Simon Crafer Gyroscopic Effect and Inertia

BTW, I'm not riding a motorcycle a great deal at the moment, about 150km on my AJS single a day out to a hill climb end of June, but, I have done about 450km on my bicycles since late April.

Which has involved a couple of repair sessions with the bikes upside down and spinning the wheels and keeping my fingers out of the spokes!

(Dropped about 12 kilos since March and planning a return to the race track in September and racing next year.

Maybe. French authorities are working against that by updating helmet specs and making airbags compulsory next year.

(It's all part of my longer term plan, no matter how ridiculous that sounds at 70)

SteveA said:

BTW, I'm not riding a motorcycle a great deal at the moment, about 150km on my AJS single a day out to a hill climb end of June, but, I have done about 450km on my bicycles since late April.

Which has involved a couple of repair sessions with the bikes upside down and spinning the wheels and keeping my fingers out of the spokes!

(Dropped about 12 kilos since March and planning a return to the race track in September and racing next year.

Maybe. French authorities are working against that by updating helmet specs and making airbags compulsory next year.

(It's all part of my longer term plan, no matter how ridiculous that sounds at 70)

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I was about 70 the last time I raced, and I did it better than ever. But I was taking Motoprolol for my heart condition and strokes. It is a betablocker which stops the adrenalin rush. If I had a moment during racing, I just did what needed to be done. For every situation, there is a standard answer. If there is a way to crash, I have already done it. I told Ray Bann who originally built the Seeley 850 with a Laverda 750 motor, about riding past Rex Wolfendens 3 superbikes when they were leading a race, he said 'perhaps you were just riding better'.
When you have adrenalin, it is part of the fun but it can help you make mistakes. I used to love an adrenalin rush - it can be controlled psychologically.
These days our controlling body asks questions about medication.

SteveA said:

Are you actually sure about that? If I push forward on my right handlebar I create a force on the right hand end of the wheel axle, and in my hemisphere, the force rotates forward 90 degrees and the wheel leans to the right, and I turn to the right! Right?

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Quite right, otherwise bikes would all have rear wheel steering. The error was presumably a typo.

I liked Lydden Hill but only raced there on a scooter. That machine definitely understeered accelerating out of the long right hand bend and I had to use force to counter the self centring due to the high slip angle of the front tyre.

SteveA said:

Are you actually sure about that? If I push forward on my right handlebar I create a force on the right hand end of the wheel axle, and in my hemisphere, the force rotates forward 90 degrees and the wheel leans to the right, and I turn to the right! Right?

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I studied physics at third year university level. When you have a gyroscope , the force VECTOR goes through the axle, and is in the direction a right-hand thread goes, If you sit on a motorcycle, the force vector for the front wheel goes from right lo left. However the magnitude and direction of the resultant force which appears in the trail is found by addition of the force vectors. I only know the direction of that vector because I memorised it. I don't know how engineers justify it. They are supposed to be experts in stress analysis. But motorcycle handling seems to have most of them stuffed. Tony Foale is good, but I have read papers on handling which came from institutes which openly admit they do not know how it works.
When a gyroscope becomes unstable in a system such as on a motorcycle - the resultant can express itself by a slow motion through the handle bars. They can look safe to grab, but if you grab hold, you will be chucked over the front quicker than you could ever imagine. I weigh about 12 stone.
Tony Foale commented that the extremes of trail result in self-steering. My bike stood up and turned the wrong way as I braked, at 94mm of trail -understeer. It is now at 106 mm of trail and over-steers very positively, when it squats. Those are probably the extremes for 27 degree rake and 18 inch wheels, with a 54 inch wheel-base.

hybridracer said:

Quite right, otherwise bikes would all have rear wheel steering. The error was presumably a typo.

I liked Lydden Hill but only raced there on a scooter. That machine definitely understeered accelerating out of the long right hand bend and I had to use force to counter the self centring due to the high slip angle of the front tyre.

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The system is dynamic, not static. If you can get a university professor to teach you how to add the force vectors involved in motorcycle handling, you will know more than most engineers. All I know is I changed the fork yokes and the bike became much faster, and I was not killed. I suspected the change might work and it did - I was lucky. Explaining the effect is something else, but it makes me uneasy when there is no explanation for something which is so critical.
I do not usually feel apprehensive when I race, but a steering problem can come from nowhere and grab you by the throat. Even when you are halfway down a straight. An unstable gyroscope can be a monster.

With increased trail, the bike has less lean, so more power can be used in corners. Most guys who race use a lot of lean, so tyres become more important and accelerating through corners becomes more difficult. You will probably find that riders do not actually lean the bike, they adapt to the angle of lean the bike adopts. It is almost impossible to increase the angle of lean on a Manx Norton. When you race, it pays to take note of what the other guys are riding, when you know how the bikes handle. It can tell you where they will be, when you are behind them. Very few bikes can go just anywhere on a race circuit.

SteveA said:

BTW, I'm not riding a motorcycle a great deal at the moment, about 150km on my AJS single a day out to a hill climb end of June, but, I have done about 450km on my bicycles since late April.

