Re: What did you do to or for or with your Laverda today?

Vince said:
I haven't ridden Brett's well sorted RGS since it got a new front tyre but I was well surprised at its hands off the bars wobble at 80kph. Fine at 70 and 90 but a powerful pulsing through the bars at 80 that rapidly progressed to alarming and according to him fine now with a new front type. And that's on an old style not at all fast steering bike. Heard that hands off thing about another bike, very very fast 3C I regularly get to chase a lot.Even though my 3C has lots of mods to speed up the steering, forks through 30mm and 15mm longer shocks and both tyres are fast approaching replacemnt time it does not exhibit this instability even on some shockingly bad roads. Both of these bikes mentioned above are owned by really fussy and tech savvy owners. No idea why and hard to fathom on this style of really stable bikes.What limits me is talent bravery physical stuff,better eye sight would be nice and the biggie here is the land of the constant companion, fear of getting caught
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Mine shows the same behaviour, disappears with a new front tyre.  Really was hoping the new forks would at least lessen the shimmy a bit... no way.  Guess it is the lack of damping from worn tyres, the BT45 shows quite some kick-back on lighter bikes when worn above 50%.  I'll just put up with it until some tyre manufacturer manages to eclipse the BT45 in regard to wet-weather grip.

piet
 
I reckon my Ducati MHR is the most stable bike I own in a straight line. Long wheelbase, rangy steering with plenty of trail, up-rated suspension both ends, reasonably rigid frame, etc. With good tyres it feels like it's on rails. But if the tyres are worn all bets are off. With old worn tyres it'll wobble like a bastard if I take my hands off the bars. Seems the rear tyre is the main culprit when it's worn flat in the middle. The dynamics of why that should be so is a mystery to me.
 
Yep when tyre is new the front end if fine in that you could even take your hands off for a second or two... but once that front wears even the pilot active now with around 3K on it is now showing some shimmy so guess its good night charlie till the next set.
Now I have heard that radials help a lot but well let someeone who has them tell us more.

Funny thing is that the 3C is the most stable in that regard even with the KT100 on the front but shhh dont tell Andy will you.  :o :o
 
I heard that...


I've been wondering whether it's the worn rear tyres which show up any play in the swing-arm bearing/bushes which is then felt as wobble at the steering head.. That said I never noticed it on my Guzzi which once had a reasonably worn rear tyre.. ::)
 
Yeh maybe but I still reckon something to do with the scalloping on the front tyre as sometimes I swap out a rear tyre and leave the front on. Also if the tyre pressures esp on the front are low it makes it more worse.

On the other hand the old K with radials can  be running near zero... well around half pressure and still doesnt have the same tendency..
 
Can't really compare Guzzis and Ducatis to Laverda handling traits.
These bikes are much lower and frames are more triangulated and weight is carried lower.
Triples really are top heavy with higher C of G and the frame design isn't optimal.
 
Well just came back from a fairly brisk run on the RGS, confirmed that is starting to oscillate through the bars now that the tyre has some wear on it. Still nothing too alarming.. what was more alarming was the rear end stepping out when I gassed it on to hard exiting a low speed corner going up Hawkesbury Road.

Been playing with the mapping to take full advantage of the TPS..........now to fine tune the jetting and job done.
 
Brett said:
Yeh maybe but I still reckon something to do with the scalloping on the front tyre as sometimes I swap out a rear tyre and leave the front on. Also if the tyre pressures esp on the front are low it makes it more worse.

On the other hand the old K with radials can  be running near zero... well around half pressure and still doesnt have the same tendency..
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Due to their construction, radials offer far more damping than diagonals.  One reason they last a lot longer, too.

The scalloping is due to too low pressure, the tread blocks are pushed "into" the tyre under braking pressure and wear unevenly.  Worn rears make themselves felt when crossing grooves in tarmac at a shallow angle, generates a twitch in the steering or the "hinge-in-the-middle" feeling from the swingarm.  The large, flat footprint doesn't know where to go at first, and is also influenced by slightest differences in tarmac height.  A rounder profile climbs over these obstacles a lot easier.

I do think true radials can be at least part of the solution to a wobble-free RGS.

piet
 
The shimmy I get can be controlled by a very light grip on the bar- tyres are not in the first flush of youth and plan to change to Bridgestone BT-016 PROs beginning of September, be interesting to see if the shimmy goes when the new tyres go on.  Certainly doesn't affect the way it handles.
 
Reggie3cl said:
The shimmy I get can be controlled by a very light grip on the bar- tyres are not in the first flush of youth and plan to change to Bridgestone BT-016 PROs beginning of September, be interesting to see if the shimmy goes when the new tyres go on.  Certainly doesn't affect the way it handles.
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Mine doesn't need any effort to keep on line either, but let the bars go, all hell breaks loose.  Absolutely no influence on handling either.

piet
 
I've nust fitted BT016 Pros to POP but it hasn't turned a wheel yet.
Will let you know how they feel.
 
Yeah, be interested in that.  Not much choice now that Avon don't make a 150 rear Storm.
 
I too have been experiencing this wobble from the RGS front end between 40 & 50 mph. Fine below & fine above. Notice it more on deceleration. Last year I had no such problems. I changed the fork oil tail end of last season but didn't notice anything dodgy with the front end. It's only since the new Michelin pilots were fitted I really noticed it. Removed the front wheel & checked balance thinking a weight had fallen off. Streering head bearings felt a bit notchy so changed them out thinking that's it sussed but no difference. Checked the swing arm bearings & greased them, no difference, changed out the rear shocks for kawa zrx1200 units. No Feckin difference. Played about with tyre pressures & it's still there.

I'm putting it down to tyres & just living with it till they get changed out. My problem then will be do I change for another brand or stick with the pilots as they are the best tyre I've ever had on the bike.
BUGGERIN WEIRD!! ???
 
I have a T30 Bridgestone Radial front.Wear is nice a feathery. I can only fit a 140 so its a Bias Sports Demon Parelli. Nice and stable with hand off.
 
Laverdalothar said:
Three things spring to mind: brake discs, wheel bearings, and tension in the Front fork...
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Wheel bearings checked when new tyres were fitted & checked again when I had wheel off to recheck balance. Discs are EBC floaters & are in good condition, running true. When I say deceleration, I mean just closing the throttle, not breaking..

Not sure what you mean by tension in front fork. ??

Smiddy
 
Smiddy said:
Wheel bearings checked when new tyres were fitted & checked again when I had wheel off to recheck balance. Discs are EBC floaters & are in good condition, running true. When I say deceleration, I mean just closing the throttle, not breaking..

Not sure what you mean by tension in front fork. ??

Smiddy
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Probably the tightness of the steering head bearings.

Cheers,

bazzee
 
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