khp
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Posts posted by khp
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Well, is it only me or picture is missing?
No, it isn't only you. It was up here when it was first posted but I don't know where it went. BTW, it was a very large image making it difficult to view it but it was up here - now its gone.
Well, by golly, I can see it now in posting #138 (03:49pm timestamp).
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Hi there,
I have been having a problem with cornering and I though I would try you guys to see if I get some sensible suggestions as to how to handle it.
first some paremeters
Bike: kwaka zx14 2008se
tyres: michelan PR2's
Tyre pressure 40psi
The problem only seems to happen when I am pushing my zx14 through a set of twisties fairly hard (double indicated +10km/hr). I sometimes feel the front end starting to slide just a little bit, it makes a kind of crackling sound and it kind of feels like a car does when it understeers....
Im wondering what Im doing wrong. In my mind tyres are designed by people who are a lot clever'er than me to work together as a pair so Im thinking that the rear should be letting go first. Is this the case ??
Im hoping the minister for war and finance will be getting me a CSS level 1 course for my birthday (she asked me this morning if it was covered by my insurance co as 'rider training', which it is) so its definately on the cards. is this a prob they will be able to fix @ level 1 ??
any thoughts on tyre choice, pressure, what I should be doing with my body position, throttle etc ?
any input would be appreciated
thanks in advance
OZ
Hi OZ,
It's hard to tell without having seen you ride the bike nor seen the tyres, as there could be several things.
1) How much wear is there on the front tyre? It could simply be that you're scrubbing off speed with the front, from the classic "fast in, slow out" riding style. Going in slower, not scrubbing off so much seed with thr front, should help both on the front understeering, but also allow you to get a better drive out.
2) If you're riding with hang-out, the bike could be reacting to some involuntary rider input as you move from side to side.
3) The suspension could be set up incorrectly for your riding style and body weight.
4) Those 40 psi's sound like an awful lot to me, especially if it's the front tyre.
A simple thing is to take a look at your tyre pressure. What is the recommended tyre pressure in the bike's manual? and what does Michelin recommend for your bike?.
The recommended pressures for my R1 roadbike are 33 front and 36 rear, but your bike is heavier than mine.
Try lowering the tyre pressure to 36 psi - this will allows the tyre to move around a little more, causing it to be warmer, which should make it more sticky. You will find that the bike feels a bit "squirmy" until the tyre has properly heated up, but stick better after that. If it helps, you might even want to try 33 psi.
As for the rear tyre breaking away first: not necessarily. The tyres deal with very different loads under different situations. Under which situations would the rear break away? - and in which situations the front?
Best regards,
Kai
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I shot my first onboard video today with my new GoPro. It took in more than I expected, so I will need to experiement with different camera angles. However, what really surprised me was that there is virtually no evidence of countersteering, but lots of evidence of massiv steering into the corners
The road is littered with 20-30 mph hairpins (when I run out of cornering clearance). Since I carried my son on the pillion, I tried to be fairly smooth when turning in, but I was/am still stunned about the lack of visible countersteering.
The handlebars don't move more than perhaps +/- 10mm, when countersteering. If you have The Twist-II DVD, there is a scene where they've put a gauge on the tank so demonstrate that you're actually countersteering, but it also shows just how little the handlebars actually move. But it still can take a massive force to move, when at higher speeds.
Kai
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My wife was one of 3 daughters, if I'd have been her dad...don't know if I would have survived it. With just one (and she is only 9), I'm taxed. My son is way low maintenance. But, interesting point, she is the one that is more interested in riding! Go figure.
As a good friend of mine is saying: I have a wife in the menopause and two teenage girls: My hearing is not impaired, it's just selective!
(this is getting waaay off topic)
Kai
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Bullet and others: Just exactly how to you do a clutch-less shift between first and second (either way)? I invariably find that trying to do that will end me up in Neutral (bummer!).
Kai
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Good to have you back, Bullet!
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I noticed an interesting picture on motogp.com yesterday, but I can't find it there for the life of it.
The shot was taken from behind the bikes, showing Pedrosa and Lorenzo in a turn where BOTH of them were very clearly leaning away from the bike with their upper bodies!