Which has involved a couple of repair sessions with the bikes upside down and spinning the wheels and keeping my fingers out of the spokes!

(Dropped about 12 kilos since March and planning a return to the race track in September and racing next year.

Maybe. French authorities are working against that by updating helmet specs and making airbags compulsory next year.

(It's all part of my longer term plan, no matter how ridiculous that sounds at 70)

Click to expand...

Air bags for motorcycles?? Sure hope that air bag virus doesn't make it to the USA.

Keep bicycling no matter what. I'd be spending money on more stuff I don't need without my cycling addiction. Cycling has a multitude of benefits that apply directly to motorcycling.

I like Al. He's probably bored stiff now that he doesn't ride anymore. I never think about any kind of science and technobabble when riding a motorcycle. I do wonder what is going to break next on my Norton though.

Same here I don't use science or even think about technical stuff, I get ideas in my head and think about and just do it, when I built my Commando/Featherbed back in early 80s I was still young in my early 20s and was the first bike I ever built, I had an idea in my head in what I wanted and just did it, worked for me I have a great light weight bike, handles great and has a lot of torque and when I had the money I threw in a few upgrades on the way, using as much of the Commando bits that fitted the Featherbed frame as I could.
What I done worked well as to this day I am still riding it, handles even better and also a bit more lighter, the motor is still the same and it's been very reliable, so too me it has proven itself and proved to my mates who thought I was going in the wrong direction and the best thing I learn/know every bit on my bike and every nut and bolt from the motor to all my hand made engine mounts are still the same from original bits on my motor to the new bolts when it put the motor in the Featherbed all them years ago (over 44+ years), nothing has shook off the bike, no major vibrations and can ride it all day without any problems at all.
So never even thought about tail, rake, off sets and the Commando frontend works perfect on the Featherbed frame, but with a better complete front brake upgrade.
I think Al just overthinks things and 14 years off a bike is way too long, that would put me in a early grave, never been without a road going British bike in 50+ years of riding.
Now to get back into the 1960 Manxman project cafe racer build, now that's been way too long.

Ashley

SteveA said:

BTW, I'm not riding a motorcycle a great deal at the moment, about 150km on my AJS single a day out to a hill climb end of June, but, I have done about 450km on my bicycles since late April.

Which has involved a couple of repair sessions with the bikes upside down and spinning the wheels and keeping my fingers out of the spokes!

(Dropped about 12 kilos since March and planning a return to the race track in September and racing next year.

Maybe. French authorities are working against that by updating helmet specs and making airbags compulsory next year.

(It's all part of my longer term plan, no matter how ridiculous that sounds at 70)

Click to expand...

Airbag leathers are a great idea Steve, authority driven or otherwise.

I think they’re even more appropriate for old, less flexible, more breakable, bones !

I’m looking at new leathers at the moment and am pretty sure I’m going for an airbag too. The technology is now cheap, and the statistics are impressive.

You can get a RST airbag suit for £600 ish. RST is good gear, just look on the WSB or IOM or any other present day grid.

I was 50/50 on the airbag thing until I pictured myself lying in a hospital bed with some horrible injury and trying to explain to my family why I declined to use airbag leathers… I’m a superstitious old fart at the end of the day…

Fast Eddie said:

Airbag leathers are a great idea Steve, authority driven or otherwise.

I think they’re even more appropriate for old, less flexible, more breakable, bones !

I’m looking at new leathers at the moment and am pretty sure I’m going for an airbag too. The technology is now cheap, and the statistics are impressive.

You can get a RST airbag suit for £600 ish. RST is good gear, just look on the WSB or IOM or any other present day grid.

I was 50/50 on the airbag thing until I pictured myself lying in a hospital bed with some horrible injury and trying to explain to my family why I declined to use airbag leathers… I’m a superstitious old fart at the end of the day…

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I was looking at airbags yesterday. I came to the conclusion new RST leathers is definitely the way to go, but currently stocks are low unless you go for the most garish! I want as much white in them as possible and better ventilation than my current black ones. Last time I ended up in a hospital bed after a helicopter ride, heat was a factor. Will also want to try them for size, after wearing RST boots for a few years, I bought new RST boots mail order and they are too small! But at least I am fairly stable at this weight now, and the size of the two sets I have is probably going to work well!

Airbags have to be on the FFM approved list, and they don't list the cheap ones. Pricing for new RST leathers ends up couple of hundred euros more that just the airbag! Economic sense, and they will be better able to cope with the exploding airbag!

I think back, my last actual race ended up with me helicoptered to hospital with 5 broken ribs and a puncture lung! Yes, this is just the sort of injury to old bodies that airbags can mitigate significantly.

First the helmet, back to Shoei, 400€. For the leathers It's just finding the cash, 850€ to 1200€ for RST.

But, wife wants a new fancy fridge and functional dishwasher, and I want a new set of wheels for my road bicycle!

SteveA said:

I was looking at airbags yesterday. I came to the conclusion new RST leathers is definitely the way to go, but currently stocks are low unless you go for the most garish! I want as much white in them as possible and better ventilation than my current black ones. Last time I ended up in a hospital bed after a helicopter ride, heat was a factor. Will also want to try them for size, after wearing RST boots for a few years, I bought new RST boots mail order and they are too small! But at least I am fairly stable at this weight now, and the size of the two sets I have is probably going to work well!

