Simon Crafer Gyroscopic Effect and Inertia

Simon Crafar is very good in his knowledge of motorcycle setup. In the discussion about the effects of increasing trail on a motorcycle. If I think of it as a static system, I would believe that more trail would give more stability, however the system which steers a motorcycle is dynamic. One of the largest forces is the gyroscopic effect of the front wheel. If you hold a pushbike wheel by the ends of its axle and rotate as if it was the front wheel of a motorcycle, when you push the right hand end of the axle, the wheel will immediately lay over to the left. The force vector caused by the rotation goes from your right to the left.
When a motorcycle is accelerating there are inertia and gyroscopic forces acting on the front wheel contact patch and the resultant forces are found by adding the force vectors, the direction of the one which represents the gyroscopic effect also determines which way the bike will turn, when it is added to the other force vectors, such as the force vector of the trail, which changes as the bike brakes and accelerates. Finding resultant forces by adding vectors is sometimes taught in third year university level physics' classes.
I don't know whether the link I post will work. Dorna place restrictions.

Probably a good application for a rev limiter or oil isolation valve

At the risk of egging on the OP, in the real world, the rotational inertia has ZERO AFFECT on steering the bike. If it had the affect you think it does, riding with no hands would immediately send you to the ground. It does not. The caster effect alone negates your theory. You're making this more difficult than it needs to be.

If you like a bike (you never ride) to understeer or oversteer, by all means, go nuts. It's your preference. It's ok. Any rationalization more than, "that's the way I like it" is unnecessary. I understand you think you're educating us, but please stop.

Go ride your bike.

t ingermanson said:

You're making this more difficult than it needs to be.

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No, he just will not agree with physics and continues to argue the moon is made of cheese.

kommando said:

No, he just will not agree with physics and continues to argue the moon is made of cheese.

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Wait, CHEESE?!?

Yes, the Dunning-Kruger Effect is in full effect.

My response is an attempt at buffering this load of BS for future people looking to the forum for good information. When coming onto a place like this that's full of great info and knowledgeable posters, it can take a while to figure out what is what, who is who, what info is good, and what's garbage. If this garbage stacks too highly with no pushback, it waters down the value of the forum, as it's only as good as the info on it.

I'm not the sharpest tool in the shed, but contribute where I can. If I can be the dummy that recognizes my own, then so be it.

Too much YouTube and not enough bike time, if your bike was so good you be riding it all the time no matter what, there is enough drama on the idiot box, seems Al likes to go against the flow, but then it's been so long since he has been on a motorcycle.

t ingermanson said:

Wait, CHEESE?!?

Yes, the Dunning-Kruger Effect is in full effect.

My response is an attempt at buffering this load of BS for future people looking to the forum for good information. When coming onto a place like this that's full of great info and knowledgeable posters, it can take a while to figure out what is what, who is who, what info is good, and what's garbage. If this garbage stacks too highly with no pushback, it waters down the value of the forum, as it's only as good as the info on it.

I'm not the sharpest tool in the shed, but contribute where I can. If I can be the dummy that recognizes my own, then so be it.

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this,,,,

o0norton0o said:

this,,,,

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But this has been attempted many times but the Moon is still cheese.

Life is too short to beat down every molehill.

Of course the moon is made of cheese. Green cheese. Have you not seen the Wallace and Gromet films. There is one where they set of for the moon to discover this very fact.

kommando said:

Life is too short to beat down every molehill.

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Of course. We can take turns though!

Most of the time the ramblings are completely unconnected to the thread, so it's easy to ignore, and obvious rambling.

Personally, I think Al has a lot of experience to share, and I know I've been horrendously wrong many, many times, but the theory stated in the original post on a new thread has little-to-zero bearing on the handling of motorcycles, so it's worth mentioning. The more times something get said on the internet, the more "right" it becomes, because these days information is so often mistaken for knowledge, and self-publishing has no consequences.

So, why aren't we bring some of that green cheese down to this FLAT Earth?

