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Stroker

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Everything posted by Stroker

  1. I still don't understand how both Suzukis got swamped at the start.
  2. Thanks for bringing up the air gap. Though i have an academic knowledge of it's working, i wonder if any of you have experimented with it and found what difference it makes?
  3. I had a very interesting introduction to preload. My friend had gotten a new bicycle with a rear monoshock. As he proudly explained this spring made the bicycle go faster, i examined it closely. I found that i could make the spring longer or shorter by turning it.I made the spring as long as possible [ minimum preload ] and rode the bicycle.It offered a comfy ride on bad roads but moved far too much on tarmac.Trying to pedal hard meant most of the force was soaked up by the spring and i just bobbed up and down in the seat. I made the spring as short as possible [ maximum preload ] and rode the bicycle. The ride was harsh and bouncy on bad roads but conducive to high speeds on tarmac. I could....put the power down so to speak and not bob up and down as before. Of course, i has not heard of the term preload as a kid but have come to the following conclusions now - 1. Every rider weighs a certain amount, and the springs that hold him up must be set to work accordingly. If the springs are set to bear a rider weighing 50 kilos and a 100 kilo man sits on the bike, the springs act as if a 50 kilo rider is on the bike, and an extra 50 kilo force is being exerted by the bumps or whatever. He therefore feels a lot of movement when riding around, the forks are diving on the brakes, the suspension feels soft etc.To eliminate these problems, the springs must be set such that - A 100 kilo rider upon the bike produces no movement. When extra force over and above the rider weight is exerted, the springs must compress and rebound as usual. Therefore preload tells the springs how much load will be put on them initially. 2. All straight rate springs produce equal amounts of compression for equal amounts of applied force. If a spring compresses 1mm for every kg force, you can take it for granted x kgs produce x mm of compression. Progressive rate springs are those which produce varying amounts of compression for the same applied force. They will compress x, 0.8 x , .065 x etc for each kg force applied. These are usually not used in bike suspension. Therefore, no matter how much preload you add or remove, the maximum extension remains the same.Preload only tells the spring - Start working soaking up forces greater than the riders weight, which is x kilos.If the spring is told [ by virtue of preload ] the rider weighs less than he really does, the spring treats the weight difference as added force that must be damped. If the spring is told the rider weighs more than he really does, the spring will pass on forces equal to the weight difference up to the rider and starts damping only after it experiences forces greater then the preload it's set to. Therefore, it is imperative to set preload correctly first and then move on to compression and rebound damping. Incorrect preload means incorrect rebound and compression damping as a rule. 3. Most lower priced bikes come with preload adjustment. It is possible the soften or stiffen the suspension to a certain extent by adding or removing preload. Going two up for longer distances mean setting the preload to allow for the extra weight. 4. The range of preload adjustment is determined by the spring rate, spring length and number of coils [ correct me if i have missed any others ] . If you weight a certain amount , get springs that work best for that weight range. If you get a spring that works best for someone 25 kilos heavier than you, it's kinda pointless. Thanks to all who contributed and YD for starting the thread. Can we move on to a discussion on setting sag? I have never done this, perhaps those who have can share their experience with pictures?
  4. Robert, how did the under inflated tire feel like on track?
  5. Hmm....looks like there wasnt enough weight on the front and the bike was understeering? That seems to have torn up the front tire a bit. Looks like you got on the gas hard as you were picking up the bike.The throttle control is good, as there is a clean area on either side of the worn area. Which bike was this? Were the tires warmed properly?
  6. Great to find this thread. I wanted to throw this out there - Why dont racers share common problems they encountered at the track and the solutions they found? You were in a race, and you encountered a loss of rear grip say. How did you ride around it? What helped the situation and what made it worse? Things like that. Information about bike prepping would also be helpful, any personal tips and tricks you can provide. We have a tires thread, i wonder if we can have a suspension thread as well where people can discuss what changes they made to the suspension and what were the results.I am very keen on learning about bike setup. Also, do keep the tires thread alive by posting pics as often as you can.
  7. Also on scooters with little wheels and basic suspension, the rear is always a much safer option.Get on the front hard and the front end will collapse alarmingly and bottom out real quick. No telling when the bargain front tire will lock up either.In fact, the rear brakes are larger than the front by design on these things.
  8. Consider that there are all kinds of bikes, with varying weight distributions and brake systems.Bikes such as this royal enfield standard below are terrible bikes.Weak frame, heavy vibrations, primitive suspension and bargain tires. Good luck applying the same technique you do on sportbikes - The front brakes on this bike offer little feel and hardly stop you. They also lock without warning.The rear is a much safer option, as there is actually more weight on the rear and a locked rear can be controlled more easily.You can lock up the rear tire and keep going for a good 200 feet. Anyone gone 200 feet with a locked up front tire?
