Been hi-sided off a commando ?

acotrel said:

If your bike has a tendency to run wide coming out of corners, you tend to lay it over more to get it back, just when you are applying urge . It is about the steering geometry.

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It is also about swing arm angle and anti squat.

I'd say one thing in addition. I've watched a lot of the videos of Kenny Cummins and Doug MacRae racing their Nortons. I am not criticizing their efforts and the depth perception in the videos is deceptive. However it looks to me like they don't get on the gas very early coming out of corners, and their bikes seem to wallow a bit, later in the corners. (They don't appear to tighten up as they come around). I love those videos they've uploaded to Youtube, they are very helpful.

I think you are correct about the swing arm angle and squat, the rake must also change in relation to those two things. My bike always feels better and inspires more confidence when I gas it hard. I think it is a very subtle and treacherous effect, and that if I had ten more horsepower and a strong cam spot, it would have launched me by now.

http://www.youtube.com/watch?v=nYYTLJ8YHi4

To stay on point of high siding a Cdo, I'd say it's the most easy and therefore the most safe from hi side of about any cycle sold. My un-tamed Combats always onset THE Hevvy Jivvies with distinct tank slapping tendencies to boot before hi side severity,to feel I'm suddenly way too stupid incompetent to even ride by having gone in so seeming safe but almost lost it. If everything is about perfect in road and wind then can get away almost real sports bike acceleratingly fast, if not then let THE Hinged lesions begin with pass or fail instant grading. If ya got sense enough to know the path and creep up on lean fouling, then max fork angle effort, then power up till break free skip step out of most or all of a tire width, you've essentially topped out on an un-tammed isolastic without becoming a sliding flat trackor. The main 'safety' factor is to get low enough and also fast enough if it does slip out a bit to hook a hi side it mostly just throws ya upright so can swing forks in direction of CoG travel to catch it and carry on to finish the turn or into an open.

Fun and dramatic as it looks a flat tracker slide is a force-load reliving action and not prone to hi sides as much as trying to hang tight in and keepping acceleration more forward than outward. It wastes traction tires and time, Unless you can use it not to loose momentum while letting bike twist to align with a new path direction then just let off throttle some for the spun tire flywheel and engine to hook up out of there.

Alan you got some insightful remarks and a sense of the forces acting and felt, so review your fork aim details thinking-feeling how it is with forks not counter steering. The sudden flip of forks into straight steer is what launches hi sides off the front axle angle to twist frame so rear gets pressed severely hard into the surface, deforms to spring back right over head. On a rigid modern there is nil warning as All cycles [but one] have some issue pilot or digi brains is having to force & fight, so they all get weird-unstable - exactly as you describe observing the vintage hot shots. I listen very close to entry throttle to know how secure they are feeling.

For every action there is a re-action and even rigid balloon tire bikes when they get to buckling frame and tire stresses that feel like crossing a plowed field can be low sided so rear swings out enough to snap a re-action that lifts it over the plowed field while twisting in flight as the frame and suspension and fork oscillations settle down for impact catch and rebound leap out of there. That takes dramatically increasing throttle exactly where the bravest brake point for grounded pilots occur.
Ya seen the bike save itself w/o pilot help, so I'm with Alan on this point, why not just learn to do it on purpose to let it automagically do the rest for ya - way faster and more powerfully than mere humans can. I've seen racers do this but only in special places and not routinely as their rides are so unpredicable in that state its like Russian Roulette bravery or foolishness click click BANG ya gone.

Robobikes actually steer this way like I can very jerky - [not like smooth counter steering pavement racers] and with hot electric cycle power they will be something else. This is not a fault in their programs its just better control in all conditions. I was flabergasted on learning and seeing them do this even on 45' loose gravel slope running along length of slope not just up and down like normal humans. I want to see if Ms Peel can give em a run for the money. May not even have to cheat with ignition static jamming.

I'd suggest that if your rear tyre is heading off towards the kerb, you have no choice whether you "steer into the slide". It's simply impossible to keep the bars straight if the rear wheel steps out of line.

Only time I ever highsided was on our "Family Racer" Commando at Pannoniaring/Hungary some years ago when I tried too hard to get past some bloody racing twostroke that had held me up for several laps in the bends and that I could not catch on the straights.

All I know is I tried way too hard, and overdid it severely on the cornering speed. Whether I shut the throttle or not when everything went into a big rear-wheel slide I still do not know.

What I did learn was a) it is the most painful crash I ever had on a racetrack and b) it happens so damn quick you don't know what has hit you until you lie on your face!

Not recommended.

Joe/Andover Norton

If ya low side or hi side unexpectedly then most likely will crash before ya know what went wrong. If expecting a skip out or trying for it then its quite possible to slide both tires and prevent or cause a hi side as desired. Its not exactly easy but plenty examples though *none* on an un-tammed Cdo I know of on tarmac. Grass Gravel Dirt Sand, Snow and light Mud can allowisolastic Cdo to play this way though still highly likely to Splat like i do on them. But, if pressing life and limb might as well get a sense for it in softer slower conditions.

