ethirteen Grappler Enduro Casing Mopo Compound tyre review

e*thirteen’s Grappler tyre is the brand’s latest gravity-focused enduro and downhill-specific mountain bike tyre, with a tread pattern that’s claimed to give control in the harshest terrain regardless of weather conditions.

It’s offered in two different carcass types: a lighter Enduro model with a 120 threads per inch (TPI) weave, and a heavier 72 TPI Downhill version.

Similarly, two compounds are available: a stickier Mopo version and a harder-wearing Endurance model. Both carcass types are available in either compound.

Highlighting its descent-focused performance are the Grappler’s headline weights.

The lightest Grappler Enduro Casing Mopo Compound 29x.2.5in tyre tipped the scales at 1,300g, while the weightiest Downhill Casing Endurance Compound 29x2.5in version weighed a whopping 1,446g.

Although weights are high, the asking prices start at $59.95 for the Enduro Casing Endurance Compound tyre and rise to $69.95 for the Mopo compound rubber in both Enduro and Downhill casings.

I’ve ridden all four variants of the Grappler in 29in guise, but am focusing my review on the Grappler Enduro Casing Mopo Compound version.

e*thirteen Grappler Enduro Casing Mopo Compound 29x2.5in tyre specifications

The Mopo Compound uses rubber with a 42a reading on the Shore Hardness scale. The scale is out of 100, so 42 is slightly softer than halfway.

The ‘a’ part of the reading refers to the group of flexible mould rubbers of varying hardness. For example, rubber bands have a 20a rating, while a telephone wire is 90a.

The Mopo compound is soft, and according to e*thirteen, has a slow rebound. This should ensure it provides as much grip as possible on the widest range of trails.

That 42a compound spans the width and depth of the tyre’s tread.

Some competitors' offerings, such as Maxxis’ 3C (three-compound) MaxxTerra and MaxxGrip tyres, have the tackiest rubber only on the knob’s surface, so as the tyre wears grip performance can drop off.

This is less likely to be a problem for the Grappler, where the entirety of each of the tread blocks is made from the 42a rubber.

As the tyre wears, the grippiest rubber is still on the blocks' surface and in contact with the trail.

The enduro casing (you can read our in-depth feature on mountain bike tyre casings) uses a dual-ply 120 TPI casing, where the threads are closely woven to reduce the amount of rubber that can penetrate between them. This helps to lower weight, but will give the tyre a softer, more malleable feel.

e*thirteen says it has included an Aramid bead and an Apex EN (which stands for enduro) insert beneath the tyre’s tread to improve puncture resistance.

On my scales, an Enduro Casing Mopo Compound 29x2.5in Grappler weighed 1,300g.

e*thirteen Grappler Enduro Casing Mopo Compound 29x2.5in tyre performance

I tested the e*thirteen Grappler tyres on my Marin Alpine Trail XR enduro bike on DT Swiss EX 1700 and ENVE MTB Foundation AM30 wheels.

Testing took place over the course of a gruellingly hot and dry summer, and then into the colder, wetter autumnal months. The tyres have been subjected to the full gamut of riding conditions over the five-month test period.

I predominantly tested them in Scotland’s Tweed Valley, home to the UK’s round of the Enduro World Series, but also spent a long weekend buzzing around my old haunts, particularly chunky downhill tracks in Morzine, France.

Fitment, inflation and width

The Grappler was surprisingly easy to fit given its chunky 1,300g weight. Wrestling with rim-damaging tyre levers to seat the final section of bead wasn’t necessary, and it popped into place using my hands only.

Getting them fully inflated and their bead seated correctly on the rim’s hook was also drama-free using only a high-volume track pump rather than a dedicated tubeless tyre inflator to get them blown up.

At 40psi, the bead was fully seated and stopped leaking air.

Testimony to their tight fit and accurate construction, the tyres didn’t leak air for the duration of the test period.

On a 30mm internal-width rim, they had a rounded profile, and the centre knobs were higher than the shoulder ones. The shoulder blocks, thanks to the rounded profile, pointed slightly outwards instead of vertically up.

