Oversuspension

[butcher bergs]

Apparently this device reduces the chances of a highside by 90%?
While I don't quite understand how this item does its magic, it is currently in use by race teams as well as a few privateers.

[theducman]

I have seen this and I don't know how it woks either.

[butcher bergs]

Someone on WERA is selling a bike with one of these installed. Seller insists it works.

Naturally, I became curious how but there's no real detail that I've been able to find, like a cutaway or description of what goes on inside.

Placebo effect?

[OreoGaborio]

Never heard of this thing either before now, but I looked into it and it seems it's a tuned mass damper.... essentially a small weight on a spring inside a tube. It aims to reduce rear end chatter.

This guy is WAY more long winded than he has to be, but there's some informative bits.
https://www.youtube.com/watch?v=3cncwp6KjbY
https://www.youtube.com/watch?v=wJe0djSDdHE

[jimmycapp]

Too slow....



Pretty cool. Decent video here. At 7:08 they show a little physics demo. But they show another bunch of examples. Never heard of it before.

[Pittenger5]

I bet I could highside it without even trying.

[virtualbong]

Too slow....



Pretty cool. Decent video here. At 7:08 they show a little physics demo. But they show another bunch of examples. Never heard of it before.

10:50...hahaha.

[ZX-12R]

My skepticism alarm has been triggered. I have a hard time believing anything you can pick up with your fingertips will have enough mass to have an effect on a motorcycle. There is way too much energy here for something of that size to have an appreciable effect.

I'd also be curious how you tune a passive tuned mass damper for an environment that changes dynamically. Engine RPMs, lean angle, tire wear, user inputs, asphalt condition, speed, etc. all change the vibrations you would see at the end of the swingarm. A passive TMD is generally optimized for the natural frequency of object it's supporting.

I wager if you follow the money, there is probably some shady shit going on.

[PurplePackage]

It does look like it would help reduce rear end chatter. I'd bet $100 that 90% reduction in highsides is cherry picked data. Where's the actual source for the hot air coming out of his mouth?

"reducing the possibility of highside on the track by up to 90%."

"by up to 90%"

wtf does that mean?

[Kurlon]

"by up to 90%"

wtf does that mean?

68% of the time it works every time.

[02redhawk]

It does look like it would help reduce rear end chatter. I'd bet $100 that 90% reduction in highsides is cherry picked data. Where's the actual source for the hot air coming out of his mouth?

"reducing the possibility of highside on the track by up to 90%."

"by up to 90%"

wtf does that mean?

It's like when you hear "Internet speeds up to 1GB".

[Paul_E_D]

I don't think it prevents highsides but it can supposedly do a good job of reducing pumping on acceleration which in theory could help prevent some crashes.

[xrocket21]

HOLD MY BEER

[jeantarrou]

This thing was discussed a while back on another forum I lurk on, I thought that the fact that you DON'T see these on top level race bikes was a pretty compelling argument that the benefits probably aren't significant.

[wiggeywackyo]

The BS-ometer is strong on this one.

I haven't watched the videos yet but, at best, aren't they just balancing the wheel? Unless there is some electronic sampling in there with some sort of driven, extremely high accelerating mass, I just don't see it. They are almost better served tuning with a tapered mass mounted on rubber along the swingarm.

[Paul_E_D]

I have seen these on some moto2 bikes. Motogp is hiding something similar in the tail sections. I don't think there is nothing to it, but it's likely pretty subtle. I had a shock body failure on my R6 last season. It was due to uncontrolled high frequency vibes from the swingarm/wheel. So there's a lot of energy there.

[loudbeard]

I expect the GP bikes are probably hiding servo controllers in the tail section, the Ducati’s anyway. Their system is a push button type, meaning they have electrical/electronic devices which can rapidly adjust ride height and preload. They’re using servo motors to do. This would be known as an active system and looks the be the most advanced in the paddock.

Others are using passive systems. The Yamaha rear squat device for example looks like a cable actuated system, see the dial they twist on the left handlebar? Same with the front ride height which looks like a ratcheting system. They activate it, then brake heavily coming into grid and the forks lock into a compressed position.

[Paul_E_D]

I expect the GP bikes are probably hiding servo controllers in the tail section, the Ducati’s anyway. Their system is a push button type, meaning they have electrical/electronic devices which can rapidly adjust ride height and preload. They’re using servo motors to do. This would be known as an active system and looks the be the most advanced in the paddock.

Others are using passive systems. The Yamaha rear squat device for example looks like a cable actuated system, see the dial they twist on the left handlebar? Same with the front ride height which looks like a ratcheting system. They activate it, then brake heavily coming into grid and the forks lock into a compressed position.

This is a separate topic. The rules prevent any electronic active suspension. All the ride height systems, ducati included are manual cable driven (hydraulic assisted) set ups. What is rumored to be in the tail of the duc is a sophisticated mass damper similar in concept to what this thread is about.

[loudbeard]

This is a separate topic. The rules prevent any electronic active suspension. All the ride height systems, ducati included are manual cable driven (hydraulic assisted) set ups. What is rumored to be in the tail of the duc is a sophisticated mass damper similar in concept to what this thread is about.

Well that's definitely interesting, did not know active systems were prohibited. Due to the nature of their control (push buttons) I made an assumption this was a servo system. It's only 10:30 and I've already spent my allowance of being wrong only once a day.

[butcher bergs]

After doing more reading, I completely forgot that Renault F1 had designed a suspension system that utilized mass dampers.... allowed at first, then Ferrari started crying about it so, banned.


Here's an example of the Ducati tail section



Now that I understand how the device works, I could see how a rider would benefit from it by suppressing swingarm/ chassis attenuation.

It sounds like the device isn't designed to cancel out all attenuation, just attenuation within a specific frequency range, hence the adjustment that's designed into it.

In architecture, this is known as a seismic damper and if you compare the size of any given structure to the size of the damper used within that structure, one could easily say there's no way something that small could affect an entire building.


I doubt I'll ever be riding at a level where I could form an opinion on this device but the science and physics of it make sense.