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Reepicheep
| | Posted on Tuesday, March 04, 2003 - 10:59 am: | 
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Oh yeah... and regardless of the coefficient of traction, downshifts could result in far more stress to the tranny and engine then WOT accelerations... How?
Duh. Because WOT means my rev limiter will kick in and keep me from going above 6800 RPM. The rev limiter can't help me if I am downshifting, and I could merrily spin the engine and drivetrain to pieces.
I've actually worried about this before. I usually don't approach redline (on acceleration) except on special occasions (like when leaving a stoplight next to an import with a fart can). But I am sure I have hit or exceeded it before on downshifts (but I have no tach so don't know for sure).
Are high revs without power applied (downshifts) as bad for the engine as high rev's with power?
Oh geesh. I am WAY off topic. Never mind  |
Bomber
| | Posted on Tuesday, March 04, 2003 - 11:17 am: |
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Reep
My guesstimate would be, yep, down-shift-induced overreving is about a damaging as the throttle-induced kind . . .. if the whirley and reciprocating bits don't like whirling and reciprocating that fast, any differences (and I'm sure there are some) are likely gonna be forensic in nature . . . .
"gosh, doctor, when the rod came through the cases, was the riding accelerating or engine braking? wehave to know for sure before we charge him with aggrivated over-reving." |
Nevco1
| | Posted on Tuesday, March 04, 2003 - 02:53 pm: |
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Thanks Reep...I never really considered myself vulnerable to Blake's Bait but I do agree with his 13 step program. The only exception is that on the street when I find myself going in way too hot, I drag a little rear brake to keep the bike balanced fore and aft. I find it much easier to get out of an unplanned sand drift that way. Must be the offroader in me, eh? |
Blake
| | Posted on Tuesday, March 04, 2003 - 05:22 pm: |
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I was considering an overly aggressive downshift with severe clutch engagement, not one that also over-revs the engine. That would be VERY bad.
Funny how we excised and transplanted this "How to turn/corner" thread from the original engine braking discussion, and now we end up back on the engine braking topic here. This could drive a moderator to drink. Too late. 
Nev,
Wow, thanks for the compliment. I pictured my ideal entry into turn two at OHR and simply wrote it down. I do agree that using the rear brake initially would probably be a good thing. The engine braking of my Nallinized 1250 mill does a pretty good job without the rear brake though. |
Nevco1
| | Posted on Tuesday, March 04, 2003 - 07:15 pm: |
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Blake...The Conjecture (Gotcha) only applies to my crystal ball. Riding aggressively is real and with all the variables, the basics are what make the difference on the street. On the track, the line and surface variables are minimal (Read: Known or Liquid) and you can push the envelope to get the gold. |
Newfie_Buell
| | Posted on Tuesday, March 04, 2003 - 09:17 pm: |
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Guys,
Interesting reading but if I had to think that much when going into a turn I would be in the ditch. |
Mikej
| | Posted on Wednesday, March 05, 2003 - 09:37 am: |
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Newf,
There are several good books and videos on the subject that help you to learn to adapt to transitional thinking so that you don't get overwhelmed (overwealmed? sp?)overloaded with mental gyrations while in heated battle or spirited rides. |
Bomber
| | Posted on Wednesday, March 05, 2003 - 09:58 am: |
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Rear brake usage is coming back into style, slowly, but some have never really stopped . . . it's a great boon, when used properly . . . tightens your line, settles the chassis, and confuses your enemies (use of this brake, in this context, refers to an extremely gentle application, of course, are not at all while engine braking on the verge of loosing rear-wheel traction, unless your name is Springsteen or Roberts or Mann) |
Newfie_Buell
| | Posted on Wednesday, March 05, 2003 - 10:16 am: |
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Mike,
What I really meant was that if I had to think about what comes naturally when going into a turn I really would not have the time to do so.
I guess I really never thought about the physics associated with a turn until I started reading this thread.
Thats what I like about this board, such a simple topic can be debated and explained so well. I usually like to sit back and read these types of discussions than really get involved.
Keep up the good work & discussions guys/gals you have always got my interest. |
Steve_A
| | Posted on Wednesday, March 05, 2003 - 12:36 pm: |
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Blake, in general, engine braking is a bad thing, and anti-back-torque clutches are there on race bikes to decrease it, not to save the driveline. Think about this: With nearly 100 percent weight transfer on the front wheel during braking for corner entry, what's the proper level of rear wheel braking during that period? Or why did the last MV Agusta four-stroke 500s wheel-hop like crazy on corner entry? It's shortly after this that the first back-torque limiting devices started showing up, and they've been common on four-stroke race bikes for the last couple of decades.
