Suspension stuff

[Wobs]

Hi y'all,

I've got a 50,000 mile 1150GS. Treated her to a new set of Wilbers about 5,000 miles ago. Front seemed really harsh and nervous but being a lazy bugger and because you've gotta take the front shock out to adjust preload, I never got round to it until now.
So I looked in the Wilbers instructions and they say set up dynamic sag at about 35mm. That puzzled my feeble brain 'cos I know BMW brag that front travel is 190mm and I always thought that sag should be set about one third of that or about 60-65mm.
My shocks had come with sag at about 35mm.
Anybody got any ideas please.

thanks wobs

 

[JohnnyBoxer]

Have you adjusted the rebound.......................worked wonders for my, new-to-me Wilbers

Front - 25

Reat -18

 

[Deleted account 190117001]

Dynamic sag is measured whilst your sat on the bike with a friend
taking the measurement.
It sounds more like your compression damping could do with reducing.

Set the sag first.

 

[Wobs]

Not yet, thought I'd set sag first. Mine set at 13 and 13 by the factory. I'm just baffled by sag 'cos I always thought you had to get that right first else everything else wouldn't work right.

 

[JohnnyBoxer]

Not yet, thought I'd set sag first. Mine set at 13 and 13 by the factory. I'm just baffled by sag 'cos I always thought you had to get that right first else everything else wouldn't work right.

Rebound is much too hard.................my bike was nearly unrideable on the factory setting of 13/12

 

[Wobs]

Hi Bez,
Yeah I checked dynamic sag and thats where question came from. I've now adjusted pre-load to give me about 60mm that being about a third of what BMW claim of total travel. Feels all nice and squishy when you sit on it now but work has stopped me taking it for a ride so far.
Still puzzled why Wilbers set sag so low. Isn't 35mm more of a sports bike setting? Or am I completely wrong?

 

[Wobs]

Have you adjusted the rebound.......................worked wonders for my, new-to-me Wilbers

Front - 25

Reat -18

Just to be sure that means 25 clicks out from max rebound right? That makes sense to me. I remember reading somewhere a long time ago that GS's should be set with minimal rebound and preload at front and just over halfway at rear. On standard shocks I think that was though although same logic should apply to aftermarket I guess.

 

[Deleted account 190117001]

Compression damping and rebound damping should be set according to the terrain you are riding on adjusted to your body/luggage weight.

For instance .
When I acquire a new motorcycle.

I usually gently wrap a tie wrap around one of the fork stanchions
so when the suspension compresses it leaves the tie wrap at the max travel
but it's tight enough to stay there.(I generally remember any major pot holes on the ride and re-set the tie wrap.)
This tells me how much travel I'm using on the chosen terrain.

Increasing or reducing the compression damping will alter the travel .
ie ,rough, bumpy off camber B roads.
I will reduce compression damping.

Fast swooping Autobahns,
I will increase compression damping.

First thing to start with Is finding how many clicks of compression and re-bound you have.
Then you can guess how many clicks up or down for the chosen terrain.

Bez.

 

[JohnnyBoxer]

Just to be sure that means 25 clicks out from max rebound right? That makes sense to me. I remember reading somewhere a long time ago that GS's should be set with minimal rebound and preload at front and just over halfway at rear. On standard shocks I think that was though although same logic should apply to aftermarket I guess.

Correct

 

[Wobs]

Compression damping and rebound damping should be set according to the terrain you are riding on adjusted to your body/luggage weight.

For instance .
When I acquire a new motorcycle.

I usually gently wrap a tie wrap around one of the fork stanchions
so when the suspension compresses it leaves the tie wrap at the max travel
but it's tight enough to stay there.(I generally remember any major pot holes on the ride and re-set the tie wrap.)
This tells me how much travel I'm using on the chosen terrain.

Increasing or reducing the compression damping will alter the travel .
ie ,rough, bumpy off camber B roads.
I will reduce compression damping.

Fast swooping Autobahns,
I will increase compression damping.

First thing to start with Is finding how many clicks of compression and re-bound you have.
Then you can guess how many clicks up or down for the chosen terrain.

Bez.

Hi Bez,
Problem is that unless theres a little screw I haven't seen I've only got pre-load and rebound adjustment on the front shock. I understand what you're saying that if compression damping too strong it could affect travel but not sag I guess.
Problem is with this Wilbers shock, you have to take the damn thing out to adjust preload. Not the cleverest design.
I'm gonna set rebound to follow JohnnyBoxer's suggestion 'cos that makes sense to me and seems I'm currently miles out.
I've done the cable trick to check sag but isn't the sole pupose of pre-load to set the sag? Question still remains, what should sag be set at for an 1150GS? 60-65mm or what the shock came with, 35mm?

 

[JohnnyBoxer]

I would guess that the 35mm has been worked out for GS's, due to their 'unconventional' suepension systems (Paralever/Telelever) which may need less sag than conventional swingarms and telescopic forks, where the 1/3rd rule (65mm) would apply

Additionally, GS's are touring, not trackbikes and regularly carry panniers/pillions............so maybe need less sag and more preload/rideheight

Only a thought, I maybe wrong

 

[Steptoe]

With 99% of bmw owners any other suspension adjustment apart from soft medium and hard is a total waste.

 

[Wobs]

With 99% of bmw owners any other suspension adjustment apart from soft medium and hard is a total waste.

Hi Steptoe,

Yeah, I'd agree. Witness the fact that I've done several '000 miles with the thing totally set up wrong.
But what I really wanted to understand initially was the sag and therefore what pre-load I should be using even before I get involved in other more complicated stuff even if my brain could cope with it.
If I set the back up with just 35mm as Wilbers have said it feels like a rock. Easy to adjust 'cos its got a hydraulic adjuster so what I did with the back is just twiddle it until it felt about right over a period of time. When I finally got round to measuring sag I found I'd got about 60mm.
Front was pre-set at about 35mm which I guess is why it always felt so hard and twitchy and to adjust the front pre-load on these pigging things you've gotta take the shock out which is why I hadn't done it until now being inherently lazy.
Now I've set dynamic sag at about 60mm at the front it feels all nice and squishy like the back (although I haven't ridden it yet) but I can't get my head round why Wilbers have said 35mm.
My very basic understanding of sag was that more or less it should be set up to account for about one third of total suspension travel. I think the gauleiters at BMW claim 190mm so 60mm sounds about right.

HELP