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Old September 13th, 2018, 06:28 AM   #3
adouglas
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Name: Gort
Location: A secret lair which, being secret, has an undisclosed location
Join Date: May 2009

Motorcycle(s): Aprilia RS660

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MOTM - Jul '18, Nov '16, Aug '14, May '13
A few things here.

First, let's get double-clutching in your car out of the way. By now that's in ingrained habit, so you're going to continue to do it. That's fine, no harm done, but that method hasn't been necessary for decades. MANY decades... ever since the synchromesh transmission was invented (introduced by Cadillac in 1928 and now universal).

Personally, when driving fast I do what race drivers do... heel-and-toe. But that's another discussion.

Rev matching, whether by blipping or allowing the clutch to slip, IS important on a bike. "Light load" has nothing to do with it. Easy to demonstrate this... next time you downshift, wait a sec between gears and then just dump the clutch to see what happens. YIKES!

TL; DR for the following: You'll be doing both (blipping and slipping) but the situation determines what's appropriate.


You can downshift using one of two methods, and you covered both, but there's a variation that's important.

- Blip as you shift to keep the engine revs up. Your application of the clutch is very brief and the shift needs to be quick or the engine revs will drop too low and the shift will be jerky.

or

- Allow the clutch to slip as you let it out. The slipping gently pulls the engine up to speed.

Here's the variation:

- You blip AND let the clutch out gradually. This is needed to rev match in really slow corners or if you're really lazy with your shifting and let the revs drop way off.

There's no one "right" answer. On the track on my slipper clutch-equipped R6, at speed I'll grab two or three very quick downshifts as I approach the end of the front straight by blipping and downshifting as I brake. Not a lot of manual clutch slipping going on there. Then I'll pause for a second or two and make the final shift for the corner a bit more gradual, gradually releasing the clutch to help with engine braking.

Engine braking is the real difference. Letting the clutch out gradually gives you control over engine braking. When you do a rapid blip downshift you don't get that... the engine is fully engaged except for the brief moment of shifting.

HOWEVER in a situation where you're going from high speed to heavy braking (like slowing down at the end of the front straight on the track), the transition from wide-open to deceleration needs to be very smooth. A botched downshift (i.e. letting the engine revs drop off and then letting the clutch out too fast) can cause the rear to brake loose if you don't have a slipper clutch (you don't). This is why I blip-blip for those first couple of shifts: it's smoother overall. It's that last one where I want the clutch to slip.

Rapid blip downshifting requires dexterity, speed of action and mechanical sympathy with the bike. Remember the herky-jerky shifts when you were learning to drive a manual transmission? That's where you are with the bike right now.

Slipping the clutch is more accommodating of leisurely, deliberate shifts. But learn how to blip, to make sure the revs are matched even if you do slip the clutch.

Have a look at this. This is Ken Condon, motojournalist and full-time instructor on a Triumph Street Triple R (which I've purchased from him and will be picking up this weekend). Ken prefers not to blip because the bike does not have a slipper clutch. Look at how fast his downshifts are. Now, he's hauling it down from 130 or so on the track...this kind of quickness isn't really needed on the street.

Link to original page on YouTube.

Also this. He narrates the lap and does talk about downshifting starting around 7:30. Stick with it for a lap or two... he also discusses blipping vs. slipping the clutch. Same track.

Link to original page on YouTube.

And this. This shows the throttle hand. At 2:20 he blips the throttle going into a very slow hairpin. At 4:40 he doesn't... and the tire breaks loose a bit.

Link to original page on YouTube.

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