BTW, I've measured overall deceleration in first gear with chopped throttle on a number of bikes, and on a Yamaha R1, at redline in first, it approaches the rear wheel traction limit -- straight up and down! Again, with minimal flywheel (desirable for best acceleration), engine braking tends to be strong, though there are certainly some tricks that can be played with the fuel injection on modern bikes to help here.
Minimizing braking and forward weight shift while cornering is why it's vital to get lightly back on the throttle as soon as you've rolled into full cornering mode -- something that riding dirt bikes on low-traction surfaces will teach you very quickly. |
Nevco1
| | Posted on Wednesday, March 05, 2003 - 12:43 pm: |
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Bomber...Can't wait for Spring when we get to confuse Lake Bueller again with our dancing brake lights. LOL
Newfie...Practice till all becomes natural. Just think of the light and optional use of the rear brake as insurance. If you over cook a turn you will be glad it is there and will know how to make a claim (read: use it to save your hide).
I used to read about rear brake trail braking but never understood the concept until I hooked up with a group of BMW riders a number of years ago. They were masters at it as their bikes were slower reving and had to keep in the power band through the twisties. They referred to it as riding smoothly. Once I got the hang of it, my corner speed and confidence increased significantly. Works well on all the bikes I have ridden both on and off the road and really makes a difference on my X1. |
Nevco1
| | Posted on Wednesday, March 05, 2003 - 12:52 pm: |
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Steve...I agree with you with the exception that I interpret Blake's method as using throttle control (engine braking) in lieu of rear brake usage on the track. I get the feeling that he is using it to balance the weight transfer while maintaining traction and remaining in the power band. |
Bomber
| | Posted on Wednesday, March 05, 2003 - 01:11 pm: |
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Nev . . . .you could be right about Blake's use of engine braking in lieu of applying th rear binder . . .. .
although they seem to be that same thing, they certainly FEEL different to me . . . .there may be a great series of formulae describing the diff |
Nevco1
| | Posted on Wednesday, March 05, 2003 - 03:04 pm: |
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Amen to multiple techniques, lines and formulae. Granted it was on a two cycle GP bike, but I would think Mick Doohan's addition of a rear brake lever on his (I believe) left hand grip is a strong indicator that finesse is required to attain max velocity. I just wonder what his technique was for clutching and braking. Anyone know? |
Nevco1
| | Posted on Wednesday, March 05, 2003 - 03:07 pm: |
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Two other racers that I think would be interesting to add to the list would be Kevin Schwantz and Kurtis Roberts as both have a tendency to really push the limits playing catch up. |
Bomber
| | Posted on Wednesday, March 05, 2003 - 03:22 pm: |
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Doohan's non-conventional control placement was, I think, more a function of a heavily damaged foot than a desire to use a, one would assume, more delicatly controlled hand to use the break . . .
most of the rags poo-poo'ed rear braking for years . . . . til doohan had the thumb control installed, then all of a sudden, poof, a miracle, we gots brakes in back, and they're useful!
(dirt trackers all over the country heard to chuckle) |
Nevco1
| | Posted on Wednesday, March 05, 2003 - 04:24 pm: |
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I knew the reason for Doohan's hand control. I was wondering about his technique in using it. Schwants and Roberts are/were two conventional riders with massive heuvos in charging the turns which prompted me to add them to the list.
Nickie Hayden is another but his backing in technique was considered radical when he started doing it and now somewhat common on the track. Still, is nothing I would care to attempt on an uncontrolled surface (read: the streets). Perhaps because it is a technique that I do not know the mechanics of. |
Blake
| | Posted on Wednesday, March 05, 2003 - 06:27 pm: |
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Steve,
Thank you for clarifying the issue. As much as it pains me to admit it, you are a solid source of level headed and honest information. ![:]](http://www.badweatherbikers.com/buell/clipart/proud.gif) Thanks for taking time to contribute.
This topic got started as an offshoot to a discussion about the causes of excess exhausting of oil through the crankcase breather (PCV) system. It was contended that engine braking was a contributer to premature engine wear and that it was in fact more damaging to the engine than anything else. Like you, I disagree with that opinion. |
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