When you need a bailout gear, you really need a bailout gear. Or so was the thinking behind the new SRAM 10-52 Eagle cassettes. The new, wider 520% range cassette options will be available for GX, XO1 and XX1 groups, mechanical and AXS.

For the wireless shifting AXS groups, you can just throw the cassette on there and ride. For mechanical Eagle groups, you’ll need a new derailleur for optimum compatibility. Here’s everything you need to know about the new cassettes, derailleurs and how to upgrade…

Is it really just a bigger cog?

sram eagle 50-tooth and 52-tooth cassette size comparison

The new SRAM Eagle XX1 10-52 on the left, next to the original 10-50 cassette on the right. Scroll down the post to see actual weights comparisons.

Yep. That’s the short of it. The rest of the cassette remains the same, going from 10 to 42. The original 50-tooth cog simply grows to 52 teeth, if you want it.

sram eagle 50-tooth and 52-tooth cassette size comparison

They’ll still offer a 10-50 Eagle cassette, plus this new 10-52 Eagle cassette.

The wireless Eagle AXS rear derailleurs are already compatible with it. This larger cassette was in development (or at least conceived) when they developed the electronic mountain bike group, so they built compatibility into it.

For mechanical rear derailleurs, since those launched way back in 2016 with XX1 and XO1, they were designed only with the 50-tooth large cog in mind. So, technically, you’ll need a new Eagle mechanical rear derailleur to go with the wider 10-52 cassette…if you want the best possible performance.

Will the original Eagle derailleur work with the new 10-52 cassette?

Technically…the answer is mostly, maybe. Mostly, in that the bottom part of the cassette hasn’t changed at all. We’ll be testing how the original derailleurs shift into the 52 and reporting back shortly.

The maybe is that SRAM’s official statement is that the new derailleurs have new, improved cages that are optimized for the larger 52-tooth cogs. They use some super soft language that basically translates to this: You could probably use your original Eagle rear derailleur with the new 10-52, but it may have a rough shift going from the 42 to the 52.

Our take: Why not try it? Then upgrade your rear derailleur if necessary. Or just put a smaller chainring on the front if you really need easier gearing, then just wait until you upgrade your complete group or bike. Because…

520% Eagle derailleurs will start coming on everything

new sram eagle mountain bike derailleurs will work with 10-52 cassettes

The new Eagle mechanical derailleurs will have “520%” etched on the back of the cage so you know it’s compatible with the new wider range cassettes.

Like that new Ibis Mojo 4, which almost jumped the gun on revealing this when it launched on Tuesday.

The 520% rear derailleur is backward compatible with the 500% range 10-50 cassette, too. So there’s no reason to buy or spec the 500% derailleur on anything. We suspect any new bike shipping with a SRAM GX, XO1 or XX Eagle group will come with the newer derailleurs.

But you can always check the back of the pulley cage to see…it’ll say 500% (for 50-tooth) or 520% (for 52-tooth) to indicate its maximum cog size compatibility.

Like before, all levels of Eagle, with certain exceptions for SX and NX groups, are interchangeable. So, you could go for the lighter XO1/XX1 cassettes while running the more affordable GX shifting parts.

Speaking of GX Eagle, they’ve completely redesigned that group. Check out all the details on that, plus a new Copper colorway for Eagle, in this post.

Can I put the new Pulley Cage on my Eagle derailleur?

what is the difference between the old sram eagle derailleurs and the new ones for the 52-tooth cassettes

The original GX Eagle derailleur is on the left. The new 520% derailleur on the right.

That’d be nice, wouldn’t it? SRAM thought of it, tested it, and almost did offer those as an aftermarket upgrade kit. But longer term testing showed that long term durability might be an issue since there are unknowns.

comparison of old and new sram eagle mountain bike rear derailleurs for 2021 upgrade

There’s only a couple millimeters difference in upper pulley location, but the entire pulley cage is stronger and more reinforced. Note the cage’s bottom has extended coverage.

You know, unknowns like not knowing who would be installing the new cage and what their skill level was. So, for the same reason they aren’t officially recommending that you use your old derailleur with the new cassette, they’re not offering an upgrade kit: Because they want their drivetrains to perform flawlessly, and they can’t guarantee that if parts start getting modified or mixed and matched outside of official recommendations.

SRAM Eagle 520% ride review & Slow Motion shifting video

We’ve been riding the new XX1 10-52 with AXS, and the new GX group’s mechanical shifting, for a few solid rides prior to launch. Our verdict? It’s as good as ever.

What surprised us was how smoothly both groups shift across that massive 10-tooth gap at the top. Whether pedaling along lightly (which never happens in the real world when you actually need to shift into a massive cog like this) or cranking it in there under load on a climb, it was quick and precise.

