mm cranks and a 11-34t cassette, including cables.
In a broadly similar spec (46/33 chainset with an unspecified crank length and 10-33 cassette), SRAM’s Rival eTap AXS groupset comes in at a claimed 3,109g.
Considering 105 Di2 relies on a larger internal battery and two Di2 wires, the fact that it comes in at 100g lighter is not to be sniffed at. That said, 100g isn’t a huge difference and is unlikely to noticeably affect performance in the real world.
|Claimed weight (grams)||Claimed weight (grams)|
|105 Di2 RD-7150 rear derailleur||302||Rival eTap AXS rear derailleur (inc battery)||366|
|105 FD-7150 front derailleur||142||Rival eTap AXS front derailleur (inc battery)||180|
|105 FC-R7100 crankset (50t, 172.5mm)||765.6||Rival eTap AXS chainset (46/33, unspecified crank length)||844|
|105 Di2 ST-R7170 shifters (pair)||423||Rival eTap AXS shifters with hose and brake calipers (pair)||845|
|105 CS-R7100-12 cassette (11-34)||361||Rival eTap AXS cassette (10-33)||282|
|CN-M7100 chain||252||Rival eTap AXS chain||266|
|SM-RT70 rotor (pair)||285.6||Paceline rotors (pair)||326|
|105 BR-R7170 disc brake calipers (pair)||282|
|SD-300 cable (x2)||19|
SRAM Rival eTap AXS retails for £1,268 in its 2x road configuration, or £1,470 with a power meter. In its 1x format, it retails for £1,056, or £1,258 with a power meter.
Shimano’s 105 Di2 has an RRP of £1,730 / $1,890. European and Australian pricing is to be confirmed.
In the past, we’ve found RRPs to not always be reflective of real-world pricing, which has been especially true with Shimano products. However, with the coronavirus pandemic and component shortages, there is unlikely to be such a disparity in pricing in the future.