They measured 2.31in/58.67mm wide at their widest point when fitted to a 30mm internal-width rim. This is slightly narrower than e*thirteen’s 2.5in-width claims.

Grip and feel

The traction offered by e*thirteen’s Mopo compound is impressive. It excels in a vast range of weather conditions and trail types.

Arguably, the Grappler is most at home on looser terrain, whether that’s in the wet or dry. The chunky, aggressively ramped tread blocks have an impressive amount of bite where they claw or dig into the ground, helped by the large spaces between each block.

On hardpack surfaces, the same terrain-munching quality is there, where under high-load situations, such as braking or cornering, the knobs are stable and tough enough to penetrate into the ground and provide grip.

This knob stability defies the tyre’s soft-feeling compound that doesn’t appear to suffer from excess deformation or steering vagueness.

Having a massive amount of cornering traction is one of the Grappler’s biggest draws, where its rounded profile augments the tacky but stable compound’s grip, permitting impressive lean angles with plenty of control.

Almost identical amounts of control are present in damp to wet conditions. The predictable, easy-to-manage grip comes from both the tacky rubber that’s soft enough to ‘chemically’ bond to the trail and the blocks that are sharp enough to dig into the ground.

However, although the Grappler is vastly impressive, it isn’t perfect.

Greasy hardpack terrain usually caused by rain after a long dry spell, and polished damp rocks and roots, are where these tyres perform the weakest, but only in comparison to how good they are elsewhere.

In these conditions, grip is still high, but there's an element of unpredictability to its consistency. While grip is stable one second, it can drop off quickly the next.

This mostly happens during direction changes or when the bike has less weight being pushed through it and the terrain shifts angle. Embedded roots or rocks, or small dips, rises or changes in camber can cause the tyres to slip off-line.

The minor reduction in traction is countered by the truly damped feel the tough carcass and sticky rubber creates.

Over chattery rough terrain, the Grappler is remarkably hushed, insulating the rider from bumps impeccably.

Wear rate and durability

The Grappler’s wear rate is impressively slow given the traction and control on offer.

Fitted as a front tyre, it took several weeks of very dry and dusty riding to blunt the knob’s sharp ramps and profile.

Despite continued use on rocky, rough terrain, the side knobs are still showing no visible signs of tearing or splitting away from their anchor points on the carcass.

The same is true for the carcass and puncture protection, where the chunky Grappler has remained puncture, rip and tear-free for the duration of the test period.

How does the e*thirteen Grappler compare to the Maxxis Assegai?

So, how does the e*thirteen Grappler Enduro Casing Mopo Compound compare to the Maxxis Assegai MaxxGrip DoubleDown?

Given the similarities between the Grappler and Assegai tread patterns, comparing the two seems logical.

In MaxxGrip guise, the most notable difference between the two is traction on greasy surfaces, where the Assegai edges ahead of the Grappler in terms of predictability. It tends to stick to the trail’s surface in a more sure-footed way.

Elsewhere, grip and performance are virtually identical.

e*thirteen’s Enduro casing is tougher than the Maxxis DoubleDown and feels more damped. In this respect, the Grappler beats the Assegai.

It’s hugely impressive the Grappler comes so close to the Assegai’s benchmark performance, cementing it as one of the grippiest and best-feeling tyres on the market.

e*thirteen Grappler Enduro Casing Mopo Compound 29x2.5in tyre bottom line

e*thirteen has worked wonders with the Grappler’s tread pattern, rubber compound and enduro casing to provide Assegai-equalling performance in almost every area. It's a worthwhile inclusion in our guide to the best mountain bike tyres for gravity-focused riding.

Masses of cornering traction and side-knob stability are blended with impressive braking performance and a long lifespan, even in dry, rubber-ripping conditions.

To boot, they have a massively damped feel, plenty of puncture protection and loads of carcass support.

There’s very little to dislike about the Grappler, and it's a fantastic alternative to the justifiably popular Maxxis Assegai.