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TonyB
9th June 2005, 08:41
On another forum, a member has asked the question "how are you supposed to deal with down hill decreasing radius bends?" I have Keith Codes book Twist Of The Wrist II. In it from memory he says that the only correct line for a corner is the one that allows you to steadily roll on the throttle to keep the bikes ideal 40/60 front/rear weight distribution. Then he says the only exception to this rule would be on down hill decreasing radius bends (i think he also throws in 'off camber'). But I'm sure he doesn't give a way of dealing with it, which is a shame, because the real world is full of the fuggen things!

So, does anyone have the answer?

FROSTY
9th June 2005, 09:00
to start with you need to establish if you A come across it unexpecctedly or B know its there
Knowing its there I'd simply enter the corner slower /wider than normal and when I sight the corner exit accelerate as per normal.
Unexpectedly -Ya know I dunno -Ive done one of two things --In a big corner Ive stood the bike up for a moment and washed a load of speed off then had another crack at the corner. In a tight corner ive hung off some more and leaned more.

Pwalo
9th June 2005, 09:05
On another forum, a member has asked the question "how are you supposed to deal with down hill decreasing radius bends?" I have Keith Codes book Twist Of The Wrist II. In it from memory he says that the only correct line for a corner is the one that allows you to steadily roll on the throttle to keep the bikes ideal 40/60 front/rear weight distribution. Then he says the only exception to this rule would be on down hill decreasing radius bends (i think he also throws in 'off camber'). But I'm sure he doesn't give a way of dealing with it, which is a shame, because the real world is full of the fuggen things!

So, does anyone have the answer?

I think that the steadily rolling on the throttle comment applies to corners where you can spot the apex and exit. Ideal on a race track, but not perhaps so good for the road.

Common sense would seem to say that caution is the word. Gentle braking, watching the vanishing point, and rolling on the throttle when you have a clear indication of corner exit.

Sorry I can't think of a foolproof system for corners on the road. Even the same corner can be different on different days, or times of the same day. You really can't apply race rules on the road.

Ixion
9th June 2005, 09:11
A downhill right hand S bend with both parts tightening would have to be the corner from hell!

I think the only thing you can do is brake really hard before the corner, slow down way below "normal" speed and then accelerate all the way through the corner (not just from the apex). Gently until you see the exit, then hard(er).

Still don't think that's good though, but everything else seems worse.

In theory having a pillion should help, putting more weight rearward. Maybe stop and wait until a hitchhiker turns up?

bugjuice
9th June 2005, 09:12
with a bend like that tho, unless you know it (in which case, this is pointless), I think you have to get steady n slow, and keep it wide, cos you just don't know what's coming up, and if you have to tighten up.

On saying 'keep it wide', remember that large vehicles like trucks and buses will often cut into the corner, so don't ride the centre line. A good measure would probably be stick in the right wheel lines of the road, then use those 'run in' marks as a guide as to what's coming and what line you should take. I pretty much use car lines as a guide to what's coming up next, as the best line is often the one that's beaten into a road. The exception here is newly laid roads. Then just really take it easy.

Id be inclind to select a higher gear and let the engine do most of the braking for you too, but not so that it's screaming. Feather the throttle to 'adjust' the amount of braking the engine is doing for you, and use the back brake more than the front. Then if/should the worst happen, the front isn't cooking up as you're riding the brakes, and you have that bit more braking at the ready.

Then just slow n steady does it.. Watch the furthest point you can see, then when the exit comes up, change down a gear and ride it out as normal

White trash
9th June 2005, 09:24
What you do is you head in far too fast, as you start to turn in, bang your motard down two gears to many to facilitate a "compression lock" of the rear wheel. This will allow the rear to swing waaaaayy outta line with the front, thus scrubbing more speed. Slide your inside foot up in front of you along the tarmac as you lean further to scrape the peg in order to emulate your hero, Boris Chambon.

Once at the later apex of a decreasing radius turn, get HARD on the gas to spin the rear wheel and thus keep it "hanging out" on the exit.

Piece of piss. :niceone:

bugjuice
9th June 2005, 09:27
What you do is you head in far too fast, as you start to turn in, bang your motard down two gears to many to facilitate a "compression lock" of the rear wheel. This will allow the rear to swing waaaaayy outta line with the front, thus scrubbing more speed. Slide your inside foot up in front of you along the tarmac as you lean further to scrape the peg in order to emulate your hero, Boris Chambon.

