Shift without clutch.... much?

[Motogeezer1949_imp]

Apples to oranges Moto GP comparision my friend
From the Moto GP site:
The so-called seamless technology, using architecture no too dissimilar to a regular gearbox, switches between ratios without cutting drive from the engine. The technology is extremely complex, yet those milliseconds it saves appear to be a cost and effort worth putting in. Rossi spoke about the areas he felt such a transmission improves.

“For me, in one lap it doesn't change a lot…I mean the lap time. A lot of people speak about two-tenths for a lap - I think it’s less than two-tenths. But the big improvement I think is in the 20 or 30 laps, because the bike becomes a lot easier to ride, is more stable, more stable in acceleration, but also more stable in braking, and in the next braking.”

He addresses the fact that a quicker shift saves time when added up over race distance, yet focussed heavily on the benefits on the feeling of the bike. Engaging a gear on a regular gearbox is something not only spectators can hear, but something riders feel reverberating through their bikes. By eliminating this movement of the bike, no matter how small, the whole package feels more stable in all parts of the track. A point the Italian noted in particular was that “…you can use the gears for riding the bike more than before. I mean that, if you need to change gear, also on the very edge [at full lean], you can do so!”

As Rossi pointed out, this added smoothness has a knock-on effect on tyre wear, and rider feeling and fatigue: “For me, it's better for the tyres, less stress for the tyres, and is also very good for the riders because the bike becomes easier to bring to the limit and it’s more difficult to make a mistake. So I think it's something very important for race distance – more so than for one lap.”
Oh and BTW, dogs get worn from the abuse of power shifts not because of being shifted clutchless in normal riding.

[kmoney_imp]

ok..trying to learn here..old dog and all

If this is common practice and won't hurt the tranny..why was it such a big deal that Yamaha didn't have a seamless tranny in MotoGP year before last (allowing clutchless shifts) while Honda did? (and Suzuki is behind because they still don't)

It was claimed clutchless shifts with the seamless gearboxes were responsible for a gain of 2/10s or 3/10ths per lap.

Though still a constant mesh manual gearbox, the seamless shift transmission is a different beast. You have two gears selected at any one time (the current one and the predicted next one), but only one is actually powering the bike and the other is queued up waiting for a hand-off.

On a normal bike, even if you shift without the clutch, you are coming off power momentarily and physically disengaging the shift dogs from one gear and locking another set onto the next gear you want -- this takes time (even if only a few hundred milliseconds).

In the seamless you have the gear you are in powering the bike and the next one pre-selected, but not being used. To pre-select the bike likely either 'guesses' which gear is next by monitoring what is occurring (rev's, throttle position,acceleration, decelerating, braking, etc...) or has the rider pre-select by picking his/her next gear (likely by lightly pushing up or down on the shift lever between shifts).

When you go to shift then there is no power to cut and no dogs to release and re-engage, as it's already done in the 'down time' between shifts. All you need to is hand-off power from one gear to the other using a more efficient form of mechanical switching. In a car (and a DCT bike actually) this is usually done by having two wet clutches (one for even and one for odd gears) that can be engaged/disengaged in about 50ms. On the GP bike, it's speculated that there is a mechanical system that instantly disengages the previous gear as soon as the next one is engaged. This is where the time-savings per lap come in -- as forward acceleration remains uninterrupted for a few milliseconds less per shift and this accrues over the course of the entire race. The chassis is also upset way less by the seamless, as the shifts are 'perfect' every time and there is no jarring or motion created by the power variation of switching gears.

The hand-off portion is really the secrecy is about, it wouldn't be hard to build a pre-selector box for a motorcycle (as said above, motorcycle DCTs are basically this), but miniaturizing it and making the engagement purely mechanical is pure engineering genius.

[the Ferret]

Ptero is right, you do learn a lot here. Thanks for the explanations kmoney, and reading kmoney is a lot easier than reading Kevin Cameron. I can't understand a thing that guy says lol

[kmoney_imp]

http://www.formula1-dictionary.net/seaml...arbox.html

This is a very well-written and relatively understandable explanation of how the seamless gearbox must work. They have been used in F1 for a while (I'm guessing this why Honda managed to beat the other competitors in Moto GP to the punch with it).

[Django]

I've gone clutchless all my life, every bike I've owned, even at the 1-2 shift. Never had a tranny or clutch or related problem and I've had plenty of bikes on which I racked up over 70k miles. There's no need to use the clutch except for starting, stopping and downshifting, AND after a while, after one learns to match revs, one can downshift in pretty near every gear with the exception the 2-1 down shift.
The motorcycle tranny is constant mesh, unlike mostly all auto/truck trannys, so it's a non-issue, a no brainer. Hurts nothing unless one is a totally inept rider.
Plus, I've never replaced a clutch cable

Well, don't worry about the clutch cable of your CB.

[mattmcuomo@yahoo.com]

Wow, didn't think I'd start an "oil thread" I didn't see any other threads on this. I did get some great responses, thanks!

Sent from my C6725 using Tapatalk

[the Ferret]

Lol far from an oil thread, and very educational.

[Papa Weeley_imp]

This was something that was news to me before about 5 or 6 years ago, too, but now about 50%+ of my upshifts are clutchless after 1-2. I only very occasionally downshift this way, and it's usually just as a novelty to see if I can - it just seems like unnecessary, undue pressure on the gearbox to me (though I have no facts to support that, and lots of folks would vehemently disagree). I'm also old school in that I always blip the throttle before downshifts to rev-match anyway, and that only seems to mess up a clutchless downshifts that I've tried.

[Motogeezer1949_imp]

I'm doubting clutchless shifts on the little old CB are going to bother it much
BMW S1000RR features factory installed shift assist for full throttle clutchless upshifts https://youtu.be/EHCIcPo1Rxg?t=6
As does Aprilia: http://www.apriliausa.com/technology/aprc.html

[MikeOxbig_imp]

I'm doubting clutchless shifts on the little old CB are going to bother it much
BMW S1000RR features factory installed shift assist for full throttle clutchless upshifts https://youtu.be/EHCIcPo1Rxg?t=6
As does Aprilia: http://www.apriliausa.com/technology/aprc.html

Yes, my Aprilia has that quick-shifter feature and it's very fun to use, but I only save it for open roads because the system works better at wide open throttle and higher rpms. Almost "too easy" as you don't even need to let off the throttle at all. Just leave it at full throttle and shift up, done, and repeat.