The Commando Weave

1up3down · May 12, 2012

Thats what it was called when Commandos first came out.

I experienced it shortly after buying my first Commando in 1971.

I was doing about 80mph on a county road and backed off the throttle a bit while at the same time leaned into a moderate turn to prepare to exit the highway.

The back end began to move side to side, then more and more, scared the crap out my 19 year old self.

It was my first "Commando Weave"

It occurs mostly on deceleration because the weight immediately moves forward, unloading the rear wheel and suspension, which then makes the lighter rear end more reactive to the rubber bushed swing arm.

This is felt especially with loosely set rear iso clearance, or simply worn out spindle to bushing slop.

I remember reading of kids buying Commandos and getting the weave and not coming out of it, as in crashing and dying. There was/is no way to prove it was rider error or machine built in design because there was no way to interview the deceased.

Makes me wonder why Norton did not simply keep the swing arm solidly bolted like a featherbed but go ahead with
the front iso and rubber head steady to cut down on vibration, the chief reason for isolastic suspension.

I keep my rear Iso clearance at a pretty tight 4 thousands, have a little more foot peg vibration, but by doing so I greatly eliminate the possibility of the Commando Weave from happening.

Memories, comments?

Flo · May 12, 2012

I have suffered with it for over 30 years.
The last 3 years I have changed wheel sizes, new head steady, super duper tyres, locked swinging arm spindle into cradle.
Guess what, maintaining a steady 95 MPH today, it didn't feel too good.
I go 2 up a lot & it never happens then, only when solo riding.

splatt · May 12, 2012

Chain tension and pull on the iso rubbers, but it wouldn't have been hard to overcome

1up3down · May 12, 2012

I go 2 up a lot & it never happens then, only when solo riding.

yes, because your passenger's weight largely keeps the swing arm from unloading

Splatt I don't see how chain tension can contribute of significance to decelerating weight unloading "weave"
Can you explain, thanks?

splatt · May 12, 2012

Sorry refering to why factory didn't mount swing arm on frame

flashbackk · May 12, 2012

I guess it is funny.
I totaled out my brand new 1973 750 Interstate when I was side by side with my buddy on a BMW 75 going into a nice left hander. I don't know how fast we were going ,but I was up in the meat of third gear. He couldn't hang and started drifting off into the loose gravel. When I saw he was in trouble I got off the throttle and all hell broke out. Next thing I know I am on my back kicking the bike out of my way. I always thought I must have touched the front brake or something because the the front end went full lock left. Now I see I must have shut down the throttle too quick.

I had never heard of the weave. It is nice to know after all these years what happened that day. Now if I had also known about the kill switch I could have avoided many hours sitting on the side of the road waiting for the bike to start again. I wasted alot of the 70's and some of the 80's before I figured out that switch.

Gotta love the internet

Hobot · May 12, 2012

This is what I wanted to hear about in THE Hinge THE Slap THE WevilWobbles. I wasn't ever brave as yoose guys, entering THE Hinge by letting off I only ran into it speeding up so had reserves to back off out of it instead of more of it. I've gotten sort of used to avoiding it but had caused it on a small handful of cycles and it onset in current crops video. Un-tamed Cdo's do it sooner is all. You can practice it more of less on low aired tires which can help reflexes as theres a control reversal thing happening, ie: counter to straight steering of bike trying both right iteslf and follow the road surface into turn to boot. I get my nuts off on the leans and chuckle at the clues staring us Cdo riders to modern elites in the face, ya just can't thrust that dang front tire to haul ya around when its really the rear that should be allowed to rule the roost. I barely survived the first time following a 1100 sports bike on an elevated 35 mph sweeper - when the speed got to the mid 80's All Hell Broke Loose. Not fun so gave up on pressing un-tamed Cdo's. Off in a few moments to join Wes for some afternoon delights.

frankdamp · May 15, 2012

If it "weaves" there's something wrong. I put over 30,000 miles on the prototypes and NEVER felt any weaving. Admittedly, the prototypes were being fettled every day by factory mechanics.

My gut feel is that any weaving is caused by problems with the Isolastics. Alignment between front and back depend entirely on them being the correct clearance and stiffness.

