Cycle News - Archive Issues - 1980's

the front one reach for the sky; it's faster a nd more controllable to use second gear, keep up co rner in g momentum (tha n ks to th e gr eat grip from th e Mich elin tir es), and pull o u t cleanl y if less spec tac u larly a t low er revs from arou nd 9500 rpm u pward s. With suc h a n a mazi ng a mou nt o f po wer o n tap a lmost a nyw here in th e upper rev ra nge, th e diffi culties o f keepin g the Suzuki's front whee l o n the grou nd in th e bottom three gears can 't be di scounted. You have to be very carefu l abo u t exactly wh ere an d how hard you open th e th rottle wide, not just because th e rear en d mi ght step o u t o n you (as it did to me o ne lap o n th e exit o f Russell s), but because it's a n acq ui red art to steer th e bike wi th the rest o f yo ur bod y wh ile riding it lik e a circ us pony o n th e back wh eel with th e front o ne wav in g in th e a ir! Sch wa ntz uses hi s body weight -to co n tro l th e bike as much as any t curren- GP rider , a nd even has a ou tput, rathe r tha n a ny u nusual chassis design: "We do play around with lots of different cha ssis sett ings a t each ra ce," admits Tongue, " b u t th e basic geometry is prett y normal by curre n t GP sta nda rds: wh eelb ase is 1420m m (56.8 in .) average, weight d istribu tion 55/45 per cent fro ntwa rds, a nd th e head a ngle 24 degrees, though we do vary th ose a li ttle every race by a ltering the ride heigh t at th e rea r, or cha nging th e static angle wi th eccentrics for th e steeri ng head. Also , th e center o f gravity 's q uite hi gh. H onda 's first NSR500 wi th the fuel tank under th e engi ne p ro ved th at a lo w-down weight d istribution doesn 't mak e a bike steer p roperl y, any how." Oka y, but I have to say th at riding th e Pep si Suzuki conveyed a qu ite diff erent impression th an the o ther GP 500s I've ridden recentl y. For a start, it ha s a less ex treme riding position whi ch pl aces much less wei ght o n th e rider' s a rms a n d (Left) MlnlliCule rea," brake, huge rear tire and asymmetrical swlngarm are de rlgeur In modern GP racing. (Bel o w ) The XR75 e n g i ne Is mnch smaller than the predou. XR74 _d now features c o n tr a r otatlug twin crank8hafts, a revised e l ect ronlcally-contrelled variable exh a u8t velume s Y8tem u sing cyUudrlcai po.'er valves, _d new exp_8lon cliambers. specia l sea t witlf a longer section so he ca n slide back and fort h in it to a lte r th e weight distribution according to ci rcu ms ta nce. Slide forward to load up th e fro n t wh eel into a turn, slide back to put weight over th e rear for added traction o n th e exit - in which case it 's not surp rising that th e Suzu ki seems to wh eeli e as eas ily as it does. Ever y lap co m ing o n to Sn euerton's main stra igh t, th e front en d wo u ld reach fo r th e sky a t anythi ng ove r 11,000 rpm with th e throttle wound open , even in seco nd a nd th ird gear. Su re, lo ts o f fun till yo u realize yo u 're head ing for th e in field a nd ha ve to franticall y try to pull it back in lin e before giving up an d sh utting o ff to let th e front wh eel resume ea rt h ly co ntact. Even us ing a hi gher gea r didn 't ma ke much differen ce - th e "T o p Gun 500 "j ust reac hed for th e sky regardless. The Suzu ki 's des ire to reach for th e stars would seem to co n firm th e sus picions h eld by riv al teams that th e XR7 5's chassis setup em bodies so me p re tty rad ica l steering geometry and weigh t distribution (which other team s have been trying unsu ccessfu lly to em u la te), with a very steep head angl e an d low center of gravity to mak e th e bike turn quickly into co rners, a nd th e engine mov ed back in - th e chassis (co m pared to current wisd om ) to im p ro ve tra ct ion. Were it tru e, th e latter m ight exp lain how eas ily the RGV500 wheelies bu t th e Pepsi Suzuki team says this .is th e effect o f a 160 bhp-plus p ow er shou lders th an