Rimpact Chain Damper
MSRP: £280 ($377 at time of publication)
Crank Compatibility: Shimano Direct Mount, Race Face Cinch, SRAM 3-bolt, SRAM 8-bolt, Hope
Chainring Options: 30, 32, 34, & 36 teeth
Blister’s Measured Weight: 238 g (Cinch mount, including 32 tooth chainring)
Intro
Ochain’s devices have become a common sight on the World Cup DH circuit, since these ‘active spiders’ help reduce unwanted feedback from pedal kickback and/or chain movement. It’s pretty widely accepted that a mountain bike’s rear suspension feels and performs better without a chain installed, but the reasons for that are varied and complex. Pedal kickback (check out he “Background” section of our review of the original Ochain for more on that) is one potential source; the weight of the chain bouncing around as the bike goes down the trail can tug at the pedals and/or impede suspension movement; derailleur clutches add resistance to the whole system; and more.
Active spiders, first widely popularized by Ochain, are intended to help reduce some of those factors, thereby improving suspension performance and mitigating harsh feedback through the frame and pedals.
Now, Rimpact has released its own take on the concept. The overall form factor of the Rimpact Chain Damper is largely similar to an Ochain, but there are some fundamental differences in the thinking behind the two devices — and how they perform on the trail.
Design
Rimpact’s Chain Damper mounts in place of a direct-mount chainring and allows the chainring to rotate rearward (i.e., counterclockwise when looking at the bike from the drive side) to mitigate feedback from the chain.
That’s essentially the same idea as an Ochain, but Rimpact has tuned the Chain Damper quite differently.
The springs in an Ochain are quite light, and it moves through its travel very freely. If the goal is to mitigate pedal kickback, that makes sense. Pedal kickback results in the crank getting pulled backward by the chain as the suspension compresses; theoretically, allowing the chainring to rotate independently takes care of that. And the less spring force that’s needed to allow the Ochain to rotate backward, the less the chain will end up tugging on the pedals.
Rimpact’s take, though, is that the weight of the chain bouncing around is a greater source of feedback in most situations. With that in mind, they’ve given their Chain Damper much firmer springs so that it offers more resistance to chain movement. The Chain Damper should still counteract pedal kickback to some extent, too, but it’s targeted at tamping down feedback from chain movement first and foremost. Rimpact even notes that the Chain Damper is effective on hardtails, which, of course, don’t exhibit any pedal kickback.
As with an Ochain, chain tension under pedaling power moves the Chain Damper through its travel until it hits a hard stop, where it’s effectively rigid (like a standard chainring). That said, the firmer springs of the Chain Damper require more force to get to that hard stop, and they require that you maintain more consistent chain tension to avoid springing forward at the top and bottom of the pedal stroke (where your power output dips).
Rimpact has recently added a lighter “Trail” spring option for folks who find the standard springs to be too stiff and interfere with their pedaling. Swapping the springs requires disassembling the Chain Damper, but it can be done with basic standard tools and is relatively straightforward. The Trail springs are sold separately.
There are some other design differences between the Chain Damper and an Ochain, beyond just spring force. Most notably, the Rimpact Chain Damper uses a proprietary chainring that is more fully integrated into the inner workings of the Chain Damper, rather than a conventional 104 mm BCD chainring as featured on an Ochain. Going the custom route lets Rimpact simplify the design of the Chain Damper considerably — the chainring houses most of the inner workings of the device, rather than being bolted to a separate part that handles that duty.
Rimpact also says that their chainring design helps them make the interface as stiff and creak-free as possible. They’re able to make the diameter of the bushings that the chainring rotates on larger than they would with a 104 mm BCD ring; they can also have those bushings ride directly on the chainring so that there are fewer interfaces between parts, and the chainring can be better supported from side loads.
Of course, this also means that replacements might be a little harder to track down. The chainrings use a narrow-wide tooth profile, are compatible with all 11- and 12-speed MTB chains (including SRAM T-Type and Shimano 12-speed), and are available in 30- to 36-tooth sizes.
The Chain Damper is currently only offered for standard cranks (in versions for most common direct-mount chainring standards), but eMTB versions are in the works.
Some Questions / Things We’re Curious About
(1) How well does the Chain Damper improve suspension performance, and under what conditions does it feel most beneficial?
(2) What is it like to do substantial climbing on the Chain Damper — both with the standard springs, and the lighter Trail versions?
(3) How does the Chain Damper compare to an Ochain?
Bottom Line (For Now)
I’ve found the Rimpact Chain Damper’s main competitor, the Ochain, to make for a very noticeable improvement in suspension performance on some bikes (and a more modest one on others), but I also suspect that Rimpact is on to something when they say that chain movement has at least as much to do with that than pedal kickback itself.
With that in mind, I’m very curious to see how the Rimpact Chain Damper compares — and have started spending time on one to find out.
Flash Review: Our Initial On-Trail Impressions
BLISTER+ members and those who purchase our Digital Access Pass can check out the Flash Review below to read our initial on-trail impressions. Get our Digital Access Pass to view all our Flash Reviews and Deep Dives, or become a BLISTER+ member today to get access to that and a LOT more, including the best worldwide Outdoor Injury Insurance, exclusive deals and discounts on skis, personalized gear recommendations from us, and much more.
Flash Review: Rimpact Chain Damper
The thinking behind the Rimpact Chain Damper is more novel than it may first appear, and its effects on bike suspension stand out, too. Here’s what we’ve learned so far during our initial testing.
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