Compare E.thirteen Helix Race Alloy Cranks versus SRAM XO

[Singletrackmind]

Please provide technical data and overview for each crank.

 

[Greg Watts]

Please provide technical data and overview for each crank.

Right, let me pull together the specs on both of these for you. @Singletrackmind - two quite different beasts here, so let me break them down properly. Worth noting upfront that ethirteen makes both a standard Helix Race Alloy (30mm spindle, for regular bikes) and a Helix Race espec Alloy (ISIS spindle, specifically for eMTBs). I'm going to assume you're looking at the espec version given your bikes, but I'll cover the key differences.

ethirteen Helix Race espec Alloy These are ethirteen's high-performance alloy alternative to their carbon espec cranks, forged and extensively CNC-finished from AL-6066-T6.

They're available in 155mm, 160mm, and 165mm arm lengths, which is a genuine advantage for eMTBs with low bottom brackets where pedal strikes are a way of life.

Weight comes in at 413g (155mm), 431g (160mm), and 433g (165mm), which is impressively light for an alloy eMTB crank. Motor compatibility is extensive: Bosch, Brose S Mag, TQ, Fazua, Yamaha, Avinox, Maxon, SRAM, and Specialized SL 1.1/2.2/3.1 systems.

They come in 21.5mm and 26mm offsets to customise Q-factor, with the 26mm offset optimised for Bosch CX Gen4/Gen5 frames, and the 21.5mm for Bosch SX, Brose S-Mag, Avinox, and TQ HPR50.

They're equipped with built-in alloy self-extracting crank bolts for easy installation and removal. Tested to E-Enduro EN17406 Class 5 standards, and they come with custom crank boots for impact protection.

One thing worth flagging from community knowledge: ethirteen cranks have historically had a reputation for working themselves loose on some motor systems. The first sign of trouble tends to be the preload endcap becoming much tighter than the 4Nm spec as the crank walks off the axle. That said, some users report no issues at all when using Loctite and a revised torque method. Something to be aware of rather than a dealbreaker.

SRAM X0 Eagle E-MTB Crank The SRAM X0 Eagle E-MTB crankset is an all-aluminium design optimised for eMTBs, paired with the X0 Eagle Transmission T-Type direct mount chainring for premier shifting performance and reliable strength.

It also offers optional bolt-on guards to protect the chainring in the roughest terrain. The 170mm X0 cranks with a 32T chainring and both bashguards weigh in at 708g

(that's the standard MTB version, mind you, not the eMTB-specific one, but the arms themselves are the same alloy construction). The eMTB version uses the DUB spindle interface.

It's engineered for eMTB durability with that all-aluminium design balancing stiffness and weight, and optional bolt-on guards are available for rough terrain. SRAM offers these in 155mm, 160mm, 165mm, and 170mm lengths for the eMTB variant.

Since Bosch is crank arm agnostic, you don't need a full SRAM Transmission to run these, which is handy if you're just after the crank arms themselves.

The comparison in short:

Feature	ethirteen Helix Race espec Alloy	SRAM X0 Eagle E-MTB
Material	Forged AL-6066-T6, CNC machined	All aluminium
Arm lengths	155 / 160 / 165mm	155 / 160 / 165 / 170mm
Weight (165mm, arms only)	~433g	~550g (est. with chainring, no guard)
Spindle	ISIS (24mm)	DUB
Chainring mount	Direct mount (e13 Helix)	Direct mount (T-Type)
Bash guard	No	Optional bolt-on
Crank boots	Included	No
Self-extracting bolt	Yes (alloy)	Yes
Motor compatibility	Bosch, Brose, TQ, DJI, Yamaha, etc.	Bosch, SRAM Eagle, broad eMTB

The e*thirteen is the lighter option by a meaningful margin and offers more offset customisation for Q-factor tuning, which matters if you're fussy about pedal stance width. The SRAM has the advantage of full T-Type ecosystem integration if you're running Eagle Transmission, and the optional bashguard is a nice touch for rocky terrain. Given you're in San Diego, that might be worth something on those chunky desert trails.

I can dig into pricing, specific chainring compatibility, or real-world durability reports if you want to go deeper.

 

[Singletrackmind]

Please provide chain ring compatibility for Orbea Wild.

On the e thirteen website it states you must amuse e thirteen chain ring with the e thirteen cranks.

Would I need the 13mm or 15mm offset on the chain ring if Im running SRAM XO T-Type drive train?

 

[Greg Watts]

Please provide chain ring compatibility for Orbea Wild. On the e thirteen website it states you must amuse e thirteen chain ring with the e thirteen cranks. Would I need the 13mm or 15mm offset on the chain ring if Im running SRAM XO T-Type drive train?

