Safe Speed Forums

Thank you toltec, you saved me the trouble



That which we call a rose, by any other name still smells as sweet

Dynamics may change but not the principles. Just because the electric model is a scaled down version of the real thing doesn’t mean it starts to defy the laws of physics - any more than the nitrous version does!!!

If it did, my next question was going to be at what scale does this phenomenon happen? Half scale? 5th? 20th?

I don’t doubt that Keith Code is a skilful rider! I also don’t doubt that he’s made a big name for himself and amassed a fortune.

Wikipedia is wrong and so is Keith Code, but I knew that from the start.

I won't go into smug mode, I'm just happy the truth is out. Now for speed scameras...

Apologies again for the TTD This dog will let the bone go now.


(PS. So a Centrifuge should really be a Cenripidge? )

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The views expressed in this post are personal opinions and do not necessarily represent the views of Safe Speed.
You will be branded a threat to society by going over a speed limit where it is safe to do so, and suffer the consequences of your actions in a way criminals do not, more so than someone who is a real threat to our society.

1. The argument about "no such thing as centrifugal force" I think stems from the misconception the people have about there being a force acting "outwards" on a body following a circular path. The truth is that the force acting on it is actually tangential rather than outward; as it attempts to obey Newton's laws and continue in a straight line. So when you swing a conker round your head the force keeping the string taut is not acting "outwards", it is simply trying not to accelerate but is being forced to do so by the continually rotating vector of the string.

So whether you call the resultant force "centrifugal" or something else it doesn't matter - it still exists and it appears to act "outwards", even though in reality it acts tangentially.

I also agree with Big Tone that if you throttle off in a corner the bike will indeed want to fall inwards. I have slightly embarrassing memories of my beloved YDS7 Yamaha doing that one to me as I tried to do a U turn in the road with a cold engine. Saw a car coming round the corner and instinctively opened the throttle causing the engine to splutter and the bike to fall into the corner so violently it fell on me - at about 5mph! The oft-quoted effect of the cornering back that sits up and goes straight on into the oncoming car is more about weight transfer and geometry in an in extremis situation.

I also agree that bikes can be steered without CS. How else would a unicycle steer (or even that chap who did a lap of the TT course on the back wheel?). My understanding is that once a cycle is moving the mass of the wheels induce a gyroscopic precession which allows it to "resist" the momentum of the rider moving slightly to one side. Once he stops moving the gyro effect ends, and the bike is now slightly off balance and falls into the corner, whereupon equilibrium is restored. CS simply speeds this up.

The complicated bit is that when the steering has some degree of castor effect (ie by raking the forks slightly) the act of moving the riders mass off centre induces CS in itself, but this shouldn't be mistaken for the belief that it is CS alone that induces the turn.

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CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

Interesting JT

To be honest, I’m still rather confused about that. I loved physics at school and wanted to teach it in adulthood.

Back then, and to this day, both Centrifugal and Centripetal force seemed to exist or so I was taught.

If you Google “Does centrifugal force exist?” you still get a whole gamut of information and forums where very educated people in that field have opposing views and have ‘done it to death’.

For myself, I am big enough to do a complete U-turn if someone shows me proof, assuming I have the intelligence to understand the argument of course. (A moot point)

With reference to the CS argument, I know the effect and I know that pushing or pulling the handlebar is not the only means of steering.

That’s what got up my nose about Keith and his blatant attempt to dupe people into believing it is the only means to steer and gets off the damn seat to 'prove' his none-point for some obscure reason. (Well, it's not obscure to me)

With reference to the great Mr K Code's promotional video: Can someone, ANYONE, please tell me why Big Keith stood up? There was absolutely no need for it and no-one questioned why he did, and yet it’s so obvious why he did that a child could understand why! To state the obvious - he couldn’t pull his leg across the seat to maintain the Centre of Gravity if he didn’t. (Dare I try it differently and post it here? I dare... )

10 out of 10 if you spotted it! That should have been the easiest 10 points anyone has ever had but hey - he's the one with the reputation, adulation and money, so he must be right - correct?

As for the Centripetal/Centrifugal debate, perhaps it’s a bit of both? Centripigal perhaps? It could be called ham and eggs for all it mattered TBH, it’s the forces at work and their effects which I was more concerned with but if someone could nail the answer to whether centrifugal force exists, or is a term we are allowed to use and in what context, I’d be grateful for the edification.

Keith Code has much more money than me and could probably sue my ass in America if I were still there, or maybe even if I'm not. He's probably SO BIG and I'm so small that I'm too insignificant to bother with anyway. But the truth always outs eventually, just as oil rises above water.

For that reason alone, I have been careful not to say too much about what I think of him Suffice to say he won't get my business or recommendation so long as that is his stance. (literally). I would have greater respect for the guy if he just sat in the saddle and told it as it is actually, but oh well - I guess he had his reasons (Oh yes, I remember now - he did sit in the seat and waggle his ass to make another none-point.)

