While staring at the subtleties of prototype tires on Rémy Métailler’s Cube Stereo 170 enduro trail bike, it was impossible not to notice his STFU chain damper. Most modern full-suspension mountain bikes opt for intricate molded rubber chainstay protectors to limit chain noise (as does that Stereo 170), but gravity mountain bike legend Chris Kovarik had something else in mind. Not happy with the chain hitting the stays at all, he spent years developing a gadget to eliminate chain slap and quiet the drivetrain on his mountain bikes while bombing downhill…
STFU chain damper quiets chainstay slap
Just take a minute (44seconds, really) and look at the difference in chain movement on the bike of Chris Kovarik aka Karver, while riding Whistler. Besides just keeping things quiet, the STFU also just manages to keep the chain from bouncing violently around at all angles. It’s got to help with overall chain retention though really choppy terrain, and claims to reduce side load & twisting forces on the chain when you start to put power down in the rough stuff.
And for those wondering, STFU stands for Silent Technology For… OK, we can’t come up with a U and don’t think Karver did either. So let’s just tell our bikes to shut the F up.
STFU noise canceling tech details… How does it work?
The Silent Technology drivetrain damping system works by threading your chain through a pair of rubber coated loops between the top of your chainring and the cassette. When you aren’t pedaling nothing but derailleur tension keeps your chain taut over the chainstay where it comes closest. So STFU offers a place for it to hit first.
Many riders will wonder whether STFU alone will eliminate chain slap. But we’ve dug through photos of the bikes of both Karver & Métailler, and none of their bikes seem to have any form of protection on the bottom of the chainstay, and only Karver still uses a protector on top of his chainstay (under the STFU.
The dual-compound construction with soft durometer rubber coating quiets your drivetrain, damping the transmission of sound, while a firmer ABS plastic core to maintain shape, structure & overall durability. Here you can see the spiky hard plastic inner skeleton providing stiffness, then the soft rubber outer that is over-molded to “take care of that nasty chain slap noise”.
The stacked elements allow for cut-to-fit adjustable height, so each rider can customize the fit for most chainstay configurations. The curved shape of the loops allow the chain to move from your 1x chainring setup up front, back to your cassette completely unobstructed. No contact & no wear when pedaling, only when it catches the bouncing chain while coasting over bumpy trails.
STFU says their silent running tech is also lightweight. Before trimming to fit they weigh around 60g for DH or 75g for trail versions, including the two loop guides. But apparently most riders will chop around 30g of that off when sizing for their bike, bring weight down even more.
The chain damper is available in available in three versions for fit every kind of gravity bike, all the way down to your regular trail bike: DH07 for 7-speed downhill bikes with tight cassette clusters, DH10 for downhill bikes with up to a 32T cassette, and Trail for modern wide-range 1x gearing with up to a max 52T cog on the cassette.
STFU pricing & availability
The STFU chain damper got a soft launch last summer in its DH version, but now they are also available for most modern XC/trail/enduro bikes. The smaller loop DH versions sell for $30, while the Trail version retails for $35 to work with wide 1x mountain bike drivetrains. There’s also a $25 single loop option for singlespeed setups that use a chain tensioner. All are available now direct from STFU, with global shipping available.
What’s next for STFU?
While it isn’t official at all, Rémy Métailler is also currently testing a single anti-slap loop labelled as the STFU Trail Mini. Maybe placed a bit further back on the chainstay, one loop would weigh half as much, look half as weird, and could still offer much of the same noise canceling and chain damping?