Room For One Less: An e*thirteen Helix Race 9-52 12-Speed Cassette Review


Room For One Less: An e*thirteen Helix Race 9-52 12-Speed Cassette Review

When modern wide-range cassettes first hit the market, it was the giant 50-tooth (and now 52-tooth) cogs that grabbed all the headlines. But 1X drivetrains arguably wouldn’t have taken over if it weren’t for the 10-tooth cog down at the other end of the stack. That’s how brands can claim their 500, 510 and 520-percent gear ranges. Still, it wasn’t enough for e*thirteen. They introduced a lineup of cassettes with 9-tooth cogs, allowing for lighter, more compact setups with as much as 556-percent range.

And then, earlier this year, they introduced a 12-speed cassette that spanned from 9 teeth to 52 teeth, netting a 578-percent range. Travis Engel had to get his hands on one, but not for his mountain bike. He wanted it for his multi-headed beast of a gravel, touring and bikepacking bike. Range is king if you can’t (or won’t) run a front derailleur. But is one less tooth worth bowing down to?

This time last year, I was somewhere along a mixed-terrain route from Hood River, Oregon to San Luis Obispo, California. It was—and still is—the longest ride I’ve done, so I spent a lot of my prep time thinking about my gear. Like, my literal gear. I’d considered sizing up to 36t chainring for the 1,300-mile, mostly pavement, mostly coastal route, but it was bookended by 360 miles of Oregon Outback gravel to the north, and by 120 miles of Los Padres jank to the south.

Plus, fully loaded, my bike was around 70 pounds. So, I gave into my mountain-bike instincts and chose a 32-tooth chainring to pair with my 10-52 SRAM Eagle cassette. I accepted I’d just have to let gravity do the work sometimes, especially during the 200 miles that descended along the Klamath River. But it actually wasn’t all that bad. I would regularly spin out on long downhills, but I never kept the inevitable uphills waiting very long. It wasn’t until I hit the ocean that I really started seeking higher highs.

With the gentlest tailwind or downslope, I’d max out my 10-tooth cog. And unlike the Klamath River Valley, PCH got boring at times. I was ready to push harder to get it over with, but my cadence would get a little frenzied. After returning home, I tried a 34-tooth ring just for yuks, but my very first fully loaded, 8-percent dirt climb tipped me from patient to pained, so I went back to 32.

Then, when I tested the microSHIFT Sword group with its 11-48-tooth cassette, I remembered that adding or removing teeth from a small cog makes an exponentially bigger difference than on a larger cog. As an experiment, consider a 29-inch bike with a 32-tooth chainring: Going from a 31-tooth to a 30-tooth cog will push that bike about 3 inches further per complete pedal rotation.

Going from 21 to 20 will add about 7 inches. From 11 teeth to 10 teeth? 26 more inches per pedal rotation. It got me thinking of e*thirteen’s audacious move of running a 9-tooth cog on their wide-range cassettes. That cog will move a bike another 32 goddamn inches farther per rotation than a 10-tooth cog. Much of e*thirteen’s selling points were around the promise of smaller, lighter cassettes that offered the same or better range than the original SRAM Eagle 10-50.

That’s why, at the time, many of their cassettes topped out at 45 or 46 teeth. But earlier this year, e*thirteen released a 9-52 cassette (9-11-13-15-17-20-23-27-31-36-43-52) boasting 578% range. Despite being aimed at mountain bikers, I’d argue this is an even better fit for 1x adventure bikes.

But I was hesitant. There was always something about the e*thirteen cassettes that bugged me. It wasn’t the potential pitfalls of such a small cog (which I’ll get to later). It’s how these things are mounted. All of e*thirteen’s cassettes are designed to work on a SRAM XD freehub body, which makes sense.

