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Everything posted by Carl_T

  1. Same comment from a Bike Magazine interview of Rossi. It helped him brake better. The photo was of him with his right foot off the peg. Same interview he felt putting wieght on the bars until turn in helped him stop faster too. Also on acceleration he used ouside peg pressure to stabilize the bike with a bit of extra traction, and inside peg pressure to reduce traction as desired to help steer. That made me smile as a couple took me to task in the distant past for thinking the same thing of peg pressures. The magazine tried the foot thing and didn't feel they got much braking aid.
  2. As I said at this point I need more information at my disposal to understand the logic behind this accurately, and will come back to this thread when I have more from reasonably reliable sources. Just quick poking around it seems racer and I both are correct........ to a point....... and the truth may even be some combination of both of us. In the meantime, NOT as an authoritative source, but more as a look at the results of someone even more obsessed with pushing bicycles in the garage than either racer or I, take a look at all of this guys web pages and his conclusions on the subject. I
  3. Hei Keith, that was your cue! ..Enter the guru himself.. (please??) Yeah, I've reached the end of my suppositions, surmises, and guestimations for now at least. Never know what tomorrow brings, but I would need additional information to go forward from here. I'll do some searching, but would be interested to know Keith's thoughts on the subject one way or another. Racer, It's an interesting discussion for sure, thanks for getting me thinking about it.
  4. We mostly agree here for sure, I only meant the rider does it through the bike. Also a riderless bike on it's own will sometimes correct itself and run on a long ways by itself until it slows enough to fall over so it does do some things "itself" due to forces acting on it and since the bike is riderless and no longer under throttle, it does them with the front wheel as well as the rear. So far, "I think" our difference is that you think the front wheel only trails along in the direction the rear points it due to the conical steering and forward momentum along a path of the rear. I think
  5. Racer, you are jumping too far ahead for me, as trail was squatting in my brain. So I'm trying to get trail settled before I catch up to the things you have added. Also you robbed me of my Sat. morning beauty sleep. I wake up at 5AM going “I have it!” (in regards to trail Sorry about the length, this is mainly about the question of TRAIL and how the front wheel knows to point into the lean more or point in less, due to how fast the bike is going. We will see the front wheel is NOT JUST trailing along, but locked in a balance of forces similar to what we were already talking about. The
  6. OK ok ok, so I'm aaalmost grasping the essence of what you're saying, but I'm still missing that final puzzle piece.. I'm with you on the whole gyro effect thing, I see how the rear will turn outwards if you apply a force to decrease lean angle (and vice versa). But how does this apply to real life riding? How would you apply that force to change the lean angle of the rear tyre? By countersteering the front wheel, or by changing BP or by throttle control...? Because you ARE talking about the REAR wheel all along..? Lets take the front wheel out of the quotation for a second: HOW would you "ste
  7. Or the inside peg until it slid away from him. :-)
  8. The BOTTOM of the bike will go where the front wheel is pointing always, regardless of whether the rider or the trail points it, unless it's not on the ground, or sliding. When it's in balance the top goes there too on a parallel path. However, the conical steering action of the front and back tires being leaned, will also be acting on radius. radius is the result of where the wheel is pointing AND the conical steering. Traveling a path on a radius produces centripetal (inward) force. Yes. If the front did not behave so, the bike would go into countersteering state instead of bala
  9. I'm too old a fart nowadays at 62, but back in the day I rode smooth dirt track, then advanced to semi pro motocross when it was very light two stroke bikes, family stuff stopped further progression. Yes it is for traction. It is also very largely for something else that has not been mentioned as of yet. When you get the bike sliding sideways as much as you can in the dirt, sitting on the high side of the bike lets the bike move a very long ways sideways underneath you before your chest/shoulder weight drags it down into a steeper lean from hanging to far off the inside (thus sliding out)
  10. I'm just going to pick on a couple of points. I do know that when the front suspension compresses rake steepens and trail shortens along with the wheelbase. The front wheel takes on more of the load of the bike's weight as well (amount depending on whether the brakes are applied or throttle off or not). If the bike is accelerating and a bump compresses the forks the rake, trail, wheelbase shorten but the front wheel may not take on more weight and could even be in a state of lessening weight due to acceleration shifting the bikes CG rearward. As to countersteering into the wind: T
  11. Amen! Thanks leftlaner, I hope I am correct, which i think I am. Here's a quote from a guy currently on a trip to and around Alaska that I think relates to this thread and the need for a balance of forces. this also helps prove in my mind that you can steer the front wheel of the cycle in a direction and the rear and indeed the whole cycle will follow so long as gravity is balanced out correctly with any forces involved. the wind was in part the centripetal force in this case. He was leaning right and still able to countersteer, then steer left and turn left while leaning rig
