Suspension bouncy when riding off the bike

[SnowRider]

Hi all,

I took a 3 day track course a few months ago (Racer5) on Honda CBR125s just to get more training in a safe environment, and was amazed what you could do with getting your butt off the bike to turn.  It was rainy for a good part of the course, so using the body to turn the bike while trying to keep the bike as upright as possible really made a difference.

Now my question is dynamics on the GS500 for street riding.  I do find it easier to steer the bike even doing something as simple as sticking the knee out without getting my butt off.  But when I do get my butt off, I find the bike bouncy and not giving me the same confidence as with the 125.  I'm not sure if this is normal (because it is a street), if I'm doing something wrong, or I have a setup problem.

FYI, I weight probably 155 with gear on, and have Sonic springs in front for that weight and Katana shocks in the rear with preload at 1 (it was at 2, but felt more balanced at 1 with the Sonics).  Just put the Sonics on this season and boy what a difference they make.  The roads in Toronto are really bad and with the stock springs, the tank would smash into my manly bits with every rough bit on the road.  The bike is so much more comfortable and controllable now, with the exception of the bounciness described above.

Thoughts?  I'm assuming I'm doing something wrong, but not sure what?

(Picture: I think I'm doing something right  )

[Joolstacho]

Very simple: Don't lean off the bike!
You'll lean the bike about twice as far as that pic without needing to lean off the bike.
You're not riding a GP race!

[SnowRider]

So it's the bike?  I figured that by taking my weight off the seat, I'm probably unweighting the suspension too much and it's designed more for comfort than handling.  Am I right?

[Watcher]

Joolstacho is basically saying "just ignore the problem," if you ask me.

I'm not an expert, so I won't claim to know why, but it may be an ergonomic change that is causing you to improperly hang off (off balance)?

Hard to imagine the suspension setup is the issue, if you've got it properly set for your weight.
Are the roads themselves, perhaps, just bouncy?

Plenty of users here track their GSs, though.  I'd be patient for a proper response.

[mr72]

Katana rear shock is a very stiff spring for someone your weight. I outweigh you by 50 lb and even my GS is quite firm with the kat600 shock in it.

Now, the problem might be that "bouncy" is not a very precise term in suspension tuning. Normally when someone says "bouncy" then my response is to add more rebound damping, because my interpretation is that it means after compressing, the suspension "bounces" up too much and this is the very purpose of rebound damping.

However, in your case, I think "bouncy" might just mean "rough". In that case you have way too much spring rate in the rear. Put the stock shock back on and see if it's any better. If you don't have a stock shock then you can have mine. Works fine, I'm just too big for it, come get it. Oh that'll also lower the rear end an inch compared to the kat shock.

I have another theory as to why you might be feeling a difference when you are "getting off" the seat. Number one, when the bike encounters a bump, if your weight is on the pegs rather than on the seat, then you might absorb some of the "shock" with your legs and the bike will then move more under these bump conditions than it would if you had your weight on the seat. Number two, if you are moving to the inside then you probably are not leaning the bike as much and this difference in lean angle will affect the suspension geometry and also make it so you feel the bike move more.

Anyway, technical reasons or not, the solution is "don't do that". Well, unless you're at the track, in which case you shouldn't have bumps, and you probably will want to dial the suspension quite differently. I still think that is too much spring for street riding if you are under 150 lb. ShowBizWolf, anything to add?

[Bluesmudge]

mr72 is right. Kat shock is way too stiff for you. You would be better served by the stock shock, an R6 shock or something tuned to your weight.
I weigh 200 lbs and it's still a little stiff for me.

[SnowRider]

Hmmm....  I think I have the stock shock somewhere.  May be worth switching it back.  But I think I switched it out because the original one may have been blown.  I remember going over a pothole and the next thing I knew, I was standing straight up in dirt bike position.

As to bouncy, not rough but soft.  It feels like the bike is moving up and down gradually, so the bike doesn't feel level.  The streets are bumpy, but I was expecting the suspension travel to absorb that.  I do stand on the pegs, so I think you're all right: keep my butt on the bike and weight on it.

But hanging off is soooooo fun   Prolly should look at another bike, but I love the simplicity of the GS500.  Airbox, Carb, Engine.  There's something elegant and fascinating about something that runs because of the way it's built, not because a computer is controlling it.  That and insurance is cheap on a 500cc.