There’s a huge install base, thanks in part to XD being open-source. But e*thirteen couldn’t just copy SRAM’s cassette design, perhaps because it is not open source, or perhaps because of the space limitations inside the 9-tooth sprocket, (which I’ll also get to later). So, the first e*thirteen casssettes used a three-piece design, where the larger two cogs would drop onto the XD freehub’s spline, and a separate cap would screw onto its threads to hold them down. Then, the smaller cog assembly would slide over that cap and, with a normal cassette lockring tool, would twist clockwise to lock into the larger cogs via six sets of interlocking tabs. But a few years ago, they abandoned that design.

Now, in the current generation of e*thirteen cassettes, those two largest cogs actually clamp onto the smooth part of the XD freehub body. That sketched me out at first. I didn’t like the idea of clamping things not designed to be clamped, especially when they’ve got bearings in them.

But when I got my test cassette, everything fit together quite perfectly. Or rather, quite tightly. That does mean there are some compatibility issues outlined on the e*thirteen website, but it’s a short list. FWIW, I also tried mounting mine on hubs from DT Swiss, i9, Spinergy, and Chris King, and had no issues.

The outer cogs still lock into the inner cogs with the same clockwise twist, but the system now has a two-piece design, with the clamp taking place of the threaded cap. Seems simple enough. The only snag I hit was that, thanks to those tight tolerances, I had to give the outer cog assembly a few not-so-gentle taps to sink it far enough onto the freehub for the interlocking tabs to catch each other.

And even then, it took a lot of force with the cassette tool to get it into its locked position. That said, after my first install and a few rides, the process was a little easier. I just highly recommend following e*thirteen’s instructions to thoroughly grease anything that touches anything else.

e*thirteen claims the Helix cassette will work with SRAM, Shimano and TRP’s 12-speed derailleurs and chains. I can confirm it works fine on an SLX derailleur, and I did my testing with SRAM GX AXS. But I didn’t have a TRP drivetrain. Nor did I have any first-generation cable-actuated Eagle derailleurs, which were designed to max out at 50 teeth. e*thirteen says they’ll work, but you should expect what’s known in the drivetrain world as “B–compatibility.”

Compatibility was low on my list of concerns, and not just because my AXS derailleur is meant for 52-tooth cogs. With a few important exceptions, I think drivetrain-industry mandates to keep like-with-like are overblown. I noticed no hesitation or grinding when shifting or pedaling. And there were no b-tension or chain-length issues in the smallest cog, but again, I didn’t expect any.

It shifted exactly as well as my GX cassette did; No better, no worse. I’m a bit spoiled by the SRAM Transmission bike hanging in my living room, and the Shimano Hyperglide + bike hanging next to it. Both of those shift really well under load. And though I may have forgotten how to ride a bike with a front derailleur, I haven’t (yet) forgotten how to be kind to my cassette and chain.

The only place where shifting the Helix differed from my bike’s native cassette was between the two largest cogs. Non-Transmission SRAM 10-52 cassettes have a 10-tooth gap at their lowest end, while the Helix Race has a 9-tooth gap. It doesn’t sound like much, but the Helix gap was noticeably less jarring. Both setups will perform the shift fine, but in those tricky moments when I’m shifting between my two lowest gears, I appreciated that the change in cadence was a little easier to swallow.

I’m usually not picky about cadence. Again, those easy gears are for high-stress situations, but when I’m just spinning my wheels and covering ground, I can adapt. And at least Helix spread is pretty even throughout the range. The gaps between those gears goes like this: 2-2-2-2-3-3-4-4-5-7-9. It’s steady. There’s no shift that feels especially different from any other, keeping things predictable. Really, the only gap that may stand out a little is the one into that 9-tooth cog, which I reckon is why we’re all here.

If you look closely, the actual material making up the small cog is not any thinner than what’s used on a 10-tooth SRAM or Shimano cog. That’s because the splines for the “lockring” tool interface are built into the cog itself. So, it’s actually a robust little piece of steel. And of course, the bearings are part of the freehub body, so none of the moving parts are any smaller.

