Ever wondered what pedal kickback is and whether it’s actually a problem to your riding?
Pinkbike says that “If the suspension is compressed while the rear wheel doesn’t rotate, the cranks will be forced to rotate backwards through a certain angle because the cassette moves further away from the chainring. This is pedal kickback”.
Pedal kickback is a hot topic in mountain biking, but, Joe isn’t convinced it’s quite what we think it is.
He’s been experimenting with a few setups, trying out an OChain anti-pedal kickback spider and doing some thinking.
He’s pretty sure he’s worked out what pedal kickback actually is, and what it probably isn’t. And the answer to whether or not pedal kickback is an issue we need to deal with at all.
As you’d expect, the answer isn’t entirely simple – and – he’s pretty sure it’s not as straightforward as a lot of us think it is!
Joe’s theory is that you should start by watching those Pinkbike Huck To Flat Super Slow Mo videos. If you do, you’ll see bikes that are experiencing pedal kickback-inducing conditions.
But look closely at those videos. The chain on those bikes aren’t under tension at the point you’d expect to see kickback.
The bikes huck and land and their chains become loose and flappy. They lose tension and lose their ability to transfer force into the cranks. After all, if a chain isn’t taught how can it transfer anything into the chain ring?
So maybe kickback isn’t actually a result of what we think it is.
But, people are certainly experiencing something that they’re attributing to pedal kickback and, Joe thinks, something is going on. In his mind, we need to get away from demonstrating pedal kickback by bouncing a bike in the car park.
If you bounce a bike in a car park, your cranks will move, and so will the rear mech and mech hanger. You’ll see what we think of as kickback.
But, it just doesn’t work in the same way on the trail. When the wheel is rotating and the suspension is compressed the chain doesn’t behave in the same way. It extends and becomes, as we see in the vids, loose.
So what is pedal kick back and what causes it?
Joe thinks it all comes down to that flapping chain. He thinks we’re feeling the movement of the chain slapping around, causing a sensation that’s enough to detect. Watch the video for the full explanation to hear his thoughts about the whole thing.
He also thinks this opens up a whole conversation about damping vibration in mountain bike frames… but we’ll let you watch the video to work that one out!
We’d love to hear your thoughts.
Swing over to YouTube and leave a comment below the video. If we get plenty of good ones, we’ll get Joe to go through them and do a follow-up video next week.
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Ex-aerospace engineer Joe Mcewan is the founder and chief engineer of Starling Cycles. Passionate, outspoken and fond of a cuppa and a debate, Joe loves to challenge the established thinking of the industry.
