The e*thirteen Optimus tyre is the American brand's cross-country/downcountry offering, with two casings available – XC and Trail.
e*thirteen sent me a pair of XC-casing 29in tyres, using the Endurance compound.
My test bike was set up with the Optimus on the front and rear, with each tyre costing £63.95 / $67.95 / €68.53 and weighing 790g (actual weight).
There were highs and lows from my time testing the Optimus XC tyre. The supple carcass provided sufficient grip on technical trails and the tread pattern was fast-rolling, however the tyre didn't fair well in the mud, did not self-clean as stated and was hard to seat on the rim.
All things considered, e*thirteen has made a tyre that proves itself in varying – albeit not all – conditions.
e*thirteen Optimus XC details and specifications
The e*thirteen Optimus tyre is crafted specifically for cross-country and downcountry riding, designed to offer a balance of speed and comfort.
It's available in one width – 2.4in – and 27.5 or 29in sizes, with options of two tyre casings: Trail and XC, both featuring e*thirteen’s Endurance compound.
The Endurance model combines medium-compound side knobs with a harder centre and base compound designed for improved tread wear and quicker rolling.
The XC casing boasts a single-ply 120 threads per inch (TPI) construction. The Trail casing, which is slightly heavier due to its 72 TPI and nylon breaker under the tread, is said to offer enhanced puncture resistance.
The Optimus tyre's tread design is intended to balance low rolling resistance with predictable traction.
Its central region showcases shorter, densely packed knobs that are aimed at maximising rolling efficiency, aiding in both acceleration and climbing prowess.
These central knobs alternate between parallel and perpendicular orientations, with the intention of boosting braking and cornering traction.
Transitional knobs, strategically spaced wider apart, are intended to help maintain control during aggressive angles and be effective in mud shedding.
The larger sidewall knobs cater to aggressive cornering and are designed to offer a secure grip even on looser terrains.
On my scales, the Optimus XC casing, Endurance compound 29x2.4in tyre weighed 790g.
e*thirteen Optimus XC tyre performance
I tested the e*thirteen Optimus tyres on my Orbea Oiz M-Team cross-country bike over a variety of terrain in South Wales and the Tweed Valley in Scotland.
I was fortunate enough to get a mix of conditions to test the tyres over a three-month period, from dry hardpack trails to soft slop and pretty much everything in between.
Installation and inflation
The tyre was incredibly easy to get on the rim, with the supple carcass slipping right on.
However, getting the tyre to seat, even with an air compressor pump, required all sorts of trickery. Once it popped onto the rim, it held air well.
At 45psi, air stopped leaking and both tyres were securely seated.
They measured 2.35in at their widest point when fitted on a 30mm rim, which is slightly less than the 2.4in e*thirteen claims.
On-trail feel
The tightly spaced centre knobs provided low rolling resistance, resulting in a smooth power delivery without any noticeable drag, which made climbs enjoyable, and the bike zipped along at speed on hardpack trails.
There was good grip on offer in shallow, loamy terrain thanks to the larger sidewall knobs constructed from a medium compound.
I could feel the tyre dig in and offer support when cornering, giving me confidence to push my speed.
This confidence was lost when hitting loose gravel, though. The bike became unpredictable and sketchy as the sidewall knobs struggled to grip into the hardpack, while the harder central compound and tightly spaced knobs grappled for traction on the moving surface.
The supple carcass moulded over features, providing good grip on technical terrain, which gave me confidence hitting features and riding rough sections of trails, even in the wet.
When it came to wet, muddy conditions, however, the tread design wasn't effective at shedding mud. Despite e*thirteen claiming they're effective self-cleaners, the tightly spaced centre knobs held soft mud, leading to the tyre becoming clogged and struggling for traction.
On numerous occasions in the Tweed Valley, rear-wheel spins meant I had to dismount and push up steep climbs.
The tyre has proven durable on rough trails in Scotland and Wales, with tread wear not yet noticeable and I've had no issues with punctures or air loss.
e*thirteen Optimus XC bottom line
The Optimus tyre excels in dry or loamy trails and the supple carcass offers good grip over technical sections, even when moist.
However, it struggles for traction when the conditions get super-wet and muddy, and loose corners can feel sketchy. Seating it properly on the rim is challenging.
Despite such drawbacks, I have been impressed by the versatility of this tyre. It may not be perfect in all conditions, but it has performed well over different terrain, from root-strewn trails to greasy rock gardens and long stretches of mountain roads.
Decent traction in most conditions and low rolling resistance make it a great choice for long-distance riding on variable terrain.
Product
| Brand | ethirteen |
| Price | 69.00 EUR,64.00 GBP,68.00 USD |
| Weight | 790.0000, GRAM (29x2.4) - |
Features
| br_bead | Folding |
| Features | TPI: 70, 120 Compound: Endurance Casing: XC, Trail |
| br_tyreSizes | 29x2.4, 27.5x2.4 |
