Clutchless Shifting

[cberkeley]

I read on the Internet somewhere (oops, I did not bookmark the site) that its perfectly fine to up-shift the gears without disengaging the clutch. But the clutch must be disengaged to down-shift.
Is there any merit in the above statements?
and if so, what's the mechanical principle involved?

[doggscube]

A former boss of mine never used a clutch while shifting a car or motorcycle, up or down. He claimed most motorcyclists followed the same practice. I doubt it's good for the transmission, but I'm certainly no expert.

Jeff

[Road_Clam]

I read on the Internet somewhere (oops, I did not bookmark the site) that its perfectly fine to up-shift the gears without disengaging the clutch. But the clutch must be disengaged to down-shift.
Is there any merit in the above statements?
and if so, what's the mechanical principle involved?

Most all bikes use a "constant mesh" type tranny. It's ok to shift clutchless PROVIDED you do it while only gently loading the gears. If you have the mentallity of rev limit shifting without the clutch, eventually excessive wear on the gear dog pins will take it's toll. When I performance shift, I simply give a slight tug on the clutch, and hold the throttle without backing off. There is no need to completely pull the clutch to the bars...

[drhach]

I did it on my Freightliner all the time. I've talked to mechanics who have claimed it's not a big deal. When my clutch cable broke in Tennessee and I needed to ge to Chicago, I rode for quite a ways before I got a new cable. I couldn't help feeling that every shift was knocking a few hundred miles off of the life of my transmission.

[argonsagas]

I think the term "dirt-simple" describes it fairly well.

On up-shift you roll off the throttle for just a moment, shift with your toe, and roll on the throttle again. This releases pressure on the gears and the gears will shift easily. Do NOT force them. Practice gentle shifts and you will get it.

For down-shift you do the same, but blip the throttle just as your toe drops. That allows a momentary rise in engine speed between gears and make the shift easier. Usually, if you are slowing down anyway, the engine would be happier at the higher speed on its own, so if you are bogging the engine then the moment you shift the gears the engine will come up a bit on its own and the gears will engage smoothly.

Anyone can do it. All you really need is practice and a gentle hand on the throttle. You need the clutch for starts, but after that you can drive all day without using the clutch by timing stop lights, traffic movements, et cetera.

[SPARKSS]

Gads how nice would it be to ride down in your neck of the woods!

The mechanical principle involved is that of matching revs to the selected gear and then "breaking torque" with the throttle while simultaneously loading the shift pedal in the desired direction. With a progressive-shift transmission like a bike uses (as opposed to a selective shift transmission like most automobiles and trucks), this works ok upshifting because when you roll off the throttle to break torque and the shifter moves, the engine abruptly slows and catches the next gear at the slower rpm. When downshifting however, because there's no neutral detent between each gear, it's unpredictible as you end up either forcing the gear to catch (the bike abruptly tries to slow down and may even momentarily skid) or revving the engine just as the shifter slides a VERY short distance to engage......with practice this can work but won't every single time.

It's a good thing to know how to do.....it'll get you home with a broken clutch cable. If you drag race you'll probably upshift this way or even use a pushbutton ignition interrupt circuit to break torque. For BEST LONG LIFE OF ALL TRANSMISSION COMPONENTS .....AND......REAR TIRES.....AND.....for BEST SAFETY you're better off using the clutch and matching revs as you downshift - with practice this becomes VERY smooth and lessens abrupt torque spikes associated with poor clutchless shifting.

One tip I got from an experienced rider once was that you'll wear out more rear tires by downshifting or rolling off the throttle from high rpm than by slowing with brakes and on secondary coarse pavement this is VERY much true. The added benefit to slowing in a higher gear or not abruptly downshifting to slow (worse when clutchless downshifting) is that on slippery surfaces (frost, ice, leaves, sandy patches) you will be less likely to induce a skid - I've proved both of these easily.

[Red Rocket GS1100]

I do it both ways

I am always aware tho of the rpms at the time of shifting. Done correctly it can prolong the life of your clutch and cable.
It's a great thing to know how to do if your cable should fail. With an appropriate hill you can get by the first gear start thing. It sure beats waiting/paying for an expensive tow truck ride.

