Shimano vs SRAM road groupsets: who has the best 12-speed tech?

With Shimano, SRAM and Campagnolo now all offering you 12-speed electronic shifting, the choice of top tier groupsets for your road bike has never been larger. But which one should you choose? We’ve run through what SRAM and Shimano have to offer and picked a winner.

We’ve discussed the advantages of an electronic groupset previously and also looked at the differences between Dura-Ace vs Ultegra and Ultegra vs 105 Di2.

But it’s not just Shimano that sells 12-speed electronic shifting, with SRAM Red AXS pitched at a similar level to Dura-Ace, Force AXS being SRAM’s equivalent of Ultegra and Rival AXS equivalent to 105 Di2. SRAM pitches 12-speed electronic shifting at a lower price point too with the Apex AXS and Apex Eagle groupsets. 

So let’s look at what each brand has to offer for the road bike rider. We’ve not covered Campagnolo here, as its electronic offering is now limited to the very expensive Super Record Wireless, which probably won’t be an option shortlisted by many riders, although it also offers the slightly lower priced Super Record S Wireless, which is more comparable in price to Dura-Ace and Red.

Gear range

The cassettes on SRAM’s 12-speed groupsets start off with a 10-tooth smallest sprocket and there are options going up as large as 36 teeth. SRAM pairs that with smaller chainrings, so that you get similar top end range to conventional compact, semi-compact and standard chainsets with 11-tooth smallest sprockets, but the option to go down below 1:1 when paired with SRAM’s 46/33 tooth chainset. SRAM calls this its X-Range gearing and one aim is to give you a wider range on the large chainring so you don’t have to make as many front changes, with their tendency to reduce momentum.

In contrast, Shimano has stuck with an 11-tooth smallest sprocket and traditional compact and semi-compact chainring sizes, although its standard chainset is now 54/40t for even higher gearing. Its cassettes go out to 34 teeth maximum, or 36 teeth for 105 Di2. 

So SRAM gives you wider gear range options and at present it’s got more cassette options too.

Advantage SRAM

SRAM X Range 

There are disadvantages to SRAM’s configuration though. Drivetrain efficiency decreases as sprockets get smaller, mainly due to the larger angle through which the chain’s links need to turn. This isn’t linear, so there’s significantly more friction passing over a 10-tooth sprocket than an 11-tooth one. Measurements by component and accessory maker Silca suggest that there’s around 0.5 watts extra frictional loss with a 10-tooth sprocket. With fewer teeth engaged with the chain there’s greater wear on the components too.

SRAM says that it’s engineered its 12-speed groupsets so that frictional loss is similar to its older 11-speed ones with an 11-tooth smallest sprocket and that it’s used materials that up the longevity of its components, but it’s still something to bear in mind.

It’s also worth thinking about whether you are going to end up with little-used lower ratios on the small chainring if you’re riding on tarmac; for most reasonably fit road cyclists over most terrain the 1:1 lowest ratio offered by Shimano is likely to be adequate. SRAM pitches its 12-speed groupsets at gravel riders too, where you might need an ultra-low gear, although Shimano offers this as well with its GRX gravel groupsets.

So although SRAM is giving you more gearing options, for lower wear and friction in the highest gear ratios, it’s:

Advantage Shimano

Lever feel

Shimano’s levers have always been miracles of miniaturisation, fitting a lot of electronics (or, for its mechanical groupsets, the cable ratchet mechanism) into a very compact lever body, alongside the hydraulic mechanisms for its disc brakes.

It’s actually made the latest 12-speed levers a little larger than its older levers, hitting the sweet spot between plenty of hood area to rest your hands on, while being small enough for those with smaller hands to grasp. The extra size also means than it’s been able to separate the up and down shifters a little more, reducing the risk of mis-shifting that was present with its 11-speed Di2 shift levers.

In contrast, SRAM’s levers are a little larger still than Shimano’s, although they've slimmed down with the latest generation and have less pronounced pommels at their ends. SRAM’s single shift lever each side means that there’s no risk of a mis-shift from hitting the wrong shift button, although you can still trigger an unwanted front shift by hitting both levers together. We still reckon that Shimano’s levers are neater though.

Advantage Shimano

Shift speed

Shimano’s 11-speed Di2 groupsets already set the mark for shift speed and that only increased when it introduced 12-speed Dura-Ace and Ultegra groupsets. In fact, Shimano claims that they’re 58 per cent faster at the rear and 45 per cent faster at the front than its previous models.

SRAM has speeded up its shifting with its latest generation groupsets, particularly the front shifting with the second generation Red AXS, although it's still not quite as razor-sharp as Shimano. Shimano’s front shifting in particular feels very rapid and surefooted, which is particularly welcome as front shifts tend to be the most critical to get right to avoid losing momentum. Shimano even lets you slow down shift speed via its e-Tube app if you find it’s too fast, whereas with SRAM shift speed is not configurable.

Advantage Shimano

Shift quality

Shimano’s shift quality has always been top-notch and that continues with its 12-speed groupsets. In fact, the Hyperglide+ engineering transferred over from its 12-speed MTB groupsets has improved it, with Shimano saying that the ramp pattern on its 12-speed cassettes, paired with its specially designed chain and faster-acting derailleur mechanisms, contributes to its more precise shifting.

