[micty]

I just learned how to do a clutchless upshift. The way it was taught to me is to preload the shifter while the throttle is cranked, then to roll off and on the throttle quickly (opposite of blipping).

My question is:
1. Is there any disadvantage to clutchless shifting? (I was told that besides being faster, it's better for the gears.)
2. Is there a minimum RPM when it is safe (for the gears, etc.) to do a clutchless upshift? The logic of the method I described above is that the gear dogs would be locked in too tightly when the throttle is cranked. This implies that at a lower rpm, they wouldn't be locked. In which case, I suppose that at lower rpms, it would shift when you just lift it up without having to roll off the throttle. Would this damage the gears, etc.?

Thanks in advance!

 

[-gary]

It's not a matter of the pressure against the gears. If you're accelerating, then there's always an immense amount of pressure on the gears no matter the RPM's. It's more a matter of synchronization. The best way to look at it, is think of the transmission as a rod with six different sized gears spinning on it and the rod is connected directly to the output shaft of the engine. The rear is attached to a gear that floats over these gears and meshes with them to spin the rear (we're pretending the clutch doesn't exist). If they're all attached to the same rod, the larger gears will be spinning faster on their outer edge. 1st is the smallest gear. Say the gear spins at 5,000 RPM in 1st and pretend that the 2nd gear is spinning at 10,000 RPM. If you just yanked it out of 1st and tried to stick it in 2nd, the gears aren't going to mesh. Actually, they will, they're just going to grind themselves together until they slip into place. = broken or worn teeth. Now imagine that we spin 2nd slower to 5,000 RPM. Then when you pull out of first, it will just slip right into 2nd and you go again and again. Let's look at the clutch like it synchronizes the speed of the gears every time you pull it. No grinding. The same works in reverse.

That's kind of a crude and simple explanation that you didn't ask for, but you should be able to see the dangers of doing it and when and why it works.

As far as being better for the gears? No. Faster? Depends. If you take a lot of time to pull the clutch and shift, then yes. If your power shifting (don't try this at home newbies), then no. You will always have to roll off the throttle unless you hit the redline. The gears will not release easily until you quit putting pressure against them (accelerating).

Man I must really be bored.

 

[micty]

Thanks gary! I guess from your answer that I shouldn't be doing those clutchless upshifts too often. [:I]

[BTW, I may have misremembered about the benefit described to me, and it could be that he said it's good for the clutch (although it seems that there's a net harm to the bike cuz of the potential extra wear on the gears).]

Question: although the edge of the larger gears would be moving faster, it seems to me that the rpm would be the same for all gears since they're all attached to the same rod, no? (am I missing something?) OTOH, I see your point about having to adjust the speed of the gears' edge to the speed of the floating gear's edge.

So, just to make sure I understand: you're saying that the reason it shifts without the clutch after "counter-blipping" is because the speed of the gear (connected to the engine) slows down to a point where the floating gear (connected to the rear wheel) can mesh with it. And the problem is that unless it's done perfectly, it causes wear on both the gears and the floating gear, which would be avoided if the clutch were used to synchronize. --> answer to the 1st question

And the answer to the second question is that it can be done at any rpm as long as you are accelerating before you preload the shifter?

 

[Blue636]

What about shifting down? I accidentally downshifted from 3rd to 2nd yesterday because my foot was resting on the damn shift pedal. Are my gears screwed? How do I prevent this from happening again? I mean, if I don't rest my foot there my ankle becomes very sore and tired. The ZX6R isn't the most comfortable riding bike. But it's badass.

 

[micty]

Some other topics from a search (should've done that before posting! doh!)

/forum/topic.asp?TOPIC_ID=7668
/forum/topic.asp?TOPIC_ID=5474

Based on what I've read in this topic, the previous topics, and my experience in shifting at high rpms, it seems that it could be better to use a clutchless upshift when the rpms, while using as little preload as possible (to ensure that it won't be forced). I do recall that when I try to shift with a clutch on the track, there's a bigger and harder "thunk" than if I use a clutchless upshift. I infer that the bigger thunk means greater wear. What do you think?

Blue636, your foot should not be resting on the shifter. The balls of your feet should be resting on the footpegs. You move to the shifter only when you have to shift, then you move it back to the footpegs.

 

[vtjballeng]

Well first off, I find it a bit hard to believe that so many people don't exploit one of the greatest advantages of the modern sportbike, a true sequential transmission. The only other vehicles in which you get as much capability is in racing and some ferrari models. Most racecar teams would kill for a durable sequential transmission in their competition.

In any case I and almost all sportbike and racecar (equipped with sportbike engines/transmissions) owners I know personally rarely use the clutch when shifting. The only scenarios are under heavy braking/high load downshifting, rain/snow, 1-2 shift for street riding (sometimes). As far as durability, the only things that I have seen fail are clutches from launches and driveshafts from nasty downshifting. If the bike tranny's can take the loading from a D sports racer (racecar with fat tires) and other equivalent car series, it sure are hell can take any loading you can put on it with a quarter sized contact patch on your rear tire (motorcycle).