Point is, no structural compromises were made to squeeze that cog’s diameter down to what it is. But there were other types of compromises. For one, wrapping the chain around such a tight radius is not ideal because it adds friction to the system. That’s the motivation behind those kooky oversized-pulley derailleur cages from Ceramic Speed and Absolute Black. While pedaling, we’re folding our chain links back and forth thousands of times per minute. The less we have to fold them, the less drag in the system.

And derailleur pulleys aren’t even in the loaded portion of the chain. A similar frontier on the friction battlefield is being waged on high-pivot mountain bikes, where an idler pulley is introduced to calm down the suspension anti-squat. The bigger the idler pulley, the less you feel the drag. But what’s different there, is that you’re in that idler pulley all the time, including long, high-torque climbs. The Helix cassette’s 9–tooth cog, on the other hand, is more of a traveling gear.

In my use-case, I was rarely mashing or sprinting when I was in that hardest gear. And even when I was, I can honestly say I didn’t feel the steady rumble of chain drag that I’ve felt while cranking up a steep climb on a high-pivot mountain bike. Logic would tell me it’s there, but it must be too subtle for me to notice. Or maybe I just can’t sense it through the chaos of going at such high speeds. Most of the time I was in that 9-tooth cog, I was maintaining the momentum of a downhill. I never really put sustained force into it for a long time. Because I never really could.

Going at a comfortable, steady cadence, I’d make it to a solid 25 MPH with my 32-9 combo. But that’s not something I can sustain for long without help from the wind or the earth. On a 10-tooth cog, that number is more like 21 MPH, which is reasonable, but still above average for me. When I was just covering ground, I was usually in the Helix cassette’s 11-tooth or 13-tooth cogs, cruising between 17 and 20 MPH. So, I looked at that 9-tooth cog sort of like the opposite of a bailout gear.

I only used it on the rare occasions when the situation demanded it. But like a bailout gear, I was glad to have it when I needed it. It makes me think e*thirteen should really get this in front of the touring and bikepacking community. Hell, even gravel and road. With a special shim, the cassette will work on the unique XDR freehub body found on some skinny-tire bikes. I suppose that, for mountain bikers, a 9-52 cassette opens the door to use 30- or even 28-tooth rings with more practicality, but I think the 1X drop-bar crowd is at least as big an audience.

So, I’m going to be using this setup on my touring bike indefinitely, and hopefully I can answer the other question we’re all here to answer: Will it last? Again, I think the structure of the cassette itself is sound, but I do worry about how quickly the teeth will wear out, and what impact it may have on the chain. I’d bet there are only three teeth carrying the load when I’m down in that 9-tooth cog. That’s a lot of force on not a lot of metal. And I wonder if it will wear out the rollers on my chain quicker, because a similar concentration of torque is happening there. My plan is to check my chain wear more often.

Probably a good practice, because this is a $380 cassette. That’s not unprecedented, with SRAM XO Eagle cassettes going for $415, but those are also lighter, weighing a (claimed) 350 grams compared to the Helix Race’s (confirmed) 407. As for the lifespan, e*thirteen seems more focused on the climbing gears, because the two-piece system allows them to sell the aluminum cogs separately. That’s how the wear tends to go on my mountain bikes, so we’ll see. I’ll come back in a year (assuming I’ve gotten enough miles to learn anything) to report my findings. In the meantime, I’m very happy to have this cassette, and very happy to still not have a front derailleur.


  • Near the range of a wide-range 2x in a 1x package
  • Compatible with common hubs and common derailleurs
  • Smart, evenly spaced gearing
  • Replaceable aluminum climbing cogs
  • Shifts and rolls as smooth as a stock SRAM cassette


  • Unknown consequences of prolonged use of 9-tooth cog
  • Lacks 2X’s small gaps and ability to dump gears with a front derailleur
  • Installation can be a little tricky
  • Not cheap

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