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Back wheel wobble when down shifting in the wet

Discussion in 'New Riders and Riding Tips' at netrider.net.au started by matressking, Jul 30, 2008.

  1. Well, the title says it all.
    I'm wondering whether its normal to feel the back wobble a bit when downshifting in the wet.

    I ride an across which i'm led to believe employs engine braking (noob alert)
    so i guess maybe the back locks for a sec causing the wobble and then rights itself?
  2. also is engine braking the norm in bikes?

    i'm so glad i don't have to look anyone in the eye when asking questions that sound as dumb as this! lol
  3. When you shift down, the wheel suddenly finds itself moving a lot faster than the engine is, so it sometimes loses traction as it slows down to match the new speed it's supposed to be spinning at.

    To counteract this you can be smoother on the clutch as you let it out, or else give the throttle a 'blip' or a bit of a rev as you shift down, which will help equalise the wheel and engine speed as you let the clutch out.

    It's nothing to worry about.
  4. Nothing wrong with being a n00b! I am too -

    Wobbling on downchanges? - sounds to me like your changes are not too smooth. If you've got the revs right when you downshift you shoudlnt have any jerkiness at all - if your revs are too high you're going to lurch forwards towards whatever it is you were wanting to slowdown for :shock: - and if your revs are too low you'll be pulled back sharply possibly locking the back wheel briefly. Loz is right - slower release of the clutch is the way to ease the transition.

    For your wheel to wobble suggests you are getting some lock up. A bit more practice (in the dry) should get your downshifts much cleaner (perhaps with a bit of a throttle 'blip' to lift revs whilst shifting) and gvie you much more control.

    I tend to employ a mixture of engine breaking and back break to slow me down gently - a bit of front break if I want to slow up more sharply or stop.

    Working your way down through the gears as you slow has the advantage of you being ready to power-off again if needs be whereas coasting around on the clutch as you slow and then tapping down to 1st before pulling away again can leave you in a bewildering no-mans land of gear selection when the lights you were going to stop at suddenly go green and you want to pick up speed again!

    I have no idea whether my technique is deemed 'correct' or not - but its working for me so far! :?
  5. hey man

    if ur back wheel is wobbling or losing tracking the downshift was probably not needed.

    use ur rear brakes in low speed maneuvers
  6. Yip - work on a smoother clutch release. Also know that if you were to do this mid-corner, you'd probably lose the bike. Particularly if it is wet, make sure you do your downshifting before corners while your fairly vertical so your back to full traction before going into a corner.
  7. thanks for the replies guys. that's something to focus on next time i'm out.

    thinking back on it my clutch release might be a bit fast. i'll also try the throttle blip.
  8. I had the same problem every now and again, and a more gentle release of the clutch sorted it without a problem.
  9. The engine braking on a small I4 is not that great. Try it on something that has plenty of torque. :)
    If its causing a loss of traction match the engine speed with the road speed by blipping as others have suggested.
    Are you backing down one gear at a time with a clutch release each time? 5th to 3rd could be "fun".
  10. No am going down one at a time. You shouldn't be putting ideas in my head! ;)
  11. oh and i've just had blipping explained to me by one of the guys in the office here so for the sake of any other noobs reading:

    - clutch in (fast)
    - blip throttle
    - down shift
    - clutch out (slower/smooth)

    does that look right?
  12. Spot on

    You know it when your coming into a corner hot and accidentally skip a gear on a Ducati (V twin). More butt shaking than at a bluelight disco!
  13. i'm really impressed, 4.5 hours and still nobody has had a go at acrosses. I wouldnt, coz an across is still better than my bike (has pedals... :oops: ), but i still cant believe that somebody hasnt had a go at them yet...

    on the wheel wobbling thing, in my sum total of 14 hours riding time, i havnt noticed anything like that, even in the wet. Matressking, have you ever driven a manual car? i'm gonna guess no, as that is how i know about slowly letting the clutch out to avoid the wobble.

    in a car, there is less tendancy to break traction, and it just bunny hops. i know nothing about engines, but i think that difference is to do with the fact that most (read: modern) cars have syncros that help slow down the car to engine speed, whereas bikes have no syncro, instead, they have a constant mesh, so there is more of a tendancy for it to grab and lock the wheel. wow, look at that, maybe i do know something about engings...

    if my syncro/constant idea is bogus, please somebody more mechanically minded let me know, as i am still learning about how an engine's organs work...


    P.S. Whooops, a lil OT there...
  14. Lobby,

    You're right in that car and bike gearboxes are different - but synchros in a car box don't actually slow the car. All they do is help match the engine and gearbox speeds so that the gears can mesh together - some would even call it SYNCHROnising (see what I did there? :p )

    The reason cars don't lock wheels is more or less down to pure weight and momentum. Cars are heavier, exerting more downward force on their TWO driven wheels and making it much more difficult to lock up. Bikes on the other hand are light (even with my fat arse on board!) and thanks to the shift of weight under brakes, unload the driven wheel easily causing the lockup.

  15. Coming down into a tight turn like turn 2 at Eastern Creek with the rear wheel chirping on each down change is one of the good things in life...

    don't stress about it :grin:
  16. Just on the outside chance it's not compression lockup, are your axle nuts tight??
  17. not 100% sure. I'm taking her across to the northen beaches tonight so ill know by then!
  18. +1.

    What J said. :)

    FWIW, you can do it in a RWD car too if you're hard on the brakes and simultaneously downshift to a very low gear without blipping the throttle, particularly ones with a static forward weight bias.

    Or I should say, you can do it, if you have no mechanical sympathy whatsoever. ;) Better to learn heel-and-toe braking for the car... And 'blipping' for the motorcycle.
  19. bah, sprained two fingers on my left hand. was looking forward to that ride.

    will practice this some other time.