A Commando should NOT weave. The P-11 is a different case. I did some tests on one after a lawsuit against the California Norton importers. As I understood the story, they had put an Atlas 750 motor into a Matchless frame (G15CS?) and sold it as a Norton without telling the factory. Norton got sued after a couple of guys were killed after getting into instabilities during high speed desert racing.

That was a scary bike. Driving down the freeway, it would start to wander, beginning about 50 mph. At 60, it was weaving about half a lane width on about a 300 yard wavelength. By 75 mph it was weaving a full lane width and you couldn't control it. When I rode it, we were still breaking it in, but later a braver man then I said when you got to 85, it stopped weaving.

During all my test riding of the Commando, I don't recall any bad behaviour.

frankdamp · May 15, 2012

P. S. - If you really want to experience weaving, try a Harley. Thery act like a 5-bar field gate with a hinge in the middle. A lot scarier than the P-11, and if you drop one, at near 900 pounds, you need a wrecker to help pick the thing up!

Matt Spencer · May 15, 2012

Mine'd weave set past 4 1/2 , or start to . 2 1/2 to 4 1/2 provideing no slack / hynge / weave / :shock: .

Changeing into top into a 80 mph sweeper convinced me to leave it at LESS than FIVE .No worries , but a pasenger for the bend .
Set it on line and with the 23 T gearing , she ran through , with a gentle schnick schnick felt through the iso's.
Std Head steady ( with 5 mm Alloy side plates ), Id thought Id see if I was being pedantic running em tight.They were around 5 - 5 1/2.

Reset em down to 2 when I got home , took say 15 miles to free off, checked at 2 1/2 at point . So TEN is a joke .

Gotta check the fronts set even Ea side setting em tight , if its missaligned its all cacked across so shim faces not parrallel , as is required
for optimum tautness.Not that Tauht is really applicable , was always very camber sensitive with the 3.00 race tyre front.Much more casual
to ride with 3.60 & 4.10 fitted, just not as precise.Literally checking runnig over a dime in a bend was repeatable . V taut Machine, all clean
& maintained .

Hobot · May 15, 2012

Thank you Frank for more thrilling history. All cycles can be made to weave and wobble if pressed harsh enough even though very careful. Only one cycle I've experienced lets this wave pass though w/o bothering it while the others I've induced it on were so upseting it was no fun at all. Its long been proven you can only tight up the vibe transmitters so much before pilot nerves or frame breaks and still not be up to the load handling of solid cycles. Solid mounts have no more attraction to me, a Princess on a Pea, vibration annoyed too easy. Of late with Trixie's new tires she delays THE HInge enough in special places I got her rear to walk out some, unexpectedly but nice and self stopping. That was on perfect road and wind conditions. In most nice sweepers with some road lumpy ness I back down to avoid any chance of THE HInge, which is always lurking in every bike. In general about 80 mph and 45-ish degrees is Cdo threshold. In general a good sports bike is still sable to over 90 in same conditions.

There is a sort of way around THE Hinge in most cycles including Cdo's, One Do Not Hold Long Held Constant leans, especially accelerating, Instead toss the bike over as sharp hard and far as you can then can straighten up some to settle down then immediately throw down again and back off the lean till set for next facet. Its always better to be able to straighten up some to finish the apex or turn rather than having to lay over more towards the end.

Ms Peel though is a exception to the rule and makes leaning over more and more while powering up more and more till every turn becomes a decreasing radius G's force magnifier.

Engie · May 16, 2012

I have always shimmed the isolastics tight and found handling superb with no sign of wobbles or weave. The only bikes that have done this are ones that have been 'down the road' and the wheels are very slightly out of alignment, then the dreaded tankslapper kicks in.

