Question for the suspension gurus

[abby normal]

So I had the BMW (s1000rr) out yesterday on a curvy but bumpy
Road.  In the corners, it felt like I was losing traction even
Though I ride at retartedly modest lean angles.  Is this a possible symptom
Of too much rebound damping?  Bike is as it came from BMW.
I never felt like I had enough experience to fool with the
Suspension settings.  This however was disturbing and if I can
Adjust it out I'm ready to try.

[Speeddog]

Tire pressures confirmed OK?

Is your 848 comfortable on the same road and pace?

Front or rear issues?

[abby normal]

Checked tire pressure just before the ride.  The 848 feels better, But
I paid the dealer to set up the suspension on that bike.  I'd say the front
Feels like it's going to wash out going around corners.  On a smooth
Corner, the slipping sensation is absent.

[Moronic]

Hard to diagnose from your description. Unfortunately, it sounds like one of those cases where you need a fair bit of the answer before you can ask the right question.

Some comments, which might or might not help.

1. Your intuitive diagnosis of too much rebound damping on the fork could be right. But forks typically don't have a lot. I've not ridden that model, but my guess would be that BMW is not a long way out with its stock settings on that bike.

2. "Retardedly modest lean angles" - hard to know whether you are being too modest with your self-assessment here. Assuming you are not, then grip on sport tyres should not be a problem even if the damping is a bit heavy at the front.

3. Bumps do diminish grip. Even if the damping is perfect, you will feel less secure than on smooth stuff.

4. A typical reaction when you feel less secure is for your body to become more tense, which commonly is expressed through a firmer grip on the handlebars. That firmer grip on the bars will reduce the level of feel you have for the way the front tyre is performing. (It will also reduce the tyre's performance, as you will be interfering with its ability to react to the road by swivelling the steering.)

5. Add 3 and 4 and you may also be using the brakes more when entering the turns. That throws your weight onto the 'bars, which can amplify 4.

6. If the 848 feels better, it might just be because the steering feels a bit slower and heavier, which could give you more confidence, which would help you relax on the 'bars and stay off the brakes.

7. It surprises me how often issues felt at the front begin at the rear. Many sport bikes are overdamped on rebound and compression at the rear (IMO). If you want to tweak the suspension, it might be more helpful to start at the rear, perhaps
by backing off the rebound a click or three.

8. I apologise in advance if this sounds patronising. Not my wish. Hard to tell where you're coming from. Just wanted to offer my best.

Good luck!

[Howie]

I would start by making sure the bike is now at base settings, just in case. 

[abby normal]

thanks everyone ... all good info.  i think i'm gonna start by having the
front / rear static sag set by someone who knows that they're doing.
when the 848 was set up by the dealer, they backed out the preload
most of the way to make it compatible with my weight.  i looked at
the front pre-load adjusters on the s1000 and it looks like they're toward
the max (all the way in) as opposed to out ... that's a big difference and
maybe a good place to look.

[Speeddog]

Some of the bike magazines have info on where they adjusted things during a test.

[freeclimbmtb]

Im no expert...but I'd say backing down on the rebound would be a good start.  Then again, compression and rebound are kind of push/pull in the valving, so I was always advised to get the compression set right and then bring the rebound up after...

Get a pad of paper, count how many clicks you can back off each of your settings and write them down.  You can back both compression and rebound off all the way and youll scare yourself silly long before you get back to that bumpy road...but if you know where you start...you can add/remove here and there and just tune it by trial and error.  as long as you dont go from 100% to 0%...your error will probably be small enough to keep in control.

ive heard of kids turning knobs and screws all over the place on their CBR's and still being able to ride the thing back to the dealer to fix...

Just takes patience and willingness to try.

EDIT:
Im sure a lot will disagree with my point of view on this, but heres how I look at it:  If your going to pay a pro to set it up anyway, why not give it a shot...it will either go from "not what you want" to either better, or worse...but at least youll have an idea as to what you changed and what the effect was.  worst case, you pay a guy to set it up in the end anyway.

[abby normal]

web-wisdom seems to indicate that 4 - 5 lines showing on the front pre-load
is a good setting for someone of my mass.  if so, then from the factory it came
with WAY too much pre-load.  one of the on-line guides i found says too much
pre-load on the front can make it fee disconnected.

i'll check it out tonight.

thanks for all the input.

[freeclimbmtb]

web-wisdom seems to indicate that 4 - 5 lines showing on the front pre-load
is a good setting for someone of my mass.  if so, then from the factory it came
with WAY too much pre-load.  one of the on-line guides i found says too much
pre-load on the front can make it fee disconnected.

i'll check it out tonight.

thanks for all the input.

I can tell you that with stock everything, my 796 does NOT have the adjustment required for my weight.  I think we figured out the 796 comes sprung for someone that weighs about 170lbs.  At 135# I cant get the rear sag set for my weight with the stock spring.  Front was a similar issue...but the front end swap eliminated that problem with new springs.  I can tell you this:  The new forks with the right springs and ballparked damping from the guy that set it up was such a night and day difference from the stock fork, that I never even bothered to set the sag.  thats on the list for this winter.

Best of luck.

[manwithgun]

There is always going to be a lot of misinformation out there but here are a few pages to rummage through.

http://www.s1000rrforum.com/forum/s1000rr-hp4-suspension-setup-tires-wheels/5035-my-suspension-settings.html

http://www.s1000rrforum.com/forum/s1000rr-hp4-suspension-setup-tires-wheels/2504-suspension-settings.html

Also look to past articles where your bike was tested as often time they post base settings that their experienced test riders found accommodating, though track settings might not be the best for the road conditions you are describing.  

[Kabulpostie]

Here is a link I found while looking at suspension. It gives a table of symptoms and potential suspension adjustment fixes.

[Slide Panda]

Abby - do you know how your weight compares to how the bike is sprung? If your mass and the suspension spring rates are too out of tune (either way) you're going to have nothing but troubles trying to tune a suspension.

[abby normal]

Abby - do you know how your weight compares to how the bike is sprung? If your mass and the suspension spring rates are too out of tune (either way) you're going to have nothing but troubles trying to tune a suspension.

I found a few tutorials indicating that for my weight (170 lbs) the front preloaded
Needs to have 4 lines showing ... Bike came set up with 2 lines showing.  I backed
Both adjusters out 4 turns to the target and will test-ride this weekend.

[Slide Panda]

Not quite what I was asking. The springs will have a rate and that needs to be inline with the weight of the bike, rider and expected cargo (not in this case) for optimum performance. More or less preload does not alter that spring rate