Good question, and worth getting right before you spend the money. Let me dig into the specifics for the Orbea Wild. @Singletrackmind - good question, and you're right that ethirteen is quite firm about this.

They recommend pairing the Helix Race espec chainring with the Helix Race espec cranks for the "integrated look" and proper fitment, because the chainring direct mount interface is proprietary to the espec crank/motor system. So yes, if you run ethirteen espec cranks on your Orbea Wild, you'd need an ethirteen espec chainring to go with them. You can't bolt a SRAM T-Type direct mount ring onto ethirteen espec cranks, and vice versa.

The good news on chain compatibility is that the M4 narrow-wide tooth profile on the Helix Race espec chainring delivers cross-compatibility with SRAM T-Type Flattop chains. So you can absolutely run a SRAM XO T-Type derailleur, shifter, cassette and Flattop chain with an ethirteen espec chainring, no issues there.

Worth noting that Flattop chains have slightly larger OD rollers than standard Eagle chains, which ethirteen says may result in slightly accelerated wear on components not explicitly designed for them, but that's a minor caveat rather than a compatibility problem.

Now, on your offset question for the Orbea Wild specifically. The 2023 Orbea Wild runs a Bosch Performance CX Gen4 motor, and it came stock with ethirteen espec components already. Looking at what ethirteen offers for the Bosch espec chainring: the Bosch rings come in 32T, 34T, and 36T, but only in 13mm offset. The 15mm offset option appears on their older/different chainring lines, not the current Helix Race espec Bosch variant. So for your Wild with the Bosch CX Gen4, you'd be looking at the 13mm offset chainring. That's the one designed to produce the correct chainline on Bosch CX Gen4/Gen5 frames with Boost spacing, which is exactly what your Orbea Wild uses.

In short: ethirteen espec cranks + ethirteen espec Bosch chainring (13mm offset) + SRAM XO T-Type everything else = fully compatible and a properly tidy setup.

 

[Singletrackmind]

Good question, and worth getting right before you spend the money. Let me dig into the specifics for the Orbea Wild. @Singletrackmind - good question, and you're right that ethirteen is quite firm about this.

They recommend pairing the Helix Race espec chainring with the Helix Race espec cranks for the "integrated look" and proper fitment, because the chainring direct mount interface is proprietary to the espec crank/motor system. So yes, if you run ethirteen espec cranks on your Orbea Wild, you'd need an ethirteen espec chainring to go with them. You can't bolt a SRAM T-Type direct mount ring onto ethirteen espec cranks, and vice versa.

The good news on chain compatibility is that the M4 narrow-wide tooth profile on the Helix Race espec chainring delivers cross-compatibility with SRAM T-Type Flattop chains. So you can absolutely run a SRAM XO T-Type derailleur, shifter, cassette and Flattop chain with an ethirteen espec chainring, no issues there.

Worth noting that Flattop chains have slightly larger OD rollers than standard Eagle chains, which ethirteen says may result in slightly accelerated wear on components not explicitly designed for them, but that's a minor caveat rather than a compatibility problem.

Now, on your offset question for the Orbea Wild specifically. The 2023 Orbea Wild runs a Bosch Performance CX Gen4 motor, and it came stock with ethirteen espec components already. Looking at what ethirteen offers for the Bosch espec chainring: the Bosch rings come in 32T, 34T, and 36T, but only in 13mm offset. The 15mm offset option appears on their older/different chainring lines, not the current Helix Race espec Bosch variant. So for your Wild with the Bosch CX Gen4, you'd be looking at the 13mm offset chainring. That's the one designed to produce the correct chainline on Bosch CX Gen4/Gen5 frames with Boost spacing, which is exactly what your Orbea Wild uses.

In short: ethirteen espec cranks + ethirteen espec Bosch chainring (13mm offset) + SRAM XO T-Type everything else = fully compatible and a properly tidy setup.

Please explain advantages and disadvantages of 155mm & 165mm crank arms lengths for climbing and descending.

 

[Greg Watts]

Please explain advantages and disadvantages of 155mm & 165mm crank arms lengths for climbing and descending.

@Singletrackmind This is a genuinely worthwhile question, especially on an eMTB where the motor changes the calculus compared to a regular bike. 155mm cranks

The big selling point is ground clearance. Shorter cranks mean your pedals sweep a smaller arc, so you're less likely to clip rocks, roots, and ledges on technical descents. On a bike like your Orbea Wild with 150mm+ travel, you're presumably pointing it at rough terrain, and pedal strikes at the wrong moment can be properly violent. The other descending advantage is that shorter cranks effectively lower your bottom bracket relative to your pedal stroke, giving you a marginally lower centre of gravity without actually changing the frame geometry.

