IENATSCH TUESDAY: Initial Throttle versus Accelerating; One guy says do this, one says do that. They’re both right.
By Nick Ienatsch August 30, 2016
Dave Crussell and Nick Ienatsch mid-corner at Phillip Island, Brad Schwab, e-tech
AHRMA Champion Dave Crussell (17) and I mid-corner at Phillip Island on TZ750s. We’ve come off the brakes and used initial throttle to load the rear tire. We’re waiting for the corner to open so we can pull the trigger on these high-horsepower, non-TC motorcycles. If we don’t wait, we don’t stay healthy.
What seems like contradictory advice in this sport is often simply “poorly detailed” advice. The speaker or writer throws out some possibly helpful words, but without context those words can be confusing. At Yamaha Champions Riding School the instructors work hard on adding context to the advice and this Ienatsch Tuesday focuses on riders who “accelerate too hard, too early.”
Trackday riders have been told to get the throttle open early on corners with big exits to get the bike driving early and “extend your straightaway”. Great advice; makes sense and you plan to really accelerate early on in the corner leading onto the longest straight.
At the next trackday you really nail the throttle early and your bike runs wide at the apex and almost off the track, forcing you to shut the throttle on the exit. You ask your favorite control rider about this and she says, “Oh, yeah, you gotta let the bike turn longer and just sneak open the throttle a little bit.”
You walk away confused and wonder which advice is wrong. The thing is, both pieces of advice are worthwhile. They just need more explanation.
At YCRS we talk about Exit corners—the corners that lead onto big-speed straights. Here, you want to get the bike slowed early, pointed, and accelerate past the apex; maximize the drive and extend your straight. Because if you can gain two mph past the apex, it will multiply all the way down the straight. Which is why passes on the brakes begin at the previous apex; slow it, turn it, drive it.
Dustin Coyner on a Yamaha R1 at Chuckwalla Valley Raceway, Robert/ CaliPhotography
This is Trackdaz’s Dustin Coyner exhibiting patience mid-corner on his R1. Patience: The often-forgotten part of riding a fast bike consistently well. Coyner’s speed and consistency is impressive and based on two pieces of advice that seem initially opposite: get your bike driving, and let your bike turn on maintenance (or neutral) throttle.
But…Loading Comes First
And loading the tire trumps Exit corners, big drives, or apex and straight-away speeds. The control rider’s advice is a core principle of how a bike works and she should have continued by telling you that every acceleration begins with a gentle sneak-open of the throttle. As the throttle sneaks open the weight begins to transfer rearward through the shock and into the rear tire. The tire gently loads and puts more rubber on the road while the fork tubes gently extend.
This is the initial throttle that the best riders use. It loads the rear shock, then the tire, and changes the bike’s geometry in a predictable and linear fashion. As the rider, you are not yet concerned with corner layouts; you are concerned with putting a linear load through the shock and into the rear tire. It can be quick, but it can’t be abrupt. Well, it can, but that’s called a highside.
And…Radius = MPH
You begin sneaking open your throttle because you are happy with your speed and direction. The above equation is in your brain and you no longer want your radius to tighten so you quit slowing your bike. A bike holding its speed with gentle initial throttle will hold its radius. An accelerating bike will open its radius and a slowing bike will tighten its radius, all things being equal like lean angle and track camber. Don’t believe me? Just go to a parking lot or maybe listen to MotoGP, SBK, or MotoAmerica Superbike winners and Formula One cars.
At this point you are ready to worry about your big exit. You’ve got the weight onto the rear tire, you’re holding your lean angle, and you’re holding gentle initial throttle, waiting for the corner to open. Perhaps on these big exit corners you over slow slightly so the bike turns into the apex even better, then stand it up to miss the inside curbing and match that reduction in lean angle with an addition of throttle.
Jeremy McWilliams at Phillip Island, AMCN
Big exits like Jeremy McWilliams gets to win at Phillip Island (on unlimited four-stroke vintage bikes) begin with the patience to let the bike turn.
Now let’s talk about the really danger: hard, early acceleration on the street. Suddenly we have a 12-ft. wide lane with the possibility of oncoming traffic in right-handers or uncomfortably hard things to hit in left-handers should we run wide. The realization of what hard acceleration does to your chassis and radius is mandatory for those of us who love back-road riding. Just like the track-day riders, we must learn to let the bike turn, then go gently to the throttle to load the tire—and then wait. Wait to accelerate until the corner opens.
The faster your bike, the more gentle initial throttle must be because every incremental turn of the throttle on a fast bike adds significant horsepower. When I rode Kenny Roberts Jr.’s Suzuki 500 in 2000 the data showed us initiating throttle at the same time, but I added too much too soon, forcing me to close it to re-point the bike. Kenny, the 500GP champion that year, initiated throttle more gently, allowing the bike to continue to turn. While I was closing the throttle to redirect the bike, he was accelerating linearly. Fast bikes simply require a finer touch.
Street or track, this is how the champions and veterans of our sport handle big exit corners. Thanks for taking the time to read this, I hope it’s a more-thorough explanation of two pieces of advice that seem to be initially contrary.
More Next Tuesday!