Rev matching..

[Huzo]

I think they called that the "slick shift " Dave....didn't last long.

My CT 110 has it..

[Ncdan]

I can’t even attempt to add any reasonable explanation as to how this shifter system functions mechanically however I can offer an account of the experience I had on an Aprilla Tuono Lucian let me ride.

After instructing me on the technique of how to do the shift, which was actually fairly straight forward and simple.
When reaching the desired more aggressive RPM range just assertively upshift. Do not back off the throttle or touch the clutch.
It really went against my comfort level to do that because one feels like if a mistake is made, out comes the tranny however the shift was smooth and obvious the bike was designed for that type of shifting with no adverse effects on the bike.

There’s no way I was going to rev that beast to 10k in third gear and conduct a speed shift.
So I thought I’d start at 7k in third which was already fast.
When I shifted up the front end came up several inches but some force within the machine forced the wheel back to the ground.
The weird thing is that after the shift the RPM only fell maybe a few hundred to 1000 and it was ready for another shift at which time when I went to 5th I was in triple digits!
Whoa….off the throttle immediately and return to the planet.

These bikes with these type features are racing machines and designed for very advanced riders of modern bikes and not old school guys like me.
It does not fracture my pride one bit to admit I’m not a good enough rider to do this type bike justice.

That’s my story and I’m sticking to it.
Carry on my friends 👍


Dan

[tris]

Because the ecu knows the gear you're in and the road speed it calculates the rpm needed for the next lower gear. With the engine on the overrun and the backlash dogs on the gears "loaded" due to driving the engine and foot pressure on the gear lever when the foot pressure threshold is reached the ecu simply blips the throttle to the required rpm. As the engine begins to accelerate to the desired rpm the split second the load comes off the gears the foot pressure on the already loaded shifter moves the drum and engages the next gear. On a bike it's not actually "blipping" the engine rpm in the manner a car with an H pattern gate is it's more "rev matching" and it all happens in a fraction of a second. The gear unloads and starts to disengage right at the start of the process of the revs increasing. The revs don't actually need to increase in reality to do this, the drive load just need to come off the gear with foot pressure applied on the gear lever. It's a similar reason a gearbox always shifts cleaner when you load the lever before you pull the clutch. As soon as the clutch has unloaded the drive dog faces the pressure that's already applied via the foot pressure drives the gear.  It's also why the system works better with engines with light cranks and multi cylinders that rev quick and at high rpm. At low rpm/slow revving engines the shift action can be faster in elapsed time than the engine can bring the revs up. When the engine is really revving it catches additional revs a lot quicker.
The lever extender mod I came up with and Chuck manufactured improved the shifting of the v11 gearbox because it reduced some of the leverage advantage your foot had over the shift mechanism so when the load came off the gear dogs and the detent spring released there was extra force already applied to the shift lever due to the reduced leverage which meant the shift action was faster and the shift cleaner. So faster cleaner shift action with reduced lever movement but with slightly heavier action. Gearbox shifting mechanics is an interesting subject and there are so many pieces that combine to make a clean shifting gearbox.

Ciao       

So you load the shifter and come off the throttle and at some point the gear box unloads enough to shift  and at that point the ECU blips the throttle?

Does sound brutal on the gear box internals ......... which brings us back to Huzo's opening post 

[lucky phil]

So you load the shifter and come off the throttle and at some point the gear box unloads enough to shift  and at that point the ECU blips the throttle?

Does sound brutal on the gear box internals ......... which brings us back to Huzo's opening post 

Almost. You normally just role off the throttle when slowing down and hit the lever and if it's set up well the load cell on the lever and the ecu take care of it and you get a seamless down shift with the right revs for the lower gear. Going up you just hold the throttle pinned or open and hit the lever and it cuts the ignition and or fuel, some do both or either and it shifts cleanly. It's only hard on the trans if it's a basic unit that's not set up right but these days the factory oem ones are pretty bullet proof. The shock loadings on the trans aren't an issue. I've never seen a trans lose a gear tooth or engagement dog through shock loads. I've seen dog corners rounded off but that's from bad shifting or incorrect set up on old type basic units that have only crude delay settings.

