"old" V11 sport frame

[luhbo]

....

I ended up by closing the holes with a sleeve. The adjustment srews are completely open on both sides.

Now the fork works much better, but still not perfect. Especially when braking the front moves down in a more controlled manner. Not perfect is the reaction of the fork on small bumps, it feels not sensible. ...

 

I would not close these wholes, because you can no longer address separately high-speed and low-speed damping now.

You couldn't really do this before, but this means also that the inbuilt bottom valve is only capable of doing high-speed jobs. High-speed damping is necessary only for the last third of the stroke, to soften/damp the badest bumps or brake manoeuvers.

 

You say you have both adjusting screws completely open now but still the C-damping seems to be too harsh for standard situations.

For the above mentioned situations like bumps or harsh braking or both your fork now is probably absolutely inadequately set up.

 

Maybe one could make this modification, but then he would need an additional valve to overtake the wholes' functionalities.

 

 

Hubert

[Guest ratchethack]

If Wilbers could build the shock to Ohlins dimensions (286mm length 70mm stroke) or even Sachs 276/60 or WP 280/64 and put a softer spring on it than HyperPro does, I would place my order tomorrow!

Chris Beauchemin wrote a nice write-up on the Wilbers Shock where he determined the travel was 58mm

http://www.v11lemans.com/forums/index.php?...ic=5898&hl=

Dave, they can build anything you specify, including custom stroke. I remember Chris B's write-up. I'm not interested in a 70mm stroke, because this has the potential of stressing the driveshaft joints beyond comfort level. I'm duplicating the stock-issue stroke, which is 60 mm plus whatever the bushing provides.

[dlaing]

Dave, they can build anything you specify, including custom stroke. I remember Chris B's write-up. I'm not interested in a 70mm stroke, because this has the potential of stressing the driveshaft joints beyond comfort level. I'm duplicating the stock-issue stroke, which is 60 mm plus whatever the bushing provides.

I almost agree with you.

The extra 10mm should not be used to reduce bottoming by riding higher.

I believe that doing so would stress the driveshaft joint and create an unstable bike by being too high in the rear.

I believe the 70mm stroke is fine if you add an additional 10mm to the sag.

It will help prevent the topping out (is that the correct term for the opposite of bottoming out?) and from what I can tell, will stress the driveshaft joints no more than bottoming out.

 

Side Note

When defining shock length and travel, the Ohlins gets very close to the limit of axle movement in both directions.

The Ohlins, WP, and Sachs all bottom out at about the limit of axle travel....bumpers change the point slightly.

The Ohins and Wilbers both top out at about the limit of axle travel.

Dark Grey represents Shock Length in mm

Blue represents Travel in mm

Grey haze approximately represents bike only sag

Orange haze approximately represents rider on bike sag

Note1-- The sag are approximate recommendations with a bias of importance on low ride height...Obviously the Sachs and Wilbers should have different sag positions within the illustrated fields.

Note2-- The Wilbers is based on Chris Beauchemin's shock, not Ratchet's.

 

If I could order any specification, I might go 284/66 with about a 550# spring

[luhbo]

David,

 

that's an interessting approach what you do now. To interprete this graph correctly resp. to draw the right conclusions I think it would be most valuable to get any "neutral" figures. I mean figures that show the design "height" of the V11. Maybe that in the manual somewhat could be found.

 

What you mention would make a real advantage for the Oehlins shock. The bike stands at the same height as with the Sachs/WP unit, but this shock gives you 10mm more negative stroke without spoiling the laden/unladen factor.

 

Hubert

[Guest Nogbad]

David,

 

that's an interessting approach what you do now. To interprete this graph correctly resp. to draw the right conclusions I think it would be most valuable to get any "neutral" figures. I mean figures that show the design "height" of the V11. Maybe that in the manual somewhat could be found.

 

What you mention would make a real advantage for the Oehlins shock. The bike stands at the same height as with the Sachs/WP unit, but this shock gives you 10mm more negative stroke without spoiling the laden/unladen factor.