  12. Just a few quick thoughts. Centripetal force is the force that is exerting it's influence/push TO THE INSIDE (center) of the turn. That's created through steering into the turnwith the front wheel AND conical turning influence of a leaned tire. Centrifugal force (to the outside) is a "felt" effect, not a force. It is what a person feels in a turn pressing them to the outside so it's given a name. HOWEVER that is the result of forward momentum trying to go straight WHILE centripetal force tries to push things to the inside creating a turn. The Centrifugal force is the felt combination of tr
  13. This is what I've been trying to say, even if poorly with too many words. I think I've stated the last half of this post more clearly than the first, but here's what I've come to. I've thought about this more. I feel I have a grasp on the basics. You have many things going on here at once. You have "conical steering" AND "car type steering" (where the rear wheel follows the front) , ALONG with "countersteering" (where the front wheel gets steered either 'out from under' or gets steered 'more underneath' the top of the bike and rider), and all these are happening at once. They are all
  14. Interesting point, and I'll play a little again the next time I'm out, probably tomorrow. It's been a long time since I've messed around with footpeg pressures odd to my normal thing. I'll reserve opinionated comment until I play with it again. My memory says there still are differences to be found, could be wrong though. If I am wrong, there's no harm in my weighting the outside peg more anyway then. :-) Where are you holding on when you weight the inside peg? Are you "locked on" with outer leg? Is it possible that your body position (hence CoG) changes and could have some eff
  15. I would want to disagree just a tiny small bit with the statement as set forth. Understandably a dirt bike is lighter than a Supersport and so reacts more to body weight inputs, however the following principle still applies to at least some degree, I believe. Street bike wheels are comparatively heavy and create significant gyroscopic forces at speed which stabilize the machine such that weighting one footpeg over another is essentially meaningless. Not to mention the relatively low speed and near zero gyro forces created while negotiating your hypothetically steep and slippery switc
  16. I would want to disagree just a tiny small bit with the statement as set forth. Understandably a dirt bike is lighter than a Supersport and so reacts more to body weight inputs, however the following principle still applies to at least some degree, I believe. Take a dirt bike and a steep downhill switchback that creates a severe off camber turn, make it a muddy turn without ruts and berms to set the tire against. Try and slide around that turn (without a foot dab) with the inside peg weighted. Secondly try and slide around that corner VERY heavily weighting the outside peg. The only way you ha
  17. Didn't Keith write about releasing and doing a quick turn "before" the suspension had a chance to rebound? I also think I remember him writing in a post above about matching the final brake force to the force that the quick turn would put on the front end so the suspension would remain stable. That's substantially different from letting the front end rebound and stabalize before turning in (and why I mentioned his method was "almost" trail braking in my mind). As to getting or reducing traction by loading the front end. I'm finding loading a wheel can increase grip some (spreading the cont
  18. That is the chapter I was trying to remember, and can't remember exactly what was said. The swingarm not having a vertical hinge for a joint like the front, being the reason for increased stability under acceleration (when weight shifts to the rear) is my own idea, not found in the book. Weight biased towards the front has the chassis weight funneling through the vertical swiveling headstock joint and so is less stable in a turn than weight shifted to the rear wheel which cannot turn left and right as it is attached by a swingarm with a horizontal joint. I think that is a major difference in
  19. If you think about trail braking so it's negative effects don't outweigh any possible benefits, it seems to me that cannot be done without also thinking about exactly what type of exact line that technique requires for the given turn. It would also seem to require thinking about what came just before the turn, what comes just after, any of the turns radius changes, elevation changes, cambers, etc. For that matter I don't see how you can do a quick flick turn without thinking carefully about the type of line you will craft/run to string the techniques of a quick flick turn and roll on together.
  20. Well, I woke up this morning thinkng "no Carl, you're exactly, TOTALLY wrong, completely mistaken about a car." Very wrong and that is the key to the bike's behavior. A car will turn in the same amount at a higher speed because the rate of inward force will also increase with the speed so long as no sliding takes place. So I'm out in the garage pushing an upright bicycle at various speeds with the wheel turned in (you've got me crazy now too). I verify an increase in forward rate increases turn in rate and describes the same arc. Now the question may be will the rate of turn in increase be ex
  21. I'm thinking of this as happening over time. A certain amount of inward turning from the cone shaped tire over half a second say, much more distance traveled in a half of a second at a high rate of speed than at a low rate of speed.
  22. Saw this discussion and had some thoughts. Just wanted to jump in here with a possible idea on the same lean angle describing a wider arc at a higher rate of speed thing. I know squat about physics, but from thinking about this: This happens with cars too right? for a given front wheel steering angle the car will cut a wider arc at a higher speed. With a car the front turned in wheels move the front of the car inside the path (turns the car) at a given rate (unless it slides). If you increase the speed the vehicle travels farther for the same given rate of inward movement (turning) the
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