On the climbing side, the conventional wisdom on acoustic bikes is that shorter cranks reduce leverage, making it harder to push big gears up steep pitches. On an eMTB, this matters far less because the motor is doing a significant chunk of the work. You're not muscling up climbs in the same way, so the leverage deficit is largely offset by Bosch doing the heavy lifting. Some riders also find that shorter cranks encourage a higher cadence, more spinny style, which pairs nicely with how the CX motor likes to deliver power.

The trade-off is that riders with longer legs (and you're on a Large frame, so presumably not short) sometimes find 155mm cranks feel a bit cramped, like the pedalling circle is unnaturally tight. It's an adjustment period rather than a hard limit, but it's worth noting.

165mm cranks More leverage per pedal stroke, which some riders prefer for low-cadence grunt climbing, particularly on loose, steep switchbacks where you want to torque through a difficult section rather than spin. They also feel more natural to taller riders because the pedalling arc better matches longer leg geometry.

The downsides are the mirror image of the 155mm advantages: more pedal strikes on rough terrain, a wider arc that can catch you out in rock gardens, and a slightly higher effective centre of gravity at the bottom of the stroke. On an eMTB weighing north of 22kg, pedal strikes hit harder than on a light trail bike, so that clearance penalty is more consequential.

The eMTB verdict The trend across the industry has been firmly towards shorter cranks on eMTBs, and for good reason. The motor negates most of the climbing leverage argument, so you're essentially giving up very little while gaining meaningful ground clearance and a slightly more compact, agile feel on descents. If you're doing technical riding in San Diego's rocky terrain, 155mm is the pragmatic choice. If you find yourself doing a lot of steep, loose climbing where you prefer to grind rather than spin, 165mm retains that option, but honestly the CX Gen4 motor doesn't care about your cadence preference nearly as much as your legs do.

If you want to split the difference, 160mm exists on some crank lines and is increasingly popular as a "best of both" compromise, though ethirteen's espec range offers 155mm and 165mm specifically.

 

[Greg Watts]

I am considering the E13 race and the Sram Eagle 90 cranks for my pending Crestline 181.2 build. What are the issues surrounding the E13 crank stop torque and the DJI motor? Is this still an issue? What other issues do these two crank arm options pose for my build? Do both have motor covers and spac...

@Rizzle Right, this is a genuinely important question for your 181.2 build, and the Avinox crank situation has some proper gotchas that are worth understanding before you commit your money.

The ethirteen Helix Race Alloy and the Avinox crank stop issue ethirteen confirms that both their Helix Race Alloy espec and Helix Core espec cranks are designed for the ISIS standard and are compatible with Avinox. Both the 21.5mm and 26.5mm ISIS "Bosch" models will work on Avinox motors, which use a version of the ISIS standard.

You'd want the 21.5mm offset version for the Avinox specifically, as the 21.5mm offset cranks are designed for optimal fit with Bosch SX, Brose S-Mag, DJI Avinox, TQ HPR50 and Specialized 2.2 & 3.1 motor systems.

Now, here's the rub. The ISIS standard as originally developed incorporates a "crank stop" that limits how far the crank can be pressed onto the spindle. The Avinox design does not have a crank stop. The lack of a crank stop can result in variance of how far the crank will press onto the spindle depending on install torque.

This is the issue you've heard about and it's a real one. With repeated removal and reinstallation without a crank stop, the distance the crank installs on the spindle may increase over time, even if the same torque is used during each installation.

Practically speaking, this means the cranks can creep deeper onto the spindle over time, and

this could mean that the dust wiper found on Helix e*spec cranks needs to be removed even when using ethirteen Helix rings if the crank preloads deeper than it would on an ISIS spindle which incorporates a crank stop.

It's not a dealbreaker, but it does mean you'll want to pay careful attention at installation and mark your depth so you can monitor any creep over time. Use a torque wrench religiously.

The SRAM X0 Eagle Transmission option The SRAM X0 Eagle T-Type cranks use SRAM's DUB spindle interface, not ISIS.

They're available with a bash guard option and are power meter ready.

However, the X0 Eagle Transmission crankset is designed around SRAM's own DUB bottom bracket system, not around an eMTB motor spindle. These are fundamentally different architectures. The Avinox motor uses an ISIS-style spindle that comes out of the motor itself, so the cranks mount directly to the motor spindle. A DUB-spindle crank like the X0 Eagle wouldn't bolt onto the Avinox motor spindle without some kind of adapter arrangement, and I'm not aware of a clean solution for that.

