Bike handling

I read in this months Motorcycle Classics magazine about a guy with a Ducati 900 bevel race bike. Apparently it had a tendency to run wide coming out of corners (understeer). So he heated the top frame tubes and pulled the steering back, which did not improve the handling. To my mind it would have made the situation worse by increasing the trail making the bike more stable. I've previously mentioned the handling of my Seeley 850 race bike which tends to oversteer if gassed when cranked over in corners. My feeling is that for most riders neutral steering in corners is more desirable. Both the Manx Norton and the TZ350 Yamaha achieved this, however people still managed to crash them. I found the following video interesting especially if, as you watch it you think about what happens if the bike noticeably tightens it's line, when gassed hard if cranked over coming out of corners :

https://www.youtube.com/watch?v=KVWLIfChUwg

Alan better pm me as N handling only applies to some conditions in each cycle and each cycle can go in and out of N to over - under steer, so not a constant -* but I tell ya what with good enough power to weight and damped out rebounding of all elements ya can select + N = handling instead of it being handed to you. Proof to me of really truly N handling is harsh accelleration into through and out of a decreasing radii... Keep study the cripples video and may find time the crowd roars as they lift a tire on such harsh side Gs, like it was something special, hehee just a type of Phase Three energy transition to me.

Thank you, Rohan. Expert as always ?

Did you spot the translation error though ?

Can't imagine that LAB is going to allow this to remain here.....

The guy with the Duc would have been better off just fitting longer rear shocks. Too much squat in the rear causes understeer exiting corners. Cranking in too much rear preload makes the back end too stiff and front dive on the brakes going in excessive. Heating and bending the front frame tubes may quicken steering slightly, but also alters wheelbase and may cause the frame to become brittle and crack.

Ugh Alan I thot the video was just more rigid fat tire corner cripples killing cycles and pilots so did not view til now - to see wild man Kieth Code my main mentor that allowed me to develop beyond ordinary counter streer and tract use of what a now call merely ho hum phase 2 counter steering. Rideer Code, who is one of my master gurus > lies to everyone *unknowingly* Dangerously saying no one ever crashed by flicking a cycle over Too Fast & that the front tire steers cycles...
UGH...

A cycle can be tossed over harsh enough to crash and often do from the fat tire patchf walking about= sudden leverage shift as it over powers front trying to aim outside turn while engine powered patch trys to trun inward. If you are actually powwering into a turn rather and scardy cat braking in worse possible effect, leaned on smaller patches with tires not in line, then engine power should be lifting forks to full extension unweighing front even to point it lifts front out of effect. This is end of all other cycles max corning forces as they transition into lazy dazy flat tracker wide slides or just low side on rear or high side off rear, because of conflicting vectors oscilation front to rear, ugh. Ya see how easy the fancy pants cycles wobble even in streer level demo on video. I am a Gravel rider which is only non paved surface that behaves like pavement - when scortching tarmac til loose as a goose on THE Gravel. Flat track that is same as doing it on cement covered in layers of marbles.

Master Code has the best video views with a stalk sticking out behind and above pilot to see what he and bike are doing. Moderns can reach almost 70* leans now and I can tell ya moderns CoG is so tall + pilot hanging out/off can allow bike to simply pivot on its horizontal CoG and lift both tires at once to take out others like boweling pins. At tire loose rates, power, leans, its more like water skiing or aircraft flying and ya do not want the gas in wing tanks to get too unbalanced, same with pilot, so when the going get tough I am perfectly centered on bike so all forces go through my mass strainght into rear axle and besides when I change direction its so freaking fast change there is NO time to shift head let alone whole body so another sign of corner cripples that work pilot to death.

Kieth almost had his crew quit on the spot over what I was doing so crazy looking but Kieth kept his word and turned me loose again to point I was able to explode into Phase Three and Phase Four engergy handling on stupid sports bikes only made for bee line rocketry which become so unpredicaable by slightest influences I swore off doing it on them but have spend a decade to get power to weight and new stance on Peel to reveal it these rear tire only power steering states.

I sniff rears and saw Cdoe main instructor had melted tire to grease, Kieth tire was abraided to little balls to roll on while my tire had the eh smeared out into transparent sheets 1/16 to 1/8 inch long, heheheheehehehehehehehehe YEEHOODOGGGIEDOO, Also when let out alone they would all come back shut down for silence, when I shut do the cooling fans ran for almost 10 min, guess who could put down WAY MO PoW even on a piss poor corner cripple. pashaw.

Also when let out alone they would all come back shut down for silence, when I shut do the cooling fans ran for almost 10 min, guess who could put down WAY MO PoW even on a piss poor corner cripple. pashaw.

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wow

I guess you really showed them

do tell us more, all about yourself being such a superior rider and all, how those modern "corner cripples" are no match for your talents?

rather depressing reactions on subject near and dear to me> indeed i show them and me too to point wished i had not waster time money on a combat clunker wanting to sell it off for something way more capable but then tri link experiment completely changed my black heart and broccoli head< you just do not know what ya missing out on> but i sure do> let go of your bars and just use body English to steer a easy turn< see which way the forks turn< hehehohohaha>

if bike must be straight steered to turn then pilot is having to fight against natural forces which can get around pretty darn fast but not nearly as fast as when nothing for pilot to fight against as all forces working together to get on around>>>

btw i really like broccoli as its dim component relieves hormonal women that are happy to see me for more
http://examine.com/supplements/Diindolylmethane

ludwig said:

What You Need
Ingredients...
...Broccoli...
...Serve immediately.

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You forgot to include "Norton Commando" in your text.

