First test: The new Red AXS groupset from SRAM

When SRAM presented its eTap electronic road bike shifting system to the public for the first time in 2015, the US manufacturer was not only greeted with admiration. Sceptics suspected that the new technology was something of an act of desperation, coupled with a high risk of failure. After all, the Americans, who had only entered the road bike business eight years earlier, were late to the game with electronic shifting components. The competition from Shimano and Campagnolo had been shifting gears at the touch of a button for years and had already secured a number of patents for it. The fact that the Red eTap sent the shifting commands along the bike via a radio signal rather than an electric cable seemed daring: could the technology work reliably and permanently, or was it too lame, sensitive or prone to interference to withstand the rigours of everyday racing?

SRAM Red AXS in action at the Giro d'Italia 2024

Almost a decade later, nobody asks such questions any more. In practice, the worries proved to be unfounded; the competition now also works wirelessly, making the modern racing bike a good deal more user-friendly. The transmission protocols are well encrypted, the batteries are sufficiently large and the electronics are robust. To date, there have been no known malfunctions or failures attributable to wireless technology. From today's perspective, the developers of the eTap must be credited with particular courage and foresight. In the course of the Giro d'Italia, SRAM launched the third generation of its wireless drivetrain in a concerted effort - with a considerable head start in development, as Shimano and Campagnolo have only just abolished cables with their latest products. The SRAM-sponsored pros switched to the new groupset in the middle of the tour, at the same time as it hit the shops and the top models of many bike manufacturers. TOUR received the new Red AXS for testing a few weeks earlier and was able to test it intensively.

SRAM Red AXS circuit diagram: simple and logical

The fact that the eTap system has been a great success for SRAM in recent years is also, but not only, due to the elimination of cables. The shifting system that was introduced with it also proved to be impressively simple and logical and was very popular with users. There are only two large shift buttons, left for smaller gears, right for larger gears, and both buttons are pressed simultaneously to change the chainring. It is virtually impossible to shift gears. Since the second generation with the addition of AXS, which emphasised a simple portfolio and uncomplicated compatibility of components, SRAM has been regarded as an innovative trendsetter among component manufacturers. This user-friendly approach probably led to SRAM being able to massively increase its market share on road bikes and especially on gravel bikes, despite some weaknesses in the mechanical details. The new Red AXS is intended to build on this success, eliminate weaknesses and make many things better. We have summarised here what makes the new components stand out in detail, where there is relevant progress and what weaknesses we have identified after hundreds of kilometres.

SRAM Red AXS: The drivetrain

SRAM has only fine-tuned the drivetrain of the new Red. The carbon crank arms have been given a new layup, which saves a few grams in weight. The chain has been slimmed down by 13 grams with cut-outs in the plates. Apart from that, the drivetrain remains largely unchanged with twelve sprockets, which can be ridden with either one or two chainrings. This also means that the drivetrain and shifting components are backwards compatible, so they can be easily combined with parts from the previous generation (and those of the cheaper twelve-speed groupsets). With the double drivetrains, SRAM is sticking to the chainring combination milled from a single piece, into which an optional power meter is integrated, which also cannot be removed. This means that if a chainring is worn, the entire unit must be replaced. SRAM charges half the price of a new part, and the old part is recycled. However, this is still expensive: 168 euros without or 448 euros with a power meter are then charged for the replacement part. The cassette milled from a single piece is also light, but not cheap, costing between 435 and 460 euros depending on the gradation, while the new chain costs 100 euros. The wearing parts are therefore around 20 per cent more expensive than the top Dura-Ace groupset from main competitor Shimano.

New translation options

New options introduced with the new Red offer plenty of choice and benefit hobby riders in particular: A sporty 10-30 and a 10-36 cassette suitable for mountain and off-road use have been added to the programme. With now five different cassettes and the three familiar chainring combinations (50/37, 48/35 and 46/33), all requirements are covered - right up to a significant reduction of 33-36 in first gear. For ambitious racers and time trial bikes, larger chainring combinations of 53/39, 54/41 and 56/43 are offered, which were previously only available for professionals and not on the open market.

