some advice re: downshifting in corner entry

Chris Burgess chris at chrisburgess.com
Tue May 10 12:59:26 PDT 2011


Um...

"The important thing to remember is unless it's raining you can and should
lift the rear wheel under braking. Keep that in mind; the ideal corner entry
has no weight on the rear wheel until you tip in, and you can't brake on
air. "

I completely disagree.  There is only one time at Pacific (for example) wher
eyou would be lifting the rear on braking and that is turn 3.  Otherwise you
shouldn't be or you are introducing toooooo much chassis pitch which
unstabilizes the bike.

-Chris

On Tue, May 10, 2011 at 12:50 PM, Randy Grein <randygrein at comcast.net>wrote:

> I think we're a little far out for a physical meet but I'll give you what I
> have online; generally I'm pretty good at corner entry - it's getting my
> carcass out of the hole that's the problem. (grin)
>
> MOST people who have corner entry problems with downshifting never raced a
> 2 stroke and end up trying for more engine braking. Bang a couple of
> downshifts, dump the clutch and wonder why the rear is hopping all over.
> Compensate for that and you end up either braking early, miss your turn-in
> point or just go slow. The important thing to remember is unless it's
> raining you can and should lift the rear wheel under braking. Keep that in
> mind; the ideal corner entry has no weight on the rear wheel until you tip
> in, and you can't brake on air. Add to that the uncontrollable nature of
> engine braking. Under most braking conditions you'll want to ease in
> (quickly) to a maximum rate, hold that level for a period of time and then
> taper off smoothly. In contrast when you let out the clutch rear wheel
> braking is greatest (by 2-4 times) as the engine spins up, drops as engine
> RPM stops accelerating and drops rapidly as the bike continues to slow. The
> slipper clutch allows a set amount of engine braking and no more, matching
> ideal racing requirements which is why they are so popular.
>
> If you want to experience maximum deceleration with high accuracy pull in
> the clutch. Do this first during practice, in a race you'll end up on your
> head. As you have time while braking bang the correct number of downshifts
> with the clutch still in, then blip the throttle to get the engine near
> redline and EASE out the clutch. When in doubt use one less downshift than
> you think you'll need, power needs at maximum lean are pretty minor and it
> will keep the rear wheel from spinning. In fact, you can usually begin
> acceleration MUCH sooner and carry a higher corner speed.
>
> This technique works best on wide and decreasing radius corners; you're in
> the entry zone for a long time and even a small increase in speed can net
> big gains. Ideally you'll want to get used to using a little rear brake as
> well. Without having excessive engine braking to contend with the rear brake
> becomes very useful when near the edge - not when straight up, but as you
> tip in and all the way to your apex. 1st gen bikes have a bigger rotor and
> too much rear brake for racing, using a smaller GSXR or 2nd gen rotor
> reduces braking leverage and it becomes quite controllable. The important
> part is to limit rear brake to a small fraction of front braking. Feet are
> not nearly as sensitive as fingers and you don't want to spend a lot of
> attention on that brake pedal that could instead be used for feeling grip.
>
> History, and why this works: I mentioned 2 strokes earlier; they have next
> to no engine braking and were THE purpose-built racebike motor for over 30
> years. The common engine lube was premix, and shutting off at the end of a
> straight cuts off cooling fuel AND lube making seizures common. The solution
> was, and is to pull the clutch at the end of the straight and (usually) blip
> the throttle during braking. Modern water cooled 2 strokes generally had
> good enough carbs to make blipping unnecessary so it's just a matter of
> banging shifts, letting out the clutch at the right time and tossing it in.
> With one less thing to worry about a good 2 stroke rider has a higher entry
> speed, a more precise apex and a higher apex speed. This is especially true
> with decreasing radius corners which throw in yet another variable. Rain
> does too. Slam a downshift under braking and the rear tire breaks loose and
> slides. You lose all braking effect and most of your steering until it hooks
> back up; if you're leaned over at the time you fall before that happens. Use
> a bit of CONTROLLABLE rear brake instead and you can outbrake the field,
> both straight up and leaned over. Just keep in mind what I said earlier -
> you are applying a SMALL amount of rear brake over a very long distance to
> scrub off speed.
>
> HTH,
> Randy Grein
>
>
> On May 10, 2011, at 11:20 AM, Jo Rhett wrote:
>
>  Anyone on this list willing to spend a few minutes talking to me about
>> downshifting?  Not street, just race corner entry downshifting.  I'm really
>> struggling with this on my z-built superbike.  Obviously a slipper clutch is
>> probably a good answer, but I'd like to learn how to do this better without
>> the technology assist.
>>
>> Beer or favorite poison of choice for time to talk about it?  Dinner on my
>> tab?
>>
>> --
>> Jo Rhett /  velociRaptor Racing
>> #553 WERA / AFM
>>
>>
>


-- 
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