What is it

In an effort to literally reinvent the mountain bike wheel, Spank injected a hard-cell foam into the hollow rim interior (see photo below). The goal is to make the Spank Spike 350 Vibrocore wheels more durable and better at damping vibration, delivering a more controlled and comfortable ride, especially when tackling rough terrain at high speeds.

Spanks says that the Vibrocore material creates a low density, pressurized core that performs a similar function to the "soft tissue inside bones, increasing inner wall strength and absorbing vibrations." It also adds about 40g of weight to each rim.

Spank Spike 350 Vibrocore Wheels

The secret sauce of the Spank Spike 350 Vibrocore wheels.​

The reasonably priced tubeless-ready aluminum Spank Spike 350 Vibrocore wheels are hand-built and feature easily replaceable triple-butted J-bend spokes in a three-cross pattern. Spoke counts are 32 front and rear, and the wheels come in both 27.5 and 29er with Shimano and SRAM XD driver freehubs and multiple hub spacing options.

Key rim measures include a shallow 17mm depth, 35mm outer width, and 30.5mm inner width. Spank contends that this rim shape maintains lateral stiffness, while also delivering 30% more radial compliance compared to traditional alloy rims with similar rim width but a deeper profile. This improved radial compliance is claimed to result in better traction over bumps and chatter, and the Vibrocore material is said to reduce the transmission of vibration, meaning more control and less fatigue. Intended use is downhill/freeride, though they certainly work for trail/enduro use, too.

Spank Spike 350 Vibrocore Wheels

Tire fitment was a tad tight, which made setup a pain but lessened the chance of burping.​

The Spank Spike 350 Vibrocore wheels also feature what the brand calls BeadBite, which is designed to enhance tubeless use with tires of all types and with a greater range of air pressures. BeadBite rims have six rows of tiny ridges that run along the vertical and horizontal faces of the bead seats. These tiny teeth aim to create air seals between the rim and tire as the bead conforms into them under pressure. That in turn increases friction on the tire bead, reducing its ability to move, thus improving tire stability and reducing burps because the bead literally becomes trapped between the ridges even at very low air pressures.

Mtbr tested a set of 27.5 Spank Spike 350 Vibrocore wheels with boost hub spacing and an XD driver body. Claimed weight according to the shipping box was ~1992 grams. Our test set with tubeless valves and tape installed came in at 2030 grams (950g front/1080g rear). And while that's definitely on the heavy side of the wheel weight spectrum, remember that these wheels are part of the brand's downhill product range.

Spank Spike 350 Vibrocore Wheels

A little Colorado high country adventuring with the Spank Spike 350 Vibrocore wheels.​


  • Smooth ride quality
  • Track exceptionally well
  • Utterly bombproof
  • Design allows for easy spoke replacement
  • Secure tire hold means lessened chance of burping
  • Reasonable price


  • Slow'ish hub engagement
  • Wheels came out of true during break-in period
  • Not particularly light
  • Finicky tubeless setup
  • Somewhat muted trail feel

Rating: 4 out of 5
Price: $699
More Info: spank-ind.com

Mtbr's Take

Based solely on the caliber of riders using the Spank Spike 350 Vibrocore wheels in competition, it's hard not to put some credence into the company's claims of durability and performance. Spank Factory Race Team riders Remi Thirion, Myriam Nicole, and Thibaut Ruffin, and Spank Factory Freeride Team members Ethan Nell, Darren Berrecloth, and Sam Reynolds have all given them the thumbs up - and put their necks on the line while barreling downhill fast with these wheels beneath them.

Spank Spike 350 Vibrocore Wheels

We are told you can do this with the Spank Spike 350 Vibrocore wheels.​

"The first time I used them was straight in at the deep end on the massive jumps at DarkFEST," recalled Reynolds. "I had some sideways landings so violent I was sure they were going to explode, but they kept on going straight and true - and the tires never burped off."

Ditto was our experience for the most part, though we obviously didn't push them anywhere near as hard as any of the riders mentioned above. Out of the box, tubeless setup with a pair of Panaracer Pandura 27.5x2.4 tires was a touch finicky, as fitment was quite tight. But once tire beads were wrangled into place and sealant installed, there were no more issues despite running pressures in the low 20s.

Spank Spike 350 Vibrocore Wheels

Rim depth is a shallow 17mm.​

However, I did have to give the spokes some TLC after a few break-in rides on what you could call moderately technical enduro-style trails. Rear spoke tension was okay, but about 6 spokes on the non-drive side needed truing, though it was all within the acceptable wheel break-in period range. The front wheel also got a touch wobbly, with about 7 spokes needing attention from a spoke wrench. But this fix was a one-time deal, as the wheels settled in from there, requiring no further maintenance.

The rest of our experience during about two months of testing was similarly positive. Though I wouldn't call rear hub engagement particularly quick, these wheels became a solid partner for all manner of XC, trail, and the occasional bike park adventure. We banged them into rocks, launched off small and medium-sized jumps, and generally did our best to recklessly test both durability and performance.

Spank Spike 350 Vibrocore Wheels

Once up to speed the wheels tracked well without being overly harsh.​

And while I can't report any game changing revelations, ride feel was controlled and precise without being overly harsh, which can certainly be the case with some far more expensive (and lighter) carbon rims. When I bottomed out the rims they didn't break or dent, and when I lowered air pressure the tires didn't burp or puncture. On chattery trail sections the wheels delivered a smooth ride feel, easily tracking the intended line and rarely getting bounced around.

Bottom line, while it's tough to absolutely isolate and quantify wheel performance, the Spank Spike 350 Vibrocore hoops certainly delivered on their promise of durability and tubeless tire security. And while they're not quite as quick on climbs or popping out of corners as some stiffer alloy wheels, they carry speed well, while delivering a smooth and controlled ride.

Spank Spike 350 Vibrocore Wheels

The wheels come in both 27.5 and 29er with Shimano and SRAM XD driver freehubs and multiple hub spacing options.​

Spank Spike 350 Vibrocore Wheels