Motorcycle General Discussion

[Graham TitmanParticipant @grahamtitman81812]

DiogenesII you have a pm

[duncan webster 1Participant @duncanwebster1]

How about a RR Pennine for simplicity, 24 cylinder sleeve valve, 46 litres.

You can see the attraction of the first gas turbines, one shaft with a compressor and a turbine, OK there were other bits like fuel and oil pumps, but a lot simpler

Edited By duncan webster on 08/08/2021 19:16:24

Edited By duncan webster on 08/08/2021 19:16:50

[old martParticipant @oldmart]

Posted by duncan webster on 08/08/2021 19:16:06:

How about a RR Pennine for simplicity, 24 cylinder sleeve valve, 46 litres.

You can see the attraction of the first gas turbines, one shaft with a compressor and a turbine, OK there were other bits like fuel and oil pumps, but a lot simpler

Edited By duncan webster on 08/08/2021 19:16:24

Edited By duncan webster on 08/08/2021 19:16:50

I would need training wheels on any motorcycle I rode with that engine in it.

[JAParticipant @ja]

Posted by duncan webster on 08/08/2021 19:16:06:

How about a RR Pennine for simplicity, 24 cylinder sleeve valve, 46 litres.

You can see the attraction of the first gas turbines, one shaft with a compressor and a turbine, OK there were other bits like fuel and oil pumps, but a lot simpler

Edited By duncan webster on 08/08/2021 19:16:24

Edited By duncan webster on 08/08/2021 19:16:50

As Hooker said, of the jet engine, “We will soon design out the simplicity”.

Aero piston engines became horridly complex after the Merlin,Griffin, Hercules, Centaurus and Sabre. None went into full scale production.

JA

[JimmieSParticipant @jimmies]

Interesting tale of building a BSA Bantam/Star bike.

http://www.bsaotter.com/graham_dale_s_bsa_banstar.html

[bernard towersParticipant @bernardtowers37738]

Roll on Sunday dry and clear here get a run in ther will be less of them for the next few months!!

[Chris MateParticipant @chrismate31303]

Posted by Nick_G on 30/10/2015 10:40:33:

.

OK I will add to this thread with a question.

I understand how centrifugal force works. But I am informed that when a motorbike is cornering it is centripetal force that keeps the machine and rider (hopefully . ) shiney side up.!

I have tried google to understand this but TBH it goes over my head. Can anybody explain to me in dunce type language how centripetal force works.?

Cheers, Nick

Years ago I crashed two times, no slide, but I could not explain what went wrong, both on corners.
I read on a magazine steer left go right, but that was not enough so I investigate.

This is my theory and maybe it can help.
You have to take the following factors in mind: Your mind &/versus body reflexes
1-Its a single track vehicle.
2-The Steer Left-Go right thing….(The excact wheel science is not important other than deeper understanding)
This is not the same as old term countersteering(Slow) like you see in stock car racing, however I believe the same can happen to a car if it travels fast enough with only 2 wheels on the ground.
—–0-10Km/h as you push steer it.
—–10-20Km/h a sort of dead zone.
——Over 20Km/h if you push the handlebar left the bike goes to the right, no matter where you lean or your passenger, this can be a powerfull force as illustrated by Sidecar cop shows. In this regard a sidecar can be a nightmare as it shape shifts in a corner.
3-You body reflexes:
——If you dont panic in upcoming situations, you will go as you planned by leaning the motorcycle or whatever you think you do to go around a corner.
——–If you panic, you were too fast, you were not paying enough attention whatever, your refkexces kicks in to defend you, however you may be "born with a car steering wheel in your hand", and the next 3 seconds of operation to the handlebar may be wrong, causing you to go where you try to avoid.
4-I took me 3 months of practice every day to change my relfexes so if I panic I pull the handlebar in the opposite direction.
5-How do you know I am not lying——Have you ever get near the pavement or a slight corner with your motorbike or bicycle, and get that enormous feeling like in a dream, you cannot get away from what you trying to avoid-?=If so your reflexes are wrong ….and may get you killed in head on colitions with oncoming traffic, you want to steer between the car you pass and oncoming vehicle, but you cannot get it in that gap, you got 3-5 seconds and if wrong your body get confused and cannot correct because you are in a reflex condition, it difficult to remember these few seconds.
Think about this, you probably won't move the handlebar the higher the speed, however its the direction of torgue your hands/arms apply to it, in reflex condition you dont think, body just acts fast or sometimes freeze if no time to react.

