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 Post subject: Friction Zone
PostPosted: Mon Aug 07, 2017 10:26 am 
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Is it possible to get into the "friction zone" ie: riding the clutch on a geared bike on a Forza? I'd like to master this for slow move maneuvers like u-turns.

Am I correct that I could apply a little rear brake, and give it a bit of throttle?


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 Post subject: Re: Friction Zone
PostPosted: Mon Aug 07, 2017 10:42 am 
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Sandymay wrote:
Is it possible to get into the "friction zone", ie: riding the clutch on a geared bike on a Forza? I'd like to master this for slow move maneuvers like u turns.

I'm I correct that I could apply a little rear brake, and give it a bit of throttle?



I kind of do the same but opposite.

I keep the throttle constant and moderate things with the rear brake.

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 Post subject: Re: Friction Zone
PostPosted: Mon Aug 07, 2017 11:18 am 
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 Post subject: Re: Friction Zone
PostPosted: Mon Aug 07, 2017 12:13 pm 
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Sandymay wrote:
Is it possible to get into the "friction zone" ie: riding the clutch on a geared bike on a Forza? I'd like to master this for slow move maneuvers like u-turns.

Am I correct that I could apply a little rear brake, and give it a bit of throttle?


Dragging the rear brake helps stabilize a slow speed sharp turn, like a U-turn on the street or parking lot. I do it all the time on my Forza and 1985 Elite 250. On the Forza the leftside brake lever works both the rear brake and (to lesser extent) the front brake, so some care is needed when apply the brake in a tight turn. Wish Honda had linked the front & rear brakes using the rightside brake lever. Wonder why they didn't? On the old Elite the rear brake is a foot pedal...some care is needed there also, as when you push on it your weight shifts forward, which tends to apply the brake more!


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 Post subject: Re: Friction Zone
PostPosted: Mon Aug 07, 2017 5:34 pm 
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SteveP wrote:
Dragging the rear brake helps stabilize a slow speed sharp turn, like a U-turn on the street or parking lot.


From a physics point of view I don't think it actually does anything. It's just a useful way of modulating the bike speed (which is a perfectly good reason to do it).

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On the Forza the leftside brake lever works both the rear brake and (to lesser extent) the front brake, so some care is needed when apply the brake in a tight turn.


The PCX has the CBS (Combined Braking System) too, but pretty sure it's only supposed to kick in at higher applications of rear brake. I'd assume it's to ensure effective stopping with less change of locking up the rear wheel.

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Wish Honda had linked the front & rear brakes using the rightside brake lever. Wonder why they didn't?


Would be a control nightmare - If you applied the front hard and it locked the rear you'd have no way to release it. The way it is, applying the rear brake will never lock the front - just too much weight shifted forward on it.


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 Post subject: Re: Friction Zone
PostPosted: Mon Aug 07, 2017 5:47 pm 
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Sandymay wrote:
Is it possible to get into the "friction zone" ie: riding the clutch on a geared bike on a Forza? I'd like to master this for slow move maneuvers like u-turns.

Am I correct that I could apply a little rear brake, and give it a bit of throttle?


Yes - but ...

Tight radius turns primarily come from an aggressive handlebar position (eg full lock or close to) - and that's only possible by having a greater lean angle (or the centripetal force will quickly try to tip you over the other way).

My encouragement is to find a parking lot - stop the bike - go full lock - put in the right amount of lean - and then practice practice practice keeping that lean in balance whilst at full lock using only the throttle. Primarily it's your throttle control that regulates your speed - which regulates centripetal force - which keeps the lean angle correct for the amount of steering input selected.

Or to put all that in English ... when I'm doing a 180, I'm full lock modulating the throttle, not the rear brake. Very quickly you should be able to go around and around and around in circles at full lock - then you'll have it mastered.

Note: That's the exercise anyway - but remember to balance using the bars if you have to to avoid falling off whilst learning to do it with the throttle.


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 Post subject: Re: Friction Zone
PostPosted: Mon Aug 07, 2017 7:40 pm 
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TheMaverick wrote:
SteveP wrote:
Dragging the rear brake helps stabilize a slow speed sharp turn, like a U-turn on the street or parking lot.


From a physics point of view I don't think it actually does anything. It's just a useful way of modulating the bike speed (which is a perfectly good reason to do it).

According to riding manuals I've read. applying the read brake in a tight turn tends to bring the bike "up", which helps give you control in a tight turn. it feels like it does exactly that. Applying to much front brake in a tight turn will cause the bike to go down, so you use hardly any.
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On the Forza the leftside brake lever works both the rear brake and (to lesser extent) the front brake, so some care is needed when apply the brake in a tight turn.



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Wish Honda had linked the front & rear brakes using the rightside brake lever. Wonder why they didn't?


Would be a control nightmare - If you applied the front hard and it locked the rear you'd have no way to release it. The way it is, applying the rear brake will never lock the front - just too much weight shifted forward on it.


Well it'd certainly have to be set up so there'd be limited braking force sent to the rear brake.


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 Post subject: Re: Friction Zone
PostPosted: Mon Aug 07, 2017 9:28 pm 
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SteveP wrote:
According to riding manuals I've read. applying the read brake in a tight turn tends to bring the bike "up", which helps give you control in a tight turn. it feels like it does exactly that. Applying to much front brake in a tight turn will cause the bike to go down, so you use hardly any.


