Cycle News - Archive Issues - 1970's

or cafe ates evasive ac tio n. In terms of time , th at means abo ut 0 .3 seconds reacti on tim e plus wh atever t ime it takes to rea ch safet y from wh ere you are . If you're already on a raci ng lin e, co m mi tt ed 100%, di st an ce to sa fe ty is eit her alo ng th e lin e yo u 've co mm itted to (no w yo u see wh y I ad vocate rid in g no harder th an 75% on the ro ad) or alon g an "evasion curve" which I'll work o ut in det ail in a future article . Th at doeesn't leave yo u too man y op tio ns should yo u en co un ter tra ff ic whil e all h un g o ff, d ragging foot pcgs, an d wide-eyed . 111 e kin d of traffic yo u encounter has a beari ng on the risk , too, since the oncomi ng vehicle 's speed determines th e closing rate and time fro m sighting to enco unte r. Best from you r sta ndp o in t is a veh icl e on a tourin g line go ing at th e posted sa fe speed (wh ich for the 100' radius co rners I've used as exa mp les . would be abo u t 25 m ph o r 3 8 ft. /see.) So me what wo rse is anothe r veh icle o n a touring line b ut h oo kin' it as fast as th e t ires will hold - which for a o ne "g" limi t would be 39 m p h , 57 ft ./sec. Ab solute worst case (d isaster . in fac t) is enco un terin g anot he r race r _0 two wh eeled o r fo ur wh eeled - ta king a rac ing lin e th rough th e same co mer-. Consid ering th is last . po ssib ility is enough to give yo u th e hechi cs abou t riding at a ll, a nd makes me wo nde r wh y more of us don 't seriously try to co n tro l access and direction of travel o n our favorit e racy -roads. Let 's hang numbers o n so me o f th ese ideas. Figures one and two are the same co rn er. view ed as a right-hander an d a left-hander, respectively. Let 's begin to an alyze t h e r igh t-h a n d e r , The lane -cutting racer is go ing to en ter thi s one in the opposin g lane, and if he'. co m mi tted h im self 100%. h e 's going to be in the left lane on his ex it, a situa tio n he ca n remed y if he star ts evasive ac tio n somewhere cl ose t o Posit io n Two (1'2) if he's on the co ns tan t speed -radi us line. An inte re sti ng th ing ab o ut this co rner is th at if he spots t o uring traffic anywhere between "0" and "P2'\ as indicated by lin e-of-sigh t lines drawn from these positions ("0 " , I C. 2C) th at traffic is alread y o f acad em ic in tere s t because he'll be t uc ked well in to ' the righ t lane a t en counter. [Th e other altern ative, ano the r racer, is sheer nightmare. b ec ause . amo ng other things. th e other racer is plain crazy , as we'll see later) . What sh ould be bu gging h im is line-of-sight " 0 " . cu tting the p oin t where he 'll cross into the o ther lane again. The rider on th e co nstan t rad ius (CR) line is 78 feet o r 1.1 second s from jeopardy , a hizh-risk situ at io n , sinc e most people simply won' t react in time to vary th at line m ore th an a foot o r two in either direction . That 's the pri ce' for being 100% co m mitted a t co nst an t speed. :'- better s tr:, tegy. is a I,!te . apex (LA) line, whi ch in so me cases is also a faster lin e , sin ce it allo ws y o u to ge t on th e thro ttle ca rly and b e accelerati ng from de ep back in th e curve . In th is case yo u pay a t im e pen alt y in th e co rner it self, bu t ga in co nsid era b le safety margin , plus so me extra "drive " fo r th e. next st ra igh t. Th e late apexer brakes a t 0.5g to PI (th us limit ing him sel f to 0.75g co rnering) . slo wing to 5 6 ii .lse c , Fro m PI t o 1'2 h e coasts before rolli ng on the throttle an d wicks it on fro m there to leave o n an exp anding rad ius. By the tim e he passes 1'4 . he 'll be d o ing 82. 1 ii .lsec. (just ove r 10 ft. /sc c . faster than th e C R line at that point ), b ut will have lost abou t 0. 3 sec o nd in th e co rn er itsel f. At this speed differential , he can gain it all back in ab o u t fo ur seconds wort h of stra igh taway. In safet y, he's gained tremenously. At any poin t fr om "0" to 1'2, he ca n see furthe r down the road (line s o f sight I L. 2L ). lIe ca n view .. 01.... th e po int whe re he 11 cro ss in to jeopardy aga in. fro m about the same posit ion as the o th er ridc r vie wing " 0 " . If th at 's his cr itica l decision point, he's got 25 mo re feet and m or e tim e t o react . Fina lly , b ecause he's accelerati ng , h e 's only pull ing about 0.75g co rn ering. All he has to do to tighten his lin e is ro ll off the throttl e an d drop hi s ins ide knee. At any poin t from 1'2 on, he can pull his exit lin e righ t back in to th e safe lan e eas ily. Th e left-bander is a nas tier animal. (Fig. 2.) If it's blind , th ere sim p ly is no safe apex -clippi ng lin e through it. Wor st case is at 1'2 on th e CR line. Touring traffi c view ed from th at point is 0.6 to 0. 7 sec o nd from enco un te r . and m eeting another racer, th e enco unter time is so close to your 0 .3 second reac tion time , you'd barely know wh at hit you . Now yo u see why I said lan e-cutting on a blind left is pure crazy? The only sa fe line through suc h a corne r is one which never cro sses the centerline. A risk-rninenization str a tegy tha t's a little quick er is to brake deep , co m e alo ng th e " safe " lin e (or just a little t o th e righ t o f it ) still bra king a t 0. 