Who was it that said, "You can fool all the people some of the time, and some of the people all the time, but you cannot fool all the people all the time?" (Rhetorical)

I don't have a problem which will affect my income or reputation - or ego! If I'm wrong, I will personally declare it here! (Unlike some). Might, as history has proved time and time again, doesn't always mean right!!!

I look forward to opposition with fervour. (I have more arrows in my quiver...)

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The views expressed in this post are personal opinions and do not necessarily represent the views of Safe Speed.
You will be branded a threat to society by going over a speed limit where it is safe to do so, and suffer the consequences of your actions in a way criminals do not, more so than someone who is a real threat to our society.

I could give you dozens of effects should this happen, but I will just give you one I know happened because I saw it. First of all Im not talking about a nutter doing 50mph up your jacksy , just imagine you are just stopping at Traffic lights where you are aware of the nice old lady smoothly pulling up behind you in full control but suddenly in your split second moment she gets confused catches the accellerator pedal and in shock slips the clutch, nudges you,your back wheel rides up her bonnet assisted by your front brake only being on, throws you off head first. If back brake was on you would skid forward and possibly remain upright even if you collide with a veh ahead. Also in simple terms 2 brakes are better than one but if you only had the back brake on after comming to a halt this could also just result in a forward slide and remain upright. Not all bumps are at speed, many are very short in distance and slow speed . A lot of biker spills could be lessened in outcome however rare you may think it could be. Using front brake only in event of rear end bump increases your likelyhood of ending up on the floor.This doesnt mean you wont end up there just using back brake or both it just means less likely but would depend on nature of crunch. If you only have the front brake on if nudged from behind, unless your wheel is absolutely strait and your bike is absolutely upright you will get a sudden loss of balance effect like one often sees when people try turning a bike in the road using front brake to assist control of the turn, bike wants to go in direct path whilst the turn of steering and brake effect fights against it, using rear brake in same situation alows greater control. car nudging you when front brake on and slightly turned or leant over can create similar effect, and often when you come to a halt at a junction where you will turn when you set off, automatically you will place your bike at the ready particularily when turning left and you front wheel will not be strait. But me thinks you may only ever find this out for yourself, hopefully not the hard way.

I also once saw something similar but the front of the car rode up over the bikes wheel, I would guess it depends on the design of the car.

Your reasoning seems sound to me, mine would go like this however-

If a car taps you from behind your foot will slip off the brake and you may drop the clutch and give the throttle a handful and the bike itself becomes your worst enemy. If you hold on the front brake with right foot down you can sit in neutral so your bike is now in a safe mode, because you do not have to switch legs to engage a gear you can do this sufficiently quickly for it not to cause a hold up.

The thing is I use both sides, I would go for left down if I knew it was a momentary stop or if vehicles were still approaching from the rear and I would be holding both the front and rear brakes as well as being ready on the throttle. If I stop at a set of traffic lights and the the vehicle behind has stopped I would probably switch to right leg and take the bike out of gear.

If you are happy that statistically left down is safer then fine, I understand why teaching new riders techniques that vary by situation may be too advanced for them to cope with.

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Driving fast is for a particular time and place, I can do it I just only do it occasionally because I am a gentleman.
- James May

LOL.. i would probably get out and thump them heh heh And you are right about teaching, we have to be very careful because not everyone we teach has much capacity for anything the best fun is teaching those who come back after passing test for a little further training, a lot of stuff goes out of the window and you can have a bit of fun.

Err........the reason why you used to be told to cover the back brake when stationary is this (nicked from UKGS'er)...

"Chaps,

I have read through the preceding pages. & I can see that this topic clearly “fires up” a few folk, so I thought I’d weigh in with my two ha’porth.

Whilst there have been a number of views presented, & often there is no single “right way, the thing that has not been discussed so far is WHY the Hendon Shuffle or Two Step was once very important, & why today it is less so.

I started my private motorcycling in 1969, & first rode Police motorcycles in 1973, becoming a Class 1 in 1974. At that time the Triumph 650cc Saint was pretty much the national standard, along with a smattering of 650cc BSA’s, & the then new Norton Commando Interpol’s were starting to win customers in Police fleets.

From the early 1960’s onwards the British manufacturers had started to change their drum front brakes from single leading shoe to twin leading shoe format ( TLS ), which gives a much better braking performance from speed; what it does not do is give any real braking effect when the bike is moving backwards.

Before someone pipes up with “I haven’t got reverse gear on my GS, you ought to be on the K1200LT forum”, this becomes relevant if the motorcycle is stationary on an up slope. The rider would come to a halt, be holding the front brake on as hard as he could, but the bike would slowly move backwards. The rear brakes however, were invariably of the 1 leading/1 trailing shoe format, so worked equally well forwards or backwards.