Shift quality is an area where SRAM still lags, although its Red AXS groupset is catching up thanks to a narrower front derailleur cage which auto-trims as you move up and down the cassette, rather than relying on the older yaw technology to prevent chain rub. 

Advantage Shimano

Battery life

Rather like electric cars, whether your battery will last out is a worry for users of electronic groupsets. It’s no fun trying to ride home if your front mech has given up, although it does give you a good spin session. 

It’s the front mech that stops shifting first if your Shimano battery is low on charge. If your SRAM rear mech battery is drained you can stop and swap it for the front derailleur battery, so again you’ll only have a working rear mech.

An advantage of Shimano’s wired configuration over SRAM’s separate batteries in its derailleurs is that Shimano’s internal battery has a higher capacity and potentially a longer battery life; whereas SRAM says its batteries will last for around 60 hours of riding each, Shimano says that its battery will power your shifters for around 1000km. 

Although these should work out about the same, anecdotally Shimano's battery lasts for longer. In both cases, it's advisable to keep an eye on your battery level via the brand's app, by linking your derailleurs up to your cycling computer or by checking the battery level LEDs on the derailleurs.

Advantage Shimano

On the other hand, it’s easier to recharge SRAM’s batteries as you just unclip them from the mechs and put them in the USB charging cradle. With Shimano you’ll need to park your bike near a power outlet and hook up the rear mech to charge it up. Shimano does give you an extra-long charging cable though.

Advantage SRAM

Power meters

A power meter has become near-essential for many riders of top-end bikes and both Shimano and SRAM offer a dual-sided measuring power meter crankset option for their two highest spec groupsets.

Shimano integrates its power meter into the Dura-Ace crank arms, with 20 strain gauges and a claimed +/-1.5 accuracy. Ultegra gets 24 strain gauges, but claimed accuracy drops to +/-2 percent.

In contrast, SRAM places its power meter in the chainring spider. It claims +/-1.5 percent accuracy, but whereas when your chainrings on a Shimano system are worn you just replace these, you need to replace the entire power meter along with the chainrings on the SRAM Red or Force AXS crankset. This is significantly more expensive, even if SRAM does discount the replacement.

Advantage Shimano

Lower down the pecking order, SRAM also offers a single sided power meter for Rival AXS and Apex, whereas Shimano 105 and 105 Di2 users will have to use a non-OEM system if they want power measurement.

Advantage SRAM

App functionality

Shimano has made some big leaps forward in configurability with its latest 12-speed groupsets. It used to be that you needed to wire the bike up to a computer and use the rather clunky PC-based eTube app to make any configuration changes. The alternative was to buy a separate D-Fly wireless unit and wire it into your Di2 system - most bikes didn’t come with this included and the use of internal wiring on many high spec bikes made it awkward to find somewhere to place it. 

Shimano now matches SRAM AXS though, with a Bluetooth antenna built into the rear mech that gives you a wireless connection to its smartphone app.

There’s a bit more you can do with the Shimano eTube app than with the SRAM AXS app. That includes changing shift points with synchronised shifting and altering the speed of shifting as well as reprogramming the third shifter button on each lever to operate other electronics.

Advantage Shimano

Braking

Both Shimano and SRAM offer brake lever reach and bite point adjustment, so you can get a disc brake set-up that suits you. Shimano includes its Servo Wave tech in its road brakes, which gives a non-linear response to the lever pull. This makes it easier to feather the brakes, while still offering the brake’s full power further into the lever stroke.

Shimano’s brake pads now retract 10 per cent further than with its older models too. Coupled with low thermal distortion brake rotors shared with its MTB groupsets, this helps reduce the potential for irritating brake rub when the brakes get hot.

It also offers a cable-operated rim brake option.

The second generation SRAM Red AXS has repositioned brake lever pivots, which make its hydraulic disc brakes very light touch. The lever action is more progressive and easier to modulate too. SRAM is definitely catching up with Shimano, but it's still:

Advantage Shimano

Weight

With the 2024 update to SRAM Red, SRAM claims to have taken back the lightest groupset spot, even if only by 66g.

Precise weights are tricky to pin down, due to there being so many different configuration options, but according to SRAM a Shimano Dura-Ace groupset weighs 2,562g as against SRAM Red AXS at 2,496g for a similar configuration. 

Ultegra R8100 comes in at 2716g versus 2922g for Force AXS while an equivalent Rival AXS 12-speed groupset will weigh around 3,205g, according to Cycling Weekly. So although SRAM may take top spot, it's by a whisker and Shimano works out lighter further down the foodchain.

Advantage Shimano

Price

At the top of the groupset tree, Shimano Dura-Ace and SRAM Red AXS are almost identical in list price. The list price for SRAM Force AXS is significantly lower than Shimano Ultegra, although discounts on Shimano tend to be greater than on SRAM groupsets.

Advantage SRAM

Our take

Both SRAM and Shimano 12-speed groupsets provide versatile, high quality shifting. SRAM gives you more gearing options than Shimano including wider range and single ring compatibility. That’s particularly useful if you’re looking to take on gravel (for which Shimano has its 11-speed and 10-speed GRX groupsets) or want a pared down rig for flat time trials. 

But for the general road rider, we reckon that Shimano wins out over SRAM with its slightly slicker shifting, probable longer range between charges and greater configurability. There are options with adequate gear range for the majority of road riders too.