Once at the later apex of a decreasing radius turn, get HARD on the gas to spin the rear wheel and thus keep it "hanging out" on the exit.

Piece of piss. :niceone:
nice.. gonna practise that on the 636...

Ixion
9th June 2005, 09:35
What you do is you head in far too fast, as you start to turn in, bang your motard down two gears to many to facilitate a "compression lock" of the rear wheel. This will allow the rear to swing waaaaayy outta line with the front, thus scrubbing more speed. Slide your inside foot up in front of you along the tarmac as you lean further to scrape the peg in order to emulate your hero, Boris Chambon.

Once at the later apex of a decreasing radius turn, get HARD on the gas to spin the rear wheel and thus keep it "hanging out" on the exit.

Piece of piss. :niceone:

Ah well,and if we're on gravel of course then the whole thing becomes simpler. Just go round sideways.

ManDownUnder
9th June 2005, 10:10
nice.. gonna practise that on the 636...

Ya huh - sounds easy... just don't ask me to do it. 200kgs of RF pushing that hot exhaust into my legs is NOT my idea of fun.

As for the corner - lose speed, stind the bike up and throw out all the anchors, punch the indise handle bar and drop the bike into the turn, easy on the brakes, keeping enough weight on the rear to maintain traction, survive the corner... take the tightest line you can so you've got room to go wider if/when you need to.

Take photos of the wreck and put your claim through as quick as you can (a la Swanny)
MDU

TonyB
9th June 2005, 10:27
Dear Mr Trash,
Can you please come back to Chch and demonstrate this technique on your GSXR on some of the down hill decreasing radius corners on the Akaroa run? I will video you, so that this techinque can be demonstrated to the appreciative KB public..... Should your attempts fail, we can then post them on the web so that bikers all over the world can have a giggle :niceone:

Oft have I wondered wether Keith Codes advice really applies well to the road. Even in racing, when you watch the on board cameras from MotoGP they don't exactly seem to be braking deep into the corner, then slamming it down for a short time, then standing it up and accelerating away... I wonder sometimes SOME if his advice is now out of date, as bikes handle far better than they did 10+ years ago....

White trash
9th June 2005, 10:29
Dear Mr Trash,
Can you please come back to Chch and demonstrate this technique on your GSXR on some of the down hill decreasing radius corners on the Akaroa run? I will video you, so that this techinque can be demonstrated to the appreciative KB public..... Should your attempts fail, we can then post them on the web so that bikers all over the world can have a giggle :niceone:


No need mate.

Anyone who's seen the state of my VERY second hand Gixxer is already giggling their arses off.

justsomeguy
9th June 2005, 10:38
What you do is you head in far too fast, as you start to turn in, bang your motard down two gears to many to facilitate a "compression lock" of the rear wheel. This will allow the rear to swing waaaaayy outta line with the front, thus scrubbing more speed. Slide your inside foot up in front of you along the tarmac as you lean further to scrape the peg in order to emulate your hero, Boris Chambon.

Once at the later apex of a decreasing radius turn, get HARD on the gas to spin the rear wheel and thus keep it "hanging out" on the exit.

Piece of piss. :niceone:

Wow drifting on a bike...... good luck - if you're name isn't Gary McCoy.......

So far buggy's making the most sense.

White trash
9th June 2005, 10:43
Wow drifting on a bike...... good luck - if you're name isn't Gary McCoy.......


Or any number of Motard wannabes.

Seen Mr Briggs doing it quite nicely at Wangavegas a year and a half ago.

eliot-ness
9th June 2005, 12:03
Ahh! The last unanswered question, (Assuming all bikers know the meaning of life.)
BJS got it as right as is possible for us mere mortals. One thing I've found useful is the speed advisory sign, Usually highly pessimistic, but I've noticed that when they advise
35kms on a corner that looks like a 70 minimum then the unexpected is about to happen. I change down two gears instead of one, forget the fastest line into it, then I can (sometimes) pick the best line out. Doesn't always work. On the worst ones there's usually no sign, but it's kept me in one piece for a long time.
P.S. W.T. Wasn't that your mangled helmet I saw posted yesterday ?????????????