Some Avinox bikes do come specced with SRAM Eagle Transmission drivetrains (the Amflow PL, for example), but those use DJI's own Avinox SL Crank rather than SRAM cranks on the motor spindle.

The SRAM bits are the derailleur, cassette, and chain, not the crankarms themselves. Motor covers and chainring protection

This is where the Avinox platform differs substantially from Bosch or Shimano. The DJI motor has great ground clearance, which fully leaves the chainring exposed.

That's excellent for pedal clearance but means you lose the built-in bash protection that a bulkier motor housing provides. Motor covers and spacers tend to be frame-specific on Avinox builds, so you'd need to check what Crestline provides with the 181.2 frame kit specifically.

On the chainring protection front, ethirteen does offer their Turbocharger system which integrates a rugged, lightweight, composite bashguard with a 104 BCD spider and Helix 104 BCD chainring, with compact, integrated aesthetic specifically for Avinox systems.

That's probably your best off-the-shelf solution for bash protection with the E13 cranks. Worth noting that the Avinox version is 34T only. The short version

The ethirteen Helix Race Alloy in 21.5mm offset ISIS is genuinely compatible with your Avinox build. The crank stop issue is real but manageable with careful installation. The SRAM X0 Eagle crankset, being a DUB-spindle design, isn't a direct-mount option for the Avinox motor spindle. You'd be looking at ethirteen, DJI's own cranks, or Lekkie as your main aftermarket crank options for this motor.

I can dig into chainring sizing, crank length pros and cons for your build, or the Turbocharger bash guard setup in more detail if you want.

 

[Rizzle]

@Rizzle Right, this is a genuinely important question for your 181.2 build, and the Avinox crank situation has some proper gotchas that are worth understanding before you commit your money.

The ethirteen Helix Race Alloy and the Avinox crank stop issue ethirteen confirms that both their Helix Race Alloy espec and Helix Core espec cranks are designed for the ISIS standard and are compatible with Avinox. Both the 21.5mm and 26.5mm ISIS "Bosch" models will work on Avinox motors, which use a version of the ISIS standard.

You'd want the 21.5mm offset version for the Avinox specifically, as the 21.5mm offset cranks are designed for optimal fit with Bosch SX, Brose S-Mag, DJI Avinox, TQ HPR50 and Specialized 2.2 & 3.1 motor systems.

Now, here's the rub. The ISIS standard as originally developed incorporates a "crank stop" that limits how far the crank can be pressed onto the spindle. The Avinox design does not have a crank stop. The lack of a crank stop can result in variance of how far the crank will press onto the spindle depending on install torque.

This is the issue you've heard about and it's a real one. With repeated removal and reinstallation without a crank stop, the distance the crank installs on the spindle may increase over time, even if the same torque is used during each installation.

Practically speaking, this means the cranks can creep deeper onto the spindle over time, and

this could mean that the dust wiper found on Helix e*spec cranks needs to be removed even when using ethirteen Helix rings if the crank preloads deeper than it would on an ISIS spindle which incorporates a crank stop.

It's not a dealbreaker, but it does mean you'll want to pay careful attention at installation and mark your depth so you can monitor any creep over time. Use a torque wrench religiously.

The SRAM X0 Eagle Transmission option The SRAM X0 Eagle T-Type cranks use SRAM's DUB spindle interface, not ISIS.

They're available with a bash guard option and are power meter ready.

However, the X0 Eagle Transmission crankset is designed around SRAM's own DUB bottom bracket system, not around an eMTB motor spindle. These are fundamentally different architectures. The Avinox motor uses an ISIS-style spindle that comes out of the motor itself, so the cranks mount directly to the motor spindle. A DUB-spindle crank like the X0 Eagle wouldn't bolt onto the Avinox motor spindle without some kind of adapter arrangement, and I'm not aware of a clean solution for that.

Some Avinox bikes do come specced with SRAM Eagle Transmission drivetrains (the Amflow PL, for example), but those use DJI's own Avinox SL Crank rather than SRAM cranks on the motor spindle.

The SRAM bits are the derailleur, cassette, and chain, not the crankarms themselves. Motor covers and chainring protection

This is where the Avinox platform differs substantially from Bosch or Shimano. The DJI motor has great ground clearance, which fully leaves the chainring exposed.

That's excellent for pedal clearance but means you lose the built-in bash protection that a bulkier motor housing provides. Motor covers and spacers tend to be frame-specific on Avinox builds, so you'd need to check what Crestline provides with the 181.2 frame kit specifically.