Seriously.... TRY to fuck it up and it is difficult. I was on a raceteam that used f2/f3/f4/f4i engines in the car. It was a university competition so we would have to train new drivers (who oftentimes did not even know how to drive a manual car, let alone handle a racecar with a motorcycle sequential gearbox). I still have a hard time believing what some new drivers did to that poor car/engine/transmission but the only problem we ever ran into was with electrical issues, oiling issues, and driveshaft/halfshaft failures (all design problems). Eventually the motors would fail but we would just rebuild them and use the same transmission internals... never needed to replace them.

 

[-gary]

The worst part about clutching is taking too long to get it done. Clutchless shifting is fine, but micity was basicly asking if it's safe. Given the example above, you can see that it is under the right conditions, and we haven't even talked about bending forks yet.

For your second question, yes. As long as the trasmission is in an unloaded state, it will shift, sometimes even when it's loaded if the gear is not meshed well, or the gears are worn. Then it will jump into a false neutral.

 

[micty]

vtjballeng, do you also avoid using the clutch even when downshifting (not counting high load downshifting)? What technique do you use to downshift smoothly without a clutch? I've got lots to learn.

 

[cRaZyTrAiN]

to add to this topic.... i know that the distance between 1st and 2nd is furthest because of neutral. The only time I plan on trying clutchless shifting is at the dragstrip, because last time I used the clutch and I want to compare times. Should I still use the clutch from first to second so it doesnt slip into neutral and bang off teh rev limiter? Or under full throttle is a roll off and a snug pull on the lever enough to skip neutral?

Thanks Guys.

 

[vtjballeng]

micty,

for a downshift without clutching i have a couple methods and which i use depends on load.

at medium load, i will blip the throttle and shift immediately. This sounds rough because you would expect a surge, then pop but once you practice it actually becomes quite a smooth action.

at light load, typically if I'm braking or just coasting off throttle/barely on throttle, you can just press down on the shift lever and wait for it to mesh. You don't have to press hard and typically the shift will happen very quickly. Once you gain some aptitude with up/downshifting you should be able to row through the gears pretty quickly.

 

[micty]

Thanks vtjballeng!

 

[Spoon]

i dont know what is called, but its senses when u are going to upshift, and automatically cuts the throttle for 60 milli seconds so u dont have to roll off the throttle. so wide open throttle upshifting. i believe that you can set the rpm where it is activated, so below the set rpm you still to used the clutch. i cant remember where i saw it though. but the internet site stated that you can gain about 15 feet between shifts vs. using the clutch. does anyone know where to get it? i know yoshimuras ems has an added accessory to add that controls this function. but according to their site they dont have an ems for our bike, and they are more expensive that a pciii

 

[Deftone636]

I've never understood clutchless shifting... i can do it fine, but i shift with the clutch just as fast.. i'm just moving an extra hand. it's probly takes me about 1/2 a second to shift.
Are people pulling in thier clutch, letting off the throttle, flicking thier foot, then giving the clutch back?
And as for downshifting, going around a corner i don't down shift untill i'm about to lean up again, i just roll off the throttle a little before the turn, keep it steady or whatever i need to through out, then as i'm coming out downshift to speed out of it. which also takes about 1/2 a second.

I figured everyone did this, am i doing it all wrong? or am i just amazing? or is everyone just not happy shifting as slow as 1/2 a second.
I'm seriously asking because i'm probly the strongest (most cordinated) rider of me and my buds, but we've all been riding only 2 - 2 1/2 years.

 

[micty]

Deftone, I think I'm doing pretty much what you're doing when you upshift (except I don't completely roll off the throttle to minimize the delay in acceleration on the next gear). As for downshifting, I downshift before the corner.
My concern is that shifting with a clutch seems a little "slow" (my shifting time varies depending on whether it's the lower or higher gears, but on 3 and up, I take about 1/2 second as well), plus the acceleration is not as continuous, and when I'm accelerating hard, it seems to be kinda harsh to the tranny.

 

[Deftone636]

i know what you mean about at higher rpms, sometimes when you let that last bit of clutch out it doesn't feel quite nice to the tran, i don't roll all the way off the throttle when i shift though, just a little, it's really a quick motion.

 

[Mythical_Rider]

i shift with and without... usually with.. to me there is no difference in speed... it just depends on the current conditions.. when using the clutch tho its usually a quick 2 finger flick and into the next gear.. all one motion.. crack off the throttle slightly.. and time it as u let the clutch out and roll back on for maximum mesh into your next gear.. all happens within a blink.. same without the clutch.. a roll off to equalize load, slip it up and roll back on..