Ciao       

[Huzo]

you get a seamless down shift with the right revs for the lower gear.

Ciao     

How does the engine achieve “the right revs for the lower gear” when it it still connected by the gear it is about to exit ?
It surely can only increase it’s revs to the target value, during the transition from the previous gear to the next. While any gear is engaged, it cannot alter it’s rpm if the road speed is constant (which it is) during the transition.
eg..
80 kph @ 3,500 rpm in 4 th  to
80 kph @ 3,000 rpm in 5th 0.2 seconds later.

[SoCV]

How does the engine achieve “the right revs for the lower gear” when it it still connected by the gear it is about to exit ?
It surely can only increase it’s revs to the target value, during the transition from the previous gear to the next. While any gear is engaged, it cannot alter it’s rpm if the road speed is constant (which it is) during the transition.
eg..
80 kph @ 3,500 rpm in 4 th  to
80 kph @ 3,000 rpm in 5th 0.2 seconds later.

 This is where the slipper clutch on modern high performance motorbikes comes into play . Watch any Irish National roadrace , you can actually hear the engines over revving on downchanges as they enter corners .

 Dusty

[lucky phil]

How does the engine achieve “the right revs for the lower gear” when it it still connected by the gear it is about to exit ?
It surely can only increase it’s revs to the target value, during the transition from the previous gear to the next. While any gear is engaged, it cannot alter it’s rpm if the road speed is constant (which it is) during the transition.
eg..
80 kph @ 3,500 rpm in 4 th  to
80 kph @ 3,000 rpm in 5th 0.2 seconds later.

Imagine the gear on the overrun with the dog faces loaded and as I've pointed out previously your foot is applying pressure on the shifter and the pressure switch (load cell) is approaching it's threshold for switching. The whole shifter mechanism is heavily loaded in the down shift position. The foot pressure now reaches the pressure sensor threshold and commands the engine to the new target rpm. Before the engine has even had the chance to increase the rpm by 10 rpm as an example the backdrive pressure is now released from the gear dogs and with the system already loaded by your foot the gearbox deselects the gear you're in and heads towards the lower gear and engages. The engine can't rev faster than you can "deselect" the gear partly because the deselection action happens immediately at the start of the engine acceleration process as soon as the increase in rpm has off loaded the gear dogs. In reality the engine rpm doesn't even need to raise for the foot pressure to deselect the gear the engine load just needs to be released same as "floating" the throttle manually. All this shifting action happens happens not in 10ths of a second but in Milliseconds. The adjustment range of my Techtronics unit is 20-120milliseconds of cut time.

Ciao

[Huzo]

Imagine the gear on the overrun with the dog faces loaded and as I've pointed out previously your foot is applying pressure on the shifter and the pressure switch (load cell) is approaching it's threshold for switching. The whole shifter mechanism is heavily loaded in the down shift position. The foot pressure now reaches the pressure sensor threshold and commands the engine to the new target rpm. Before the engine has even had the chance to increase the rpm by 10 rpm as an example the backdrive pressure is now released from the gear dogs and with the system already loaded by your foot the gearbox deselects the gear you're in and heads towards the lower gear and engages. The engine can't rev faster than you can "deselect" the gear partly because the deselection action happens immediately at the start of the engine acceleration process as soon as the increase in rpm has off loaded the gear dogs. In reality the engine rpm doesn't even need to raise for the foot pressure to deselect the gear the engine load just needs to be released same as "floating" the throttle manually. All this shifting action happens happens not in 10ths of a second but in Milliseconds. The adjustment range of my Techtronics unit is 20-120milliseconds of cut time.

Ciao

Ok, I accept the premise of what you’re saying Phil, but I think it serves my point more than it does yours.

In your (educated) opinion, can or has the flywheel had enough time time accelerate (or decelerate) by say 500 rpm, in the amount of time that the drivetrain is “between gears” ?
There has to be a finite time that this “between gears” state exists, by virtue of the fact that it’s not in two gears at once, even though they are constantly meshed and what would you suggest that period of time is ?

