Ever ridden chainless down a trail? If so, you would have noticed how much better your suspension felt. If you've not done it, we suggest you give it a go. It's quite striking how much more sensitive your suspension feels without making any changes to the shock itself. But obviously, there's a downside to riding chainless: you've got a bike you can't pedal anywhere...

The Rimpact Chain Dampener is a product that allows you to get that same chainless suspension performance while still allowing you to pedal your bike.

Below we've included an explanation about how the product works as well as our own experience with the product. This is such a long description because this product category, along with the Ochain competitor product, has created a bit of controversy in the riding community. There seems to be a bit of doubt about whether this is snake oil or not, we can assure you that it is not.

How it works
The chain negatively impacts suspension performance in 2 ways:

Chain growth: 
As you compress a bikes suspension the rear wheel moves away from the pedals. As this happens, the distance between your casette and chainring increases which pulls your chain backwards. Your pedal stance naturally opposes this motion which adds resistance to the movement of the rear suspension. The downsides here are two-fold: 1) more resistance stops your suspension from compressing as easily and 2) you strongly feel that through your feet as ‘pedal kickback’ as your feet experiencing a significant feedback force which makes your suspension feel harsh. Without a chain your suspension just compresses and you don't experience this feedback force. High pivot bikes do help mitigate this issue.

Chain flap:
The faster you ride, the harder your chain flings about - we're sure you hear it. That's more chain growth, it’s just in the opposite direction (think about how much chain is below vs above your cogs). As the chain flaps about it pulls on the chainring and cassette, creating more of the same problem above.

Essentially, your chain fairly violently pulls your cranks back and forth in a way that makes your bike feel harsh to ride.

So how does this chain damper help? Well, it rotates with the chain. 4° of forwards rotation helps with chain flap and 8.6° backwards of backwards rotation allows the rear suspension to compress without being limited by chain growth.

Jonos experience 
As of December 16, I (Jono) have been riding with a Rimpact Chain Dampener for about 8 weeks. When I installed the product, the difference to the feel of my suspension was pretty clear.

The most obvious thing to me is that fast chattery bumps at the Christchurch Adventure Park now almost feel "smooth" on my feet. I have very flat feet, ride flat pedals and my foot arches tend to get quite worn out when riding, especially when I'm not well conditioned. I've found the Chain Dampener to significantly reduce the load that's been going through my feet, and I'm feeling fresher for much longer. It’s allowing me to do more laps in a day than I usually would be comfortable doing.

I'm now in the firmly sold camp. The Chain Dampener significantly improves the comfort of my bike in choppy terrain and it helps me ride harder for longer. It's also clear that my bike has more traction when I'm cornering over choppy terrain where there isn't supportive berms to hold my hand.

FAQ

Can I just use a hub with less points of engagement (POE)? Yes and no. A low POE hub won’t absorb chain flap forces. It can help somewhat (10-20% as effective as this) with the chain growth issue, but even that will be inconsistent. If your hub happens to be in a position where it needs to rotate a reasonable amount before engaging than sure, the suspension will be able to compress unhindered until the hub engages. But if the hub is about to engage then it wont help at all. Unlike a low POE hub, the chain damper will always show up for work.

Isn’t this the same as Ochain? You may have seen a similar product, Ochain, being used by many worldcup DH racers over the last couple of seasons. While O chain is similar, it doesn’t rotate forwards, and therefore doesn't isolate the suspension from chain flap forces.

What about the ethirteen sidekick hub? Good question. We’ve not tried one but it looks pretty promising. We suspect that it might not deal with chain flap as well as this product. Beyond our suspicions though, to use that hub you’re going to have fork out a lot more money for the hub ($750 at the time of writing) and then have to entirely re-build a wheel. And as to the longevity of those hubs, we have no idea. We’re firmly in the camp that a crank mounted solution will win out in the long term.

Are other chain ring sizes available? It is necessary to use a specific rimpact chainring. We will have more sizes and replacements soon!

Does it feel weird to pedal? Yes, a bit. The pedals rotate a bit before the chain engages. Once it's engaged it feels normal until you take pressure off. If you're the kind of person that prioritises hyper-technical climbing then this might be an issue for you. For the rest of us, it's not an issue.

Does it work on a hardtail? Absolutely. Chain flap causes a lot of the force you need to resist through your pedals. 

Chainless memories Remember the time that Aaron Gwin won a world cup chainless? 😅 https://www.youtube.com/watch?v=KMJTnB-50zE