I'm guessing age 85 and losing touch but still wanting to be relevant but forgot what relevant means. Be kind. Most of us will be there someday.

Sounds like POTUS syndrome.

NORTSTER1974 said:

Sounds like POTUS syndrome.

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Here goes the political bullshit again. Give it a rest, it’s not funny.

I am sorry as I do respect our olders and Al seems like a nice old age person who has done a lot of good in his life, we all know he hasn't been on a road going bike since he was 29 and the times if you add it all up with racing classic bitsa bikes, maybe one or 2 races sessions a year in his early days but as he got older, years without racing or on the track, I think it's well over 12+ years since he even been on the track of late.
But being so long without throwing a leg over the bike and some of the things Al writes goes against what others know or do about setting up bikes for racing who still race and even for road riding each bike is different to the next and each rider is different and see things different when setting up their bike for road (weather sports or cruising or just local), track, full on racing or classic bike racing, all four are different from the other each one is different too the other, steering, rake, tail and of course everyone will agree to disagree it's all human nature and we all have our own ideas/ways of doing things and any bike we build, buy or own will be different.
We all have our ramblings and I be the first to admit to that, but I do know my own bike, I brought it new, I made big change early and built it for me, myself and I, no one else, I learned by others mistakes as well my own, it's part of motorcycling life, but I still ride, a week won't go by without being on the Norton or my Thruxton, but I have had a bit of gap the last few months with the wife getting a few eye OPs, but the bikes are all ready and so am I.
But with Al he has some good points I suppose but has way to many bad points that folks can't get their heads around, old age, too much YouTube, not enough bike time, scared to ride on the road or even thinking about crashing/dying, lost of good mates, we all will get to that point in our lives, hopefully it be when I am 105, my bikes and riding them all the time is my life.
So Al you need to get off watching YouTube and do something with your bike and bring up racing in near all threads that you reply too, does get a bit much and I know I have a few I have upset with my ramblings over the years as I say we all have our ways, but tail, rake, steering, suspensions does do my head in but I have set my own bikes up pretty good without over thinking things, I know what works and what doesn't, that's what 50+ years of riding 2 wheels does from riding dirt bikes to road going bikes, I still have both dirt and road and only been off the road by my own doings, 3 left knee injuries, 1 fracture left arm and 3 license suspensions not bad for 50+ years of life on 2 wheels.
Anyway ramblings over, Al just get back into/on your bike and forget everything else, it's a good hobby and it keeps me young at heart, body and solo.

Ashley

lazyeye6 said:

I'm guessing age 85 and losing touch but still wanting to be relevant but forgot what relevant means. Be kind. Most of us will be there someday.

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There is no kind way to disagree with any person who is this consistently wrong about a known science, (like of rake, offset, and trail) and is also so persistent that they are actually right and everyone else just doesn't understand it as well as he does. As T ingermansen pointed out, it's a choice between letting the false information stack up as correct information or breaking the person's balls about their mistakes.

If he was less persistent that he's right when he's actually wrong then probably everyone would just gloss over his comments, but he posts 3 or 4 times in a row. How do you kindly say, "You're wrong and would you please shut up" to someone without being insulting? When a person claims to be a higher authority and someone tells them they are wrong, it just sends them into "Lecture the class" mode... How is that kind approach done?