Now the “blip” of the throttle may (or may not) be able to accelerate the flywheel to the required rpm for the next ratio for a downshift, but it certainly would not “spin down” to the required figure in the case of an upshifting in the minuscule time you nominate. How then has it achieved the target value ?
If you run your engine up to 5,000 rpm in neutral and chop the throttle, there is a clearly observable time required for the crank to drop the 500 rpm.
In the real world of a clutchless shift, there is nothing slowing that crank other than the frictional drag and work being done, in the engine internals.
I again suggest that the quick shifter will engage the next higher gear before the crank has FULLY dropped to the target figure and the gearbox dogs will mesh and the excess energy will be dissipated in the (INAUDIBLE) crash that the gearbox will feel.
If I am provably incorrect in that assumption, then my argument is over.

Now I routinely drive a truck with a 15 litre engine and an 18 speed Eaton Fuller Roadranger manual gearbox, almost all changes are clutchless and silent. That is because I can flip the box into neutral momentarily and match the rpm for the downshift of wait for the engine to spin down for the upshifting..(about 2 seconds typically).
The input and output shafts need to be spinning at correct revs relative to each other for proper engagement.
Same with the bike, whether the gears are constantly meshed, sequential.. or otherwise, it does not exclude the operator from that fact.
ie The input shaft has to be spinning at the correct rate relative to the output shaft.
I suggest that any torture that is being dished out, is either of low enough impact to be inaudible or indiscernible .
OR
The operator does not keep the thing for long enough that his mechanical lack of sympathy is repaid in failed/prematurely worn, internals...(That’s for the next poor guy).

I think that’s it unless I read something that targets my point.

[lucky phil]

This is where the slipper clutch on modern high performance motorbikes comes into play . Watch any Irish National roadrace , you can actually hear the engines over revving on downchanges as they enter corners .

 Dusty

Slipper clutches are to stop or prevent over revving on the overrun and rear wheel locking primarily. You set up a slipper clutch so the engine never overrevs as in max engine rpm on the overrun. What you are hearing on the racers is the slipper clutch preventing rear wheel lock up under heavy braking when the rider has banged it down multiple gears quickly and is approached the limit of rear tyre grip for a given engine overrun load. So the shifter system will allow you to shift all the way back through the gears matching the target rpm for those gears ( unless you overshift to a stupid degree and exceed the engine rev limiter setting then the ecu can't accelerated the engine on the down shifts above the overrev limit of course)
So mechanically the system may allow you to backshift to a gear a lot lower than is necessary and without exceeding the maximum engine rpm on the overrun but the rear tyre wont be able to handle that kind of backdrive load under brakes especially and will start to lock. This is where the slipper clutch activates and slips to maintain a maximum level of engine rpm on the overrun until the road speed drops and the tyre grip is sufficient. On a well set up system it all happens very seamlessly and you hear the engine rev to a particular point and the revs stop climbing on the overrun and as the road speed drops off you can hear the equilibrium return as the slipper stops slipping. My track bike has an EVR slipper which is one of the best and I can hear and feel it working at one spot, at Phillip Island turn 4 which is a slow 120 deg corner preceded by the very fast "Stoner" corner with a short straight section between. Coming out of Stoner corner at maybe 240kph you just barely get the bike stood up and it's very hard on the brakes and back 3 gears really fast for turn 4 which is maybe 60kph. The slipper works here because I'm shifting back as quickly as possible and the road speed exceeds the engine speed at which rear tyre lock would happen.

Ciao     

[SoCV]

 That's kinda what I said Phil . By allowing the engine to over rev it prevents wheel hop , ask Huzo if I didn't already tell him that .

 Dusty

[LowRyter]

You know all this stuff about quick shifters pretty much defeats the fun and satisfaction of executing a perfect downshift with your own hands and feet.   

The QS was an option on my Ducati.  The unit has proven to be unreliable and occasionally causes ignition failure.  The newer units are perfect but what fun is that?  Anyway, I couldn't go an extra couple $ thou for a quick shift and some gold colored suspension pieces.  The bike has a slipper clutch, I've felt it kick in a couple of times in pretty sedate situations.

OK, just my opinion. 

[Bulldog9]

You know all this stuff about quick shifters pretty much defeats the fun and satisfaction of executing a perfect downshift with your own hands and feet.   

