Feels like I'm low-siding...

[Mr Earl]

On occasion (and I don't know what causes these occasions) when rounding a corner, the bike feels like it's starting to low-side.  It happened again yesterday afternoon.  It's pretty much always when making a right turn at an intersection, can't recall it happening in twisties.  And rarely in left turns.  Clearly there's no traction loss, it just feels like that.  I usually straighten up the bike instinctively, no ill after-effects.

When I got the bike, I accidentally reduced the shock pre-load too far (PO was a big guy and had cranked it up) and suffered this same symptom.  Corrected the pre-load, and it seemed to fix the problem.  Then I noticed it recur with too-low air pressure, so I started running 35-36 PSI in the rear, and that seemed to help.

Yesterday when it happened, I was out test-riding after installing 900SS Showa forks (wow!) and Swatt clip-ons (sweet).  The bike was responding really well even at the stock suspension settings, then I went around the right-hand corner and boom.

The shock seems pretty stiff right now, and I'm reluctant to crank up the pre-load.  The rebound damping is stock at 8(?) clicks out from full clockwise.

Any ideas?

[scott_araujo]

I have the same bike.  I did this a couple of times at the track, feels like I'm losing the rear, straighten up, bike corrects no sweat.  I was catching the low slung exhaust.  It's really subtle, no major grinding noise or anything, just slow, easy loss of traction at the rear that's easy to recover from.  On the left I catch the side stand.  Low preload or low pressure would make this more likely to happen.  Check your muffler on the right.  If the little slanty section where it meets the pipe has fresh scuff marks, mysery solved.

One note: I was catching the exhaust.  My friend on his 620 was dragging pegs.  I guess depending on how the suspension is set up and how heavy you are can affect what touches down first.

Hope this helps,
Scott

[Mr Earl]

Scott,

I can't find any recent drag marks on suspect parts.  The bike is not really leaned over when this happens, I've had it lower in twisties with no problem.  It seems that it's a suspension issue.  Could it be compression damping of the shock?

BTW, I weigh about 175 now (shooting for 170) so I doubt if I am unduly compressing the suspension.

[Speeddog]

What condition are your tires in?

Is there a lot of crown on the road where this occurs?
This makes the camber changes on the road a bit weird, and can make the bike feel odd.

[somegirl]

What condition are your tires in?

Is there a lot of crown on the road where this occurs?
This makes the camber changes on the road a bit weird, and can make the bike feel odd.

I was thinking possibly squared-off tires.

[Raux]

i'm gonna ask this and please don't get offended...
how is your turning technique? if it only happens on right handers...

[scott_araujo]

In addition to what others above mentioned, is your back wheel aligned?  If it's not in line with the center of the bike turning to one side will feel different than the other.  As a quick check you can lay a ruler against the rear sprocket.  If it doesn't fall on the line of the chain you're rear wheel is probably skewed to one side.

Scott

[RB]

I was thinking possibly squared-off tires.

+1

since the profile of the tire is no longer a nice arc/curve, the tipping point on the edge of the square will make the bike feel wobbly at tip-in. So the effect on the rider is a grey area where the lean angle of the bike/rider is different from where the tire square is occuring. This would explain why you haven't noticed it in the twisties. It is still there, but you are leaning harder, and using the less used portion of the tire.

[Mr Earl]

What condition are your tires in?

Is there a lot of crown on the road where this occurs?
This makes the camber changes on the road a bit weird, and can make the bike feel odd.

The tires are good, Diablo front <2 years old/<4000 miles with little to no flat spot, Diablo Strada rear about 1 year old/<2500 miles in perfect condition.

I looked at the turn last night while sitting in the opposing traffic lane at the light.  The surface is good, no tar snakes, dips, etc. and the crown is minimal.

i'm gonna ask this and please don't get offended...
how is your turning technique? if it only happens on right handers...

No offense taken.  I don't pretend to be particularly skilled.  I decelerate as I approach, usually left-of-center, then sort of unconsciously pick a line, even out on the throttle, push the right bar, and mildly accelerate through the corner.  I'm thinking the right-handers at intersections are tighter than most other turns and that may somehow be a factor.  If anyone has a technique to suggest, I'm all ears.