5g, co rneri ng a t 0.75g, end ing your braking a t 54 ft . /se c. (34 mph ). posit io n PI ; coast from 1'1 t o 1'2 while tightening your line to a one 109" lim it at 54 ft./sec; then begin to roll it o n. 'Ib is allows a safe entry in yo ur own lane, committed less than 100% aft er y o u finish brak ing , but able to see aro und th e co rner th e entire length o f the lan e you'll be cu tting as yo u ge t o n th e t h ro ttle (line of sigh t 2M) . See so methi ng, and you 've go t t im e and room 'to roll o ff th e th rottle and fade to the right. By point "0" you ca n st ar t br eathing, becau se on th at line -o f-sigh t, if yo u 've sti1l seen noth ing, you 've go t time to leave it sc rewed o n and co m plete the lan e-cut, By doing this , yo u're nOlo goi ng through as fast as th e full apex-clip at 70.5 ft. /sec. , bu t yo u're not pl ayin g Ru ssian roulett e, either. As wit h the right-h ander, you've lost so me time through th e co rn er itsel f , but yo u exit the co rn er at 74 ft./sec ., gain ing a b ike len gth a second o r bett er on the guy taking th e "safe" line (which ma kes it worth the tro uble) , a nd eve n a tad faster than the gu y in the fu ll apex-clip (though he 's waxed yo u on time and lon g go ne, assu ming he 's st ill alive) . Figu re three is a bit more co m p lex example. tho ugh in moun ta in co un try, it '5 quite co mmo n: a series o f esses with a rock wa ll o n the righ t, and a sheer dr o p on the left. Oddly enough , th is is one of the safest lane-cu ts . though there 's o ne q uirk . Note th a t as yo u approach the bli nd right-han d er, y o ur vi ew limit creeps up th e road toward yo u, decreasing yo ur avo idance time and dista nce as yo u ge t nearer. Th e geo metry of this set-u p is such that yo u stay in pr e tty go od sh ape. A t PI , yo u ca n see both th e blind side of the co m er yo u're -ex iting, and a good de al o f th e -ap pro ach to th e ne xt right-hand er. As you en te r th e o p posing lan e a t 1'2, yo u're 2. 3 seconds a way fr om sa fe ty alo ng your co m mi tted lin e a t you r o ne "g" limit of 6 5 ii .lsec, (44.3 mph ). To ur ing tra ffi c seen alo ng lin e-of-sigh t " 2 " is 3 .7 o r 2 .5 seco nds fr om point " S", d ep endi ng o n wheth er the o ther guy is coolin ' it or ho o kin ' it. No swe at. Wo rst case for view ing is P3, ye t fro m there yo u 're a hal f seco nd fro m safety and touring tra ffi c is nearly tw o seco nds away , when you sigh t it . A racer sigh te d at 1'3 is less than a second to enco unter. and agai n it should give you willies about riding a ro ad w ithoui being sure o f who else is on it and wh ich wa y t hey 're goi ng. But aga in. from the other guy's direc ti on. with the ro ck wall o n th e left , he 's got t o be plain crazy to he lane-cu ttin g to a fu ll apex-clip in such a place. It 's even worse than 'fo r a simple lcft-hander, because corn ers in su ch close succ essio n always spit you out of one firm ly co mmitt ed to the next , so you've got less op tions fo r ta king unorthodox lines. Any attem p t at a risk-mi nim izing late apex line in o nc co rn er just screws u p yo ur ap proach to the next , so wi th a rock wa ll o n the left, suc h a series of blind csses is best taken in yo ur o wn lan e and forget ta king any ch an ces . These ex a m p les arc o bviously over -sim plified, rela tivel y slo w corners . As you r speed goes up, yo ur tim e a nd room to react generally go down drasti cally. An evasio n mane uver tha t 's well wit h in the co n fines of a 20 foot roa d be d a t 45 mph will put yo u over th e side at 70 . Plu s if th e ro ad is placarded for high er co rn ering spe ed s. your o nco ming t raffic will be closing at a higher rate. I wat ched o ne fellow cu t a blind left -hander just ahea d o f me and narrowly miss getting plastered by a Chrysler Newport b ecause th eleadbar ge was o nly doing 15 mph, rubber-necking at th e sce nery. What if ' it had been a Porshe 91 4 a t full chat in st ead ? Here's ano ther. You see a truck a t P I in a blind right-hander, " meaning he's alrea dy o ut o f yo ur way . Bu t what's usu ally beh ind a slo w truck in th e mounta ins ? Throw ing yo urself a t full song int o any blind co rn er, even o n a risk-minimi zing line. is in th e end an ac t of fai th o n y o ur part - an ac t o f fa it h th at is o n sh aky th eol ogical ground . even if yo u kn ow th e road and have . been o ver it hundreds of times. So me people kiss cobras as a n ac t o f faith , to o , bu t sho u ld their fait h fa il th em , th eir death d oesn 't bring hordes of cop s d o wn o n the rest of th e faith ful. When yo ur invo lvemen t with fas t ridin g ge ts so intense th at y o u're wan t ing to be th e fastest d ud c in th e pack inst ead o f sett ling into an easy rhy th m an d having fun , yo u're about t o gra d uate fro m the public road s to th e race track. T hen th ere's a flagm an a t that blind corn er , and yo u a re free to be as inten se as yo ur abili ties wiII allow. • ..- 17

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