I know a QS was an option on my Ducati.  The unit has proven to be unreliable and occasionally causes ignition failure.  The newer units are perfect but what fun is that?  Anyway, I couldn't go an extra couple $ thou for a quick shift and some gold colored suspension pieces.  The bike has a slipper clutch, I've felt it kick in a couple of times in pretty sedate situations.

OK, just my opinion.

Agreed. I've never add one and will do my best to not buy a bike with this. Only 1 of my bikes has ABS/TC and none have Cruise. IMO, these things rob WHY I ride.  Thankfully, the ABS on the V7 is excellent, and the TC rarely intrudes.

[Huzo]

That's kinda what I said Phil . By allowing the engine to over rev it prevents wheel hop , ask Huzo if I didn't already tell him that .

 Dusty

Oh now I get it.
The slipper clutch in my Norge, blends the sharp edges off my clutchless changes and smooths it all out with Italian fairy dust.
How did I miss that...?

[lucky phil]

Ok, I accept the premise of what you’re saying Phil, but I think it serves my point more than it does yours.

In your (educated) opinion, can or has the flywheel had enough time time accelerate (or decelerate) by say 500 rpm, in the amount of time that the drivetrain is “between gears” ?
There has to be a finite time that this “between gears” state exists, by virtue of the fact that it’s not in two gears at once, even though they are constantly meshed and what would you suggest that period of time is ?

Now the “blip” of the throttle may (or may not) be able to accelerate the flywheel to the required rpm for the next ratio for a downshift, but it certainly would not “spin down” to the required figure in the case of an upshifting in the minuscule time you nominate. How then has it achieved the target value ?
If you run your engine up to 5,000 rpm in neutral and chop the throttle, there is a clearly observable time required for the crank to drop the 500 rpm.
In the real world of a clutchless shift, there is nothing slowing that crank other than the frictional drag and work being done, in the engine internals.
I again suggest that the quick shifter will engage the next higher gear before the crank has FULLY dropped to the target figure and the gearbox dogs will mesh and the excess energy will be dissipated in the (INAUDIBLE) crash that the gearbox will feel.
If I am provably incorrect in that assumption, then my argument is over.

Now I routinely drive a truck with a 15 litre engine and an 18 speed Eaton Fuller Roadranger manual gearbox, almost all changes are clutchless and silent. That is because I can flip the box into neutral momentarily and match the rpm for the downshift of wait for the engine to spin down for the upshifting..(about 2 seconds typically).
The input and output shafts need to be spinning at correct revs relative to each other for proper engagement.
Same with the bike, whether the gears are constantly meshed, sequential.. or otherwise, it does not exclude the operator from that fact.
ie The input shaft has to be spinning at the correct rate relative to the output shaft.
I suggest that any torture that is being dished out, is either of low enough impact to be inaudible or indiscernible .
OR
The operator does not keep the thing for long enough that his mechanical lack of sympathy is repaid in failed/prematurely worn, internals...(That’s for the next poor guy).

I think that’s it unless I read something that targets my point.

Remember Huzo these things are primarily for performance applications and their forte is on bikes that are in the upper areas of the rev range and have by Guzzi standards no flywheel effect at all. So rotating at 10,000rpm the engine can catch an extra 500rpm very fast. Add to this that its not about perfection in getting the engine and gearbox meshing speed absolutely perfect but close enough to get a clean smooth transfer of load.
It probably also helps to picture the motorcycle drive system holistically from the crank to the tyre contact patch. An older dry clutch Ducati had a cush damper in the clutch hub, a chain and another cush damper in the rear wheel and a rubber tyre between the torque generator (crank) and the load (road surface). All these combine to reduce the shock loading on the transmission. Is that enough? Real world experience suggests it is adequate enough. Some shifting systems also use fuel cut to achieve the unloading of the transmission and a "staged" re introduction of the fuel to ease the shock loads. A motorcycle is also a fairly small mass in the grand scheme of things so if that shock load can also be accommodated by a jerk in acceleration an extending of the suspension etc and with a light crank a speeding up or slowing down of that component. it's a bit like an elastic band in some ways and helps mitigate the shock to the drive system. I know components are designed for their intended purpose but you get the idea when it's compared to a big diesel truck pulling a lot of weight. There the shock loading can only dissipate through any drive plate cushioning arrangements and enormous drive train and chassis movements and twisting. You're not going to get much help from a single tyre that can flex and deform to help. I've seen trucks on occasions pulling away from a standstill loaded up and then shifting gears and I always cringe at the thought of whats happening to the drive train.

