I've ridden 250km with SRAM's new 'toughest ever' mechanical derailleur and this is what I've found

SRAM’s new derailleur-hanger-free Eagle 70 and 90 Transmission gearing is operated by a cable, offering a number of the same benefits as its electronic brethren at a fraction of the cost.

Shifting under power feels very well managed, and once cable tension has settled down, quick shifts between cogs feel accurate and punchy.

However, the feel through the shifter is something of a mixed experience.

Just like its wireless counterpart, there are no B-tension or limit screws to worry about, which should make setup swift, plus it’s claimed to be just as tough as the electronic derailleur – and to be the toughest mechanical derailleur ever made.

Yes, that’s right, you can, apparently, stand on the derailleur without killing it, although we wouldn't recommend doing so.

Most important of all, it’s far cheaper than the top-tier XX, X0 and GX Eagle AXS Transmission gearing, with the Eagle 70 derailleur costing £120 and the complete Eagle 90 group £655.

Should you total part of the derailleur, spares are available to rebuild it, which is a nice touch and bolsters the value.

SRAM Eagle 90 ride impressions – Rob Weaver

I’ve had the Eagle 90 Transmission on a Specialized Epic 8 Expert for a little over a month and clocked up around 250km while testing it.

While I’m a long way from being able to deliver a definitive verdict, I can at least give you some insight as to how Eagle 90 has performed so far.

When it comes to performance, the first thing worth commenting on is the shifter feel and performance.

Push the larger of the two paddles to access an easier gear and you can feel the cable progressively tensioning as you increase thumb pressure.

The paddle travels a little way until you hit an indexed click and the gear shifts from one sprocket to the next.

The feel of this push is somewhat softer than that of a Shimano equivalent, which seems to travel less and offers a more solid, positive click when the shift is initiated.

On the flipside, shifting into a harder gear feels quicker and easier, thanks to the limited travel that the smaller of the two paddles has, with a positive click that feels as though it's reached more rapidly than that of a Shimano shifter.

In terms of accuracy at the cassette, my first couple of rides in muddy conditions left me twiddling the barrel adjuster at the shifter to tweak the indexing.

While 11 of the 12 gears seemed to shift perfectly, I had some issues when selecting the third sprocket, where the derailleur seemed to jump around when I was really putting the power down.

I put this down to cable stretch, added some tension at the barrel adjuster and have since had no other issues.

While I’m on the subject of accuracy, it’s worth noting that despite the lack of limit screws, I’ve had zero issues with the derailleur over-shifting at either end of the cassette.

Where I’ve been really impressed with the Eagle AXS Transmission is just how reckless you can be when shifting under power.

Thankfully, this carries over to the mechanical version. I’ve shifted countless times while sprinting – both up and down the cassette – and found the gear I’m after each and every time without any skipping or crunching. It’s really impressive in that regard.

Only time will tell how it all holds up over time. I’ll keep putting the miles in and report back when I’ve put it thoroughly through the wringer.

Ditching the derailleur hanger… again

As if we’re stuck on Groundhog Day, SRAM has once again re-written the rulebook and ditched the derailleur hanger on its latest product.

Moving to the brand’s Full Mount design – pioneered on the electronic AXS derailleurs – means SRAM has also done away with high and low limit screws, the B-tension screw and the fiddly chain-gap tool used on Eagle drivetrains.

As before, the move to a Full Mount design means the derailleur bolts through the frame’s Hangerless Interface, which is claimed to be much sturdier than a traditional design.

This interface – which is simply a hole at the dropout – is in the same place on all bikes, dictated by SRAM’s open-source UDH patent.

And because it’s in the same place on all bikes, and all Eagle Transmission – AXS or mechanical – cassettes are the same, SRAM has ported the installation and setup process to Eagle 90 and 70 Transmission.

Still simple to set up

Adding cables usually increases complexity – or at least requires the mechanical nous needed to fine-tune tension – but according to SRAM, that’s not the case with Eagle 90 and 70.

As with the AXS equivalent, SRAM’s setup method for the cable-operated version relies on frame data collated on SRAM’s chain-length guide web page to determine several factors.