Ixion
9th June 2005, 12:25
.. One thing I've found useful is the speed advisory sign, Usually highly pessimistic, but I've noticed that when they advise
35kms on a corner that looks like a 70 minimum then the unexpected is about to happen. ..

Yes , those signs are good. Add something to the higher ones (I've found it pays to be careful on the 25kph ones. Often they DO mean 25kph). But as you say, the real benefit is when what looks like a nice 80kph is signposted as 35kph, And the similar looking corners before it have been signed at 55. Hm, something gonna be odd here.

bugjuice
9th June 2005, 12:32
Yes , those signs are good. Add something to the higher ones (I've found it pays to be careful on the 25kph ones. Often they DO mean 25kph). But as you say, the real benefit is when what looks like a nice 80kph is signposted as 35kph, And the similar looking corners before it have been signed at 55. Hm, something gonna be odd here.
nah, 25khp - 50kph are potential knee-down corners, and should be taken as tho. Anything higher are 'wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee' corners.. Apart from 'Swanny' corners, which go something like: 'Wheeeeeeeeee ooooooooooooo aaaarrrrrrrrrrrgggggghhhhhhh fuuuuuuuuuuuukkkkkkkk ouch ouch oo ouch arrrgh ouch bugger.'

White trash
9th June 2005, 12:34
P.S. W.T. Wasn't that your mangled helmet I saw posted yesterday ?????????????

You misunderstand, I was merely advising what "should" be done, not what I can do. Obvious from the helmet damage.

eliot-ness
9th June 2005, 12:41
Sorry WT couldn't resist it.

-------------------
Plan to be spontaneous,...........Err......tomorrow... maybe

Fryin Finn
9th June 2005, 12:59
I got some practice on decreasing radius downhill turns last monday riding over the Hope Saddle towards Nelson. I did it twice just to make sure :yes:

TonyB
9th June 2005, 13:02
Hmm, so far no one seems to have a definative answer, which is a bit of a worry eh! WT, your technique sounds fuggen cool but if you can't do it then what hope do I have???

To be honest I'm not 100% sure what I do either, but I THINK this is what I TRY to do: If I know the road, I brake deep into the corner- not cornering as such but not straight up and down either, more of a gentle curve to position myself on the road. Then I stop braking, lean it over staying out wide till I can see or almost see the exit, then I cut in and apex very late while rolling on the gas. I find you have to have a hell of a lot of confidence in the front end to ride a DHDR (Down Hill Decreasing Radius) Bend at any sort of pace.... hence I get eaten alive by cars on such corners.... :o

Artifice
9th June 2005, 13:49
i find the hardest part is letting go of the front brake lever. it handles so much better once you let go and of course gets mostly rid of the chance of the front washing out. but it dont make it easier to let go of the brake.

XP@
9th June 2005, 13:58
In theory you should be able to stop, on your side of the road in 1/2 the visible distance. :wait:
Hmm... not really the same in practice is it!
So what you going to do about it?

Basically slow so you don't get caught out. REALLY IMPORTANT if you don't know the road & bend and you can't see the exit.
Both Brakes
Gear down to a gear which will allow you to power through the corner
Delay the apex to give as much visibility as possible.
Eyes just past the vanishing point.
Plan to use no more than 50 - 60% of your cornering ability at the given speed.
Aim to exit the bend on the center of the lane.

Then if the radius starts to tighten counter steer harder you will still have heaps left in reserve.

Even if you know a corner it can unexpectedly turn in to a decreasing radius... a sheep in the middle of the road, a car cutting the corner and you will have to decrease your radius.

So when you enter a corner plan for your line to be changed.

Motu
9th June 2005, 15:28
Good point XP@,all corners are decreasing radius if you have to change course - so expect all corners to be so and allow for it.I ride dirt bikes so have much more body English to use and can push down and pick up the bike easier and with more effect,but yeah,decreasing radius and off camber are nasty and can catch you out.For me the worst are gravel down hill off camber right handers - you have to go wide to be safe...but that's where all the loose stuff is and so it's always slowly does it.On an open corner I can see through I will cut to the inside apex and this changes the camber and radius,on left handers with visable exit I go wide to the gutter,again changing the radius.Naturally you only do this if you can see clear road with enough room to change tack again if needed....sometimes it only needs a little bit of extra road for the anal spincture to release the seat cover....

