I will look again…nothing jumped out at me. I was looking for a DIY design that somebody has done all the trial and error on so i can just build it and go.
Enginerds, can someone figure out the correct pivot positions to make this work. This could fix the out of the saddle experience if pressure on one side causes the central pivot to “fall” off that side. Our natural pressure on the bars and weight shift out of the saddle should encourage the subtle sway needed to rock the plate counter to the downward pedal pressure.
I have several versions of this in SolidWorks. You need to ditch the middle link for starters. It prevents the side rotating links from working properly and leads to binding.
There is a massive amount of complexity in a 4-bar design and it’s one reason I haven’t one built one yet. There are also a massive amount of possibilities. It boils down to looking at center of mass and instant center of the linkage at various points in lean, as well as centered.
I plan a simple test to identify some important points of interest, and then refine my concept enough to build a real unit.
Yeah…what we need isn’t a “rocker plate”…it’s a passive “motion base” with some number of DOF points…beyond that, I dream of an ERG/SIM controlled 3DOF base with immersive video…
So is the idea here that you need the trainer to track laterally (side to side), effectively mimicking the shallow s-turns that the rear wheel would travel when you’re out of the saddle, rather than just mechanically tipping (rotating around longitudinal axis), like most rocker plates do?
What if you combined the design with the angled linkages, minus the middle link, and then used one of these inflatable balance disks between to put some spring in the system. https://www.amazon.com/gp/product/B00NGO7K8W/ref=s9_acsd_hps_bw_cr_x__a_w
Most likely, there will need to be spring assistance. It may be possible to use pure gravity, but based on my analysis, I don’t that that is so if you also get the motion directions that are intended.
Mostly speculation right now, as I have only built rockers with pivots below the trainer deck right now. I have been mulling this stuff over for 3+ years and still not happy with my solutions at this time.
Make the central pivot a carbon flex plate? I need to find some free time to throw some wood on the mull and see what I can come up with for a trial. I also need to figure out what angles a lay my bike over on a sprint or climb. Thanks for this btw Chad.
If you make a “flex plate”, what is it’s purpose?
ANGLE: I find that around 7-8 degrees at max is plenty. Any more and it is too close to “tipping”, IMHO.
Most of the normal range is about 1-2 degrees while seated and 4-5 degrees in “controlled” standing. I only hit the limits on mine if I am leaning off-center.
Happy to have this and anything rocker related.
Here’s a small sample of one of my comparison designs. Looking at a higher pivot, simple design (top sketch). Then a 4-bar linkage design used to mimic, but also alter the motion (bottom 2 sketches).
Note: This excludes the center of mass points that I try to track (BB height, saddle/bar/rider center).
Got busy on my day off last week. Lots of links in Chad’s group on Facebook for those considering a build or looking for ideas and options.
Comfort for me on the trainer hasn’t really ever been an issue however with some time & cash to burn it tickled my fancy.
Having watched my top tube on the rollers I found that I really don’t need a huge amount of movement when seated. The extra ‘throw’ when out of the saddle is quite nice and notable on the Rocker plate though.
Could well have done this with a single sheet of MDF but owning a coupe doesn’t let itself well to transporting 6x4ft sheets of MDF… and I also wanted something a little wider than 600mm at the rear.
Staples in the covering are temporary
I move my trainer in & out of the garage so stuck a cupboard handle on the rear to give a backstop and point of reference.
6 tennis balls were good enough for me. I have an additional pillow bearing, to make 6 in total, that I will fit the next time it’s apart as the middle flex’s when stepping on/off but with such little clearance between the tops of the bearing housing and the bases it’s really not an issue, nor a springboard.
Fashioned some blocks to reduce rock by raising the balls up slightly, not fixing them to the base allowed for easy play/fettling.
Do you feel it was worth the effort of making it?
I love hearing feedback from new builders and rocker riders.
Thanks. At first I was a little underwhelmed, well actually at first it felt a bit like a space hopper
But that said I think riding without one now would be a lot more noticeable to me and I would probably miss it. It took a little getting used to, in order to feel properly ‘anchored’ again having ridden indoors with zero movement for years.
Out of the saddle I find it does relieve tension by allowing me to work the bike much more similarly to when out on the road. So I find there is actually a benefit to the legs from getting out the saddle, rather than just the arse.
It’s another distraction for when the suffer turns up too
Great to hear. Thanks for the thoughts. After more time, you may well find that going back to rigid feels very strange. I know it does for me. The lack of motion is unsettling to say the least.
I have to get a picture of my cheap-ass setup. Despite being an engineer and the love of over-designing things, I’ve gone as minimal design as I think I have ever done. Used 6 “balance pods” - https://www.amazon.ca/SPRI-BP-SET-Balance-Pods-Set/dp/B0015SBRCG sitting around as they make ideal suspension units. I threw a piece of 1/4 ply on them, one under each leg of my TACX Vortex and two in the middle. A couple of pieces of 4x4 raised the front end enough. The pods are tough and have a just enough give to cushion without feeling loose. Total cost zero because it was ll re-purposed stuff.
@ZeroGravity Please post a pic when you can; I’d love to see the setup. I love @mcneese.chad setup but need something mobile (I live in a one bed/bath) and this sounds like it might do the trick for Worldwide “Disaster” Day.
It’s not pretty but it works. I’d probably “upgrade” to 1/2 ply but other than that it is all function over form
This aligns with a video I want to do. I want to make one about the “lowest-cost” rocker plate possible. Something that can be done for $50 or less (USD) and noting more than a trip to the hardware and/or general store (Walmart/Target).
@ZeroGravity This would work perfectly for what I want to accomplish! Thanks for the pics.
I’ll license my patented low-cost design to you for an honourable mention in the video Those pods can be had from Amazon for less the link I posted and they are super tough - like mini Bosu balls. They act just like airbag suspension, have a some give and don’t rebound too quickly. I’ve done 3 or 4 rides now including a 90minute on with form sprints and it hasn’t slipped or otherwise felt like it was going to blow apart
@ZeroGravity, do you have to do anything extra to keep your trainer on top of the plywood? This design looks promising for a MVP. I’d like to build @mcneese.chad’s design (thanks for sharing the videos and PDF, btw), but this seems a little easier to pull off to see if it’s something I’ll like riding on.
Thanks for sharing pictures! I found those balance pods on US Amazon and have them saved.