Need a suspension guru

agnes

agnes

agnes

Soldato
Joined
1 Dec 2006
Posts
16,900
Location
Amsterdam, NL
Afternoon all, I need someone who is good with suspension to help me understand a few things.

It's for a motorbike but if I am thinking correctly the same principles still apply. When the bike is fully loaded up with pillion, panniers and top box, in 'Urban' mode it's too soft on the rear, sags pretty low and has hit the sump guard plates on some speed bumps and has bottomed out once or twice.

The bike is a Ducati Multistrada 1200S, it has electronic Ohlins suspension, of which you can change the rider mode between sports, touring, urban and enduro. Whilst each setting also adjusts the amount of power, aggression of the power, traction control and ABS. It also adjusts preload, compression and rebound.

Each of the 4 rider modes also has a further 4 presets from there, rider, rider and luggage, rider and pillion and rider, pillion and luggage... You get the picture now I hope.

Anyway, amongst the settings you can go in and alter the compression, rebound and preload.

Here is a quick screenshot of a excel sheet for just the RPL mode (rider, pillion and luggage) to show what the defaults are.

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My question is this, what can I adjust to reduce the chance of bottoming out and stop the bike riding so low when fully loaded up in Urban mode, and the same but not as much in Touring mode.

I'm cack at suspension stuff. I can provide a link to the original spreadsheet if anyone needs it? Thanks go to www.motorcycleinfo.co.uk for the suspension settings sheet.
 
Yea, it's a common upgrade, the standard rear Ohlins comes with a 85Nm spring, the upgrade is to 100Nm... However, it will cost me an arm and a leg (over £350...) just to upgrade it. So I was hoping to adjust some settings and at least get less sag and stiffen up the suspension a little.
 
If you increase preload that should reduce the amount that the bike drops when you add mass to it. Increasing compression stiffness will reduce the amount of give in the suspension when you hit speedbumps etc.

Edit - looks like the numbers are counter intuitive on the compression/rebound side of things. More damping Slows the response of the damper to a shock event (such as a bump). In order to minimise grounding you will want a slower compression reaction (so more compression damping) and/or a faster rebound reaction (so less rebound damping). So reduce the compression number, increase the rebound number and increase preload should all help in some way.
 
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If the preload can be wound up any further then that will add some springrate also upping the bump damping might help with the bottoming out when hitting a speed bump but in the end it's the springrate that will make the difference.
 
Dogbreath said:
Pre-load has no effect on spring rate (unless it's a progressively wound spring), but it is the only adjustable parameter that will increase the suspension height when loaded up.
Click to expand...

I stand corrected, I've always been under the impression preload would change the spring rate from my experience with messing about with mountain bike suspension.

But it looks like on road vehicles changing the spring to a stiffer one is the way to do it.
 
Sadly, preload is at max (16), so that's no longer an option.

I will adjust the other 2.

Thanks guys.
 
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