Thanks acotrel.
The others may be correct that it is not Commando specific but I enjoyed watching it and appreciate you having posted it.
Ta.

There are a zillion non-Norton thingies on u-tube Owen, doesn't take any skill whatsoever to find em.

Got a problem with your Duc.
Post it to the Norton Forum, they'll sort it out.
If this had been posted to the Anything Else section it may not be so offensive,
and LAB won't exercise his delete button...

Mike Hailwood used to say "slow into a corner, fast out."
It worked for him.
Running wide = not using the brakes enough, may indicate a braking problem.
With the rider ?

Got a problem with your Duc.
Post it to the Norton Forum, they'll sort it out.

:lol:

I had a '72 Ducati 750 Sport - same chassis.

IIRC, that thing had a 60" wheelbase and 6" of trail, and maybe 29* of rake.
Say no more, at any speed below 60 or 70 MPH it was a pig BUT at speeds above 100 MPH it was magical.
You could really work it - push the front, power steer it with the rear, walk it - front/rear, "bitchin," as they said back then.
It didn't work in tight canyons but on the big fast federal mountain highways of So Cal, she was unbeatable, magic.

When Cook Neilson won at Daytona in '77, that track was the big banked tri-oval with one chicane.
His bike's chassis, at that time, couldn't have been better for that track's high average speeds.

Your friend should leave it alone, it is what it is, the engine is long, therefore the wheelbase is long.

xbacksideslider said:

it is what it is, the engine is long, therefore the wheelbase is long.

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Haven't the MotoGP Race Team been grappling with this same 'problem' in MotoGP for some while now too.
At some point, it was said the carbon-fibre frame was too rigid, then it was the engine was too long,
it'll have to be redesigned to make the engine shorter (!!).

Nortons went to some lengths (pardon the pun) to make the Commando longer, so it was a man sized bike.
It could have been made short and cobby, but that avenue previously led to some sales resistance....

Rohan said:

Nortons went to some lengths (pardon the pun) to make the Commando longer, so it was a man sized bike.
It could have been made short and cobby, but that avenue previously led to some sales resistance....

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My 36" inseam thanks them for that
..

Rohan said:

Nortons went to some lengths (pardon the pun) to make the Commando longer, so it was a man sized bike.

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what's the story?

It could have been made short and cobby, but that avenue previously led to some sales resistance....

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i assume the atlas?

re; "I read in this months Motorcycle Classics magazine about a guy with a Ducati 900 bevel race bike. Apparently it had a tendency to run wide coming out of corners (understeer). So he heated the top frame tubes and pulled the steering back, which did not improve the handling. To my mind it would have made the situation worse by increasing the trail making the bike more stable. "


This appears to be from someone who obtained the idea from someone in a conversation a pub- and believed them :!: :shock:

The tyre choice alone can have an underlying effect on a bikes handling, along with the wrong tyre pressures -some tyres will not grip when banked over whilst others will (notwithstanding the age of the tyres -an old race compound tyrewill be sH*t)
The Duke is one of the good handling bikes even though it has a longest wheel base.

There are 101 other ways to improve the bikes handling in corners all of which I would try first.

xbacksideslider said:

I had a '72 Ducati 750 Sport - same chassis.

IIRC, that thing had a 60" wheelbase and 6" of trail, and maybe 29* of rake.
Say no more, at any speed below 60 or 70 MPH it was a pig BUT at speeds above 100 MPH it was magical.
You could really work it - push the front, power steer it with the rear, walk it - front/rear, "bitchin," as they said back then.
It didn't work in tight canyons but on the big fast federal mountain highways of So Cal, she was unbeatable, magic.

When Cook Neilson won at Daytona in '77, that track was the big banked tri-oval with one chicane.
His bike's chassis, at that time, couldn't have been better for that track's high average speeds.

Your friend should leave it alone, it is what it is, the engine is long, therefore the wheelbase is long.

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Amen to that! Ducati persisted with that steering geometry for several decades. The first 8 valve Ducati I had was a 748 SP which had exactly the characteristics you describe. On the Isle of Man, for example, those long, very fast sweepers (of which there are many) were a real joy - steady as a rock, planted and oh-so-precise. On slow corners it would run wide but I lived with it

I have been lucky enough to ride virtually every model of bike produced during the early 70s and the Commando is one of the sweetest handlers of any of them when it has a set of decent tyres, a rod end head steady and is generally straight and true. It has that great combination that people commended Honda for many years later: lightish steering, stable and will hold a line when hard over, and is wieldy at slow speeds too. Those vids you posted on Youtube confirm that. If some people say it lacks any of the above, something's wrong. Go fix it.

In the article in Motorcycle classics, it mentioned that the position of the Ducati 900 crankshaft was central and the weight of the bike was centralised. Perhaps that is the reason that Vtwin Ducatis use such strange steering geometry. If you compare it with a Manx which has the weight well forward with 24.5 degree rake and very small offset on the yokes, the Ducati is radically different. One of the things I've become aware of is that most good handling bikes become stable under brakes, and oversteer slightly under acceleration. This is achieved by the variation in rake and trail as the front of the bike rises and falls. This probably means the length of the bike and the torque characteristics of the motor become a factor. I know with my own bike that after riding peaky two strokes, if it powered like one of those the handling would mean instant hi-side. The Seeley is 54 inch wheel base, and about 92mm trail with a 27 degree head angle. I think 70s TZ 350 Yamahas had much more neutral steering. The original Manx I rode was extremely confidence inspiring. If you got a bit off-line coming out of a corner, you just gave it more stick. I've ridden a Ducati 900 SD, and it felt as though you could climb up on the tank and jump up and down while it was cranked over.