Suspension Dyno

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MarkST

· #3 · Jul 11, 2012

Where's Thirdway when we need him

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DuckMan

· #4 · Jul 11, 2012

MarkST said:
Where's thirdway when we need him

I was thinking it. But I wasn't gonna say it.

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MarkST

· #5 · Jul 11, 2012

Christ that was quick Mike.

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pgeller

· #6 · Jul 11, 2012 (Edited)

You guys!!!

Its easier to understand if you "unfold it" at the zero-crossing, so it looks like a boomerang. Right of zero (velocity) is the compression of the fork, left of zero is rebound. The dyno puts a displacement into the fork to simulate the wheel reacting to hitting a bump, and measures damping force applied by the damping circuits. The velocity will be high for that upward stroke, to quickly absorb the shock and dissipate it before the bike is upset and your teeth fall out. The velocity will be lower for the rebound of the fork, allowing the bike to recover without overshoot, bounce, your stomach stays inside you, etc. The nice smooth slopes show that the forks were very linear and controlled in their responses, meaning the damping circuits work as designed. A cheap shock/fork will have lumpy, non-linear curves and the wrong slopes. There is a bit of hysteresis at the zero crossing, because there is no real damping for tiny movements (that's the tire's job) and there is always some "stiction".

If it rides and handles well, congratulations. If not, it's Thirdway's fault.

pg
DD

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cb4265

· #7 · Jul 11, 2012

pgeller said:
You guys!!!

If it rides and handles well, congratulations. If not, it's Thirdway's fault.

pg
DD

Talk about make a name for yourself in a really short time...................

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MarkST

· #8 · Jul 11, 2012

How did the UK visit go Craig, got any pics ?

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cb4265

· #9 · Jul 12, 2012

5

Had a great trip Mark, too many photos, they will take me forever to upload to Photobucket.

Another member on here ColinST, took me under his wing and looked after me at Silverstone, so that was great & much appreciated.

My visit to the Ducati factory / museum during WDK was very memorable. Unfortunately, due to earthquakes, no factory tours were available, but the museum was fantastic, I went back twice.

I had seen this online home so I was quite familiar with what I was looking at, but so much better in the flesh.

I highly recommend the tour, but your English summers suck!
Isle of Man was brilliant except for the weather, but that was expected.

Thread high jack over.

Craig

The Tourist Trophy, Kirk Michael, Creg Ny Baa, me on the right, & Start line at Silverstone.

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stryder

· #10 · Jul 12, 2012

pgeller said:
You guys!!!

Its easier to understand if you "unfold it" at the zero-crossing, so it looks like a boomerang. Right of zero (velocity) is the compression of the fork, left of zero is rebound. The dyno puts a displacement into the fork to simulate the wheel reacting to hitting a bump, and measures damping force applied by the damping circuits. The velocity will be high for that upward stroke, to quickly absorb the shock and dissipate it before the bike is upset and your teeth fall out. The velocity will be lower for the rebound of the fork, allowing the bike to recover without overshoot, bounce, your stomach stays inside you, etc. The nice smooth slopes show that the forks were very linear and controlled in their responses, meaning the damping circuits work as designed. A cheap shock/fork will have lumpy, non-linear curves and the wrong slopes. There is a bit of hysteresis at the zero crossing, because there is no real damping for tiny movements (that's the tire's job) and there is always some "stiction".

If it rides and handles well, congratulations. If not, it's Thirdway's fault.

pg
DD

Thanks Paul.

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jssport

Discussion Starter · #11 · Jul 12, 2012

pgeller said:
Its easier to understand if you "unfold it" at the zero-crossing, so it looks like a boomerang. Right of zero (velocity) is the compression of the fork, left of zero is rebound. pg
DD

Paul, thanks for the explanation, I've read your response about 5 times now and I almost understand it

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Thirdway

· #12 · Jul 12, 2012

MarkST said:
Where's Thirdway when we need him

Still here and struggling to post:

Suspension dyno, whatever next

had that done by Maxton, it only works on static suspension and ensures there are no major faults. Trouble is, throw the bike on its ear and the perfect traces go out the window. An engine doesn't suffer like that as it is largely in a static environment.