Now, I have my own little pet theory about why they do that, but spilling the beans don't make much for conversation. So, any takers - why do they do it?
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Well, if this topic isn't on the verge of being profetical ... Randy de Puniet went down in the German MotoGP at Sachsenring just yesterday, breaking the tibia and fibula (just like Rossi).
The breaking of the leg wasn't even caused by his own crash, but my Mikka Kallio hitting his leg.
http://www.motogp.com/en/news/2010/de+puniet+on+surgery+after+sachsenring+crash
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What are the benefits of aftermarket clipon handlebars opposed to the stock items on my bike, are they worth getting or best just waiting until mine break then replace them.
I would wait until I break the stock clipons
As for the aftermarket parts, they are often made of higher quality aluminium (ie they don't break as easily, and they can be bent back into shape, rather than just snap off), are easier to repair and order spare parts for. Also, they tend to be more adjustable on the fork leg.
My PP Tuning clipons were fitted to the bike when I bought it
Regards,
Kai
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...picture a corner, maybe entry speed 60 mph, scenario 1 you go no brakes, arive at your desired turn point at 60, turn and do the corner!
scenario 2 you brake very hard from a high speed approaching your turn point, arrive at your turn point at 60, turn in and do the corner!
No trail braking or anything, just simply getting to your turn point and turning, would scenario 2 not give a bit more front end grip than scenario 1 right at the turn point?
Bobby
That's a great question Bobby...beyond my pay grade mind you but you framed it very well.
BTW, I dunno the answer but do understand the question.
I can't say I know (or even understand) the answer, but let's pitch the two situations against each other from a physics point of view:
The "no braking" entry, with a steady pace:
- The front tire just rolls along, with approx 40-45% of the load from the bike+pilot on it.
The "hard braking entry, with a gas-it, brake-it pace:
- During the acceleration phase, lets than 40% of the weight is placed on the tyre, due to the gas transferring most or even all the weight to the rear tyre. Hence, the tyre will deform less and thereby generate less heat in it.
- During the braking phase, almost 100% of the weight is transferred to the front tyre, deforming it from the forces and also some of the kinetic energy from the bike is bound to end up at heat in the tyre. Thus, the tyre should see a significant heating from the braking action.
Unless I have missed something obvious (if I have, do speak up please!), the braking entry is bound to give you a warmer tyre, which in turn should give you more grip*. If I understand the tyre experts right, the difference between a race tyre and a road tyre is that a race tyre offers a very high level of grip, but in a rather narrow temperature range, whereas a road tyre is designed to yield a good level of grip (but not quite as high as from a race tyre), but over a fairly broad range of temperature.
*) assuming that the tyre isn't decomposing from the heat, of course
So yes, I think ACE is right in claiming that the braking action will give you a better grip level. The question remains: do they actually need this extra grip in order to make the turn? I haven't seen any of the motoGP races this year, but I recall at least Stoner explaining that he had a hard time "loading up the front end" to get the grip that he wanted.
If that's the case, then maybe we're killing two birds with one stone in this thread!
Cheers,
Kai
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I guess I'm still riding mostly on the road.
Until a couple of months ago, I hadn't even tried doing a clutchless downshift, but thanks to this forum, I am now able to do a clutchless downshift.
On the road, I mainly use the clutch both up and down, but I'm practising doing clutchless shifting for the benefit of the track riding (I've changed the gear lever on the road bike to match the racebike).
On the track, I predominantly use clutchless upshifting, but use the clutch when going down. Since I have to be at fair low rpm to make a nice, positive clutchless downshift without gearbox noises, I don't do them much if at all (haven't got the time, you know ;-).
Kai
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Glad to hear this. A standing request to you (and any student really): if your training is not going as you expect/hope it should, don't hesitate one second to talk with either Jet or Andy (in other words the Chief Riding Coach or School Director).
Thanks, I understand that.
I realize I didn't explain well why I was disappointed with my first Level 4. Allow me correct that: it had everything to do with myself, and nothing to do with neither coach nor Liaison.
