Moto heads know all about the pangs of vibration that wear on their muscles and tendons throughout a ride. Lacking the engine rev, mountain bikes send far less feedback to the rider, but over a long day, the trampled stones and chattered frequencies add to our overall fatigue. Some folks are loosening spokes to reduce that trail feedback, which is great if you have a mechanic to re-true them at the end of every descent. Spank takes a different approach, filling their aluminum rims and handlebars with Slimer-colored foam to eat up the taxing frequencies. Graf Works Wheel Building recently sent a set for us to test out.
I wasn’t convinced on my first few local descents with the Spank 359 Vibrocore rear and 350 Vibrocore front wheels. While they felt every bit as stiff and responsive as I would expect from a race-inspired gravity wheel set, the damping foam didn’t make its merit apparent right away. I had to head to the bike park to really get the point, and get it I did. Riding these wheels back to back with another set of 32-spoke alloy hoops that have the same tires on the same bike was a good way to learn their story.
At my maximum speed, across medium and bread loaf size braking bumps, the Slimer foam starts to show its value. My hands and forearms feel slightly less fatigued at the end of a hard run with the Spank rims, meaning I should be able to do more runs with better grip control. For enduro racers in particular, this small shift in vibration absorption could be the difference between a confident and commanding final run, or one that’s plagued by arm pump and lobster claws. Additionally, while I’m fortunate to not suffer from arm pump, these rims would be on my list of things to try if I did. The foam doesn’t reinvent the wheel for you, but it does make a difference at a higher speed when that difference counts. Spank says that the Vibrocore foam also extends the life of the rim, which is a welcome element for any set of circles.
A set of Vibrocore 350/359 wheels isn’t only going to reduce some appendage fatigue, it’s also a sturdy and affordable option for rough descent lovers. At $700 total for the pair (sold at Wiggle and other online retailers), you have a wheel set that’s ready for whatever DH or enduro track you want to throw it at, with your choice of 28 or 32 spokes, Boost or Superboost spacing, and any of the current three freehub bodies.
The rims have a 30.5mm hooked internal measurement to hold 2.0-2.6″ tires in place, and a 19mm profile that allows for more radial flex or “compliance” than some taller alloy rims. Rims come taped and valved with 32 J-bend, triple-butted spokes laces 3X and tightened down with an equal number of brass nipples. In the center, an aluminum hub shell houses an alloy axle and freehub body, where 102 teeth and 6 pawls create a tight and relatively quiet 3.5° of engagement. Six Torx bolts hold the rotors in place, so you’ll always have a spare 5mm bolt in a pinch.
The 359 rims have a taller profile than the 350 version by 2mm, offering a touch more rigidity and dent resistance for heavier riders and jankier tracks. If you’re someone who goes through rims faster than chains, using the 359 on the rear wheel may be a good idea. The heftier rim is also better for e-bike applications and fallout DH racing where the sphere will take additional abuse. I found that these hand-laced rims provide ample flex to allow me to fudge a line in messy situations, while they remain stiff enough to hold the line when it matters. The brand didn’t write “radial compliance” on their rims for marketing alone, as these truly are comfortably forgiving wheels that I felt at home on quickly.
There are a few superlatives in our little industry, and any hub engagement tighter than 3° might be one of them. At 3.5° of engagement, the Spank hubs spin up plenty fast and ratchet with all of the immediacy that any technical climber could desire. While hubs with tighter engagement feel and sound cool, this set offers reasonable functionality that should work for most riders.
Back to the burly, the Spank rims, hub bearings, and spokes have held up swimmingly over the past few months of testing. They’ve been slammed through the same stones and sticks as the other wheels I’ve tested this summer, and have only slight rim dents to show for it. This could be the result of their “radial compliance,” heftier rims, Slimer foam, spoke tension, rim shape, or a combination of factors, and whatever it is, it works. The spokes have endured countless catches on roots and rocks, and they’ve managed to hold the wheels true throughout. The lighter 28h sets do come with alloy nipples to drop a little weight, which is something lighter riders may want to consider.
To squish it all together, this is a sweet wheel set at a reasonable price that should last most gravity riders a good while. The Vibrocore foam blown inside may not blow minds, but it will make a long descent day feel even more decent. There are loads of options with this set, designed to suit a variety of riders and bikes. Get all the details on the Spank website.