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Everything posted by faffi

  1. Well, I am probably guilty of everything you pointed out, Jaybird 😄 However, when it comes to lowering and/or lengthening a vehicle for better stopping or acceleration, it is a result of the vehicle's ability to resist flopping over forwards or backwards. Although only if you already slowed or accelerated hard enough for that to be an issue, of course. This partly explains it https://www.physio-pedia.com/Centre_of_Gravity#:~:text=Stability and the Centre of Gravity,-The direction of&text=When the line of gravity,is said to be stable. Sorry if I just dug myself a bigger grave h
  2. If you lower the CoG, less weight will be shifted forward and you can stop harder before you do a stoppie. Which is also why a long and low bike can stop (and accelerate) harder than a tall and short one. However, I am not certain that the fork will compress more doing a stoppie while sitting upright with stiff arms, than doing a stoppie laying low with the resulting lower CoG. Since you can now slow down harder, would not even more force be fed into the suspension? But for the same rate of retardation, you probably will end up with slightly less compression of the fork laying down. Howev
  3. faffi

    Jorge vs Doohan

    Noticed Lorenzo was hopelessly slower than everybody else at the recent test, more than 3 seconds off the Aprilias. The explaination was that he is unfit and have not ridden since January. I remember Doohan in 1999 at PI. He could not walk properly and had to be lifted onto the bike, and his hand did not have the power to pull the clutch. The bike had a totally new powerband due to Criville wanting top end over driveability. Doohan dis not know the tires, the setup or anything else as the plan was to just wave to the crowd. As I remember it, he waved most of the first lap, found it f
  4. Would that not depend on how much power is fed in and how much the bike is leaned over at the time of throttle application, plus how much more lean is needed? But it does seem like a recipe for loss of traction.
  5. Could be l used to be more abrupt, and l definitely was braking late on purpose, so that could well be the issue. On the Honda, l now brake less hard and ease off them, then going directly to rolling on the throttle. I am beginning to get to grips with setting the entry speed early, but with 40 years of braking deep it is what I know. At the age of 16, riding a CB100 limited to 50 mph, l would brake at the latest moment possible as often as l could, and l gave myself a maximum of one yard error - if l stopped sooner or, much worse, overshot, it wad considered a fail. I did this on all sor
  6. No, meaning I explained myself poorly. All previous bikes I can recall having attempted early throttle application with would fight me and go wide, usually enough to make me get off the throttle again for a moment. That was the case with the NT650V until l replaced the tires recently. The XVS is a bike l rode gently home on 20 year old tires in November and have restored since. It is fitted with new diagonal Pirelli touring tires. It did not react well to my normal riding habits, which is how I subsequently ended up going in slower and exiting faster, and that the bike acted absolute
  7. Something happened recently when I fitted new tires on my NT650V, when I suddenly found I could apply throttle very early in a corner - slow or fastish - without the bike wanting to noticeably widen its trajectory. And now I found the same thing with my other bike (although it does not belong in a sporty setting), an XVS650: I can roll on the throttle fully (it is, however, a slow bike) the instant I am at full lean and it will not deviate from its chosen line one inch, nor does it take any effort to retain the trajectory; I remain relaxed at the bars. Now I wonder if I have changed somet
  8. Thanks, Jaybird, good video. This is absolutely correct, and very well explained in a simple manner. It is not as dramatic as the video suggest - I think it is about 4 degrees difference between a 130 and a 240 mm wide rear tire, all things else being equal - but it is significant. Not the primary reason on my bike as it has a 120/70 front and a 150/70 rear tire.
  9. Ah, thank you for explaining. The tendency to stand up was very noticeable, I had to use quite a bit of constant force to keep the bike leaned over. Now, if I let go of the bars, the bike will take a little tighter line than the planned trajectory, but quite minutely so. It was reasonably neutral with the Michelin fronts effort-wise, but with the soft front it was difficult to keep a smooth line around corners, the bike seemed to constantly vary lean and trajectory and the bike had to be constantly but gently guided. If that makes any sense. Regarding profile; the Bridgestone had worn ra