Thinking the experience over later, I found that I wasn't very clear on which parts of my riding that I wanted to work on, and why, ahead of time. I was more like "OK, doing a single day when I'm driving all the way from Denmark to Silverstone and back, so why don't I do both Level 3 and 4 while I'm there.", and the results followed (OK, pissing rain didn't help either. But that's just me). I didn't have a plan for the day.
Since then, I've taken time to observe and work with my driving, in order to better pinpoint the places where I needed help. And that's what made all the difference.
I wonder if other students who did their first Level 4 just the day after another level have observed the same "doldrum"?
Best regards,
Kai
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Just like Hansi, I was at Gelleråsen for CSS classes in the past weekend.
I'd like to say a big thanks to JET, Spidey and Nemo, who were my Level 4 Liaisons and coaches (JET and Spidey swapped roles from Friday to Saturday - actually a brilliant idea).
We had a very intimate little Level 4 group going with just three students on both Friday and Saturday, so Spidey & JET got to film all three of us in all the sessions.
On the first day, we got working on getting rid of my tunnel vision, and getting that drive working right from the lean angle is set, instead of waiting to the apex, and on the second day I was working on body position. Sheesh, that Knee flick is still difficult to get right! My (very) long legs and arms also meant that I had to figure out a way to move my arms when going into and out of the Hook Turn position, as my knee is in the way of my elbow.
Before coming the Gelleråsen, I was a little hesitant regarding doing several Level 4 days in a row, since I was a little disappointed from my first Level 4. What made all the difference was that this time around, I was arriving with a clear idea of where and what I wanted to improve.
I had mounted my video camera pointing forwards, and it was actually useful from time to time, since the coaches had problems with their GoPro camera, so we actually used my video to review both my lines, but also one of the other students, as I had happened to be just behind him for about a lap, before passing him.
All in all a big thumbs up to the entire CSS UK team and the SMC team for organizing the days, and providing the wrangling, cornerworking and other services.
Cheers,
Kai
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Hi Hansi,
Yeah, it was really hot over the weekend at Gelleråsen. I was doing two days of Level 4 on Friday & Saturday.
Great photos by Gary "picman" as usual.
Regards,
Kai (the tall dane on a blue R1)
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Hi Kai and Razor,
It sounds to me like you are both really saying the same thing, let me summarize see if I understand it as you mean it:
A bike can be shifted without the quick shift/shift assist, but it's not as fast as with it.
Do I have that correct?
Yes, absolutely correct.
Best regards,
Kai
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What a great accomplishment, congratulations. I race with WERA and know two guys that have overcome disability to do what they love. One lost an arm and is amputated at the shoulder an one has an arm but has to use a prothesis to hold on to the bar. There is also a guy that rides NESBA track days who is paraplegic and has an assist mechanism for getting on the bike in the paddock.
Talan,
Congrats from Scandinavia too.
Just to add to the list of people who has overcome disabilities to ride and race: one of the Swedish racers is a double leg-amputee (just below the knee, I believe).
Way to go!
Kai
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A quick-shifter allows you to change gear in about 2 milli-seconds (2/1000 second), that's what it does - it cuts the ignition just enough to do the gear change. A "normal" clutchless shift requires you to slightly close and then reopen the throttle, to take the forces off the clutch gears (this takes maybe 50-100 milliseconds).
As discussed earlier at length, you can do clutchless up- and down-shifts without a quick-shifter.
Try a bike with a quick shifter and then we talk. I know that I can do my upshift in my bike without a clutch. but there is a big difference
in speed and timing when I used mi quick shift. Also, there is a reason that the quick shifter was invented and at all levels of racing is been used.
Cheers to you too.
The razor.
Hi Razor,
I'm probably dense today, but where exactly do you disagree with my post?
Best regards, Kai
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Can we do clutchless downshifting with Shift Assist? As far as I know, racers don't use clutch when upshifting at high rpms.
I have a CBR1000RR with a BAZZAZ sytem (fuel mapping, traction control and quick shifter). I love the quick shifter. It is supposed to be used only for upshifting, you have to use the clutch for downshifting unless you want to time the downshifting with the RPM. Also the shifter works better with high RPM. I do not know about the BMW, but I figure it is the same. I will find out in August went I take my fisrt class and I get to ride the BMW.