My most thrilling and spectacular experience on my Commando in 1977 was in Costa Mesa CA on a 1970 Fastback. On my way to work I would turn at this self-serve gas station every day at about 30 mph. I would just lay it over to the peg and stand it back up going 90 degrees to where I started. I didn't pay enough attention to what was really happening, it was just routine. One day I got it laid over all the way to the foot peg when I noticed that the road was wet from the gas station washing its parking lot! I was sliding sideways at 30 mph and as the road became dryer I realized I would high side pretty soon if I didn't spin the back wheel. I grabbed some throttle and kept the slide going and when I got to completely dry pavement I was at full throttle doing a big wheelie down the street-yelling in my helmet: "Did anyone see that??!!!!!!"

Survival is number one priority. The best way off a bike at any speed, is a gentle slide to the deck.

motorson said:

My most thrilling and spectacular experience on my Commando in 1977 was in Costa Mesa CA on a 1970 Fastback. On my way to work I would turn at this self-serve gas station every day at about 30 mph. I would just lay it over to the peg and stand it back up going 90 degrees to where I started. I didn't pay enough attention to what was really happening, it was just routine. One day I got it laid over all the way to the foot peg when I noticed that the road was wet from the gas station washing its parking lot! I was sliding sideways at 30 mph and as the road became dryer I realized I would high side pretty soon if I didn't spin the back wheel. I grabbed some throttle and kept the slide going and when I got to completely dry pavement I was at full throttle doing a big wheelie down the street-yelling in my helmet: "Did anyone see that??!!!!!!"

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Great story. Love the ending.

hobot see's ya pulling off a miracle Cdo stunt motorson and still ringing from the screaming part.
I had the reverse situation happen early on my SV650 in light rain slowed down hill to turn into a station and took the far side of ramp as didn't want to crowd my new friend Wes on his wet drum brake '71, so about 25 mph laid over decently on the paved section off hwy no problemo to see pavement didn't extend far enough so instantly knew I'd go down on THE G#^%$&%^ at the loads needed to miss the culvert = either go over the edge Gravel rashed sideways tumbling or straighten up and take fate like a man, which I did to land ~20 feet out 5 ft down almost at bottom of grass ditch - on both tires too so suspension took most the impact but the soggy sod let go and dumped bike in mud on me. Able to ride it home with minor damage and injury to ego.

Don't know if its a V twin sport bike characteristic vs inline 4 type but my '00 SV tends to sudden skip out-down too easy vs hooking a hi side went pressed pass traction and nil hint tires were at limits as I didn't think was developing that much G anywho>>WoooHOooie. SV is willing to lean over so easy it begins to fall on its own so tried to straight steer it like Peel in a favorite wide corner but dang SV slides its 120 front tire for scary rescue barely in time, not fun so no longer attempt that on anything else.

acotrel said:

It isn't shutting the throttle which usually causes the problem. It is usually a top end motor being pedaled too hard which causes the slide in the first place. The natural tendency is to correct by turning into the direction of the slide, and backing off. The tyre then grabs and stands the bike up, sending the rider into orbit. It is sometimes possible to turn into the direction of the slide, get on the gas even harder and drive the bike upright under you, with a really vicious wheel spin. The MotoGP guys cannot do that with 200 BHP, it all happens too quickly. I suggest most commando based racers seem to be more forgiving of idiocy. With my bike, the steering is so quick, if you think you want to be somewhere, you are there, - however the motor is not vicious. With two strokes you learn to feed the throttle on slowly. I find that with my Seeley, I can gas it extremely hard very early in corners, and even with the quick self-steering or perhaps because of it, it never steps out. I still wouldn't slam the throttle open coming out of a corner. When you have crashed enough, you learn to be smooth. Peter Williams once said 'nothing happens quickly on a commando'. I don't think he discovered the joys of greatly reduced trail with a 27 degree rake steering head.

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PW did race the factory production based Commandos in the production class, as well as racing the F750 class, so I guess he knows what he’s talking about :!:

'PW did race the factory production based Commandos in the production class, as well as racing the F750 class, so I guess he knows what he’s talking about :!:'

The story is always about development. A recent documentary about Stoner /Ducati showed three sets of fork yokes in a draw in their vehicle. Who knows where Norton went , and what was tried by the factory ? I don't believe much experimentation with steering geometry occurred in the 70s, Seeley/Gus Kuhn were probably the most progressive. Seeley frames all used 27 degree rake, and I believe Metal Profiles forks. (I don't know the offset). You might believe that Norton had the Holy Grail and access to the Bible, however Gus Kuhn probably achieved more. In any case it appears that PW was pretty much stymied by the company administration in developing his ideas.