As trainer season approaches I’d like to address the saddle-of-pain issue that, for me, only occurs indoors. After reading all the complex work being done on rocker plates it made me wonder if one of the many suspension seat posts might be a cheaper, simpler, and potentially more effective option. In addition, I also have a height constraint in my basement setup which makes a rocker plate tough to implement.
Instead of rocking the whole bike and trainer, why not just the saddle/seatpost instead? Normally one would not want side to side movement on a saddle, but seems like maybe we need more play on our saddle instead. It’s not clear to me what is the important dimension of movement needed - fore/aft? side-to-side? up-and-down? All of the above? By way of reference, my old MTB has a dropper seatpost which has developed some play in it, but it doesn’t bother me at all on the trail.
Curious if anyone has played around with this or has any experience here.
Interesting question, here are my initial thoughts:
One key complaint about suspension seat posts is that their motion leads to constant changes in the seat height length and effective leg extension. Depending on the actual direction and amount of travel, it may be minimal, but it exists with most designs.
The direction of travel of a suspension seatpost is often inline with the seat post (telescoping designs) or arc rearward (pivot or linkage designs). But in all cases, the saddle remains level to the ground, along with the bike and trainer.
I disagree with this assumption. Based on my testing and observations of dozens of riders on the road, people lean the bike far more than they realize. We tend to assume that the bike is “stationary & vertical” most of the time. I see the exact opposite.
We are constantly shifting the angle of the bike up to what I predict is around 2* frequently. Steering is obvious and requires leaning the bike to perform properly.
Even ignoring that and assuming a straight direction of travel, we are often shifting our location on the road left and right. This also requires leaning.
And finally, I see lots of slight shifting from the rider during the actual pedal stroke. People have just adopted this without realizing it, but I feel it is the key to comfort compared to rigid setups inside.
These angular changes are what lead to the “relief” that we tend to associate with outside riding on a “free” bike vs inside on a rigid vertical trainer.
My saddle pressure mapping video shows the differences in peak saddle pressure with rigid and different levels of rocker plate leveling spring settings. The key take away is that there is a notable reduction in peak pressure due to the slight rocking action. This action is what I see as the main attribute that makes rocker plates often successful to the goal of increasing comfort vs a rigid setup.
Unless you are riding on super smooth and steady trails, I’d suggest this is not a great comparison. Riding trails hides all sorts of motion (from dropper slop to full suspension) and is not ideal to consider to the more consistent nature of typical road riding.
I have not tried it, but have the Redshift Sports suspension seatpost and could try a test some time. I’d love to test with my pressure mapper, but it died a while ago and my boss has not gotten it repaired yet.
I think it is an interesting test idea, and may be helpful, but I see it as a different solution than the goal of rockers adding the rotary angular motion we typically get outside.
Wow, you really scienced this out! Yup, I was thinking of the redshift specifically, but was looking for any anecdotes to support my winter dreams of finishing a movie while on the trainer.
I think the average user around these parts is emotionally predisposed to not have a suspension seatpost lying around
It is fascinating this bike thing. As of a few years ago, Academics were still not in agreement on the underlying physics behind bikes and how we/they balance so effectively. Saddle design/comfort seems to be another black art…
I am a big proponent of suspension seqatposts…at least on gravel and CX bikes…and hard tails when I used to ride them. I have had a suspension post on those bikes for 20+ years…kinda amazes me more people don’t use them.
But for a trainer, I don’t think you’ll get much benefit. You would have to have a pretty choppy pedal stroke to get any kind of consistent activation…or have it set so soft you would be bouncing up and down anyway.
I built a rocker plate this summer…still trying to decide if I like it. When seated, it is fine and I can stay seated longer than I normally would before having to stand and get some blood flowing to the nether regions. Standing, however, I lose power and still haven’t quite figured out the right movements to align with the rocker motion (it is opposite of what you experienc eon the road)…so I look like a frog on a skateboard when I get out of the saddle, my power drops and my HR spikes.
You mentioned having a low ceiling height issue. For these cases, the rib-style rocker plate can be a great option. You end up with the deck thickness (around 3/4") and the center rib height (around 1" depending on the design), so around 2" or less height increase.
I can get you more info on these designs if that sounds like something you want to consider.
If you have a Kickr and a low ceiling, you can just run it at the 650b wheel height and then not use a riser block on the front. It probably buys you a couple of inches.
One DIY option in the US is this very expensive, machined aluminum rib kit:
This company sells complete units in wood, for about the same price above:
I have been wanting to try making one of these myself. If you are interested, I could cut some extras for you. Will be hand cut and sanded, so far from fancy and perfect, but something to test at least.
I bought an InsideRide Kickr E-Flex and while it helps a bit, my focus indoors is still on seated sprints and neuromuscular work. Motion also helps with a bit with comfort, but I still find 2 hours inside to be a pain in the a**.
My saddle spring steel suspension device came in early this week. I had been riding on the kinetic rock and roll machine for many years before it got damaged and replaced with the tacx neo2. The neo2 was fantastic but not as comfortable. In search for comfort i changed to a better bib (assos) and that made a big difference. Instead of rocker plate i googled amazon and tried the spring suspension. Well …the device didnt help. It bobbed up and down a wee too much on the tacx as one get into the workout. I felt that power is affected somewhat but more importantly it felt less comfortable. I will continue to try it out with some adjustments and see how it goes. I have only tried it indoors coz thats what i bought it for. I am aware it is not a true suspension seat post like those from cane creek so may be there is still some hope. I am sure rocker plates will help but they are fairly big and i m trying to avoid that.