Lou Girardin
9th June 2005, 15:55
What you do is you head in far too fast, as you start to turn in, bang your motard down two gears to many to facilitate a "compression lock" of the rear wheel. This will allow the rear to swing waaaaayy outta line with the front, thus scrubbing more speed. Slide your inside foot up in front of you along the tarmac as you lean further to scrape the peg in order to emulate your hero, Boris Chambon.

Once at the later apex of a decreasing radius turn, get HARD on the gas to spin the rear wheel and thus keep it "hanging out" on the exit.

Piece of piss. :niceone:

In other words, just normal commuting technique.

Lou Girardin
9th June 2005, 15:57
I got some practice on decreasing radius downhill turns last monday riding over the Hope Saddle towards Nelson. I did it twice just to make sure :yes:

Great, aren't they. You wouldn't believe how fast this chickie pedalled her Nissan Pulsar through that stretch when we were down there.

Ixion
9th June 2005, 16:00
In other words, just normal commuting technique.

Well. no because you don't have any cages to foot off for direction changes

TwoSeven
9th June 2005, 16:31
A decreasing radius turn is always done with a slow entry, constant progress and fast exit - doesnt matter what the slope of the turn is or the camber. The most common mistake is picking where the entry is - many of them are at the end of a normal radius corner forcing a throttle action which throws the bike off line.

Downhill simply means your front is loaded up, the way to unload the front is to either be on the gas, or more simply off the brakes - I find constant throttle often helps.

A quick corner is one where you get the bike down, turned and up as fast as possible - a long radius in the turn means the bike has to be leaned over which prevents opening the throttle until after the apex. Remember, changing the throttle action mid corner buggers the line.

So that gives you only one option for a decreasing radius turn - you cant be on the gas because you'll have the long turn until the exit point, you need a slow entry - so it kind of implies you need to hold a constant throttle (it will have weight on the rear).

Thats how I work it out. Stick a nice off camber there and you'll really find it interesting.

Lou Girardin
9th June 2005, 16:40
Well. no because you don't have any cages to foot off for direction changes

True. Does a knee into the door count as 'knee down'?

Motu
9th June 2005, 17:26
A decreasing radius turn is always done with a slow entry, constant progress and fast exit - doesnt matter what the slope of the turn is or the camber. The most common mistake is picking where the entry is - many of them are at the end of a normal radius corner forcing a throttle action which throws the bike off line.

Downhill simply means your front is loaded up, the way to unload the front is to either be on the gas, or more simply off the brakes - I find constant throttle often helps.

A quick corner is one where you get the bike down, turned and up as fast as possible - a long radius in the turn means the bike has to be leaned over which prevents opening the throttle until after the apex. Remember, changing the throttle action mid corner buggers the line.

So that gives you only one option for a decreasing radius turn - you cant be on the gas because you'll have the long turn until the exit point, you need a slow entry - so it kind of implies you need to hold a constant throttle (it will have weight on the rear).

Thats how I work it out. Stick a nice off camber there and you'll really find it interesting.
A touch of rear brake will give rear weight bias...if you're up to it,rear brake and throttle at the same time helps steady the bike.

TwoSeven
9th June 2005, 19:37
A little squat always helps :)

Specially after a good curry...

Two Smoker
9th June 2005, 19:57
A touch of rear brake will give rear weight bias...if you're up to it,rear brake and throttle at the same time helps steady the bike.

I do this when racing, works a treat and limits wheelspin... Done it a few times on the RG too...

Ixion
9th June 2005, 21:32
A touch of rear brake will give rear weight bias...if you're up to it,rear brake and throttle at the same time helps steady the bike.

I usually do this - a snake taught it to me. The rear brake sort of steadies things and the throttle on sort of pulls you through. Throttle just sort of steady though balanced against the speed - just so the rear wheel isn't driving the engine. Then at the apex, brake off and throttle on.

sAsLEX
9th June 2005, 21:46
I do this when racing, works a treat and limits wheelspin... Done it a few times on the RG too...

that other famous kinda guy does it to........now whats his name?? ........oh thats right Rossi

TwoSeven
9th June 2005, 22:58
They all do it - settling the bike in and out of corners is a basic learners technique.

XP@
9th June 2005, 23:34
I do this when racing, works a treat and limits wheelspin... Done it a few times on the RG too...
...on the track, not recommended practice on the road. too many things can go wrong!