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Do all bikes do this... Or just mine?

Discussion in 'Technical and Troubleshooting Torque' started by Nocker, Feb 14, 2007.

  1. Hey,

    I was riding along at about 70km (I think) yesterday and had to do an emergency stop. I didn't have time to gear down or anything and just rammed on the brakes. As I was braking (quite hard) the gears notched themselves down. :shock:

    I have a 1998 GPX250. Do all bikes do this? Does anyone know if it is common for a GPX? I've had it happen once before but not as many gears.

    I was a bit concerned and wondered if anyone has had a similar thing happen or if there is something that I can adjust to stop it from happening again.

    Thanks for your feedback.
  2. Did you use the clutch?!!
  3. No, only right at the end so that it didn't stall.
  4. doesn't happen on my cbr250.

    you might have pushed the gears down as you braked.
    clutch doesn't need to be pulled in for the gears to change.
  5. Yeah I thought of that but then it would have only been one gear... right? I think it went down like 3
  6. It has changed down probably due to the stresses placed on the motor/gearbox by the sudden, huge reduction in speed. Something has to give, and in this case it was transferred through the driveline to the shift mechanism and has dropped down a few cogs. Probably a sign of a pretty tired gearbox.

    A good reason to use your clutch when emergency stopping!
  7. LOL I have this happen to me!! as it turns out I automatically for some reason without realizing it down shift... and I use the cluch too... I was made aware of this only when I did a HART course and we were practicing emergency stoping... the instructor was not happy with me down changing apparently I was concentrating to much on getting the bike into the right gear... lol as I said b4 I was not aware I was doing it...
  8. Pull your clutch in next time, when you're braking.
  9. cant say my bike does that but how cool. if i ever needed to do an emergency brake, i hope my bike would do that too.
  10. I don't care if it is meant to do it but I'm a bit particular about my vehicles and when these sort of things happen and when unexpected things happen I'm freakin out about it.

    Anyway, I did an oil and filter change on the weekend. I also bought a fuel filter to go right after the fuel tap but don't have clamps to hold the pipe onto the filter so haven't installed it yet.

    I hope everything is ok with my bike. It is my only way to work and uni so I need it to be reliable.

    Thanks peoples :wink:
  11. When the clutch is in the bike has no engine power to control the bike. If you're quickly squeezing the clutch in to change gears, you won't notice it much, but if you're just holding it the whole time you're braking, you'll actually take a lot longer to stop coz you've taken out engine braking. Even without going down a gear the engine still helps slow you ... unless you have the clutch in. Clutch in effectively equals free rolling = less control. So don't do it unnecessarily!

    My understanding is that the idea of the clutch is to help the bike match the engine revs for the gear you're changing to. If you're already at the revs required and have some weight on your gear lever, yes - you'll change down a gear. You can do the same for going up gears by having your foot with a little pressure under the gear lever. Problem is, it won't necessarily be as smooth as with the clutch, or ideally - with blipping. But that's a different topic. Basically, yes, it's fine that your bike changes gear while you have pressure on the gear lever.

    So why not do all the gear changes that way? If you only change down a gear when you're already at the revs it can handle without clutch, you're not using much engine braking at all. If you only change up a gear when you're at the revs that will change, you won't have much acceleration. Every speed change will be less responsive. That's my general experience anyway. Well, unless you help it with blipping. But yeah, do a search on that.
  12. Yes and there's a thing called the rear brake.

    Which when used with the front brake on and the clutch puled in will stop you just as quickly, without causing undue strain on the engine and gearbox!!
  13. No way. Are you serious?!

    I understand the desire to wear out brake pads rather than your engine, but unless you're doing heavy down-changes your engine isn't going to cause a strain.

    Have you ever compared it on the road? If you're game, go down a hill (just to exaggerate the effect) at night/when nobody's about and see how well you brake with the clutch in Vs clutch out. The rear brake helps for sure, but without the traction of the engine you're really just rolling, trying to stop an out of control bike, rather than working with the bike to stop.

    To isolate the effect of the clutch forget about the brakes for a moment. Get on your bike and ride at whatever gear you think is appropriate. Then pull in the clutch, feel the rolling, then release the clutch and feel the pull. You weren't in too low a gear coz you'd already chosen it to be appropriate, so you weren't straining the engine, and yet it helped you slow down. Why not use it??

    Especially in an emergency, as described in the OP, I would want to use anything I had to stop - front brake, rear brake, down-changing, engine braking. Pull out all your stops - pun intended!

    I would be extremely surprised if an experienced rider ever advised the use of holding the clutch in for braking.
  14. HART Tullamarine taught us to ignore gear changing during an emergency stop, and basically leave the clutch until the very last moment before the engine stalls.

    Their reasoning is that you're progressively pulling harder on the front brake as more weight shifts onto the front wheel (which is good)... then when you pull in the clutch all the way with your other hand, your body unconciously relaxes the braking hand - or at least stops the progressive increase in braking power.

    Better to concentrate completely on controlling the front and rear brakes, and deal with that gearbox thing once you're safely stopped.

    They pulled me up on it several times. Probably an instinct from mountainbiking - grabbing a fistful of both levers.
  15. Thanks Spots. I was taught the same. I have since learnt that down-changing can be done quickly and very effectively to add to it, but it's a more advanced skill that they don't teach at HART (not for Ls or licence). So unless you have the skill to do all that, absolutely - just brake! And clutch in at the very end so you don't stall. Even then, stopping is your priority, so as long as you do that, stalling the bike would be well worth it for if you forgot the clutch completely.
  16. You ARE kidding...right!?
    In any braking situation you need to have at your disposal ALL possible braking performance...just in case you might need it suddenly!.
    This INCLUDES engine braking...DO NOT pull your clutch in until you are almost stopped, and only then to prevent the engine from stalling.

    In an emergency, where you might not even have time to downchange, DO NOT touch the clutch lever until you have either avoided whatever it was you were going to hit and need to declutch to keep your engine running, or until you HIT the thing you were trying to avoid - in which case, it does'nt matter!

    I repeat...and as Pinkxie explained to you...DO NOT hold the clutch in while braking.

    (And try not to be smart-ar*se while you're busy showing people what you don't know)
  17. +1 for this... if for no other reason than the gearbox will help slow the bike... i'd account a few saved points on my p's test for letting the bike stall on emergency breaking