In addition to what others above mentioned, is your back wheel aligned?  If it's not in line with the center of the bike turning to one side will feel different than the other.  As a quick check you can lay a ruler against the rear sprocket.  If it doesn't fall on the line of the chain you're rear wheel is probably skewed to one side.

Scott

I'm careful to align the back wheel using the straightedge on the sprocket technique whenever I loosen the axle bolts.  I'll double-check it, but I think it's probably OK.

+1

since the profile of the tire is no longer a nice arc/curve, the tipping point on the edge of the square will make the bike feel wobbly at tip-in. So the effect on the rider is a grey area where the lean angle of the bike/rider is different from where the tire square is occuring. This would explain why you haven't noticed it in the twisties. It is still there, but you are leaning harder, and using the less used portion of the tire.

When the new Strada went on the rear, I immediately noticed a big improvement in turning ease and feel, and hoped that the low-side thing would go away as a result.  Nope.

Note that this doesn't happen on every right-hander, but I can't figure out why it does happen.

[somegirl]

No offense taken.  I don't pretend to be particularly skilled.  I decelerate as I approach, usually left-of-center, then sort of unconsciously pick a line, even out on the throttle, push the right bar, and mildly accelerate through the corner.  I'm thinking the right-handers at intersections are tighter than most other turns and that may somehow be a factor.  If anyone has a technique to suggest, I'm all ears.

Well, right turns at intersections will be sharper in general than left turns (in a place where we drive/ride on the right).

What type of line are you taking?

[He Man]

I used to get the feeling of low siding, my suspension was pretty f*ed up. Some of it was litterally broken. So i upgraded and it felt more solid. Then it came back, but it was my tires that got pretty squared off. then as i progressed in skill, i came again. except this time i really was low siding. 

Id have someone else ride your bike (thats familar with it and that you trust) get a second opinion. If its the bike, then someone else will feel it too.

[Mr Earl]

Usually the standard apex.  This and most intersection right turns locally have pretty good visibility and wide lanes, so late apex turns are typically not necessary.  I've read Proficient Motorcycling and Total Control, and try to incorporate the proper techniques in my riding.  That's not to say I'm always successful.

In the event, the wash-out feeling occurs at the apex or just slightly past it.  I usually begin accelerating just before the apex.  And note that I'm not a really aggressive rider.  My objective is simply to be on a motorcycle, not to challenge Rossi.

I rode home tonight taking the long way (~15 miles), and trying to concentrate on what is happening in turns.  Of course, everything was okey-dokey.  Maybe my problem is related to slackening concentration.

I used to get the feeling of low siding, my suspension was pretty f*ed up. Some of it was litterally broken. So i upgraded and it felt more solid. Then it came back, but it was my tires that got pretty squared off. then as i progressed in skill, i came again. except this time i really was low siding. 

Id have someone else ride your bike (thats familar with it and that you trust) get a second opinion. If its the bike, then someone else will feel it too.

Well thanks, that's comforting to hear.  Without much to base it on, I suspect that my shock is not what it could be.  I'll be installing an S4 adjustable soon, so we'll see how that goes.  The Showas now on the front tell me what POSs the Marzocchis were.

Unfortunately, there is no-one I know who is both familiar with my or any Ducatis and whom I trust... 

[somegirl]

Unfortunately, there is no-one I know who is both familiar with my or any Ducatis and whom I trust... 

No local DMFers that you know?

[Speeddog]

At 4k miles on your front, it could be worn enough to notice a difference.
They can get worn 'triangular', and the bike will tend to fall in easier.

[corey]

In addition to what others above mentioned, is your back wheel aligned?  If it's not in line with the center of the bike turning to one side will feel different than the other.  As a quick check you can lay a ruler against the rear sprocket.  If it doesn't fall on the line of the chain you're rear wheel is probably skewed to one side.

Scott

on this same note, you said you just installed forks... are you sure you got everything lined up properly out front?