With the rear derailleur, which can cope with a maximum of 36 teeth, and the initially offered cranks with 48 or 50 teeth, the use as a single drivetrain is initially limited to the road, for example for time trial bikes or maximum undulating terrain. A genuine gravel version with a chainring is not yet available, but there are rumours that SRAM will soon introduce off-road ratios with smaller single cranks, larger cassettes and a suitable rear derailleur.

+ Smoother running, many transmission options

- Expensive spare parts

SRAM Red AXS: The drivetrain

The new rear derailleur, the proverbial shifting centre of the system, is slightly lighter and somewhat smoother. Larger derailleur pulleys are intended to improve the efficiency of the drivetrain, while the familiar oil damper prevents the chain from slapping in the event of vibrations. Although the sprocket set is unchanged, the shifting behaviour at the rear is somewhat smoother and less noisy than what we are used to from SRAM. On the first test bike, we could hardly make out any difference to Shimano drivetrains, which are considered to be particularly quiet. Our guess is that the new chain contributes to this: The generous recesses in the plates should make the chain a little more flexible. Later tests will have to show how wear-resistant the chain is - SRAM has recently caught up considerably, at least with the high-quality chains, and is on a par with the competition. The new derailleur is e.g. available from Bike-Components.

Better switching behaviour, sensitive adjustment

We noticed a noticeable difference when riding with the front derailleur and the shifting behaviour on the chainrings. The derailleur now has an automatic trimming function, so it adjusts itself automatically when the chain moves over the rear sprockets. As a result, the cage has become significantly narrower and guides the chain better when changing the chainrings. In our tests, the chain changes noticeably faster, more precisely and more quietly than with the previous changer. However, the correct installation and adjustment of the derailleur remains extremely sensitive and not very intuitive. However, an included template and detailed instructions make adjustment possible even without the many years of experience of a bike mechanic.

The batteries of the shifting components are unchanged and can still be interchanged if one of the components runs out of power. Their range is on a par with the competition: depending on the switching intensity, 2000 kilometres and more are possible. They are charged exclusively in a charging port.

+ Improved front shifting function, only one rear derailleur for all gear ratios

- Sensitive adjustment of the derailleur

SRAM Red AXS: The ergonomics

The levers of the new SRAM groupset have undergone the biggest visual and therefore haptic change, which goes hand in hand with the greatly improved function of the brakes. Because the hydraulic cylinder of the brake is no longer positioned vertically in the grip hump, but lies horizontally in the grip body, these can be narrower and the grip hump is less pronounced. On the other hand, the grip body is a few millimetres longer. Small hands can grip the new grips better when sprinting and pedalling, while large hands now have more space between the brake lever and handlebars - also because the shift buttons behind the lever are now somewhat slimmer. The new lever shape extends the seat length of the bike by around seven millimetres, which should be taken into account by riders who pay close attention to their riding position.

The grip width and pressure point of the brake can be adjusted independently of each other and customised to your own needs. The pivot point of the brake lever has been moved significantly upwards so that more leverage is available when braking. The brake levers are slightly flatter and more ergonomic at the front than the old version; the shift buttons leave more space to the handlebars, but are slightly higher and are therefore easier to reach from the lower and upper handlebars than before.

New button on the handle body

Another new feature is an additional, small control button on the inside of the hump, which is easy to reach with the thumb when holding the brake lever. It can either be assigned the shifting function, but in our experience the feedback is not precise enough for this and the position is superfluous. The option of using it to control the bike computer is better - this allows you to change the views on the display without taking your hands off the handlebars.

+ Additional control button, improved ergonomics

SRAM Red AXS: The brakes

The revised brakes are undoubtedly the highlight of the new Red. Explaining the almost miraculous increase in braking power in physical terms is complicated: In short, the pistons in the brake calliper have moved slightly away from the hub and compress the pads outside the braking surface. The pads themselves sit a little closer to the centre of the wheel again and fit precisely on the braking surface of the standard diameter disc. Together with the changed pivot point of the brake lever, this has the effect of braking on a larger disc than the 160 millimetre disc fitted. In practice, the innovation is completely convincing: There is almost an abundance of braking power available, even on steep descents you can easily perform an emergency stop from high speeds without needing more than two fingers. The braking power clearly surpasses the previous front runners from Shimano and Campagnolo. Even at high power, the brakes are easy to modulate, and at moderate speeds everything can be done with the index finger. The Paceline disc remains noiseless, at least in dry conditions; however, squeaking noises in wet conditions must also be expected with the new Red brake.

