Clutchless gear shifting?

[Monolith NZ]

Hi guys

I have a mate with a Hyosung GT250R who wants to give me a drag for $100 some time soon, somebody recommened I shouldn't bother with the clutch as It will make shifting faster.

My question is:

Is that a good idea? I.E is it bad for the bike if not done properly?

Please help out a newbie :confused:

Thanks

[Max Preload]

See here (http://www.kiwibiker.co.nz/forums/showthread.php?t=34427&highlight=clutchless+shifting).

[Quasievil]

I do it racing but not on the street, hard on the gas quick blip of the throttle clip it in gear and away you go (for 2nd and above)
Low revs prob not the go high revs its easy

[Gremlin]

If done correctly, there is little harm, and can be marginally quicker (we're talking 250s here, not superbikes)

If not done correctly, you're ruining components, and it certainly won't be quicker.

[vtec]

Do not ever do it between first and second gears will often hit neutral. Also, make sure you are well practiced otherwise you will stuff it up. I learnt while I was racing, cause my arm got arm pump and I needed to give it a break.

[slofox]

Do it all the time meself - usually when I am too scared to let go the hand grip to pull in the clutch...........

[Monolith NZ]

Sweet as, thanks for the input everyone

[Max Preload]

Do it all the time meself - usually when I am too scared to let go the hand grip to pull in the clutch...........

Let go? Don't you have an opposable thumb?

[driftn]

I to do it all the time, Track or road. Use the clutch to cahnge down though or things could get ugly.

[driftn]

Do not ever do it between first and second gears will often hit neutral. Also, make sure you are well practiced otherwise you will stuff it up. I learnt while I was racing, cause my arm got arm pump and I needed to give it a break.



Don't listen to this guy. If your hitting neutral between 1st & 2nd then you are clearly not doing it right. Unless your riding a KTM RC8 they dont like it much.

[scrivy]

When I'm racing, I go up and down with no clutch - works well for me.

Clutch just off the start line.

[sidecar bob]

When I'm racing, I go up and down with no clutch - works well for me.

Clutch just off the start line.

Not on my bloody beemer you wont be.:nono:

[scrivy]

Not on my bloody beemer you wont be.:nono:

I'll double it just for you Bob!! :2thumbsup:wacko::whistle:

[Mooch]

Hi guys

I have a mate with a Hyosung GT250R who wants to give me a drag for $100 some time soon, somebody recommened I shouldn't bother with the clutch as It will make shifting faster.

My question is:

Is that a good idea? I.E is it bad for the bike if not done properly?

Please help out a newbie :confused:

Thanks


Take his / her $100 and shift normally , it's not worth the grief if you stuff up the gear change though being rough.

BTW of course , you shouldn't be drag racing unless of course your on a closed road / racetrack and have both parents permisson otherwise you risk the warth of the PCB here on KB :msn-wink:

[scuzeme]

I did it first time at round 6 and found it easier and quicker thanks to Choppas advice.
You can put pressure on the gear lever and it wont change until you momentarily throttle off for each gear change as stated dont try it between 1st and 2nd gear.

[Weaver]

I've been told the fastest shift you'll ever do is if you load up the gear lever and wait till the bike hits its rev limiter. It'll slot straight in.
Never tried though

[svr]

I've been told the fastest shift you'll ever do is if you load up the gear lever and wait till the bike hits its rev limiter. It'll slot straight in.
Never tried though

You're well past peak power at the limiter tho (normally)
You can just keep the throttle pinned and use the clutch - the intertia provided by the extra revs will help *acceleration. This is a short-term technique...
*Do Hyosung 250s accelerate?

[vifferman]

You can put pressure on the gear lever and it wont change until you momentarily throttle off for each gear change as stated
It will on my bike - the Evo Star shifter shifts when you touch it with your toe.

[WarrenW]

If you are really bodgy you can hold the pressure on the lever and hold the gas on until it hits the rev limiter and it will slip in smoothly. BUT peak power is usually just a touch below the limiter so you may end up going slower! Also some bikes don't have rev limiters (ouch).

[wharfy]

You can just keep the throttle pinned and use the clutch - the intertia provided by the extra revs will help *acceleration. This is a short-term technique...
This is my preferred method when drag racing, but I did come LAST at the Nationals, so take it with as many grains of salt as you like ... :)

[k14]

I just keep the throttle pinned and it always goes straight in.... thanks mr quick shifter :)

[Ivan]

I dont use clutch for up shift never have.

I just slightly back off and click up easy as that.

[CB ARGH]

I gave this a go last night on the CBR250RR. Works excellent once you get a hang of it, feels like shit when doing it at low rpm's though. Definately much quicker than using a clutch.

Myth PLAUSABLE!!! :niceone:

[wysper]

I to do it all the time, Track or road. Use the clutch to cahnge down though or things could get ugly.

Must be a definite knack to clutchless downshifting. I can do it ok going up. Not that I usually bother, I am such a nana that using the clutch is ok by me. :msn-wink:




Myth PLAUSABLE!!! :niceone:

Nice mythbusters reference.:first:

[Max Preload]

Must be a definite knack to clutchless downshifting.

Helps to blip the throttle just as with a clutched downshift. Practice makes perfect. It doesn't take long for it to become second-nature.

[Mishy]

man, i can't imagine shifting any other way ! You should do it - It's easy, and fast :) Big point is this - remember to preload the gearlever BEFORE you blip the throttle closed then open. The gearbox won't shift with the throttle wide open, and as soon as you shut it it'll go right through :)
Cool huh ?