  10. Thank you 😎 The bike has shaft drive so wheel alignment is fixed, but a good thought
  11. There was only 2 mm difference in diameter between the old Bridgestone and the new Maxxis front, so a 1mm difference in height. I made a much bigger actual change earlier when I cut off just over 4 inches of the soft portion of my stock springs to stiffen the front end. This gave me about 15 mm less dive under the same kind of braking, meaning it should also hold the front end up a similar amount higher during brisk cornering. I also changed from 35 to 57 cSt fork oil, which naturally slowed down the rate of compression (and rebound) to compensate for the stiffer springs. Static sag was h
  12. Forgot to mention that I now also find myself going on the throttle noticeably earlier than on any other bike ever before, because early throttle application does not push the bike wide. Part is down to having little power, no doubt, but there is zero fighting or insecurity when opening the throttle once max lean is reached and the exit determined. I always felt the need to wait until I began picking the bike up before I began smooth acceleration to avoid running wide, but there is no need for that on this bike at the moment.
  13. Not that this will have much interest to anybody but me, but here is an update anyway 😄 When I bought the bike, it had a new Michelin PR4 on the rear and rather worn PR3 up front. Soon after, I replaced the brake discs and took the opportunity to fit a Pilot street, the mentioned narrower 110/70R17. When the new discs also warped, I fitted the spare wheel with stock, straight discs and a 65% worn Bridgestone BT30F mounted. With all these three front tires together with the PR4 rear, the bike demanded more lean than expected. With the PR3 and PS the bike steered fairly neutral and wo
  14. Follow what Hotfoot says. Adding lean and brake is probably as ill advised as adding lean and throttle. At 35 degrees of lean, you have about 80% grip left for braking, IIRC, whereas at 45 degrees it is rapidly closing in on zero. This is under ideal conditions; warm asphalt, warm and grippy tires and with a good rider not spending grip by holding on too tight and/or giving the bike confusing/harsh inputs, which also use chunks of your grip account.
  15. I don't mind if people want to include all running costs in their fantasy 😃 So which one would rate above the other, then?
  16. If you could have any track bike in the world, from the classic era to a current MotoGP bike, but it would also be your only track bike, what would you choose?
  17. As to small bikes - I think I have mentioned it once or twice before, but Kenny Roberts Sr's favourite street bike back around 1985 was a Yamaha 250 Phazer. That was both down to its handling, at the time as close as he could get to his race bikes, and the lack of power that demanded a very high level of accuracy in order to maintain a fast average pace.
  18. I began my city riding days on a limited Honda CB100 back in 1980. The law back then said no more than 7 hp and no more than 50 mph top speed for motorcycles operated by people aged 16-18. From 18-up you could ride unlimited bikes. Statistically, the less powerful bikes are also involved in fewer accidents than high powered bikes. Anyhoo, my riding naturally had to evolve around low power and slow acceleration. Since then, I have never felt the need for lots of power, especially during city riding. If I would have to rely on surplous power to keep me safe, I would consider I had already p
  19. Being a mediocre rider with a history of more brawn than brains, I have had to stand the bike up to slow down before continuing at a reduced pace countless times. Sometimes from running out of cornering clearance, sometimes just running out of courage. I have never planned for it or practiced it, it's just a result of my SR.
  20. They often send slow-mo with 1000fps of how the tires move during a race or practice session on TV, and it is amazing how much the tires deform and change shape constantly, especially over rumble strips. If they slow the footage real down and the light is good, you can see it really clearly. This probably has as much to do with the low pressure as with the tire construction.
  21. I am talking about the flexibility of the carcass.
  22. Some seems to relax if they get a ton of information from the tires, others get stressed by it. Luca Cadalora was a rider who only wanted to know about significant issues like actual loss of grip, but I am not sure if he is typical or atypical when it comes to top level racers. Watching how soft current MotoGP tires are, it would seem difficult to get a ton of information about tiny imperfections through them, but I have no idea, really.
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