You still have to ride it to see if it works.......against my better scientific judgement mind you

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MarkST

· #13 · Jul 12, 2012 (Edited)

Thirdway said:
Still here and struggling to post:

Struggling to post, how come ?
Something to do with 02 network perhaps ?

Thirdway said:
You still have to ride it to see if it works.......against my better scientific judgement mind you

Classic

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pgeller

· #14 · Jul 12, 2012

Third,

Certainly for street bike suspension, the suspension dynos are simple creatures with limited utility. Like you suggest, they can verify that the damper works properly, there's no valve leaks or blockage, simple stuff. The typical suspension dyno only operates on one damper - fork leg or shock - at a time, off of the bike, so doesn't take into account the myriad complexities of a full bike/suspension system in motion.

For racing, suspension dynos can be very useful, and can actually allow pre-installation setup of tuning parameters. Using accelerometers and other feedback devices, data can be captured from the actual suspension on a particular race track. This data is then fed into the suspension dyno to operate the damper/spring exactly as if it were installed on the vehicle and racing around the track. The damper can then be tuned for best response. Very cool stuff.

I suppose some enterprising (good looking) entrepreneur could develop a dynamic suspension dyno that exercised the bike's suspension in-situ, take it to race tracks and shops, and make a fortune.

Cheers

pg
DD

Thirdway said:
Still here and struggling to post:

Suspension dyno, whatever next had that done by Maxton, it only works on static suspension and ensures there are no major faults. Trouble is, throw the bike on its ear and the perfect traces go out the window. An engine doesn't suffer like that as it is largely in a static environment.

You still have to ride it to see if it works.......against my better scientific judgement mind you

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SP3

· #15 · Jul 13, 2012

pgeller said:
Third,

Certainly for street bike suspension, the suspension dynos are simple creatures with limited utility. Like you suggest, they can verify that the damper works properly, there's no valve leaks or blockage, simple stuff. The typical suspension dyno only operates on one damper - fork leg or shock - at a time, off of the bike, so doesn't take into account the myriad complexities of a full bike/suspension system in motion.

For racing, suspension dynos can be very useful, and can actually allow pre-installation setup of tuning parameters. Using accelerometers and other feedback devices, data can be captured from the actual suspension on a particular race track. This data is then fed into the suspension dyno to operate the damper/spring exactly as if it were installed on the vehicle and racing around the track. The damper can then be tuned for best response. Very cool stuff.

I suppose some enterprising (good looking) entrepreneur could develop a dynamic suspension dyno that exercised the bike's suspension in-situ, take it to race tracks and shops, and make a fortune.

Cheers

pg
DD

a damper dyno is for testing the dampers only. they cannot test the suspension. one could be made but.... that would be better handled by a 'shaker' rig. as yet, I don't know of a motorcycle capable shaker (meaning one that can reproduce the loads perpendicular to the road surface and and 'normal' cornering loads simultaneously). that would be impressive.

dynos are very useful to those that have been in the business long enough to a) actually know what they are doing with dampers and what the dyno is telling them and b) have baseline settings for a wide range of bikes/riders/usage. are they more useful in a racing environment? yes, because most times, a street bike customer is just going to say, "I want that fancy kit in my fork/shock", pay, and never come back to make it still better. Places like Cogent can make full use of a dyno even for street riders. The local bike dealer? Hell no.

the argument that dynos are of little use can also be applied to shaker rigs, engine dynos, differential dynos, brake dynos. they are only as useful as the operator acting upon the resulting info.

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Thirdway

· #16 · Jul 13, 2012

MarkST said:
Struggling to post, how come ?
Something to do with 02 network perhaps ?Classic

No, the server seems to be struggling to cope. It's often impossible to log in or post. No problem with other forums just this one.

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MarkST

· #17 · Jul 13, 2012

Thirdway said:
No, the server seems to be struggling to cope. It's often impossible to log in or post. No problem with other forums just this one.

Odd. I've never had a problem my end in the 4 or 5 years I've been on here.

Can't think what to suggest really, unless it's something to do with your antivirus or firewall permissions or something like that.

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