I’m a big fan of rocker plates–those platforms you place beneath your trainer which allow your bike and trainer to tilt side to side. I’ve used various plates for over three years now, and logging over 16,000 Zwift miles atop a rocking platform of some kind.
But there’s one thing that really bugs me about some (or even most) rocker plate setups I see, and it’s time to get it off my chest.
This issue isn’t confined to the DIY rocker plate crowd, although I’ve seen it there. And it’s not just a problem for cycling newbies–I’ve watched many expert cyclists make the same mistake.
So what’s the problem? The rocker plates are too tight.
What does that mean, exactly? Well, “tightness” in this context refers to how much force it takes to move your bike from side to side. Next time you ride outside, pay attention to how far your handlebars swing when you’re out of the saddle climbing or sprinting. Chances are they’re moving 4-6 inches side to side.
Now watch this CyclingTips video where James is trying out the Saris MP1 rocker plate. (I’ve started the video at 6:24, where James is using the MP1):
Notice how small the range of motion is? That’s because the MP1’s leveling springs are very tight.
Tight vs Loose
Are tight springs always worse than loose springs? Not necessarily–there are plusses and minuses for each setup. I chatted with rocker plate wizard Chad McNeese about this, and we came up with a list of pros and cons for tight vs loose springs:
- Pro: feels more stable, which is nice for new users
- Pro: more comfortable than a typical rigid trainer setup (even a bit of movement makes a big difference)
- Pro: reduces frame stress created by typical rigid trainer setup
- Con: usually results in incorrect bike lean/pedal timing (more on this below)
- Pro: increased range of motion allows a more realistic feel
- Pro: more comfortable than a typical rigid trainer setup
- Pro: reduces frame stress even more than a tight spring setup
- Con: less stable, requiring more body engagement/rider attention
In summary: new rocker plate users will probably feel more comfortable on a tighter setup, because that little bit of movement takes some getting used to when you’ve been training on a rigid setup. But once you’re used to the motion, chances are you will want to loosen it so you can get full, natural motion out of the saddle.
By far the biggest problem with an overly-tight setup is that it leads riders to adopt terribly incorrect out of the saddle form.
Here an (admittedly crappy) screengrab of Peter Sagan winning at the 2017 Grand Prix Cycliste de Québec. Note the out of the saddle sprint form of all these pro riders: specifically, that the bike is leaning away from the leg that has the pedal down.
This is proper, natural pedaling form– pulling on the handlebars and leaning the bike add power to the downstroke, as the lean is effectively pulling the pedal up while your leg is pushing the pedal down. And as you lean the bike one way, your body counteracts that lean with its weight in the other direction so you stay balanced.
In fact, it can’t work any other way outside–if the bike was leaning in the same direction as your body and down leg, you would fall over!
GPLama Shane Miller talks about this very problem is his “Round 2 Rockit Launcher” video (below). Around the 2:50 mark he says, “Every video we’ve seen of people out of the saddle on a rocker plate looks like this.” And he’s not wrong–I’ve seen so many bad videos.
But it is possible to have proper out of the saddle form indoors. Here’s a quick demo video I shot which demonstrates basic, proper form out of the saddle on a rocker plate–both climbing and sprinting:
Now compare my form to what I saw at the Saris booth during Eurobike 2019. (Keep in mind this was an experienced, paid rider–and the other booth rider was exhibiting the same form!)
Saris isn’t the only one who can’t seem to market their own product well. Even SBR, whose rocker plate I really love, displays a demo video on their homepage showing this backward form:
Tight rocker plates lend themselves to this poor form because the rider is forced to use their own body weight to lean the bike over.
Proper technique has the bike swinging side to side quite freely while the body stays upright, counterbalancing the tilting bike. But a tight plate requires the body to lean right in order to tilt the bike right, then lean left to tilt the bike left.
Best of Both Worlds
So what’s the solution to this rocking quandary?
Adjustable tightness, and awareness of proper form. That’s it!
Most rocker plates use some form of adjustable spring: the SBR ROCKR uses inflatable rubber balls (less air for a looser feel), as does the CoPlate. Chad McNeese’s DIY Rockit Launcher uses foam blocks that can be swapped out to vary the tightness. There’s just one notable exception: the Saris MP1, which costs around twice as much as the ROCKR and CoPlate, is not adjustable. Ouch.
(I don’t want to bag on Saris too much: the MP1’s build quality is rock solid, and it allows significant fore-aft movement, which the other rocker plates do not. But the spring’s tightness combined with a lack of adjustability is a deal killer for me.)
Once you have a plate with variable tightness, set it where you’re comfortable, while being careful to maintain proper out of the saddle form. If you can’t lean your bike to one side without also leaning your body to that side, your setup is too tight. Loosen it up, get used to the feeling of having your core more engaged and your bike a little more free-floating… and enjoy it!
Are rocker plates just a passing fancy, or victims of their own poor marketing? Share your thoughts below!