Good to know
-The Boulder X is an approach shoe for technical routes where friction footwork is needed. Its engineers included past technologies in it, albeit tweaked to respond to the varying demands of approach adventurers. La Sportiva highlights its Mythos lacing, which delivers a customized fit.
-The midsole unit combines a LaSpEVA cushioning layer atop a 2mm polypropylene insole and a Micropore EVA for support. As for the outsole, the designers went with the Vibram Idrogrip for stickiness even when stepping on wet rocks.
La Sportiva’s Boulder X is for men and women. It’s a low-top shoe with a lace-up closure (called Mythos) whose construction provides volume adjustment through its to-toe eyelets. La Sportiva mentions that it delivers an adaptable fit.
The Boulder X features a Vibram outsole that uses a compound called Idrogrip. It is optimized for wet terrain. According to its manufacturer, outsoles with this compound are designed for tackling challenging technical trails. A free climbing rubber was the inspiration behind the creation of this outsole compound.
This unit has lugs of different shapes. The circular protrusions are for slip resistance while the slanted ones grant grip on rocky trails. Serving as a platform for edging is the front tip of the outsole.
The outsole is built with Impact Brake System (IBS). The lug placement creates stopping power by 20% max.
La Sportiva designers built this midsole unit with long approaches in mind. That’s why they added a LaSpEVA padding to the polypropylene insole. The combination functions as a cushioning system.
Beneath the insole is a Micropore EVA midsole. It absorbs shock upon each step. The shoe is board-lasted to maintain torsional rigidity and deliver support.
The Boulder X from La Sportiva comes with a leather upper, making it durable. It is partially lined with mesh (tongue and back-half sections) to deliver breathability. It has a full rubber rand combined with a slingshot rand at the heel for durability and additional stickiness. The slingshot rand, which bears the La Sportiva logo, also provides protection when scrambling.
The closure is called Mythos lacing. It features combination eyelets with a pair of polygonal grommets at the top. This system is for managing the fit. The back has a pull tab for quick on and off.
In terms of structure and features, the Boulder X and the TX4 (both are approach shoes from La Sportiva) have quite a lot of differences. This part lists and describes the components of each offering.
Midsole. The Boulder X has extra cushioning for long approaches in the form of a layer on top of the insole. It also has a shock-absorbing EVA midsole. As for the TX4, The MEMlex midsole with STB Control System delivers support and torsional rigidity.
Closure system. The Boulder X uses a system called Mythos (see the Upper section for the construction of this feature). As for the TX4, it also uses a similar lace-up closure, but with a different structure--the upper-most pair of cord eyelets meet at the back of the shoe’s heel, forming a kind of loop that may be adjusted for an even more personalized fit.
Upper material. Both approach shoes are made of leather. The Boulder X has a partial mesh lining, while the TX4 has a slip-resistant mesh lining. Although these shoes have a full rand, the former comes with a slingshot rand. As for the latter, its rand is part of the STB Control System, and it works with the midsole to give structure to the shoe. Both shoes have a rand designed with the La Sportiva logo.
At the Back of the Boulder X is a pull tab. The said component is not present in the TX4.
Outsole. The common features between the two are the Impact Brake System and the circular lugs on the outsole. More info on this can be seen in the Outsole section above. As for the rubber compound, they differ. The rubber of the Boulder X uses the Idrogrip, while the TX4 uses the Megagrip. The outsole of the latter is also built with an enhanced stability area and comes with a heel brake for stopping power.
Fit. The Boulder X has a regular width overall. On the other hand, the TX4 is wide in the toe box area.