The only worrying thing the bike does is it waggles the front forks forward and backward slightly when you look along them at about 90mph but I was informed by an aircooled Ducati owner of similar vintage that his does it too, so don't watch the forks flex at speed because they do. A bit like being in a plane and watching the wings flex. :shock:

Hobot · May 16, 2012

Engie you are the first to verify what I've seen while testing stability and traction in power leans, the lower end of forks turn to a blur in fro/aft oscillation. One quick glance is all I'd chance before nailing it more to slide rear around some to slow up in one direction and convert the energy into a new direction before splatting into a bluff face or over a railing. I could not feel it in bars nor sense any bad effect on front traction but worried me that maybe I'd just not pressed hard enough to find out the hard way. It took tedious exam to only find the slightest bit of slack in the top bushes giving about 1/8" play at axle level. I can't speak for anyone else but I absolutely do not trust the front end to help turn when I'm getting on it, so front can wash out or even leave surface w/o any bother to my tri-linked Combat. Its a regular routine occurrence on THE Gravel, even just toddling along sanely 35-45 mph can suddenly be on inches deep marbled turn, so I only use rear to steer with and only use front to help rear tip and steer or once slipping out just let font dolly wheel on its own to follow the dictates of the rear patch thrust. Of course Ms Peel is a one in a row abnormality so I absolutely don't see any other bikes Commando or others as able to go around harsh enough not to depend on front tire traction, so Guess what I'm as limited and scared or *more so* on regular Cdo's or other sports bikes as any one else. Almost all my own crashes have occurred on THE Gravel going straight ahead when THE HInge onset d/t washboards or series of pot holes with stones in them, both on my modern fat tire bike and my un-tammed skiiny tyre Cdo. Not on tri-linked Peel though.

I'll try out JS's composite bushes to see if that tames the axle level blurring, but am consoled by your report its common in the elitest cycles, so may not matter to ignore. On my race tired SuVee650 and new tire Trixie Combaat I can't go around fast enough to notice fork end blurring, just the whole cycle getting upset too much to enjoy so back off with their limits impressed to my bones to forever avoid again.

I ain't that great or brave pilot, only a few years in saddle this last decade+ so can't wait till a real pilot trys out Ms Peel's combo of mods to get back to us with. Forks with extra travel but mainly stiffened against twist ups with progressive dampening and spring rates plus the rump rod an its two helpers. Losing like 50 lb mass sure helps too but have played while loaded down to find not much interference to haul ass in leans.

Dances with Shrapnel · May 16, 2012

Engie said:
The only worrying thing the bike does is it waggles the front forks forward and backward slightly when you look along them at about 90mph but I was informed by an aircooled Ducati owner of similar vintage that his does it too, so don't watch the forks flex at speed because they do. A bit like being in a plane and watching the wings flex. :shock:

Clear sign that front wheel needs balancing.

rpatton · May 16, 2012

Another thing to look at for high speed weave might be what shape your shocks are in, especially rebound dampning. Shocks don't last forever.

Hobot · May 16, 2012

Certainly out of balance could aggravate this, but Peel had balanced front wheel and I could not detect this blurring fro/aft over the ton on straight smooth roads, only on wild far over flings when front not fully gripping. I have not noticed it on my SuVee in same places with unbalanced slapped on used tire, but then again I can only go around on it half fast compared to Peel. I do/did get SuVee's forks to blur in instants of tank slap side/side twists fighting her back up in time or side/side laterally trying do turns like Peel but the big fat tire just slides sideways as my modern can't take the straight steer fork flip over, which feels like snicking another gear to go around faster. Best I can determine is above some frequency these fork vibes are a non-issue but below some freq. they pile up with the chassis and suspension to get really exciting. Before I put on RGM's fork brace the forks felt like rubber bands connecting grips to axle. The brace did not stop the twist up, but did increase stiffness to raise twist freq above affecting anything I could tell. i got 3x's the mileage on my SV and can control its chassis and tank slap on lift ups but can trust her hot race tires to grip. Race tires I find are securer up to a point, then they let go more suddenly than regular compound street tires. I took off the Scott's steering damper as only helps on THE Gravel but interfered with the fast/harsh pilot twists to recover the lost front or rear in time. Crashed me once on THE Gravel going straight ahead and that was it for me.

Someday want to video the various parts on Peel to see what's happening better when she transitions on or off road into other modes of handling. Flat tract slide/drifts are just extensions of counter steering and is load relieving, so not how I live doing hard turns.

Dances with Shrapnel · May 16, 2012

hobot said:
Race tires I find are securer up to a point, then they let go more suddenly than regular compound street tires.

