R1150RT stock suspension measurements.

[AndyS]

Hi all.

Does anyone have their stock (OEM) measurements from the bike. I am looking for the difference between when the bike is off the ground to that when it is sat on its own, (free sag).

 

Thanks

 

Andy

[greiffster]

I took a couple measurements this morning.

 

For what it's worth, the bike has a nearly empty gas tank and all three bags were on, but empty....

 

The front suspension, measured parallel to the fork, dropped about 1 cm from the side stand to off the ground on the center stand. I didn't have a helper this morning so I couldn't measure the bike vertical.

 

The rear had no measurable sag from the side stand to off the ground on the center stand. I do have the pre-load cranked nearly all the way down for 2 up + bags.

 

I was surprised to not see any sag, but the weight on the side stand cannot be discounted. So, my numbers probably don't mean much. I can check again tonight when someone can help me hold the bike vertical while I measure it.

[AndyS]

Thanks greiffster.

However the change from side-stand to centre stand is not an accurate way to do it. I do appreciate you looking though. It really needs to be on level ground and go from Centre stand to being upright under its own weight.

I measure from a datum on the RHS rear bodywork to an 'edge' on the final drive so each of the measurements is repeatable.

 

On the front, I measure from the lower edge of the top 'triple clamp' to the top edge of the front mudguard bolt.

[greiffster]

Ok, measured from the center stand with weight off the tires to level, vertical under own weight...

 

33mm front

7mm rear

[AndyS]

Thanks greiffster.

That is way different to mine. I think I need to eliminate some of my static sag.

I have 39mm front and 20 rear.

My target is 20-30 Front and 5-15 rear.

[Oldironken]

Hmmm, is there a reference thread or website somewhere that explains all this in layman's terms? (What is this sag you speak of, and why is it important?)

 

For reference i replaced the stock suspension on my '04 RT with Yacugar shocks and springs that were tuned to my weight and riding style.

 

I installed them as delivered and have no idea if they are adjusted correctly or how to change them if they aren't.

 

FWIW - They are a huge improvement over the originals as delivered.

[greiffster]

Thanks greiffster.

That is way different to mine. I think I need to eliminate some of my static sag.

I have 39mm front and 20 rear.

My target is 20-30 Front and 5-15 rear.

 

Do you have the preload cranked all the way down?

[AndyS]

No, it is set about midway, but I want to have more available for when I have pillion and luggage aboard.

[AndyS]

Hmmm, is there a reference thread or website somewhere that explains all this in layman's terms? (What is this sag you speak of, and why is it important?)

 

As you can imagine, setting suspension up 'just so' is almost a black art.

The initial set up is relatively straight forward.

Fortunately the manufacturer has done most of the footwork.

For aftermarket shock absorbers here are a few things we need to consider:

How much does the bike weigh,

how much do we weigh with our luggage.

How much suspension travel can we have,

how comfortable do we want the ride to be.

 

So the suspension travel is dictated by the amount of movement in the front forks / swing arm before anything bad happens.

So the spring needs to support the bikes own weight without losing too much of the available travel.

However, with the bike sat under its own weight we don't want that spring pre-loading to be so strong as to give you full travel of the suspension. Why? well when you are riding and go over a bridge, the bike has to allow the suspension to extend more to allow the wheels to stay in contact with the road as far as is possible. Topping out is not a good thing.

So this little bit of suspension compression is called 'static sag'.

Next, we want to make sure that under normal riding conditions (clothing and luggage), we don't use up too much of the suspension travel.

If the correct spring is fitted, we can adjust the tension on it (pre-load)to give us the correct 'ride height'.

Once the static sag and ride height are set to the manufacturers setting, we can then go about adjusting the damping rates. Often we only have rebound damping control, but occasionally some units have compression damping control too.

These adjustments again have 'ball park' settings and then the end user can adjust for personal preferences; either a softer or firmer ride depending on road/track conditions. If the road is very rough, the damping can be softened a bit otherwise the handling can become sqirrely and road-holding is impaired. Conversely if it is set too soft, the ride can become wallowy.

[Oldironken]

Thank you Andy, that was helpful. I just may spend some cold winter days looking into this deeper.