My two cents.
Actually, my 2009 zx6r has no shift assist or quick shifter, nevertheless I can upshift with no clutch. So what will the quick shifter change?
A quick-shifter allows you to change gear in about 2 milli-seconds (2/1000 second), that's what it does - it cuts the ignition just enough to do the gear change. A "normal" clutchless shift requires you to slightly close and then reopen the throttle, to take the forces off the clutch gears (this takes maybe 50-100 milliseconds).
As discussed earlier at length, you can do clutchless up- and down-shifts without a quick-shifter.
Cheers,
Kai
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The Go-Pro has been just fine by me, I've just got the new HD one, but haven't had a chance to get it out on track yet.
As far as angles go, I have tried almost everything, and have found that the front, facing back at you is the best one to help figure out riding position and throttle control.
Here's link to one I put up on youtube: Rear Facing at Jennings FL
As already mentioned the go pro comes with heaps of mounting solutions, so this wasn't hard to do.
Cheers,
Link doesn't work for me. I'm interested in seeing the video
There was a http// too much in that link. This should work better:
Cheers,
Kai
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Another weird front end issue, about Simoncelli in today's race:
He was pushing de Puniet when he let off thebrakes too early and the front end washed away on
the 14th lap.
Can you let off the brakes too early? Or do they mean too quickly?
The only explanation I can imagine is that they've set up the front end to rebound very quickly, and that would take the weight off the front end, causing the wash-out.
Kai
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So, not many students or at least non-coaches has chipped into Cobie's thread, so let's try it this way.
Which track is your favourite track for coaching/honing you skills? - and why?
And which one do you like the best, overall - and why?
I've been to two tracks with CSS so far: Gelleråsen in Sweden and Silverstone South (before they changed the track).
I found Silverstone South to be quite open and of a "gas it" track rather than technical, whereas Gelleråsen is the opposite: lots of turns leading from one to the other, with much less straights.
Of the other tracks I've visited, I probably like Ring Knutstorp the best - lots of elevation changes and different types of turn ... and, hey, it' damn close to my home
Some call it "The Nurburgring of Sweden", and I can relate to that. Speaking of the Nordschliefe, it's awesome and fearsomely dangerous. I don't consider it to be a real track, although I find it fascinating - officially it's a one-way, toll-collect, no-speed-limit highway.Speak up!
Kai
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Motorcycles have rear brakes?
I find the rear brake quite handy .... but mostly on the road.
Why is the rear brake handy?
- Using the rear brake doesn't change the weight distribution as much as when using the front brake
- Using the rear brake doesn't affect the steering geometry as much as using the front brake
- It's much easier to just ease off a bit of speed than when using the front brake (useful when you're getting a whee bit too close for comfort to the guy in front, you just want to back off a bit, not brake hard)
- Applying the rear brake a split second before the front brake will make the rear of the bike quat a bit, lowering the centre of gravity, allowing you to brake harder before the rear end comes up (this is primarily for emergency braking on the road, where you want to come to a halt as quickly as possible - something you very very rarely need on the track)
- If you get hit by a car from the rear, when you're stationary, using the rear brake will reduce the risk of the bike getting thrown around the steering head pivot point (hard to describe, but easy to demonstrate: sit on your bike and apply the front brake alone - have a friend push the bike from behind. Now try the same with just the rear brake applied. Huge difference in how the bike reacts).
Except for #5, the rear brake is just a "helper", not the primary brake.
Kai
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I get to around 45 degrees, I reckon, but I know the bike and tyres can take quite a bit more. The problem is my built-in fear limiter that prevents me from getting lower. I fear that I do not have enough grip
Don't we all have that fear? That's part of why I ride on the track - to challenge that fear in a safe and fun environment.
The funny thing is probably that I cannot understand that anybody would question the tyre's ability to grip at 25 degrees, whereas Spies etc. cannot understand why I fear the tyre's ability to grip at a lousy 45 degrees.
In other words, for the very majority of people riding around on the streets of the world, our idea of where the actual limit is, is not only highly subjective, but also positively pessimistic and very wrong.