I have only persisted with this subject because I consider it to be important. One of the only regrets I have about getting older is about the people whom I do not converse with enough. However many of those would probably never have told me anything which would give me a competitive advantage. I have been attending road race meetings since 1958. From then until 1963, the Manx Nortons were king. I saw Athur Pimm win an A grade All powers race on a Norvin, and Ken Rumble win a few with a Featherbed framed Gold Star BSA - the rest were all Manx Nortons except for Ron Tombs on the 4-valve Henderson G50 Matchless.
In about 1963 Graeme Osbourne beat all the 500cc Manx Nortons in A grade with a 250cc TD1A Yamaha.
It was a completely different kind of motorcycle. The angles of lean were extreme.
Most of us seem to believe that motorcycle development is a continuum. However I suggest there are two types of road racing motorcycle - one which is based on top end power and the other which is based upon torque. The required handling characteristics of both are different from each other.
When I changed the trail on my Seeley850, it was because it mishandled. I went from 94mm of trail to 106mm by reducing yoke offset by 12mm. If you watch the guy in the Superduke video, he went from 100mm to 101mm, and noted a significant difference in the handling. The largest trail I have seen mentioned for a race bike, was on an Aprilia MotoGP bike - at 106mm.
The problem is progressively increasing trail can be expensive and dangerous - the results are based on subjective assessment. The rider adapts to the bike and the better it feels, the faster we ride.
Most riders would never grab a big handful of throttle when halfway through a corner.

Before I rode under and past Rex Wolfenden's three 1100cc CB750s at the start of that road race. I knew the bike was capable of doing it, however I was very apprehensive. I usually know when I am likely to crash. That might be the reason, I have not been back to do the job properly.

lazyeye6 said:

I'm guessing age 85 and losing touch but still wanting to be relevant but forgot what relevant means. Be kind. Most of us will be there someday.

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Statistically, most of us won't!

People over 80 is a pretty small percentage of any population.

The majority of forum members seem to be male, so we can ignore the bump in female life expectancy.

acotrel said:

I have only persisted with this subject because I consider it to be important. One of the only regrets I have about getting older is about the people whom I do not converse with enough. However many of those would probably never have told me anything which would give me a competitive advantage. I have been attending road race meetings since 1958. From then until 1963, the Manx Nortons were king. I saw Athur Pimm win an A grade All powers race on a Norvin, and Ken Rumble win a few with a Featherbed framed Gold Star BSA - the rest were all Manx Nortons except for Ron Tombs on the 4-valve Henderson G50 Matchless.
In about 1963 Graeme Osbourne beat all the 500cc Manx Nortons in A grade with a 250cc TD1A Yamaha.
It was a completely different kind of motorcycle. The angles of lean were extreme.
Most of us seem to believe that motorcycle development is a continuum. However I suggest there are two types of road racing motorcycle - one which is based on top end power and the other which is based upon torque. The required handling characteristics of both are different from each other.
When I changed the trail on my Seeley850, it was because it mishandled. I went from 94mm of trail to 106mm by reducing yoke offset by 12mm. If you watch the guy in the Superduke video, he went from 100mm to 101mm, and noted a significant difference in the handling. The largest trail I have seen mentioned for a race bike, was on an Aprilia MotoGP bike - at 106mm.
The problem is progressively increasing trail can be expensive and dangerous - the results are based on subjective assessment. The rider adapts to the bike and the better it feels, the faster we ride.
Most riders would never grab a big handful of throttle when halfway through a corner.

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I watched a video of a race I was in in 2015 this morning, it came up as a Facebook memory.

It was at Lydden, Kent, UK. Small tight circuit where handling rider skills has always been more important than power. I have been quicker on my 500 single than my 750 twin!

The race was won by Mike Bevan on a 750 long stroke Seeley Norton. Original geometry. Mike is a great and smooth rider, still racing today, though perhaps not winning as much as he did.

I was 4th on my original framed Rickman Norton shorts stroke 750. Original geometry. Between us were a couple of bikes, one of 920 and one of 1100cc. None of us was going particularly quickly, Mike is the kind of guy who believes in winning at the slowest possible speed. He is very smooth and likes a bike to be easy to ride.

I will say it again, if your Seeley framed bike mishandles, there is something basically wrong with it. They are pretty much the benchmark 1970s race bike.

acotrel said:

.........One of the largest forces is the gyroscopic effect of the front wheel. If you hold a pushbike wheel by the ends of its axle and rotate as if it was the front wheel of a motorcycle, when you push the right hand end of the axle, the wheel will immediately lay over to the left. The force vector caused by the rotation goes from your right to the left.
..................

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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?