Where have I heard this before (so many times before) where a fellow puts race compound tires on a street bike for street use; they push them without getting up to proper temperature and then splat!!!, the rider goes down. Very predicatable.

pete.v · May 16, 2012

On 72 front disk and beyond, the offset is large. Due to the fact the one side is tensioned so much the the other, it can degrade over time. It is well worth checking for this. I would ride unable to take my hand off the handle bay because it would pull so bad. I discovered the I was 3/16 off center.

After making the correction, it rides true with no hands. This may not have anything to do with weave, but it could be a contributing factor

Hobot · May 16, 2012

Where have I heard this before (so many times before) where a fellow puts race compund tires on a street bike for street use; they push them without getting up to propertemperature and then splat!!!, the rider goes down. Very predicatable.+/quote]

Hehe Dances, does not apply to me, one of the biggest chickens ever to try to ride anything. It may take a few more years for your assumptions on hobot to get resolved but realize my tires are already warm to the touch and completely micro cut to brushy texture by time they touch pavement, then it takes me 20 more miles to get to places I can get them hot to touch and and about 10 miles ~ 7 min. to work up testing more and more till the let goes get conistant, then I'm free to play as I like with full awareness of when and where they will let go, so then my choice not fates. Once non DOT tires are full hot they are so soft they will not hold pebbles embedded past horizontal. Prior to pre-race heating them they embed to grip pebbles so deep/firm they don't scrap off rubbing loudly on the fender. So when I say I know about race tires greasy to digital behavior its same as race guys not uninitated cold tire novices. Race compound was my saving grace to continue to ride my SV balloon bike on THE Gravel as tire grips THE Grit in place till thrown to rear so more effective traction than hard cleated tires. Noisey as hell on way out but silent on return. I have crashed one on new tire with molding on, on winter night, after zips up down the grass bank to road then entered hwy at ~5 mph creeping to make slow 90' turn into traffic direction to have a slow motion slide out of rear onto LHand, which was caught under the bar end. Lifted back up and got home in awe how slick a new tire is at froozen temps on polished hwy crown.

pvisseriii, good point I'd wondered about on the front centered in fork effects and rim stability.

I work a cycle up to limits over a year or so by 3 limiting factors of lean, rear & front grip.
Last year on terrible tires I got Trixie's full sense of lean fouling behavior with factory pegs then on lifted rear sets so only the stand fouls on L and muffer on R. This last week I finally got to taste rear power lean lets goes, with careful attention to pick place NO Hinge onset.
This only leaves front tire to over come on tarmac as already got that down on THE Gravel travel. On THE Gravel its loose enough to over power through THE Hinge but that also speeds us up a good bit so all hell breaks loose on let offs for hazards. Depending on the turn radius, looseness and banking this takes me into 60-70 mph w/o much leaning possible, in turns radius hwy dept marks with warning sign 35 to 45 mph. On tarmac a good Commando can double those speeds with some care and low level lumps of course. If I ride like normal people Trixie onsets THE Hinge within legal limits in turns, but already knew about that so let it happen just to refresh bone memory not to ride like normal people if kicking up heels. When I frisky, I get way back on seat and hunch lower to CoG and try to lift forks off contact and then hang on to power on mainly the rear tire. I leave front fork steering to real experts, as I'm too chicken forever more on that.

If yoose guys ever try foot forward pegs on fork brace you will find out you absolutely can not flick a turn w/o forks extending unless slowing up hard which is opposite of going around faster.

cmessenk · May 16, 2012

I was experiencing the "weave" a couple of months ago...very troubling as the bike had been rock steady all winter...very pronounced and scary at highway speeds. Replaced my worn out AM26 rear tire with brand new treads and symptoms disappeared....all good.

Also had a bad "weave" experience on the same bike back in the 70's....low speed, sudden wobble at 35 mph...felt like it wanted to give me a "high side" at low speed. Turned out my stock 750 head steady had cracked in half was the culprit....switched immediately to the 850 style "box" style mount and problem solved....of course I won't ever have to worry about that nowdays w/ the DT headsteady upgrade.

The Commando Weave

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