[Max Preload]

Helps to blip the throttle just as with a clutched downshift.

Forgot to mention, a servicable and well adjusted chain is a must for smooth clutchless downshifts, otherwise there will be too much drivetrain backlash.

[slofox]

Let go? Don't you have an opposable thumb?

Two things here....
1. Yes I do have an opposable thumb......I think....it's the bit next to the big toe, yes?
2. It is at the BACK of the grip.....under full acceleration, the G's backwards are so great that I can't hang on with just the thumb......loosen the fingers and I fall off the back.....quite normal for a V-twin y'know.........:rofl:

[The Stranger]

Helps to blip the throttle just as with a clutched downshift.

O....K.... this is a piss take right.
You are coming up to a corner and want a smooth entry and you are going to blip the throttle with the bike in gear and the clutch engaged?

[trumpy]

O....K.... this is a piss take right.
You are coming up to a corner and want a smooth entry and you are going to blip the throttle with the bike in gear and the clutch engaged?

Nope. You do it as you go through the gearchange. Takes a bit of practice but once you can it becomes second nature, although I suspect what gearbox ratios you are running can either help or hinder the situation.
I rarely use the clutch in either direction (depending on speed) and after 45,000kms the gearbox changes sweet as ever (bit of a surprise for a Triumph.....:rolleyes:).
I cut my teeth (excuse the bad pun) on racecar straight cut "dog" boxes which helped but, like anything else, it's just practice, practice, practice...

[The Stranger]

Nope. You do it as you go through the gearchange. Takes a bit of practice but once you can it becomes second nature, although I suspect what gearbox ratios you are running can either help or hinder the situation.
I rarely use the clutch in either direction (depending on speed) and after 45,000kms the gearbox changes sweet as ever (bit of a surprise for a Triumph.....:rolleyes:).
I cut my teeth (excuse the bad pun) on racecar straight cut "dog" boxes which helped but, like anything else, it's just practice, practice, practice...

Fark, ok. Learn something new every day. Don't anticipate I will be trying it as I will have about a milisecond in which to blip the throttle and for the engine to respond. Beside the XT slips through smooth as silk without clutch in either direction.

[Max Preload]

O....K.... this is a piss take right.
You are coming up to a corner and want a smooth entry and you are going to blip the throttle with the bike in gear and the clutch engaged?


Nope. You do it as you go through the gearchange.

Correct-a-mundo - I should have been a bit clearer on that.

[ckai]

Hi guys

I have a mate with a Hyosung GT250R who wants to give me a drag for $100 some time soon, somebody recommened I shouldn't bother with the clutch as It will make shifting faster.

My question is:

Is that a good idea? I.E is it bad for the bike if not done properly?

Please help out a newbie :confused:

Thanks

So who won???? Do you get to shout with your cool winnings?

Personally because the ninny is about .3 seconds faster to 100km/h I would have said change normal and make it a good close race. :) And, unless you have fat man syndrome, your bike is lighter.

[GaZBur]

Im with svr in holding the throttle wide open flick the clutch and gear lever simultaneously as I believe you are fractionally faster on the power and less likely to stuff up the change than clutchless and adjusting the throttle on the change. Try both ways yourself and see which works best for you and your bike. I wouldn't downshift without the clutch unless i am going straight as a rough change can really unsettle your bike particularly with bikes that have heavy engine breaking.

[mattathm]

If your bike isnt a hyo 250, then you have probably won the race already, hehehehee

[Leseid]

Ok I'm only a noob as a motorcyclist, but I've somehow (by mistake) learnt how to change gear using throttle and left foot.

But as a qualified mechanical engineer I've naturally analysed this technique of changing gear and what effect it would have on the bike.

So here's where my thinking is at the moment (by all means correct me if I've gone down the wrong train of thought).

Suddenly backing off the throttle just a little slackens the chain, removing the load from the teeth in the gear box. Or more specificatively the backlash in the dog teeth, that engage drive from the shaft to the gear. A pre loaded gear shifts in like silk.

Now here is where I think motorcycle gear boxes might be really cleaver. The gear ratios between gears are matched so that the revs you've just dropped it to slacken the drivetrain, so the dog teeth of the next gear slide right in. The reason for this thinking is it's only possible on my cbr125 to flat shift from gear 3 upwards, but there's no reason a race bike could do this for all gears. I also assume the dog teeth won't be straight cut, so with a bit of taper you can flat shift with some tolerance.

If any one is qualified to confirm or deny this I would be really interested in learning more about this.

[Maki]

I used to have a Kawasaki 250R and the only way I could keep up with others on certain KB group rides was by shifting clutchless. If you want to race the hyo practice shifting up through the box a few times before the actual race. When the shifts feel silky and effortless you have it nailed...

[p.dath]

This is way beyond my knowledge Leseid, but I found this info that looks related to your question:

http://www.eng-tips.com/viewthread.cfm?qid=142609&page=11


In a motorcycle dog-clutch transmission the drivetrain provides a cushion for the change in speed of the clutch /and engine if reqd. The rubber damper in both the clutch inner hub and the rear wheel hub provide lots of cushion. The dogs also have a lot of slack in rotation to increase the likelihood of a clean engagement. The ratios tend to be close which helps a lot.

Just apply simple kinematics. You need to look at how many degrees engine rotation you can get from the flex you have in all the parts from the clutch disk to the tires, and assume it all acts like a torsion spring. Estimate the engine inertia. Calculate the resultant torque (T = I x angular accel) required to decelerate the engine speed from one gear to the next over that many degress.