So its not as easy as telling somebody you should steer left to go right, you have to get your reflexces right, thats when it matters and its unlikely you get it embedded in one day practise.
I dont think theres an easy selution to this for most.

Note:To further prove you can change a reflex, I usually twisted my anckle with pain, so around the same time as this, I practised if I step on one foot the wrong way, I relax that side, so it does not put pressure on the wrong move and worsen the problem, and since then I never twisted an anckle again, and it worked.

I have seen videos of motrorcycole racing drivers that was killed by incorrect steering reflex with much space to spare. Knowing about it is not alone good enough, you must have the reflex working correct.

With this in mind rewatch videos motorcycle or bycicle accidents that looks like steering accidents, you have to watch carefully those few seconds….Interesting.

[duncan webster 1Participant @duncanwebster1]

My theory for what it's worth, and it is quite a lot of years since I rode a bike in anger. Going in a straight line with the bars held straight, push on the left bar, the bike tries to turn right and so inertia makes it lean to the left, at which point your subconscious turns the bars to the left and the bike turns left. I just did it, didn't think about it until someone mentioned it, so I tried it out. Hands off, just give one of the bars a push and it magically turns the opposite way

[Bill PudneyParticipant @billpudney37759]

I always thought that it was gyroscopic precession that provided this, so-called "counter steering" effect,. Back in the 70s I was interested in all this sort of thing, I did some experiments. The numbers that I remember are a bit vague, it was 50 years ago after all, but the principle remains. Riding along from walking pace up to about 15 mph, push forward on the right hand handlebar, bike turns left, with little or no lean. Over about 15mph the opposite is true, push forward on the right hand handlebar, the rotating front wheel resists the force with an opposite force which causes the motorcycle to lean and turn to the right. As the bike is ridden faster the resisting force increases considerably.

I would hazard a guess that the rotating mass of the front wheel would have some effect, so some of the huge front brake drums would probably make things worse. Another reason for using discs!!

cheers

Bill

[John OlsenParticipant @johnolsen79199]

Gyroscopic forces have got very little to do with it all. Bikes have been built with counter rotating flywheels beside each wheel, which can be used to completely cancel any gyroscopic effects. It is still very easy to ride such a bike.

The main factor in balance on a bike is like balancing a broomstick on your hand, except you only have one plane to worry about with the bike. When you are going straight, you move the steering as required to keep the centre of support under the centre of gravity. When you want to turn, you steer to move the centre of support out to one side, then steer so that all the forces balance. So you actually push slightly the "wrong' way to start the turn, then steer slightly with the turn, Then to come out, you steer a little tighter into the turn to get the bike upright again. It doesn't pay to think to hard about this while you do it!

Centrifugal force only exists if you have a rotating frame of reference, what is actually happening is that as you turn you have a centripetal acceleration, which to the rider in his rotating frame of reference appears as if there is a force away from the centre. This is not a real force, it is just things trying to continue in a straight line.

Forces from the tyres also make a difference, that and castor and trail on the front are why a bike can continue for a while with no input from the rider, although it will usually tend to drop into a curve.

John

[Peter Jones 20Participant @peterjones20]

It's a very long time since I read much about the 'counter-steering and gyroscopic effect with relation to motorcycles. The 'steer left to go right' is very wrong way to explain what's happening.

Yes, you do move left bar to go right but the amount is miniscule plus, if you don't, you can still go around corners by 'forcing' the bike to lean over by turning steering slightly in direction you want to go. Weighting footrest one side is thought to be irrelevant but personally, without touching bars and just putting pressure one side, the bike turns. The faster you go though, the less the effect which to me, proves gyroscopic effect is keeping bike in a straight line and so, upright (along with rake and trail)

Personally, I don't see how a counter rotating flywheel can counter gyroscopic effect? (I was a motorcycle tech not a physicist) The fact you have gyroscopes spinning opposite directions may cancel out mathematically but physically you now have multiple gyroscopes trying to resist changes in direction.