[Dave8338]

Any transmission with synchromesh-type gearing can be shifted without the clutch...provided that you have no load on the gearing, as mentioned above, it's all about engine RPM's. When you get to the point that you can tell your ground speed, based on the gear that you're in and the RPM you turning...clutchless shifting is as easy as using the clutch, if not easier.

[nabrams]

You eventually get the feel for what RPM is right for clutchless up-shifting between various gear transitions (for example, it may be a different RPM for shifting from-2-to-3 than from-3-to-4). I was forced to do this when my clutch cable broke. Downshifting, however, is much harder to do clutchless in a smooth fashion (for the reasons stated by others above).
My advice: I'd rather put wear and tear on the clutch (easily replaced) than the transmission (which is NOT easily replaced). You don't want to be bending shift forks, wearing out gears, etc. Of course, a very unskilled rider can even put significant stress on the tranny even if he/she clutches for every shift.

[drhach]

Just remember that you have to get a good running start to shift in to first from a start (ala Fred Flintstone).

[Steve]

Done correctly it can prolong the life of your clutch and cable.

May prolong the life of clutch and cable, but might kill transmission or engine. :shock:
Generally, I prefer to wear out the more easily-replaceable parts first.

Any transmission with synchromesh-type gearing can be shifted without the clutch...provided that you have no load on the gearing, as mentioned above, it's all about engine RPM's. When you get to the point that you can tell your ground speed, based on the gear that you're in and the RPM you turning...clutchless shifting is as easy as using the clutch, if not easier.

I'll argue that, to a point. Like drhach, I used to drive a truck (Peterbilt \\/). I was taught to use the clutch to get the truck going, then ignore it until you needed to get going from a stop again. I tried the same thing with my Toyotas (Corolla and pickup) and found that it was harder. Not sure if it was the synchromesh that was interfering with the smooth shifts or simply the lack of mass. The gears in a Peterbilt-sized transmission have quite a bit of mass, and will keep spinning while the selector moves through neutral to the next gear. The gears in the Toyotas seemed to be dragged down by oil viscosity, making smooth shifting very difficult.

On my wife's 850, I have found that the 1-2 shift is better with a clutch, but the rest of them are closely-spaced enough that I can shift through them as smoothly as an automatic. \\/
However, the ratios on my Wing are so far apart that I would rather not even try. I have done it to determine that it is possible, but, because it is so jerky I will save it for a last-resort situation. 8-[


.

[Dave8338]

I'll argue that, to a point. Like drhach, I used to drive a truck (Peterbilt \\/). I was taught to use the clutch to get the truck going, then ignore it until you needed to get going from a stop again. I tried the same thing with my Toyotas (Corolla and pickup) and found that it was harder. Not sure if it was the synchromesh that was interfering with the smooth shifts or simply the lack of mass. The gears in a Peterbilt-sized transmission have quite a bit of mass, and will keep spinning while the selector moves through neutral to the next gear. The gears in the Toyotas seemed to be dragged down by oil viscosity, making smooth shifting very difficult.

On my wife's 850, I have found that the 1-2 shift is better with a clutch, but the rest of them are closely-spaced enough that I can shift through them as smoothly as an automatic. \\/
However, the ratios on my Wing are so far apart that I would rather not even try. I have done it to determine that it is possible, but, because it is so jerky I will save it for a last-resort situation. 8-[


.

True, the "flywheel effect" of the larger transmissions ie. (Roadranger's and others) does make the shifting easier ( can shift them slower) vs. a small trans or trans-axle and actual "wear" on the trans helps a great deal for the smaller units. Factor in the closer ratios of the Roadranger's gearing and yes, it is easier by far than a car or small truck, but it is all in the timing. :-D

[t3rmin]

There are a lot of bikes out there with 1 -> 2 shifting issues and I'd always assumed that was mostly due to "powershifting". I'll do it occasionally, but as mentioned, I'd rather replace clutch cables and clutches than trannies.

[Dave8338]

There are a lot of bikes out there with 1 -> 2 shifting issues and I'd always assumed that was mostly due to "powershifting". I'll do it occasionally, but as mentioned, I'd rather replace clutch cables and clutches than trannies.

No Doubt...If it's my bike...Clutch clutch it baby! Though just on a Sunday afternoon cruise, if you don't know exactly when to shift, you probablyyyyyyy wan't to use the clutch. :?

[cberkeley]

I think I will stick to using that clutch!