Ciao       

[Offcamber1]

You know all this stuff about quick shifters pretty much defeats the fun and satisfaction of executing a perfect downshift with your own hands and feet.   

Indeed.  It surely has taken the "art" out of it as well.

[Huzo]

Remember Huzo these things are primarily for performance applications and their forte is on bikes that are in the upper areas of the rev range and have by Guzzi stands now flywheel effect at all. So rotating at 10,000rpm the engine can catch an extra 500rpm very fast. Add to this that its not about perfection in getting the engine and gearbox meshing speed absolutely perfect but close enough to get a clean smooth transfer of load.
It probably also helps to picture the motorcycle drive system holistically from the crank to the tyre contact patch. An older dry clutch Ducati had a cush damper in the clutch hub, a chain and another cush damper in the rear wheel and a rubber tyre between the torque generator (crank) and the load (road surface). All these combine to reduce the shock loading on the transmission. Is that enough? Real world experience suggests it is adequate enough. Some shifting systems also use fuel cut to achieve the unloading of the transmission and a "staged" re introduction of the fuel to ease the shock loads. A motorcycle is also a fairly small mass in the grand scheme of things so if that shock load can also be accommodated by a jerk in acceleration an extending of the suspension etc and with a light crank a speeding up or slowing down of that component. it's a bit like an elastic band in some ways and helps mitigate the shock to the drive system. I know components are designed for their intended purpose but you get the idea when it's compared to a big diesel truck pulling a lot of weight. There the shock loading can only dissipate through any drive plate cushioning arrangements and enormous drive train and chassis movements and twisting. You're not going to get much help from a single tyre that can flex and deform to help. I've seen trucks on occasions pulling away from a standstill loaded up and then shifting gears and I always cringe at the thought of whats happening to the drive train.

Ciao     

As usual Phil, you have dissected the relevant parts of this puzzle beautifully.
None of it is news to me, but a great bit of revision/revalidation.
You sound like you would be prepared to admit that the issue I highlighted does exist to some degree, but the total of all the shock absorption in the system, renders the issue too small to be of significant effect, but not totally absent.
 ?
Now THAT I accept.

[Bulldog9]

Oh now I get it.
The slipper clutch in my Norge, blends the sharp edges off my clutchless changes and smooths it all out with Italian fairy dust.
How did I miss that...?

They still allow fairy dust in Australia? I thought they had you guys on uber levels of lockdown 

Not sure why you are being obdurate Huzo, you seem to be arguing with yourself in a circular pattern. FWIW, when 'clutchless shifting' blipping the throttle (more of a dip or release) when the shifter is preloaded momentarily releases pressure on the dogs and allows the change to the higher or lower gears. This is in my experience more difficult in the CARC bikes in the lower gears due to the weight and centrifugal force of the flywheel to do smoothly, at least I havent been able to, after years of shifting clutchless. As I said before not a problem at all with the V7 or MGX-21.

However, I feel at this point I MUST say that the Convert has the smoothest clutchless shifting up and down the rev range of any bike I have owned or ridden 

[lucky phil]

Indeed.  It surely has taken the "art" out of it as well.

Remember they were originally designed for racing and racers don't generally care much about the "art" of rev matching they are more interested in reduced lap time. Interestingly though these things may have one benefit to road riders esp as you get older and stiffer in the joints, they save you from left wrist soreness due to the reduced clutching efforts. At the track on my GSXR which doesn't have a shifter my left wrist would be trashed at the end of a day of maybe 60 laps if I used the clutch for upshifts. Clutchless upshifts and normal downshifts reduced the wrist load and my wrist was fine at the end of the day. I don't have issues road riding but I dont do any city riding but for those with wrist related joint issues these systems may help enough to mitigate the problem. If you can reduce the lever pulling by 75% it would probably help.