There is probably a lot more known about gyroscopes today compared to early 1970's when there was only a single scientist doing research on/with gyroscopes (I remember seeing Royal institute Christmas Lecture about it on B&W tv long time ago).

AFAIK, there is only one university offering a degree course in motorcycles, design etc and it is in Italy (but I haven't looked for about 12 years) They did publish a lot of information and research online but much of the math was way over my head. They had a lot of very interesting animations though which were easy to understand

[John OlsenParticipant @johnolsen79199]

A gyroscope will move at right angles to the force applied. They don't really resist movement, they just try to move at right angles to the force applied. So if you have a gyroscope with a vertical axis and you push the top away from you, it will actually move to the right or left. Which way will depend on the way the gyroscope is turning. So now if you have two gyroscopes of the same mass and rotational speed on the same axis, one turning clockwise and the other turning anticlockwise, when you push away, one will want to move right and the other will want to move left, both with the same force, so they will cancel. The only remaining resistance to movement will now come from the total inertia of the system.

You do generally move the bars to initiate the lean, but it is only by a very small amount. If you think about the fact that you might only want to move the track of the wheels across by a foot or so, and you might be traveling at fifty feet per second or so, you can see that a very small angle on the handlebars would shift the track of the wheels sideways by a large distance quite quickly. (It is not too hard to exceed fifty feet per second on a bicycle, let alone on a motorcycle.)

Getting a motorbike or bicycle to lean by shifting weight is one of those things where the tyre contact forces come into play. Shifting your weight to one side makes the tyre contact area with the road change, which introduces forces into the steering. You will I think notice that the control available in this way is very limited compared to what can be achieved with the bars.

John

[Bill PudneyParticipant @billpudney37759]

Which all goes to show, how little we know!!

cheers

Bill

[CirclipParticipant @circlip]

And hanging over the left hand side of the bike was always easier. Watching todays MotoGP riders scraping their elbows on corners certainly shows that tyre technology has advanced in leaps and bounds (no pun intended).

Regards Ian.

[Mike PooleParticipant @mikepoole82104]

Keith Code wrote some interesting books on motorcycle handling and riding, I loaned mine to someone and I don’t think I will see them again.

Mike

[Chris MateParticipant @chrismate31303]

For me its about accidents you cannot explain easily, like if I slide on oil on a corner, there you have your answer immediately. If I overtake a car, get next to it, and suddenly another car appear from the front, if its fast enough to… trigger my reflexces, I would apply a force to the handlebar without thought which will be wrong, I will then end up in the oncoming car head on, the object my body(Not me) was trying to avoid, and these accidents are deadly mostly, and I certainly had a sace to get through between the two apposing vehicles seeing the with of the motorcycle, but just could not.

So over many years I never saw the mentionuing of "reflexes=wrong" in this regard. While you in a reflex condition, it's very difficult to remember those few seconds which is understandable from the relex perspective, muscle memory.

The gyroscopic effects are not exactly the same as is explained with holding a bycicle wheel from one side of the centre spinning, in this case theres the road as a reference also. If I steer with the handlebar at speed over 20km/h, My passenger can lean the opposite way, but the bike will go where i steer it, it maybe unstable as a result. As with anything there will be many argumuments about the science behind it.
-If you keep ia still standing motorcyclle upright, it will just simply fall over.
-If you take the rider off a motorcycle at speed, like some accidents do, it may seems like it has a gost rider on it as it progress forward…
-If you lock up both brakes/wheels at speed, you have a "dead" motorcycle.
-If you strike strong diesel flow on a straight road, dont lock up the brakes, you have an alive motocyle, and can coast safely without applying brakes to stadstill (This happenned to me at 120km/h). After I stopped, the bike was full of splashed diesel. If I did not knew this, brakes wiould e applied and I was injured as a result.