I think of - and explain it - in this way: Basically, we are all working with two sets of limits: the physical (hard) limits of the bike & the road, and the mental (soft) limits in our mind. To most of us, the mental limit comes much before the physical limit.
If you're at your own mental limit of, say, lean-angle, pushing that handlebar more to lean over the bike more will take quite an effort, since you're convinced that you're going to crash. Unfortunately, pushing violently through this "fear barrier" will often make you end up on the road, rubber side up, since the Survival Reactions from your Reptilian Brain makes you do the wrong actions.
But you can challenge and move your mental limits by experiencing that your mental limit is bogus - and while that experience is usually learned first hand, it can also coming from watching other people ride: About 8 years ago, I was regularly doing trackdays at the same track with a couple of friends. Generally our pace were very similar, but in a particular 270 degree (the Carousel of Anderstorp) I could ride a bit faster than them and I got held up by them in that turn. In the paddock I mentioned to them that they could go quicker than the current pace, one of them immediately shot back "well why don't you just pass us then". Sure enough, I passed them both on consecutive laps on the outside in that particular turn in the next session. That had an immediate effect: next session they had increased their speed in the very same turn!
Basically, I was moving their mental frame or limit for them: since we could all go at the same speed everywhere else, they surely could ride just as fast in that turn as I did .... and I had just proven to them that we could safely move our mental limit closer to the the physical limit.
Now, I would argue that the "if he can ride that fast, then I can do that too" approach should be applied very judiciously, but then again, maybe that's why I'm not riding in MotoGP
Now, off to bed and up in the morning for a 4 x 20min practice session at Sturup Raceway.
Kai
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Some of you know, some might not, but one thing that we have taken to doing at the 2-day camps is run the 2nd day in the oppostite direction. We can do this at some tracks, but not all are appropriate for it (can't do it at Laguna for example).
Really gives the rider 2 tracks instead of one to work on, see how well they can use their new found (or fine tuned) skills.
That or we are just mean.
I think it's an excellent idea! for many tracks, it will force you to learn dealing with decreasing-radius turns.
I take that the road-worthiness test of the A* outfit was done at a different venue, since Miller was a Crash-Free Zone?
Kai
Suspension Question - Instability Under Hard Braking
in School Questions/General Discussion
Posted
Ever since I got my 'new' YZF-R6 2008, I've been experience a bit of rear end instability while braking - something that I didn't experience with my old R6 (a 2001 model).
The old bike had the original Yamaha shock and front fork, but with slightly harder springs (Öhlins, 0.95kg/mm) to accommodate the 87kg of fleshy bits on top of it. And it didn't have a steering damper either. In short, pretty much stock conditions.
The new bike, on the other hand, is decked out with Öhlins everywhere: Öhlins YA789 TTX36 rear shock, Öhlins FGK137 Front fork kit, and Öhlins steering (Yes, the swede I bought the bike from was very patriotic
).
What I experience is that if I brake medium hard to very hard, the rear end feels like it is squirming around. Enough to distract me, but not in any way that it feels dangerous. If I brake hard enough to lift the rear tyre, the squirming feeling goes away (had to do that when a guy cut across my front tyre a one point).
So far I have put zip ties around the front fork legs to verify that the forks don't bottom out (check - there's about an inch of travel to spare) and tried to turn out the rebound damping on the rear end two clicks (from 8 to 6 out from minimum) to see if it made a difference - It didn't.
The rear shock is length adjustable, but it's at the standard (~minimum) length. What I can see is that the front fork has been lowered 10mm through the triple-clamps (the service manual says "flush mounted"). I checked out the bike of a guy who's racing at the national level here in Denmark, and they have also lowered the front by 10mm on his bike (but he's probably 6" shorter and maybe 15kgs lighter than me
).
I'm starting to wonder if the lowered front is making all the trouble, but since I'm quite a newbie when it comes to dialling in suspensions, I'd appreciate any input.
As I'm going to a local track that I know well for 3 days this weekend, so I should have plenty of time to experiment with any suggestions.
Thanks,
Kai