Ciao     

[Huzo]

Not sure why you are being obdurate Huzo,
due to the weight and centrifugal force of the flywheel

It’s because I’m trying to get the topic onto the flywheel and not what “some guys mate used to do back in the day on his Speed Twin”.
Also, I’m trying to have a conversation about physics, with someone that confused centrifugal (which is actually centripetal) force, with angular momentum.
See why I need to argue ?
Should I just walk away ?
Centrifugal or centripetal force, has no place in this conversation.
It is irrelevant.
The reason these conversations go on so long, is that more than half the time is spent ironing out wrinkles in basic terminology and principles...(sometimes it’s me I hasten to add), but I cannot address an issue that is constantly being dragged into a different sphere.

[Bulldog9]

It’s because I’m trying to get the topic onto the flywheel and not what “some guys mate used to do back in the day on his Speed Twin”.
Also, I’m trying to have a conversation about physics, with someone that confused centrifugal (which is actually centripetal) force, with angular momentum.
See why I need to argue ?
Should I just walk away ?

Of course not, crack open another beer and have at it!   

[lucky phil]

It’s because I’m trying to get the topic onto the flywheel and not what “some guys mate used to do back in the day on his Speed Twin”.
Also, I’m trying to have a conversation about physics, with someone that confused centrifugal (which is actually centripetal) force, with angular momentum.
See why I need to argue ?
Should I just walk away ?
Centrifugal or centripetal force, has no place in this conversation.
It is irrelevant.
The reason these conversations go on so long, is that more than half the time is spent ironing out wrinkles in basic terminology and principles...(sometimes it’s me I hasten to add), but I cannot address an issue that is constantly being dragged into a different sphere.

I've got nothing more to add which is probably a good thing but if you really want to "do your head in" consider the MotoGP seamless gearbox. All 100% mechanical and transmits torque from one gear to the next without disengaging any form of clutch and zero loss of drive so no torque dip between gears. It actually selects the next gear before deselecting the driving gear and the transfer of torque is uninterrupted. No more neutral between 1st and 2nd and neutral is selected from a lever on the left handlebar when needed like stopping in the pits or on the start line before the race or a practice start. So N,1,2,3,4,5,6. Plans are afoot for a road road bike version in the not to distant future.
Get your head around that gearbox.

Ciao

[tris]

One question before you call it quits Phil

Is the slipper set to some nominal value, or is it controlled, i.e. does it sense the the rear wheel speed and adjust the amount it slips to avoid any rear wheel lock up?

Tris

PS thanks everyone - every day's a school day 

[Ncdan]

This was all beyond my mechanical comprehension but my hats off to all who was involved for keeping it on topic and all responses were clean and respectful.
Good job Pete👍


Dan

[lucky phil]

One question before you call it quits Phil

Is the slipper set to some nominal value, or is it controlled, i.e. does it sense the the rear wheel speed and adjust the amount it slips to avoid any rear wheel lock up?

Tris

PS thanks everyone - every day's a school day 

The std aftermarket type fitted to my Ducati and also most of the OEM ones I've seen the back torque is set by spring pressure by a dedicated spider style spring or in some designs by multiple coil springs which you can change to different tension versions to adjust the back torque to what you need. So they come with a selection of different colour springs for the purpose. My RSV1000 Aprilia had a std slipper that was controlled by engine inlet manifold vacuum and a large diaphragm on the clutch cover so theoretically it had a variable component to it. I never had it apart but as I mentioned previously it didn't seem to work when I really needed it. Other bikes use different strategies for anti wheel lock on the overrun and my MV Agusta 1000 used a throttle air bypass system on one cylinder controlled by a small electronic box so on the overrun it electronically opened an air port around the #2 throttle blade and at the same time pulsed the injector for that cylinder to raise the idle rpm to prevent rear wheel lockup.
To my knowledge a modern GP bike and possibly even the high end Ducati road bikes now use a combination of a mechanical slipper and sophisticated electronically controlled engine management strategies to manage back torque. Even my Royal Enfield 650 Interceptor has a mechanical slipper. 

Ciao       

[tris]

Thanks for that