Time for something different. I’m ignoring the balls setup completely and going with pneumatic bellows.
I use these regularly and we have units from the 1980’s which run 24/7 that are still as good as new.
Better mounting, precise pressure repeatability between units and WAY more rugged. I’m finishing off a CAD design which will utilise these along with Rexroth linear ball rails and guides. Along its entire length will be a central pivot.
I intend to use long stroke ACE hydraulic shock absorbers to absorb any heavy fore / aft movement and use a turnbuckle spring system so spring tension can be fine tuned.
If anybody is interested I will post updates on here…
I am always curious about new parts and designs. I have seen those and generally presumed the stiffness of the rubber walls would lead to a more dead feel than a thin walled ball. Placement from the pivot axis will really matter here one way or the other.
And I am interested in your shocks for fore-aft. I have a damper for testing, but the fluid and resistance is way too stiff. So I need to drive it with linkage or swap fluid to a lower viscosity to get any use from it.
We use little mini shock absorbers which have a dial on them. They go from being able to push fully home with your little finger to being pretty rock solid.
Thinking about it, it would be possible to dismiss the spring entirely and just run within.the range of the damper. IE the dampers are always in contact
You might see an improvement on sprint power utilizing these with a progressive damping rate.
Yeah, the damper I have is a larger motorcycle steering damper. It is adjustable, but I had no idea how light it would go until I got it. I do want a damper with adjustable flow, to dial in for preference at the least. I also think having it adjustable from the bike would be great to have it loose for regular riding, and stiffen (of fully lock) it for racing or harder training.
I think it is an avenue that really needs to be explored, so it’s great to see you headed in that direction. I am keen to see the design and hear your feedback
No issues that I have seen. The typical f-a motion is under an inch and as long as you mount the balls between flat surfaces, or have properly chamfered edges for any holes, they work and wear well.
Most balls in use are the “playground / dodge ball” variety, and they have plenty of abrasion resistance and durability.
Thanks for the link on the dampers. Will dig into those
Based on that, you can find many reviews (linked above) of any of those that will give you an idea of how they work.
Hard to say with something like that since it can vary widely between individuals, but I personally have more comfort and less saddle issues with my trainer motion.
The most common reason for, and benefit from adding trainer motion is “comfort”. That can yield better overall experience with lower instances of sores. But I know some people who still struggle with sores after adding motion, because they have issues beyond the motion, and are more fit related.
While I rarely get saddle sores, having some motion (simple hack and then InsideRide) is welcome but didn’t improve comfort that much. Even coupled with getting out of the saddle every 5 minutes. On a gen1 Trek Domane with a seat mast that moves quite a bit because its a 58cm frame. In other words, a 90+ minute indoor trainer ride is still quite literally a pain in the ass. I’ve done 3 hours indoors and simply got off the bike every 30 minutes to finish it without too much drama. FWIW outside I’ve done 6-16 hour days, bike fit is not an issue.
I live around the corner from Swim Bike Run, makers of the SBR Rocker which is selling like hot cakes. I built my own in February for $200. I put on several coats of acrylic polyurethane so I can sweat all over it without issues.
I decided to go the route of using small inflatable balls and bushings down the middle. I also soldered together a pole for my unit’s controller.
I can post a link to the plans if anyone is interested.
Hi there.Awesome post on the Rocker plate Building one now and just ordered those same mounts.What screws did you specifically use for both sides to sit flush too and bottom? Thanks