Thanks all.  I think butt on bike is the trick for now.

[Bluesmudge]

You can find low mileage stock shocks pretty cheap.
If you are serious about pushing the GS to its limits you should do some reading on suspension tuning. My GS feels like it's on rails, no matter my body position. What is the spring rate on your sonic springs? What weight fork oil are you using? How much preload do you have? I am thinking you dont have enough preload or the front fork weight is too light.

Also. Dont listen to these guys. When riding on pavement, hanging off will reduce lean angle, which will leave more traction for cornering and braking. The only reason not to hang off the bike is because you are lazy or think it looks stupid. But at any given speed it's actually safer. If you like to practice proper road riding technique, go for it, it's just completely unnecessary if you are within the speed limit. At legal speeds, hanging off will result in cornering with the bike almost completely upright. At street speeds it's almost more fun to have bad technique so the bike leans over farther.

If you haven't yet, read Twist of the Wrist Volume II and practice, practice, practice. You should only weight the outside peg when transferring body positions between corners. Never put weight on the handlebars. You should be supported by one knee, butt, inside peg, and core strength.

[ShowBizWolf]

ShowBizWolf, anything to add?

You said it all very well mr72

I agree, I think the R6 shock would be a better choice here. I weigh ~150lbs without gear and I liked the R6 shock when I had it.

Currently I have the SV650 shock and I like it too... but it adds 2" to the stock height and it's set to the lowest preload so I could get the sag right.

[SnowRider]

Bluesmudge,

I've got the Sonic Springs running 0.75 kg/mm, 10w oil, with the recommended preload (spacer flushed with top of tube). I'm going to see if I can pick up the old rear shocks and put those in, although I want to fix less and ride more since I spent all of last season with my bike on the stand (trying to fix a bike in a garage parking spot with a headlight is a pain).  Will a stiff rear shock cause the bike to float like what I described?  I thought a softer shock would do that, not a stiffer one.

The big realisation with hanging off the bike was how stable the bike was in the rain.  The whole emphasis of the course was "keep bike up to get more traction and get your bike to turn via body positioning.  I definitely felt confident using that technique vs. leaning the bike and was doing things I didn't think I could do.

Will definitely read up on suspension.  Last time I had to worry about suspension was on my go kart, but that was more chassis flex, tire pressures, and how much padding you have on your butt.  That's also why I love the GS500: it's only slightly more complicated than a kart.

[ShowBizWolf]

Just had a thought... do you have the rear sag set up properly?

[Watcher]

Also. Dont listen to these guys. When riding on pavement, hanging off will reduce lean angle, which will leave more traction for cornering and braking. The only reason not to hang off the bike is because you are lazy or think it looks stupid.

It's also a hot button for cops, which is good incentive not to do it.

I'm firmly on the fence, here.  Yes, hang-off technique has real world application.  Yes, it does take more energy and "looks stupid" at low speed.

But there are ways to move your body weight around and gain the benefits without being "street Rossi".  Hand placement on the grips and upper body position (drop the elbow) is more than sufficient for most to all street cornering.

[Joolstacho]

Joolstacho is basically saying "just ignore the problem," if you ask me.

No Watcher, what I'm saying is: Don't CREATE a problem that in reality is NON-EXISTANT!

I think what is happening is this:
Sliding bodyweight towards one side of the machine, diminishes the 'solidity' between body and bike, allowing the rear end of the bike to move up and down more because of the full weight of your body isn't bearing fully on the rear suspension -you're inducing a little amount of flexibility into the system.

At moderate angles of lean I got around Philip Island quicker on my GSXR when I stayed 'planted' than when I used body slides to lean off.
Only at very extreme angles did I find leaning off helped. Just my experience.
Blokes leaning off at moderate angles of lean looks totally pretentious and ridiculous anyway doesn't it?

[SnowRider]

Just had a thought... do you have the rear sag set up properly?

I think I remember getting the sag set properly when I installed the shock, but can't remember exactly.  Probably dial it to the lowest setting if it's not already there.

As to damping, I have it set at 1.  I was riding around with 2 on the stock front, but reduced it to 1 when I installed the Sonic Springs to get the front and rear response to match.