These include chain length, setup key position, which gear the derailleur needs to be fixed in and, in turn, which cog on the cassette is required to determine the derailleur-to-cassette chain gap.

The final step involves setting cable tension, which is very similar to all other cable-operated systems, from all manufacturers, that preceded Eagle 90 and 70 Transmission.

Crisp-click shifting

Because Eagle 90 and 70 Transmission use the same cassettes as Eagle Transmission AXS, in theory they’ll share the electronic system’s crisp, high-quality on-power shifting it has become famed for.

Here, 44 shift lanes and the X-Sync tooth profile combine to create what the brand claims is the “best mechanical shift performance under load there is”.

While the cassette and derailleur deal with the dirty end of shifting, the shifter – as your only point of contact – is where it really counts.

The new shifter – which is visually very different from Eagle drivetrain shifters – is slim and sleek, hiding beneath the handlebar and under the brake lever.

Its cables, like SRAM’s Stealth brake lines, are routed parallel to the bar for a clean look.

However, there are only two variants of Eagle 90 and 70 shifter; one with a single click that’s mandatory for ebikes and another with two clicks for non-assisted bikes.

While Eagle drivetrain single-click ebike shifters have existed all along, the ‘normal’ version previously enabled up to five clicks or gear changes with one actuation.

Whether you see that as a positive, neutral or negative will depend on your shifting habits.

Smashed up the derailleur? Rebuild it entirely

Taking a large number of steps further than the impressively rebuildable AXS Transmission derailleurs, all of Eagle 90’s derailleur parts can be replaced.

The brand's claim that this is “the most rebuildable derailleur ever” might, in fact, be true.

The list of replacement part kits is impressive:

• B-knuckle replacement kit: £62 / $64 / €70
• P-knuckle replacement kit: £33 / $34 / €37
• Skid plate, outer and inner-link replacement kit: £33 / $34 / €37
• Cage and damper (clutch) assembly kit (also sold without the damper): £83 / $85 / €93
• Inner cage replacement kit: £27 / $28 / €31
• Pully replacement kit: £17 / $17 / €19
• Bushing replacement kit: £18 / $18 / €20

Cranking up the options

Both cranksets have forged aluminium arms and spin on a SRAM DUB bottom bracket.

While the Eagle 90 cranks are available in 155, 160, 165, 170 and 175mm lengths (plus 150mm on the ebike version), the Eagle 70 arms come only in 165, 170 and 175mm options.

The two new Transmissions use different direct-mount chainring standards – eight-bolt for Eagle 90 and three-bolt for Eagle 70.

While Eagle 90’s silver-coloured rings are available in stamped steel or aluminium, Eagle 70’s black ones are steel-only.

Only three sizes are available – 30, 32 and 34t – but both Transmissions are also compatible with AXS chainrings of the same mounting standard.

Eagle 90 or 70 Transmission?

SRAM says Eagle 90 Transmission components and upgrade kits are fully available aftermarket, while Eagle 70 Transmission is original equipment on full bikes.

However, individual replacement Eagle 70 Transmission components will be on sale, to ensure riders can replace broken or used parts like-for-like.

A dropper lever not for Reverbs

Also in SRAM’s new line-up is a cable-operated dropper post lever that’s not compatible with any of SRAM’s own electronic or hydraulic dropper posts.

Mimicking the design of the new Eagle 90 and 70 Transmission shifter, it runs the cable close to the bar.

It’s compatible with most cable-operated droppers – according to SRAM – and should round out your newest cable SRAM cockpit.

SRAM Eagle 90 and 70 Transmission prices

A full Eagle 90 Transmission drivetrain (derailleur, shifter, cranks, chainring, chain, cassette) costs £655 / $670 / €730.

Compared to SRAM’s most affordable AXS Transmission – GX – an equivalent groupset costs £1,180 / $1,099 / €1,300.

Removing the electronics slashes the price almost in half.

Other highlights include a £185 / $190 / €205 Eagle 90 Transmission rear derailleur price and a £50 / $50 / €55 shifter cost.