I've read the same in places too. I'm quite fascinated by these kinds of things so I spent a few hours Googling it one Saturday morning; Keeping in mind that there's a lot written about bike control on the internet, but that doesn't mean that all of it is correct (YouTube videos on counter-steering is a great example - most just don't understand gyroscopic precession so their explanations are usually incorrect). From a physics point of view, using the rear brake to stabilize a turn just doesn't make a lot of sense for anything other than just speed control - on one hand you've got a transmission trying to accelerate the rear wheel, but on the other, a brake trying to decelerate it - so the two simply offset each other - there's no other "magic" happening. It's been suggested that the higher engine RPM may have more of a gyroscopic effect on maintaining a given lean angle, but a revved engine and a gearbox in neutral don't seem to produce any significant stabilising moment, so I don't think that part is contributing anything. On a conventional motorbike, coordinating engine RPM and clutch position whilst full lock and leaned over can be challenging - and in that respect using the rear brake is an effective way to modulate bike speed precisely (if the bike is and remains full lock then bike speed is the ONLY remaining variable to coordinate/balance the turn). On a scooter though, we don't have an issue with minimum RPM, and the clutch sorts itself out, so it's less of an issue. I've tried using the rear brake to coordinate a minimum radius turn (having read the same advice) but in the end I found it was really only substituting for my poor throttle control; once I got the throttle sorted the need to modulate speed with the rear brake disappeared.

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Well it'd certainly have to be set up so there'd be limited braking force sent to the rear brake.


I really can't see the point of it to be honest - if really aggressive braking is required then it's the front doing all the work (the back locks very easily) - so it would need to be quite a complex system to account for different road surfaces.


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 Post subject: Re: Friction Zone
PostPosted: Mon Aug 07, 2017 10:44 pm 
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[quote=
I've read the same in places too. I'm quite fascinated by these kinds of things so I spent a few hours Googling it one Saturday morning; Keeping in mind that there's a lot written about bike control on the internet, but that doesn't mean that all of it is correct (YouTube videos on counter-steering is a great example - most just don't understand gyroscopic precession so their explanations are usually incorrect). From a physics point of view, using the rear brake to stabilize a turn just doesn't make a lot of sense for anything other than just speed control - on one hand you've got a transmission trying to accelerate the rear wheel, but on the other, a brake trying to decelerate it - so the two simply offset each other - there's no other "magic" happening. It's been suggested that the higher engine RPM may have more of a gyroscopic effect on maintaining a given lean angle, but a revved engine and a gearbox in neutral don't seem to produce any significant stabilising moment, so I don't think that part is contributing anything. On a conventional motorbike, coordinating engine RPM and clutch position whilst full lock and leaned over can be challenging - and in that respect using the rear brake is an effective way to modulate bike speed precisely (if the bike is and remains full lock then bike speed is the ONLY remaining variable to coordinate/balance the turn). On a scooter though, we don't have an issue with minimum RPM, and the clutch sorts itself out, so it's less of an issue. I've tried using the rear brake to coordinate a minimum radius turn (having read the same advice) but in the end I found it was really only substituting for my poor throttle control; once I got the throttle sorted the need to modulate speed with the rear brake disappeared.

Whatever the actual reason is, I've found dragging the rear brake lightly while applying a bit of throttle on sharp low speed turns definitely helps stabilize the bike...motorcycle or scooter.


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 Post subject: Re: Friction Zone
PostPosted: Tue Aug 08, 2017 12:05 am 
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SteveP wrote:
Whatever the actual reason is, I've found dragging the rear brake lightly while applying a bit of throttle on sharp low speed turns definitely helps stabilize the bike...motorcycle or scooter.


I don't disagree with you per se - but I'm 99% convinced that the "stability" is only coming from being able to fine-tune speed (which is the only way to balance a bike in a turn at full lock) (assuming rider weight shifts are to be ruled out). Or put that another way (on a scooter anyway) "you can achieve the same 'stability' with just throttle control".


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 Post subject: Re: Friction Zone
PostPosted: Tue Aug 08, 2017 12:19 am 
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[quote=


Whatever the actual reason is, I've found dragging the rear brake lightly while applying a bit of throttle on sharp low speed turns definitely helps stabilize the bike...motorcycle or scooter.[/quote]

It certainly does but never argue with a Google expert. You are on a hiding to nothing.

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 Post subject: Re: Friction Zone
PostPosted: Tue Aug 08, 2017 12:36 am 
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you you wrote:
It certainly does but never argue with a Google expert. You are on a hiding to nothing.


Not sure who's arguing, nor who the "Google expert" is, but assuming the dig is aimed at me, again, I'm merely having a rational discussion - one in which my formal training in gyroscopics and aviation qualify me to at least know something of what I'm talking about.

If you have any credible theories about braking a rear wheel provides increased stability whereas a throttle input that achieves exactly the same speed doesn't, then I'm all ears.


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 Post subject: Re: Friction Zone
PostPosted: Tue Aug 08, 2017 12:48 am 
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Little snip from the book "Motorcycle Safety & Dynamics - Colour" - Page 68:

https://books.google.co.nz/books?id=yG4 ... &q&f=false

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