Cycle News - Archive Issues - 1970's

> OF FAST RIDING AND OTHER SEMI-LITERATES----~- little deep, slow and wide, tailoring their approach to intentionally cut a late . apex. This is a good, safe strategy; I highly recommend it. Maybe already you get an inkling of the value of experience, of having been here before. . ---_.. . ~~ Now look at Fig. 2 which is a pair of fairly straightforward 90's connected by a short straight. Your average rider, Rider A, en tering this section cold will try to apex the first comer at its midpoint, aiming for a max constan t radius for that comer taken alone. Look what happens to him. Around the bend the second comer becomes visible; the rider sees he's going to run out of road if he holds his present line. So you get a bobble, some frantic braking and Rider A settles into a less advantageous line. Result: He exits the section considerable slower than he wen t in with an ET of 8.85 sec. Rider B is an astute cat. He's been here before and knows what to expect. He deliberately aims for an apex about ten feet beyond A's apex, pulls a constant radius of 77 ft. through the section, clipping a second apex on tum two, but actually treating the entire section as a single curve. Result: He comes out 5 fL/see. faster··that's just over 3 mph--than A with an ET of 5.7 sec. Once again note what I said earlier. The guy who is familiar wi th the ground has the advantage, not just because he can remember the lie of a particular comer but also because he can think and ride one or more comers ahead of himself. Fig. 3 is another such example. This one is a typical tight ess curve and again Rider A is assumed to be going in cold, taking the first part of the ess as if it we,re a comer alone. So he apexes it at its geometric midpoint like a good little boy, and look what happens. His apex commits him to an exit line which is all wrong for the second half of the ess. In round numbers he went into the esses on a perfect 60' radius at 26 mph but has to tighten up to 48' radius and 23 J!lph for the second half. Rider B is thinking one comer ahead. He pushes his apex down road about I I feet, takes a slightly less than ideal line at 56' radius (25 mph) through the frrst half of the ess. But now look: He is on an exit curve perfectly placed to take a smooth 56' radius at 2~ mph through end of a quarter mile are 13.2 sec. ana 13.0 sec., respectively. Their terminal speeds will be in the neighborhood of 110 mph. The 2/10 sec. gained by line B, measured at 11 0 mph, comes to just under 35 feet or about six bike lengths. SoB's line is ddini tely a passing strategy. Here's another strategy to think abo u t. Note I said earlier that it happened the two ET's through the comer were virtually equal. So what's to preven t us from reversing A's line? That is, come in on a 48' radius and leave on a 60' radius. Crazy. Exit speed is now 26 mph and we gain 3/10 sec. at the' end .of a quarter mile, an extra tenth over the B line and an extra three bike lengths at speed. . -- Fig. 2: Two 50 foot radius 90 degree corners connected by a short straight. Note that if the first turn if it were a single corner alone could be taken comfortably on an 84 foot radius at 30.6 mph. This is assuming a 0.75 g safe limit. The hooker is where this places the rider for his entry into turn two. Carried off without braking it runs out of road. With braking it barely makes it but with considerable loss of speed and self assurance. Note: A lot of guys have this happen to them on unfamiliar stretches of road. With practice a corner like this is easy: blending the lines through turns one and two into one smooth curve, no bobbles, no loss' of speed, 0.15 seconds better ET. Note also: Just fooling around on the road, that 0.15 sec. is just a good feeling of skill and confidence. On the track just that 0.15 sec. a lap is good for a substantial lead after 40 or more laps. Dig? the second half. Now as it happens the geometry of all this works out such that the time difference through the esses for the two riders is about nil, so what's to be gained~ The answer is in exit speed. On the road or in a race the terminal speed and the ET down any straight will depend on the speed coming out of the previous comer. Let's hang numbers on this idea. Let's assume !;hat a quarter mile straight follows oU}' esses and that both A and B go BTTW on bikes of near equal acceleration capability. For our example we'll use an average acceleration rate of 10 ft./sec./sec., just less than 1/3 g, which is a pretty typical figure for a hot 250. If A comes out at 23 mph and B comes out at 25 mph their ET's at the So now _you know what you may have guessed. There's a lot of strategy to this business of fast cornering. In fact it's a bit like chess. The better player is the one who can think the most moves ah ead of the game and judge the consequences of each move. It truly takes more than just nerve, it takes focused intellect. Yet because no two comers are alike nor are conditions the same in a given comer from day to day, there are too many variables at hand for even the greatest intellect to comprehend and react on at racing speeds. This is one among many reasons why fast riding remains a truly high art and why the great riders possess something that slips tick engineers like me will never cap ture, though we try hard to understand. This is why to this day a great mystique still shrouds this business of line. BAKER· ~ TUN~~~i~KS!lj Available for the first time RACING FRAMES CHASSIS SEATS ALLOYS TANKS FOR MX ·TPCOW·TRAI LI NG' ROAD RACI NG Mfg. by C & J Precision Products 3873 So. Main St. Santa Ana, Ca. 92707 (714) 540·7350 547-v358 $44.90 (includ ing springs) 11900W.PlcoBlvd. W. Los Angeles, Cal. 90064 (213) 477-

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