[mr72]

The damping on the rear shock has nothing to do with the spring rate. And if you put .75kg/mm springs in the forks then the rear spring rate is WAY firmer with the Kat shock. And you need more damping with a harder spring rate, not less.

My math says the katana shock is something like 35% stiffer than the stock GS500 shock, and it's about 1.5" longer. The stock fork springs are like 0.65kg/mm IIRC To get the front spring rate to balance with a Katana shock, you will need about 0.85-0.90kg/mm springs, and to control that harder spring you'll need 15wt fork oil with the stock fork damper.

Also I don't know how you can set the sag correctly with the kat shock and your weight. When I weighed 230 lb I had the right amount of sag on my GS with zero preload on a kat shock and 0.90kg/mm fork springs. To get the front end ride height to match the rear with the longer shock, I lowered the fork tubes in the triples almost an inch. Now that I'm under 200 lb there is very little additional sag when I get on the bike, and it's pretty tall.

I don't know nearly enough about performance riding to comment about your riding technique or how that affects suspension feel, since I just ride like a grandpa within the speed limit. But I can tell you that your rear spring is too stiff for what you're trying to do. The stock shock will have a better spring rate but the damper is very basic and may not be tuneable to your taste, although it is very much like the kat shock on "1". There are other options with the stock spring rate and adjustable damper.

[SnowRider]

I don't know nearly enough about performance riding to comment about your riding technique or how that affects suspension feel, since I just ride like a grandpa within the speed limit. But I can tell you that your rear spring is too stiff for what you're trying to do. The stock shock will have a better spring rate but the damper is very basic and may not be tuneable to your taste, although it is very much like the kat shock on "1". There are other options with the stock spring rate and adjustable damper.

I think R6 shock is my next step.  Saw a few on eBay for a good price shipped to Canada.  Either that or put on 50lbs, which would be a lot more work and more expensive. 😂

Thanks everyone for the help!

[qcbaker]

I don't know much about the intricacies of suspension setups as the stock one seems to work fine for me . But, I do know about a decent bit about sport riding and hanging off is proper sport riding technique. It's not strictly necessary, and I'm not saying you should be dragging knees on the street or anything crazy like that, but hanging off just enough to shift the center of mass and keep the bike a little more upright helps keeps the bike stable. Plus, it gives you more "wiggle room" to adjust your line or slow down if necessary, since you're using less of the bike's available traction to complete the turn.

I think what is happening is this:
Sliding bodyweight towards one side of the machine, diminishes the 'solidity' between body and bike, allowing the rear end of the bike to move up and down more because of the full weight of your body isn't bearing fully on the rear suspension -you're inducing a little amount of flexibility into the system.

No disrespect, but that "little amount of flexibility" is exactly what you want when hanging off. You want flexibility so that you can make adjustments without upsetting the bike. You want the suspension (front and rear) to be right about in the center of travel and be able to move to adapt to steering inputs and imperfections in the road. Plus, like I said before, having that extra bit of traction available as an "evasive maneuver" buffer is safer for you as a rider.

At moderate angles of lean I got around Philip Island quicker on my GSXR when I stayed 'planted' than when I used body slides to lean off.
Only at very extreme angles did I find leaning off helped. Just my experience.

Not saying your experience is invalid, but my guess is that had a lot more to do with your own confidence than it does actual body position. Smooth steering inputs are more important than lean angle unless you're at the absolute limit of traction. But, using proper body position keeps you further from that limit and personally, gives me the confidence necessary to stay smooth.

Blokes leaning off at moderate angles of lean looks totally pretentious and ridiculous anyway doesn't it?

Don't really care much how other people think I look when I ride as long as I'm not endangering them. I'd much rather you point and laugh as I stick my knee out cornering at 45mph than lowside because I tried to scrub off a little speed during the corner and overwhelmed the front tire because the bike was leaned over further than necessary...

[ShowBizWolf]

Also I don't know how you can set the sag correctly with the kat shock and your weight.

+1

I have .75 Sonics in my forks too. I'm not sure of the method you used to set your sag but I agree with mr72, it's hard for me to imagine it possible to get it set correctly with the Kat shock.

Here's a good video about setting sag:
https://www.youtube.com/watch?v=ZtzTyCKh5fY