 

Hubert

 

Isn't 10mm "negative travel" just the same as 10mm extra "sag"

[luhbo]

Isn't 10mm "negative travel" just the same as 10mm extra "sag"

 

Yes, that's the same, probably. But then this implies also that all the ladden/unladden relations as percentage from one or the other value, maybe relative to overall stroke as well, are more than "relative".

 

Hubert

[Guest ratchethack]

I almost agree with you.

The extra 10mm should not be used to reduce bottoming by riding higher.

I believe that doing so would stress the driveshaft joint and create an unstable bike by being too high in the rear.

Dave, there are many many cases where the popular misconception of "more = better" does not apply. IMHO, this is one of 'em.

 

I believe it unwise in this situation to second-guess the Guzzi engineers, who have limited driveshaft angle for a purpose -- that purpose is to keep the driveshaft within safe operating conditions at all times. I ride in some pretty rough conditions and this is certainly critical to me, but every rider encounters unexpected road conditions that can bottom-out and top-out the rear suspension.

 

It's not enough to consider only the "normal operating range" around laden sag here when it comes to driveshaft angle. If you increase shock stroke beyond the OEM length, no matter how you set preload, you are increasing either bottom-out or top-out, or both, depending on what you do with the eye-to-eye length. IMHO, if you lengthen shock stroke (and therefore increase top-out and/or bottom-out points) you are exceeding the safe operation of the driveshaft.

 

Your graph is constructed to show laden and unladen sags across every shock in the graph as a percentage of eye-to-eye measurement. This is incorrect. Laden and unladen sags are correctly considered as a percentage of available shock travel -- or more correctly -- available wheel travel, which is of course directly proportional to shock travel.

 

When you increase shock stroke over stock while maintaining stock eye-to-eye length, you are increasing wheel travel by double the increase. When you increase eye-to-eye length, you are again likewise increasing wheel travel by double this. When you increase BOTH, you're compounding the doubling, substantially increasing driveshaft joint angle in the downward direction. In this case, you can adjust sags any way you like, but the ride height will have been increased considerably and the chassis geometry will have been altered with it.

 

It's very easy to get into trouble with geometries once you start meddling. . . . . IMHO, best stick with the intent of the engineers who designed it when it comes to intricacies of chassis geometry. . . . unless you know better, that is. . . .

 

BAA, TJM, & YMMV

[dlaing]

Dave, I believe it unwise in this situation to second-guess the Guzzi engineers,

SNIP

I am not second guessing them.

Guzzi engineers spec Ohlins, WP, and Sachs for our bike.

Even Chris's Wilbers fall within range.

The numbers 284/66 will travel 2mm less, both up and down, then the Ohlins.

[Guest ratchethack]

Of course Guzzi specs various mfgrs shocks. I have no direct way of knowing what shock stroke they spec other than what they spec'd for my Guzzi. Do you? Many shock mfgrs can make anything you can dream up, and undoubtedly sell "off the shelf" shocks for many applications that are out of Guzzi spec WRT shock travel. What you can get custom or aftermarket has no bearing on what Guzzi spec'd. I'll stick with what I know was spec'd for mine without trying to second-guess what they may have spec'd for somebody else's.

 

BAA, TJM & YMMV

[dlaing]

Your graph is constructed to show laden and unladen sags across every shock in the graph as a percentage of eye-to-eye measurement. This is incorrect. Laden and unladen sags are correctly considered as a percentage of shock travel -- or more correctly -- of overall wheel spindle travel, which is of course directly proportional to shock travel.

Perhaps I did not stress Note1 enough:

"Note1-- The sag are approximate recommendations with a bias of importance on low ride height...Obviously the Sachs and Wilbers should have different sag positions within the illustrated fields."

I believe ride height is very important.

I also believe "proper" sag as a percentage is important.

I have already explained how I believe the Ohlins should have nearly 10 more mm of sag than the Sachs.