A motorcycle with a sidecar:
Since I knew about this, the 1981 around, I was one day passed at 140Km/h by a guy and his wife on a Kawasakie with a sidecar and a child in the sidecar. Now I know there was a corner just before the town approaching, that day I took my hat off for this trio.
As the sidecar at speed entred the corner, the sidecar with child starts to lift, that guys wife climed in the sidecar in the corner with the child and the made it around somewhat in a zig zag fashion, this told me this guy had a lot of experience but maybe not the full understanding, because how much weight do you need to suppress the gyroscopic forces of a 3-track vehicle, that suddenly turns into a single track vehicle-?

Think about this……

[Graham TitmanParticipant @grahamtitman81812]

A friend now deceased had a BSA A10 and palmer sidecar forks built by exe sidecar racer call Bill Cooper wheels were 16inch dunlop sidecar racing his party piece was put it on full left lock a big handful of throttel and watch the sidecar wheel go backwards .the bike was built that low the sidecar wheel hardly ever come of the floor.

[Graham StoppaniParticipant @grahamstoppani46499]

Posted by Mike Poole on 08/10/2021 09:24:33:

Keith Code wrote some interesting books on motorcycle handling and riding, I loaned mine to someone and I don’t think I will see them again.

Mike

Had the pleasure of Meeting Keith Code when doing the California Superbike School at Silverstone in 2011

And this is me trying to put it all into practice!

[Michael GilliganParticipant @michaelgilligan61133]

This is probably as ‘general’ as the motorcycle discussion can get : **LINK**

https://www.bbc.co.uk/news/world-asia-india-59036542

MichaelG.

[JimmieSParticipant @jimmies]

Some 65 years ago I had my first pillion ride on a NSU Max and have always had a liking for the bike and 'followed' them in local road races in the classic era days. The late Sir John once noted in passing that he had been involved in the conversion of this model to racer spec, ie Sportmax replicas. Anyone else with experience or knowledge of the conversion details?

Jim

[WindyParticipant @windy30762]

A memorable time at the show that I posted earlier.

Just a change from ordinary vehicles on the 12th and 13th of February at Elvington Airfield there is a show of Record breaking motorcycles, cars, drag racing machines I understand Guy Martin who will be pilot of Alex McFazdine Gem turbine two wheel streamliner is going.

Steam jet bike and fastest lady UK bike rider are their plus some of the machines from my racing era.

On the Saturday after listening to a talk by my friend Graham Sykes on the massive modification to his steam rocket bike I was taken to another place as I climbed the steps there was something I never expected this had being arranged from about November last year.

There was a tear in my eyes my speed family had a Birthday Party for me as on the Sunday 13th I am 80.

It was packed out with speed record enthusiasts.

An 8 page Birthday card was given to me and around the room bunting with photo's of my machines etc.

What a kind thing to do for me the work that was done by the ladies on the catering and all the other enthusiasts that made this possible.

Edited By Windy on 18/02/2022 13:01:58

[HopperParticipant @hopper]

Happy Birthday, Windy! Well done.

[Jeff DaymanParticipant @jeffdayman43397]

Happy birthday Windy, and best wishes!

[WindyParticipant @windy30762]

One of the Hayabusa bikes that was at the show used to belong to a member on this forum.

The member sold it to my good friends Andy and Helen they did over 200mph on it.

Andy passed it on to another enthusiast who did a fresh paint job etc on it and managed 238mph.

It's now for sale again ME member Pete do you fancy another go on it.

Pete what was your fastest speed you did at think Woodbridge airfield?

[Pete RimmerParticipant @peterimmer30576]

Hi Windy, my fastest official speed was 215.7mph but that was on the first turbo system good for 300hp although when I did the speed mentioned it was at 230hp. The second system I built with a charge cooler and much larger turbo and the one it's fitted with now is currently running at about 320hp I believe but it's good for around 500 which should on a good day push it past 250mph.

I have thought about buying the bike again before now and I'd be interested in hearing a price. If you have an idea what the asking price is, and how it's changed from when I sold it, let me know by PM please.

[Author]

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