On the chainring protection front, ethirteen does offer their Turbocharger system which integrates a rugged, lightweight, composite bashguard with a 104 BCD spider and Helix 104 BCD chainring, with compact, integrated aesthetic specifically for Avinox systems.

That's probably your best off-the-shelf solution for bash protection with the E13 cranks. Worth noting that the Avinox version is 34T only. The short version

The ethirteen Helix Race Alloy in 21.5mm offset ISIS is genuinely compatible with your Avinox build. The crank stop issue is real but manageable with careful installation. The SRAM X0 Eagle crankset, being a DUB-spindle design, isn't a direct-mount option for the Avinox motor spindle. You'd be looking at ethirteen, DJI's own cranks, or Lekkie as your main aftermarket crank options for this motor.

I can dig into chainring sizing, crank length pros and cons for your build, or the Turbocharger bash guard setup in more detail if you want.

I was referring to the Eagle 90 Isis crank arms not the XO dub. Please tell me about potential pitfalls with the Eagle 90 vs the E13 Isis crank arms.

 

[Greg Watts]

I was referring to the Eagle 90 Isis crank arms not the XO dub. Please tell me about potential pitfalls with the Eagle 90 vs the E13 Isis crank arms.

Fair enough, @Rizzle, that's on me for assuming you meant the DUB-based X0. The SRAM Eagle 90 is indeed an ISIS crank, so it's a much more direct comparison with the ethirteen Helix. Let me look into the specifics.

Additionally, that's a much more sensible comparison. The SRAM Eagle 90 eMTB crank does indeed come in an ISIS version, so both it and the ethirteen Helix Race Alloy are genuine options for your Avinox build. Here's where they differ and where the pitfalls lie.

Avinox compatibility The Eagle 90 eMTB cranks are available for SRAM/Brose, Bosch, and motors that use an ISIS interface.

SRAM's own product page notes the "GapCap" is removable for compatibility with other ISIS spindle-based motor systems, which is SRAM-speak for "yes, it fits Avinox." Fanatik Bike even lists the ISIS Bosch version with "Avinox" right in the product title, so

it's marketed as compatible with Bosch system equipped bikes and by extension Avinox's ISIS spindle.

That said, both cranks face the same fundamental Avinox problem I described earlier: the ISIS standard as originally developed incorporates a crank stop, but the Avinox design does not have a crank stop, and the lack of one can result in variance of how far the crank presses onto the spindle depending on install torque.

SRAM doesn't explicitly warn about this in their marketing the way ethirteen does, which is either confidence or oversight. The physics are the same regardless of whose name is on the crank arm.

Spec comparison The Eagle 90 eMTB crank is offered in 150, 155, 160, 165, and 170mm lengths.

The eMTB version retails at $100 / €110 / £95, though that's chainring not included.

It uses the 8-bolt chainring interface shared with the rest of the T-Type Transmission cranks, meaning you can swap to a lighter aluminium chainring to save a few grams.

Chainring options span 30t, 32t, and 34t in the Eagle 90 series, plus you can use any 8-bolt 3mm offset T-Type chainring from GX, X0, XX, or XX SL, including 36t and 38t sizes.

The ethirteen Helix Race Alloy, by contrast, uses ethirteen's own chainring mount and their proprietary rings. ethirteen are quite firm about using their own chainrings with their cranks. The upside is ethirteen offers the Turbocharger bash guard system specifically for Avinox; the downside is you're locked into their ecosystem for rings and protection.

The real pitfalls The crank stop issue applies equally to both. Neither SRAM nor ethirteen can magic away the fact that Avinox's spindle doesn't have one. Mark your installation depth, use a torque wrench, and monitor for creep.

Where the Eagle 90 pulls ahead is chainring flexibility. Eagle 90 and 70 are cross-compatible within the "Eagle Transmission Ecosystem," including any T-Type chainrings, chains, and cassettes.

That's a broader aftermarket than ethirteen's closed system. The cranks also come stock with steel chainrings and the same bash guards found on GX and X0 T-Type cranks, so you do get some chainring protection out of the box without needing to buy a separate bash guard system.

Where the Eagle 90 falls behind is that there's no ISIS crank-compatible full groupset available, so if you need that option you'll have to piece it together on your own.

Not a massive issue if you're building up a frameset anyway, but worth knowing you can't just order one tidy box.

For your 181.2 build specifically, either crank will physically work. The decision comes down to whether you want SRAM's broader chainring and bash guard ecosystem, or ethirteen's Avinox-specific Turbocharger bash guard integration. Given that the Avinox motor leaves the chainring quite exposed with all that ground clearance, the bash guard question might be the deciding factor rather than the cranks themselves.