More power, less weight

Grinding noises, on the other hand, are apparently a thing of the past. A greater distance between the pads gives the disc more clearance, and even after hard braking we were unable to detect any grinding during our test period. The new disc will only be available with a centre lock mount, which has become the standard for road bike wheels. 160 and 140 millimetre discs are available; in view of the braking performance, the smaller discs could once again be an option for certain applications such as light riders and flat terrain. The last Red generation no longer had to contend with heat problems; generous cut-outs in the brake calliper should ensure that the brake is cooled even better and is also lighter: according to the manufacturer, 83 grams have been shaved off the entire brake system.

+ Braking power in abundance

- Occasional squeaking in wet conditions

SRAM Red AXS: The software and additional functions

With the introduction of the AXS series, SRAM set new standards in terms of software connectivity. The components can be easily connected to a smartphone and the app can be used to call up the battery status, fine-tune the rear derailleur or change the button assignment. There are even more options via an associated web application, especially when it comes to analysing the rides. Gear statistics, performance data and even tyre pressure can be analysed on the PC afterwards, provided the corresponding sensors are installed. If you want, you can have messages sent to your smartphone when a battery is running low or a chain change is due. The purchase of navigation specialist Hammerhead was the preparation for SRAM to raise the bar even higher. New is the improved integration of the Hammerhead Karoo computer, which has also been updated and is now regarded by SRAM as an integral part of the groupset. If you buy the groupset separately, you get the computer with it, and it is also already installed on many complete bikes. With the Hammerhead applications, not only can routes be planned on the computer and then navigated; it can also display the battery status, the gear engaged and the data from the power meter without the components having to be laboriously coupled and set up first. The bike computer recognises all components automatically and integrates them seamlessly into the system. In terms of its range of functions and technology, the Karoo has nothing to hide from the established competition. The range of functions is huge, the operation simple. A better processor, a sharp and glare-free touch display and a larger battery put the device on a par with the top models from other providers such as Garmin or Wahoo. In addition, the user-friendly software is not overwhelming and makes many things easier. We particularly liked the intuitive route planning on the PC with good, free maps and the fully automatic synchronisation with the device.

Sub-optimal additional switches

The optional additional buttons called "blips", which can be mounted anywhere on the handlebars - usually on the upper handlebars or as a sprint switch in the handlebar arch - have been criticised. With their integrated battery, they are relatively bulky and the feedback from the buttons could be better. The battery of the buttons cannot be replaced. Even if SRAM promises a service life of at least two years with normal use, the price of 100 euros for new shifters is steep due to empty batteries.

+ Wide range of functions, simple operation, many evaluation options

- No battery change possible for additional switches

SRAM Red AXS: Our conclusion

Several testers are more enthusiastic about important new features than is rarely the case with new products. The brakes in particular are impressive, putting everything that has gone before on a road bike in the shade. It should go without saying that the drivetrain and gears also function precisely, smoothly and quietly in a top groupset - it has been a rocky road for SRAM since 2007 to reach this level of mechanics and come up to par with Campagnolo and Shimano, both of which can look back on several decades more experience with derailleur systems. Meanwhile, the Americans are pulling ahead of the competition in another area: the fact that a modern bike computer is an integral part of a groupset is a novelty, but a logical addition to the electronic platform. With the new Red AXS, SRAM impressively demonstrates how well and simply shifting, power measurement, navigation and analysis can work together when everything comes from a single source. Annoying pairing of different devices or problems with routes in unreadable formats are a thing of the past with the setup presented here. There is one fly in the ointment: The luxury is still expensive. SRAM charges at least €4,500 for the Red groupset, and over €5,000 with the Powermeter. The price is somewhat relativised by the "on-board computer", which alone costs 500 euros, but this still limits the number of buyers. However, if the approach is extended to more affordable groupsets, which is to be expected, then this is likely to be just the start of another small revolution that will make road cycling a little easier and more comfortable again.