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Revs & gear changing

Discussion in 'New Riders and Riding Tips' started by johnmoz, Aug 24, 2012.

  1. OK, I'm used to a 6 speed car that develops max horsepower at 8K with a substantially flat torque curve from 2K pootling around 60KPH in 4th at 2K, then I get on this little 250CC screamer that redlines at 17.5 K. I haven't been able to find torque/ horsepower curves for the Across and although I know it's probably right, it just feels wrong doing 6K at 60KPH in 5th. Is 6th normally considered like overdrive in the car that you only tend to use it over 80Kph-ish or do you accept the fact that you'll drop down a couple if you need a quick burst and sit in 6th to keep the revs down, what's the accepted norm?

    As far as gearchanges go, I'm perfectly happy with my clutch control up and down the gears, god knows I've done a million or so gearchanges in the car, but clutchless changes on the bike are beautifully smooth. Once again what's the accepted norm, do most people only use the clutch for a complete stop and not bother the rest of the time? I'm not 100% up on the exact mechanics of the constant mesh gearboxes, so I'm a little unsure if it'll lead to accelerated wear?

    All discussion accepted with interest.

  2. If I remember correctly peak torque for the Across is somewhere around 10-11,000rpm - so this is where you want the tacho to be sitting when you go to accelerate. Trying to accelerate from 6k will actually cause far more harm to the engine.

    So, no 6th gear is not an overdrive - and you should learn to use the revs available as this was how the bike was designed to be used.
  3. I know what you mean. My ZXR redlines at 19,000 rpm and it took me a while to get used to revving it. But that's the design of the motor, once you get used to it boy is it fun.

    For general riding I keep between 6-8k rpm, if it dips below that I downshift. But for decent acceleration you definitely want to be above 10,000 rpm.
  4. It's best to produce your torque higher in the rev range to take advantage of the gearbox.
    Bikes are geared to pass noise and emissions tests.
    That doesn't make them geared properly for the road.
    A motor is a motor. So the damage you cause will be the same.
    Scream it's titts off everywhere and you will be rebuilding the top end in no time.
    Lug it and bog it down all the time and the bottom end will mix with the top in no time.

    Get the figures and facts out of your head and let your ass tell you when to change up or down.
    Riding is feeling and seeing. You don't have time to think or read a book on one.
    The bike will tell you soon enough if your doing it right
    • Agree Agree x 1
  5. Yeh, I know I'm overthinking it but I want to try and start out with the correct norms as much as possible...

  6. Actually the reason for having torque high in the rev range is to produce an adequate amount of power (power being torque x rpm). If peak torque was the same value, but at 5-6k, then the bike would struggle to break 100kph no matter how many gears you had.
  7. Ah I don't think so. His math was flawed...apparently... I no nothing lol.
    The magic 5,500 is where torque becomes power isn't it ? The trick is to get that torque to hold it's limit of power longer.
    Gears aid torque. And let us have it higher in our rev bracket. So without gears we would never get off the line and be able to make 100
  8. Gears don't aid torque, they compensate for a lack of it. This is why electric bikes can have very high maximum rpms, and yet only need one gear.
  9. Um what does compensate mean .. too assist
  10. Compensate means to make up for something. Technically it is only aiding because the item isn't good enough to do it itself...
  11. What Krollinator said. Design an engine for power, by making the redline as high as possible, and you need gears to compensate for the narrow torque band.

    A broader torque band, like that found in the OPs car, means gears are less important (why American V8s used to get away with a 2-speed auto). The downside is that you need a far greater capacity (and greater overall torque) to achieve the same speed - though there is a certain appeal to a 600cc single compare to a 4-clyinder 250 (in much the same way a 7.2L V8 has an appeal compared with a 2L turbo).
  12. haha that's why we have turbocharges.
  13. So, to help me with gearing, I have just started riding A hyo 650, and at the present time I'm usually in second at about 4.5k rpm for 50km/h and often have to shift down to first for roundabouts and right angle turns, is this normal?

    In my 250 Zeal I would stay in second for turns and 3rd at 6k rpm for 50km/h so it's a little strange for me. But I feel being in second for sharper turns is letting the rev range get to low.

    Any advice?
  14. Torque != Across

    These two cannot be used in the same sentence.

    You've got a 4-pot screamer with pistons the size of thimbles....
    This engine is tuned for peak Horsepower not torque (very low rotational inertia)
    You will need to wind it up before you'll feel any discernible pull.
  15. Hehe yep I'm beginning to come to terms with that, 6K in 5th at 60K seems normal now. There's a particular underpass that I tend to go out of my way to blat through in the M3 with the sunroof open and windows down, I've now discovered the Across at 16K sounds just as good in its own way as the M3 at 8K...

  16. Bigger engine = more torque = lower gear for a given speed (usually).

    That said first gear isn't really ideal for low speed corners, as it can be a little "snatchy" on acceleration. I'd be leaving it in second unless the engine seems to be struggling. (Edit: Though hopefully another Hyo rider can shed some light on what they usually do).
  17. rev the nuts off it, dont worry just do it your engine will be fine its made it this far.
  18. With my hyo 650 I take roundabouts and tight turns in 2nd, just dont use too much throttle and have it low in the rev range - bike has enough torque to pull out of a tight turn quite easily compared to my old cbr250rr. 1st is too snatchy and the bike jumps around quite a bit
  19. Okay I'll try taking corners etc in 2nd, what about in a 50 zone? Second as well? As if I bump up to third I'm running at about 3k rpm just seems too low.
  20. 3k rpm is quite fine on my bike, although I do have a TBR exhaust on mine which I'm sure made it alit easier for the bike to breathe down at that rev range - just give it a smooth roll on the power as you come through the corner and pin it at the end. Always puts a smile on my face
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