  9. Honda have introduced linked brakes and linked abs [ combi brake and C-ABS according to them ] on scooters and bikes because most riders in Asia rely solely on the use of the rear brake. The front brake isnt even functioning on many bikes, with the lever hanging off or no brake fluid in the reservoir. Have experienced this in person. The idea as mentioned above, is that rear brake usage causes a proportional front brake application automatically. Front brake works as usual. Honda make a big fuss about this while marketing them here.
  10. I have seen Marquez carry 64 degrees of lean as indicated by the lean o meter during the motogp races. I think you need to be going quite fast to carry that kind of lean....at slower speeds you would crash. Also at higher cornering speeds, isnt there an increased force on the tires?
  11. A highly interesting observation.....thanks Eirik. Has anyone on the forum dragged an elbow though?
  12. Congrats on the new bike....do put up some pics. Prices on that shop are astronomical.
  13. Anyone who own Ducati's do post pics?
  14. Hey Guys, interesting info at the end of the article. What is your opinion on keeping the forearms small and changing the number of fingers you use on the lever? http://www.crash.net/motogp/news/217385/1/electronics-taunting-eugene-laverty.html
  15. Thanks guys. I'll look into the tech spec snake skin given there is no track here and i'll be wearing my leathers only occasionally. Don't want a hole in my jeans. Benny, i'm healing ok...no clue about the bike.
  16. Will i need a hair dryer to install them? Don't have one. Tech Spec apparently can be taken off and re positioned about 8-10 times. There were some people who had air bubbles form under the stompgrip pads. I guess it's all in the install. I will usually be wearing jeans on the bike. Will it be uncomfortable to ride around on the street with the stompgrips?
  17. Hey Guys, I am considering getting tank grips for my bike when it is fixed. Could you all tell me what brand you use, how much you paid, how easy it was to install and your experience using it? Anecdotes regarding others experiences also welcome.Suggestions regarding the best brand also welcome.
  18. AAh....i have heard talk that these Jap bikes are usually tested by fairly light riders in the 120-140 pound range in full kit. The suspension is dialed in for this weight range. Add another 100 pounds and the spring is punching wayy above it's weight. Add to this the valving etc, and you need a full suspension tune before the stock suspension can handle your weight. Aftermarket is the way to go, and if you are holding on to this bike for a bit, invest money in good suspension front and rear.
  19. Could you put up pics of the lovely F4? You could try the " Bouncing the bike " technique to see if the compression and rebound are off and get them to a good starting place.Mark a reference point on the forks noting the amount of travel available when the bike is held upright.Have a friend hold up the bike and push down on the seat.The suspension should - 1. Go down when you press down on the bike , but not collapse rapidly. If it does you need more compression damping. If it is too slow and difficult to push down you need less damping. Applicable for both front and rear. 2. When it returns , it should not go up past the reference point and down for another stroke or two. This means you need more rebound damping.If it slows down on the way to the reference point and does not cross it, you need less damping. Applicable for the forks. 3. When you have set the rebound, have your friend press down again.The front and rear of the bike should come back up as one. If rebound is off whack, then one side will rise faster than the other. 4. Make sure you set the preload before doing the above, and also ride around for a bit so the fork oil has gotten to temperature. I trust you know how to adjust the settings on your bike? Fine tune on track. How heavy are you in full kit?
  20. Hi Eric, I'll give you my academic speculation here - The rebound on the rear is too fast and the compression looks slow.There might also be a preload issue. The rebound on the front is slow and compression is fast.Again, might be a preload issue. The wear pattern on the rear looks ok...good throttle habits.The very edge looks a little ragged to me.Perhaps you got on the gas a little hard when leaned over? You have not used the front tire fully, and the area that served as the " Edge " with respect to the amount you used looks ragged. If i am correct, the slow rebound meant the suspension collapsed early but did not recover in time, leading to punishment on the front tire. Was the bike understeering? Tyler, to be honest the tire wear looked great....maybe like you ran it on concrete. That's the kinda powdery residue i got on my tires when i ran them on concrete. Would have never guessed it was on a new surface. If anyone else has pictures of their tires, do post them.
  21. I'm guessing the rear tire went on the edge of a pothole or some thing, slid into the pothole and then abruptly encountered the upward rise which caused the highside. Either way, the result was violent.
  22. Thanks Kevin. The problem is that the stretch for a few hundred feet was bumpy as is typical in India.Now that you mention it, I distinctly remember seeing a reflective red sign on the divider ahead....there was a bit of a gap for a crossing. I picked the bike up a bit.....and then got thrown off the bike. Was it that act of picking the bike up a bit that caused the crash?
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