If the rider came to halt on a slope, placed his bike in neutral, then placed his gear foot down, he could then hold the bike comfortably & safely on the rear brake, until the time came to move off, when he performed the required dance steps, & off he went.

Bear in mind this was the early 70’s, so the Police rider was “he”, & also, just to further confuse, we were at that time in the process of going over from the traditional British style right-side gear change to the now universal left-side.

In 1976 my Force, Gloucestershire, changed over to BMW’s - 75/6’s - & many other Forces opted for the Commando Interpol, but one thing they had in common was that both these machines were equipped with front disc brakes. They were nowhere near as good as the brakes we take for granted today, but they did, of course, work equally well in either direction.

Our Regional Driving School took the view that the “shuffle” was no longer needed, so the rider could come to a halt, snick into neutral, but place his back brake foot down, leaving his “gear foot” on the foot peg ready for the off.

I have to say I had forgotten the real reason for the “shuffle” until a few years ago when I rode an old drum braked R75/5 around the Cotswolds, equipped as standard with a TLS front brake. I came to a “Give Way” line on a steep upward slope, came to a smooth halt, then had a hells’ own job holding the plot upright as gravity kicked in, & back she tried to roll. Then I remembered.

To concur with some of the very well reasoned arguments above, some from serving or retired colleagues, & I am pretty sure I know a number of you already, the camber & state of the road is most important, & when Testing I look for the candidate to show that they are in control of their machine, & they can use which ever foot they wish, as long as they are comfortable & the machine is stable.

If carrying a pillion & luggage, or in adverse weather, with high winds, even worse if those winds are gusting, I may well place both feet down, & of course linked- or semi-linked brakes just muddy the waters a little more.

I do like to keep a wary eye on my mirrors, to see what’s approaching me whilst I am stationary, ready for evasive action, so perhaps we can start a new thread of “How close should I stop to the car in front?”.

Just my thoughts, you may differ"

So now you know.......

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"The Wrong Way Round..."

Interesting Speedy23, thanks.

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Driving fast is for a particular time and place, I can do it I just only do it occasionally because I am a gentleman.
- James May

Yes - at 5 mph! After this, the bike will sit up when you brake - and before you ask, yes I spent all morning on Friday trying it out on roundabouts on the way from Stratford to Northampton - there's a few good un's on the A43 - you start to notice the effect at about 25 mph +.....just a gentle reduction of lean angle, but imagine if you were going balls-out round a bend at high speed, overcook it, start to drift to the outside (through lack of CS input) and you panic brake - the bike will sit up sharply, you will straighten up and game over!



It's a unicycle not a bicycle, isn't it? It turns in exactly the same way as any other wheel - by moving the contact patch to one side by yawing the wheel and generating a torque around the wheels roll axis that makes it lean over.



But how do you know if this is the case?

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"The Wrong Way Round..."

Exactly-and if someone rear ends you then you don't bounce forward into oncoming traffic as they hit your tyre.(I had this happen to me-she hit me while she was accelerating hard and I had the rear brake on while stationary. I went directly upwards and landed on her bonnet. The bike only went 10 feet. If I hadn't had the rear brake on it would have gone a LOT further)If you're holding the front brake the wheel goes under and you go down.

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Smokebelching,CO2 making,child murdering planet raping,granny mugging,politically incorrect globally warming (or is it climate changing now it's getting colder?)thug.
That's what the government want you to believe of me. If they get back in I'm emigrating.

Hi Speedy. Interesting site. There seems to be one for everything these days. I bet there’s one for used chewing gum.

I think the bottom line for feet down is to do what you are most comfortable with. Over time people will work out what works best for them and sooner or later you’re bound to come across every eventually or mishap and decide what you prefer. Interesting about not being able to stop a bike on a hill with the front brake. The only time I haven’t been able to do so on tarmac was when the surface was gritty. I'm sure it varies from bike to bike too.

With regards to the CS; I still maintain it’s doable without touching the bars and I do it all the time. If I wanted to be pedantic, which I am, Keith himself did it although he tried his best not to. If you look closely at his video, despite his considerable attempts to stay on course in a straight line, you will see from the marking on the road that he himself does in fact start to turn off course which, by definition, is steering! I'd like to see him explain or refute that?

I feel I have been somewhat OTT over this matter though, for which I apologise. Again, I’m not having a go at you. My beef is with Keith. Hey, I’m a poet and didn’t know it

I will either get footage of it at >25mph or I'll do one myself. Regardless of speed, if you simply throttle off while banked over, (leaving brakes out of it because I never mentioned them in this process apart from the engine braking), your turning cirlce will diminish.

BTW Cotswolds? Stratford? That my patch! We should have that drink sometime

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The views expressed in this post are personal opinions and do not necessarily represent the views of Safe Speed.
You will be branded a threat to society by going over a speed limit where it is safe to do so, and suffer the consequences of your actions in a way criminals do not, more so than someone who is a real threat to our society.