Watch the video to see it shifting in and out of the 52-tooth cog in slow motion, along with a few shifts while climbing. You’ll also get a good look at that new GX group.

sram gx eagle 10-52 cassette ride review

Honestly, there’s not a lot to say other than:

  • It’s a bigger cog that makes climbing even easier
  • Both wireless AXS and mechanical derailleurs handled the shift smoothly
  • It doesn’t add much weight, so there’s virtually no downside to opting for the 10-52
  • It’s a bit of a bummer that mechanical groups aren’t technically compatible, but we’ll see about that soon…

sram xx1 eagle 10-52 cassette ride review

The takeaway? If you have an AXS-equipped bike and you want an easier gear and don’t mind dropping the coin for a new cassette, go for it. Otherwise, as an upgrade option, it makes more sense to get it on your next bike, or use it as an excuse to go ahead and upgrade more of your drivetrain.

Eagle 10-50 versus 10-52 actual weight comparison

actual weights for sram eagle 10-50 and 10-52 cassettes

The original XX1 10-50 cassette weighs in at 363g, and the new XX1 10-52 cassette weighs 373g. So, just 10g more for the larger cog. Check out the actual weights for every Eagle AXS and Eagle XX1/XO1 group component, too.

sram gx eagle 10-52 cassette actual weight

The GX group’s original Full Pin cassette, which uses a pinned construction rather than the one-piece machined base structure of the higher end cassettes, weighed in at 448g. The new 10-52 cassette comes in at 452g, just 4g heavier.



  1. El Pataron on

    Somehow, all this pisses me off. I can’t quite articulate why just now, but somehow, this makes me really angry….

  2. John on

    When can we expect the big price discounts on Sram 11-speed stuff? XG 1175 Cassette still ~$200, 1180 is $250+. Pretty spendy for components that have been out for six (seven?) years.

  3. nedersotan on

    Not very happy about this.

    First: they slapped the 52t on the same 11 cogs below it, so the jump is bigger, right in the range where cadence and shifting matters most.

    Second: who needs 520% range on their mtb? That was why it was so great when we went from 3×9 > 2×10 > 1×11. We got rid of the excess top and bottom gears.
    Most of the time, I don’t even use the full 420% range of my 10-42 on my local trails. For big mountains with high speed descents, 460% pretty much covers it.
    Back in the early (11 speed) days of EWS, even Jerome Clementz pointed out he didn’t need more than a 32 or 34t chainring. It’s not road racing, downhill speed is not normally limited by pedaling.

    The bad thing about this, is that these will come stock on many new bikes. If you don’t need it, you are stuck with a large amount of unsprung weight, dangling low to the ground in the back of your bike. If you want to change it, it’s a $200+ swap…

    • mateo on

      You’re most concerned about cadence on your two lowest gears? Nonsense. If you’re spending the majority of your time in the 42 and 50/52 cogs, you need a (much) smaller chainring. As for the rest of your complaints, the market disagrees. Non-pros love lower gears because they don’t get paid to be in shape.

      As for the jumps, I find it funny that people complain about big jumps, but also praise Shimano’s ability to shift two gears at a time. If you have to shift two gears, then I guess the gaps are too small, no?

      The 52 is totally a bailout gear, but what is wrong with that?

  4. nedersotan on

    “The takeaway? If you have an AXS-equipped bike and you want an easier gear and don’t mind dropping the coin for a new cassette, go for it. Otherwise, as an upgrade option, it makes more sense to get it on your next bike, or use it as an excuse to go ahead and upgrade more of your drivetrain”

    Why? If you want an easier gear, the better solution is a smaller chainring:
    1- way cheaper
    2- drops some weight, ins tend of increasing it
    3- increases ground clearance instead of decreasing it.

    No new bike, drivetrain or cassete needed.

  5. Chris on

    +1 My guess is they won’t offer 12 speed road mechanical until Shimano starts to sell it. Until then they can get max profit margins for electronic 12 speed road.

  6. OriginalMV on

    I guess you can expect prices to fall when raw material costs plunge or an epic reduction in machining costs occurs. Or market demand for those parts falls so hard that wholesalers are willing to sell at a loss just to clear out shelf space. I mean, premium bike parts aren’t fashion apparel for which sellers need to blow out inventory when people stop wanting to buy it and wear it. Or at least not consumable parts like cassettes and chains.

    A better question would be “when will the 500% mechanical derailleurs get price slashed?” Consumers and OEM aren’t going to want to buy the less capable units, and wholesalers won’t want to stock them. If there is a lot of unsold units in the supply chain, sellers will blow them out.

  7. Alan on

    why I like sunrace 11 speed cassette vs shimano – no uneven jump to smallest sprocket! Luckily this cassette won’t be troubling me ever

    • Ol' Shel' on

      You must be a youngster. I joined the fashionable crowd, running 26/36/48 back in the day. And this was with 12-30 cassettes. My knees still hurt.

  8. triple fan on

    Correct me if I am wrong, but sometimes ago, 52t was the size of a large chainring at the front. I think it’s about time to go back to double and even triple chainrings for the mere mortals ! I am 63, with a “few” additional kg and live in the mountains and there is no way I can do with only one chainring on the trails.


COMMENT HERE: (For best results, log in through Wordpress or your social media account. Anonymous/fake email comments may be unapproved or deleted. ALL first-time commenter's posts are held for moderation. Check our Comment Policy for full details.)

This site uses Akismet to reduce spam. Learn how your comment data is processed.