This is primarily due to ride height, but also due to getting the bike spending more tiime riding at a lower shaft angle.

Looking at the two extremely different shocks, the Wilbers and the Sachs we see that if you use the same sag as a percentage of travel, you will get very different ride heights and shaft angles.

But if you set the sag relative to ride height, as illustrated in the chart, you will get a more similar ride height and shaft angle. But this too has a problem, that I believe is the reason for your objection; set to the same ride height, with the same spring weight, the Sachs would be more prone to topping out and the Wilbers would be more prone to bottoming out.

FWIW I prefer the Sachs measurements to the Wilbers, and I believe you are much better off aiming roughly for the Sachs numbers with your Wilbers, as you suggested you are doing.

[dlaing]

Of course Guzzi specs various mfgrs shocks. I have no direct way of knowing what shock stroke they spec other than what they spec'd for my Guzzi. Do you? Many shock mfgrs can make anything you can dream up, and undoubtedly sell "off the shelf" shocks for many applications that are out of Guzzi spec WRT shock travel. What you can get custom or aftermarket has no bearing on what Guzzi spec'd. I'll stick with what I know was spec'd for mine without trying to second-guess what they may have spec'd for somebody else's.

 

BAA, TJM & YMMV

A while back I took the trouble of removing the shock to see how far the swing arm would travel.

In both the topping out and bottoming out direction, I could tell that the Ohlins shock spec fell within the range.

I could also tell it was very close to reaching a failure point, especially in the direction of bottoming.

This made me regret having trimmed my shock bumper....but there were still a few mm of clearance left.

I did not measure the shaft angle, but as I understand it the V1100 sport has a greater angle and it survived the WP shock...but again, it is not the same bike, and maybe they refabricated the swingarm for our bike.

I am not worried about the risk of putting a shock with the Ohlins numbers on my bike.

I understand and respect your decision to be eliminate that risk.

[luhbo]

..

Looking at the two extremely different shocks, the Wilbers and the Sachs we see that if you use the same sag as a percentage of travel, you will get very different ride heights and shaft angles.

.....

 

That's it, Dave. I don't think that anyone will say that sag is more important but the correct ride height.

 

The absolute height is what counts for the correct chassis geometry, and not what percentage of stroke it stands for.

 

Hubert

[Guest ratchethack]

That's it, Dave. I don't think that anyone will say that sag is more important but the correct ride height.

 

The absolute height is what counts for the correct chassis geometry, and not what percentage of stroke it stands for.

 

Hubert

Hubert, I disagree.

 

Yes, ride height is a different consideration than sag settings. However, you can put a broom handle between the shock mounting points to achieve ideal ride height and correct chassis geometry at all times (thereby achieving ZERO laden and unladen sags), but I suspect the ride and handling would leave lots to be desired.

 

Percentage of available wheel travel WRT both laden and unladen sags is what counts for ride and handling, and correct laden sag -- as a percentage of wheel travel -- should maintain as close to ideal chassis geometry as possible over all riding conditions. Again -- the only way to achieve this is by correctly matching spring rate to load.

[Guest ratchethack]

A while back I took the trouble of removing the shock to see how far the swing arm would travel.

In both the topping out and bottoming out direction, I could tell that the Ohlins shock spec fell within the range.

Here's where you went wrong IMHO. It's the stroke of the shock that limits swingarm travel. When you take the shock out, you've removed the limits spec'd by the factory, allowing the swingarm and driveshaft to reach angles dangerous to the driveshaft joints. If you select a shock to fit whatever arc the swingarm describes without the limitations spec'd by Guzzi, y'er off on y'er own. . . . . .

I could also tell it was very close to reaching a failure point, especially in the direction of bottoming.

Unless you had the engineering specs on the safe angle limitations of the drive joints and very carefully measured them against the extremes of swingarm travel, how would you have any idea where the failure point is? This sounds entirely arbitrary to me.

[Guest Nogbad]

I intend to plough my own furrow.

 

To hell with Ohlins and the rest.

 

Fournales