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Riding the clutch and rear brake to keep the bike upright

Discussion in 'New Riders and Riding Tips' at netrider.net.au started by ptb, Jul 20, 2012.

  1. I'm having trouble with this. I'm fine riding the clutch and slow rolling the bike at walking pace but no matter how much I try, riding the clutch and rear brake together doesn't seem to do anything to help keep the bike upright.

    I also don't understand how the physics could, you've got something providing and resisting turning force on a chassis, not between the two contact patches on the road.

    Could someone please explain it? I'd love some examples where it's meant to work and practise suggestions.

  2. The rear brake is for speed control while slipping the clutch, not for added stability.

    As you point out, physics says it can't really help at all.
  3. You don't use the clutch and rear brake at the same time. You let the clutch fully out and use throttle against rear brake. That way you don't stall the engine even if you go below idle, which lets you do really slow work and definitely stabilizes the bike. Give it a shot while you do some figure 8s or something.

    It's also good training for whoolies. :)
  4. As for how it helps, keeping the throttle slightly open against the rear brake removes all transmission snatch. The bike is literally pulling taut against itself, so the rear brake becomes half brake, half throttle with total precision. If the bike feels like it's falling into a u-turn, letting the tiniest bit of brake off can pick it up in an instant.
    • Like Like x 2
  5. The spinning mass in the engine has a gyroscopic effect which resists the bike falling over. The technique is fast idle, to spin up the gyroscope, then use the brake to control speed. Slipping the clutch is just incidental to let the engine spin.

    Try it out stopping gently in a straight line. With a fast idle it's easier to keep the bike upright and delay putting your feet down.
  6. When doing the really slow stuff, don't let the clutch fully out, leave it about half way in the fiction zone and keep the RPM up. Then use the brake to control speed. Using that technique I can get a Harley through the MOST.
  7. As paul n lucifer said

    Dont be tempted to use throttle and or clutch for
    Speed control - that is s bigger tip than u think
    Its all in the rear brake
  8. Will engine orientation or type impact this gyro effect?

    Dragging rear brake flattens out the swing arm. That gives additional stability.

    - - -
    Tapatalking loud, saying somethin'
  9. ...by changing the rake angle.
  10. I've picked up using the rear brake as a fine tune throttle and with more practice, I'll get better at it.

    I watched an American rider training video a few weeks back, I can't remember the name but it had riders predominantly on police Harleys and spent a fair bit of time on slow speed maneuvers. Unless I misunderstood it, the message was to keep the revs above idle, riding the clutch and rear brake together will help keep the bike upright and more stable/maneuverable.

    I'm now more confused than ever.....
  11. Nah dont rekon its gyro of engine it basically keeping
    Forward drive to wheel for stabilty.
    You need drive for stabilty
  12. Yep, I think I understand the torque on the top of the chain pulling the top of the rear sprocket higher than the swingarm pivot point will compress the rear spring.

    My original post was I don't understand is how or why this will make the bike more stable. The gyroscopic effect makes sense but how much effect does it have for such a small and relatively slow rotating mass compared to the weight of the rider and bike?
  13. I think the engine's Contribution to gyroscopic inertia is not significant.
    Else the bike would be able to balance on its own while you rev the hell out of it.
    This would come in handy when the foot slips on the floor sometimes.
    The wheels and unsprung mass having greater radius (the effect is squared or something) has a greater contribution to keeping the bike upright.
  14. Flatter swing arm equals longer wheel base and lower centre of mass. Both add to stability. But also, having drive against a solid load (rear braked wheel) at low speed means a more confident low speed manouvre.

    - - -
    Tapatalking loud, saying somethin'
  15. Gyro effect is **** all. Clutch fully out, throttle against rear brake. Only touch the clutch if you're actually gonna stop.
    • Like Like x 3
  16. Not much. It won't stop the bike falling over, just a little resistance.

    with all the elements of the slow riding technique:
    - rear suspension slightly compressed
    - slack in transmission taken up
    - fine control of speed with brake
    everything is braced with a little resistance.
  17. Where to start ????
    Five main things give the gyro effect.
    The effect can be controlled or the amount of it.
    As for it being fark all................. Please explain how I can get a 400kg bike to go from peg to peg at less than twenty K's an hour. How do I keep a fully laden Police or Paramedic bike up doing clover leafs ???
    Cause they don't have to do fig 8's. They have to do clovers with fully laden bikes.

    Ok the wheels. These two things at road speed and above are your main gyro effecting things.

    Forward momentum ???? WTF is that. The breeze ? What

    And your crank has a reasonable affect. Nothing like the wheels at eighty k an hour or more.

    And lastly you disc brake rotors. When you apply brakes to them they stand the bike right up. Specially the front brake.
    So there are the five main things.

    1. The throttle is for engine speed.....so you don't stall. That's about it.

    2. The clutch is your drive. How much forward momentum you want out of the motor. remembering we want to use the rear brake as well. So we are going to give it a fair bit of throttle so we don't stall.
    And we want the bikes motor to fight the drive train a little so it increases the gyro effect of the crank. Which is good but not great.

    3. The rear brake is your best gyro enhancer at low speed. So we use enough rear brake to add gyro. And then enough to keep the bike steady at these low speeds.
    The rear brake controlls ground speed. How fast you want to go

    So I am hoping with this terrible hang over I am making sense.
    if so now you should realise the slower I want to go the more I bring on all these things.
    More rear brake against more throttle with the clutch almost out so I am bogging that motor down to almost a stall. draining every bit of righting motion it has out of it.
    I love this shit. Even very experienced riders give me cred for this stuff.
    It really is so easy to learn. And absolutely painless if you get it wrong. Costs a bit in bars and levers tho at first haha
  18. How many Newtons of righting force will you get when you spin the motor? How did you calculate this? I'm not trolling but gyro forces are not big compared to what the tires can do. http://en.wikipedia.org/wiki/Gyroscope

    If it is gryo forces how come it is just as easy to turn in both directions?

    Obviously the skill can be executed without understanding the physics (and vice versa).
  19. TBH your better off not understanding. It really is a feel thing. Just go hard and feel it.
    The thing is falling is fark all. So why not got hard at it.
    Once again as always your eyes will make it easy or hard for you
  20. If your going really slow.. Like walking pace. And using the rear brake, put a little bit of weight on your left foot peg also.

    I find I can balance the bike a lot easier like that. I can even come to a complete stop for a short time without putting my feet down.