Airbags have to be on the FFM approved list, and they don't list the cheap ones. Pricing for new RST leathers ends up couple of hundred euros more that just the airbag! Economic sense, and they will be better able to cope with the exploding airbag!

I think back, my last actual race ended up with me helicoptered to hospital with 5 broken ribs and a puncture lung! Yes, this is just the sort of injury to old bodies that airbags can mitigate significantly.

First the helmet, back to Shoei, 400€. For the leathers It's just finding the cash, 850€ to 1200€ for RST.

But, wife wants a new fancy fridge and functional dishwasher, and I want a new set of wheels for my road bicycle!

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New fridge / dishwasher / bicycle wheels sound good… but none of them will protect your ribs, lungs, spine Steve…

Jus’ Sayin’ …

Fast Eddie said:

New fridge / dishwasher / bicycle wheels sound good… but none of them with protect your ribs, lungs, spine Steve…

Jus’ Sayin’ …

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Some family members think the way to protect your ribs, lungs, spine is to stay off motorcycles, particularly at my age! Odd people!

Most people say motorcycles are dangerous, so is life, but motorcycles are so much fun.

ashman said:

Most people say motorcycles are dangerous, so is life, but motorcycles are so much fun.

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When I told the CEO of Winton Raceway 'motorcycle road racing is safe' he was incredulous. The only time it is really dangerous, is the first time you do it. You need to learn to crash safely. The tank slapper and the high-side need to be handled properly. If the back of the bike comes around, the natural reaction is to try to correct it. A better reaction is to steer the other way and slide the bike onto the ground. You will usually be completely unhurt. The other way, you can be shot up into the air - the fall from height is what breaks bones. Th other way to get hurt is the tank slapper - you must let go of the bars, grab the tank and wait. The only other ways to crash are by hitting another bike or by being hit, and everyone is usually awake. If you get into a corner too hot, trail brake while holding the bike upright and hanging off the inside of the bike, and after you judge you have lost enough speed - accelerate. Once you know these things, you should never have a problem.

I do not believe I overthink things. When I was in high school, I always had two jobs in the evening to fund motorcycling. I cannot learn much by rote, everything needs to be in context. In classrooms there were always two conversations in my head, I do not believe much without evidence. What I did with motorcycles shaped my thinking as a scientist. So I probably look at things very differently to many people. Sometimes there is a lot of commonality. For example - octane rating of fuels is similar to the concept of brisance with gun propellant. The combustion process is similar. When the rate of rise of pressure divided by the time, is measured - you get an acceleration rate.
It is just a different way of thinking - not especially clever.
I was trained in laboratories by Jews and Nazis. I always loved my jobs. You need a sense of humour - 'some things are so bad that they are good'.

All of my tertiary studies were completed on a part-time basis while working. I have a Diploma of Applied Chemistry, and a Post-Graduate Diploma of Occupational Hygiene. I was once at a scientific conference where there were doctors. We discussed our jobs. The doctors told me they fixed the people who were injured by the effects of the work I did in defence. That is one way of looking at it.

I've always looked askance at people who quote their academic credentials as justification for their publicly advocated abstract theories. I am a fan of
highly trained academics who don't tell you about their credentials, but let their knowledge speak for itself .

lazyeye6 said:

I've always looked askance at people who quote their academic credentials as justification for their publicly advocated abstract theories. I am a fan of
highly trained academics who don't tell you about their credentials, but let their knowledge speak for itself .

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Even academic and sciences gets things wrong and Al's way of thinking seems to be completely different to others who know best about bike set ups and racing, but he keeps telling us, but over thinking things can be dangerous, my brain would explode overthinking things, I didn't need to be academic to be smart, I learned more in life than any book could teach me.

I would never have posted this stuff about trail, if I did not think it is important. If you think I am wrong about it, get yourself and your bike down to Benalla, and I will teach you how to ride a motorcycle.
My Seeley was originally built as a Seeley Laverda 750 by Ray Bann. He is almost exactly my age, and has a lot of racing experience. I got the Seeley as a rolling chassis, but even though I psid for the motor, I could not get it. Ray raced the Seeley Laverda at Sandown. With the fork yokes it had, it was dangerous. But mostly it's problem went un-noticed. The bike mis-handled two times. It nearly got my mate and it almost got me. When I changed the yokes, I knew they might be OK, but it took a few rides to really find out how to use the bike with that set-up. I do not need to race again, because I know I will win every time. Nobody can beat my bike when it goes full blast from the beginning of the corner, around it and up the next straight. - You think about where you personally stop breaking as you enter corners and start accelerating. If you think I am full of shit, come and find out - I will teach you ride the bike.

I cannot understand why some of you guys worry so much about crashing. You need to learn how to put a motorcycle on the ground without hurting yourself. The only problem with doing it, is if where it happens is not a smooth surface, so choose where you stick your neck out. And if you crash - keep your arms and legs in and don't try to save yourself.
Riding on public roads is ten times as dangerous as racing.