Shifting

[Thingy]

That does not really have anything to do with it.
How do you figure? Your theory below is flawed.

In order to shift up or down, you simply need to have no load on the transmission.
Prefered by most mechanics but not true.

**True.  I guess I meant in order to easily shift.
  
When slowing down for the corner and downshifting, there is a 'deceleration load' on the transmission.  Blipping the throttle reduces that load and allows you to shift.
Without using the clutch or passing through neutral how are you blipping the throttle with out putting an 'acceleration load' on the tranny?

**You are actually just taking away 'deceleration load' to the point where there is no load.

It is easier to imagine when accelerating.  When accelerating down the straight, if you just try to toe the shifter into the next gear, you can't do it beacuse the transmission is under that 'acceleration load'.
I know plenty of drag racers that upshift full throttle, no clutch.

**Full Throttle?  No clutch?  While it is probably possible, I would be willing to bet they are useing an electric or air shifter.  An electric shifter works the same way as 'un-blipping the throttle momentarily.

If you get of the throtle real quick (un-blip), taking away that 'acceleration load', the shifter will slip easily into the next gear.
Again preferred method but not necessary.

**True

Some responses are above.

OK...I'm just trying to help.  Maybe I don't understand your questions.  Maybe we just have different terminology here.  It sounds to me like you think that the engine must be able to rev freely (ie: clutch pulled in or in neutral) for it to be a true blip of the throttle.  So, are you asking how the engine revs freely when we blip the throttle?  If that is what you are asking, it is just different terminology.

[bweber]

BC61, Hitchcock is right.  During both acceleration and deceleration there is a tremendous load on the dogs of the transmission gears.  Blipping the throttle only helps match the engine rpms with the expected tranmission rpm so the rear tire does not lose traction from engine braking.  That is why Dave said with a slipper clutch you do not need to do it.
Although the shift drum in the transmission is designed with enough mechanical advantage to move the transmission drive and driven gears under load, the best way to shift is with no load on the transmission gears.  The clutch disengages the input shaft from the crank and allows the gears to move and mesh properly.  You can shift both up and down without using the clutch...for a short time.  It will catch up with you and something will break if you don't use the clutch.  I use the clutch on both upshifts and downshifts on all my racebikes since I started racing in 1997.  I never had to replace any transmission parts in one of my racebikes, but I have done plenty in other guys bikes.  I have seen FZR's, CBR's, GSXR's etc need shift forks and new gears from abuse and clutchless shifting.  I don't think I have gained or lost any positions in any race throughout my career because I did or did not use the clutch.  Continued full throttle upshifts (or downshifts) will round the engagement dogs on the transmission gears and cause more false neutrals and a vague, notchy shift within one season of racing.  I will guarantee you that.  Unless you have the budget to replace transmission parts and you ride at a level that the .005 seconds it might cost you per lap is important, I recommend using the clutch.

[BC61]

You are actually just taking away 'deceleration load' to the point where there is no load.
Doesn't make sense, if you are adding power without engaging the cluch or passing through neutral you are putting a load on the tranny.

Full Throttle?  No clutch?  While it is probably possible, I would be willing to bet they are useing an electric or air shifter.  An electric shifter works the same way as 'un-blipping the throttle momentarily.
I've roadraced many cars with straight cut gears, dog ring trannies, same as a bike tranny, you don't need to release the throttle to up shift. Not the easiest on tranny parts but it is easily done.

It sounds to me like you think that the engine must be able to rev freely (ie: clutch pulled in or in neutral) for it to be a true blip of the throttle.
Yep, without that you are accelerating if you give it throttle.


So, are you asking how the engine revs freely when we blip the throttle?
With out the cluch or neutral, yes.

[BC61]

Bweber, thanks for the comentary. I am fully aware of how a dog ring/straight gear tranny works, used to build them for race cars. I said shifting full throttle is possible but not recommended by mechanics, ie reliability.

CCSracer13's response didn't make sense if he was addressing my original question, blipping without the clutch.

[Eric Kelcher]

Bill by blipping throttle under decleration you DO momentarily load the tranny with aceraltion the tranny unloads again to decleration so in two points you have no load on tranny so tranny can be easily moved OUT of gear. Now into the next gear I would think there would be some stresses invloved and is why I always use a clutch.

Now on my dirtbike I can load the shifter with just a little pressure and when powerband levels off it unloads tranny and it slips into next gear.

[BC61]

Now on my dirtbike I can load the shifter with just a little pressure and when powerband levels off it unloads tranny and it slips into next gear.

Thats pretty much how you down shift without the clutch on any bike. Still don't see how you blip the throttle and not upset the bike. Nothing like accelerating while trying to brake as hard as you can. ::)

[TZ_Boy]

Blipping on the downshift does seem to be counterproductive when trying to slow down.

As far as full throttle up-shifts with the clutch this sounds like a good way to over-rev/float a valve.  Since you are at or near red-line with the motor loaded then you un-load it with the throttle pinned.

Letting off the throttle or using the clutch does essentially the same thing which is un-load the motor, transmission wear would be the same.  There is no mechanical advantage to a shift drum, only the shift lever.

[Thingy]

Still don't see how you blip the throttle and not upset the bike. Nothing like accelerating while trying to brake as hard as you can. ::)

I think we are getting closer to understanding each other.  I agree whole heartedly with you that it is hard to do it with out upsetting the chasis, as you stated above.  No one said it is easy.  I certainly don't do it.

How about an example.  Let's say that you are in 6th gear and doing 100 mph, off the gas and slowing down.  If you give it just a little bit of gas, you don't start accelerating.  You have to give it enough gas to overcome the deceleration before you start accelerating again.  that split second where you go from deceleration to acceleration is when there is no load on the tranny.

So, in response to your last post,

Doesn't make sense, if you are adding power without engaging the cluch or passing through neutral you are putting a load on the tranny.
I agree.  But, a load opposite of the deceleration load of the tranny.  Give it just the right amount of gas and they eqaul each other and you have no load.  If you go to far and give it more gas than that, you have acceleration again. :)

[bweber]

I think it is obvious that when you upshift under full power, you should roll off the throttle as you engage the clutch as not to rev the engine. With dexterity and practice this becomes second nature and you don't even think about the movements.
I am not telling anyone to leave the throttle pinned, pull the clutch in to the bar, slowly depress the shift petal, and drop the clutch as you roll down the front straight.  Lets be reasonable ;).

[bweber]

 ???Mechanical advantage is found at the shift pedal, at the shift mechanism behind the clutch and on the drum itself.  I was wondering what your engineering diploma says.  Mine says Bachelor of Science in Engineering from The University of Iowa.  Although I did not get to take the class "dynamics and kinesiology of a sportbike transmission", I did read the textbook. ;D

[MightyDuc Racing]

Last year at the Daytona 200, after Kurtis Roberts broke his exhaust and his bike sounded like a 1972 Harley chopper...lol...you could clearly hear him going into turn one with no blips of the throttle.  He was downshifting very quickly and keeping the RPM's up.  That is probably one of the fastest braking areas in the world, so if it works there, it's gotta work just about anywhere...just my .02.

[bweber]

I don't doubt that.  But Curtis Roberts had one of the best slipper clutches made (HRC) and his tranny was most likely completely rebuilt/replaced after the race.  He did not need to blip the throttle or worry about longevity of the transmission components.