its curren t rivals. It feels more like a H onda of two or more years ago th an a cu rrent Co ba sin spired design which accentua tes the ma chine's sta tic fro n t en d weigh t bias by sh ifti ng forward as much o f the ri der's weig ht as poss ible. O f co urse, much of this ma y co me from Kevin 's unusu all y upright rid in g sta nce. The result is a bike that is reall y easy, a lmost co m fort ab I to rid e, I was su rp rised to be told a fter my first sessio n how wide th e stee ri ng angle is. It feel s like a bike tha t h as a very st eep front e n d g eometry, with hardly any trail (a fact th e flat yo kes, wi th minimal offset , would seem to co n firm) , not o n ly because o f th e speed an d ease with wh ich it ca n be laid into turns, but a lso because th e handl eba rs shake from side -to side in a stra ig h t lin e, usuall y a su re sign o f a steep h ead angle. Then th ere was th e ti me I messed up my gea r ch ange pattern a nd went into R ich es one gear too h igh, a nd abou t IO mph too fast. Grabbing a handful of front brake in mid-turn produced a m ind-warping fro nt- end wobble, as th e wh eel flapped from side to side in stead o f understeering toward s the o u tside o f th e turn as I was expecting, an d p reparing to co pe wi th. I was luc ky to ge t a way with th at o ne, but after my pulse ra te had return ed fr om ove rloa d, I rem ai ned more co n vinced th an ever th at th e Suzuki 's chassis setup is indeed d ifferent from the cu rre nt norm. H ow ever th ey've done it , th ere's no doubt th e R G V500 Su zu ki ' steers brilliantl y. You can lay it into a turn a lmos t on autopilot , without havin g to wrestl e it into subm issio n lik e last year's NSR500 Honda. That p rogressive, flexi ble power del ivery co mes to th e help of th e rider, ena bling th e revs to be fed in as fast a s h e' s co m fo rta b le with . H er e , th e increased co m p ressio n dampin g a t th e rear (w h ich is th e major difference between th e X R75 chassis and th e previous XR74 design , acc ord in g to T ongue) isa key factor in sto p p ing th e rear end from sq ua ttin g excessively under p ow er and running o u t o f da m p ing. That was espe cia ll y no ticeabl e th rough the bu m ps a t Co ram , where as th e track ope ns up you wind th e pow er on hard in fourth gea r w hi le sti ll cra n ked over, without the back en d gett ing a ll loos e. Mind yo u, I n ever go t brav e enough to em u la te th e ap proved ch wa n tz tech niq ue in slower tu rns. He just ch ucks her in hard , sta nds on the back brak e in mid-corner to kic k th e back whee l into line, th en fires it o ut o f th e turn o n a semipermanent wh eelstand, using bod y Englis h to keep it in line. G iven tha t th e way Schwantz rides, th e front wheel hardl y seems to touch the ground, th e impressive pe rformance o f the Kayab a inv erted fork s might n ot seem so important , but they 're undoubtedl y o ne reason th e bike h andles so well. Switch in g back to th eir long-time su p p lier Ka yaba after a spe ll with Sh owa , Suzuki wa s th e on ly learn to use Kayaba 's new upside-d own forks thi s season. These a re full y-adjustab le ex ternally for all sus pe ns io n fun ctions, in cluding both low - a nd hi gh-speed damping. T hey were certa in ly too go od for me to criticize in any way, a nd in fact th e Pepsi lea rn says th ey've hardly a ltere d th e internal se tt in gs a ll seaso n: " We just fitt ed them as th ey came . Kevin was ecsta tic abo u t them first tim e he tried th em , a nd th ey've ha rdl y been touch ed since," sa ys Tongue . T he rear end was th e subject of m ore experime nta tio n , in cl ud ing bri ef)y fitting a shorte r swingarm th at d idn 't work so well (may be th ey a lready had enough weight on th e ba ck wh eel?!), a ll aimed a t maxim izing traction out of co rne rs, an a rea which th e XR75's co nsidera b le midra n ge torque mak es a cr itica l aspect. And fin all y - th e brakes. U n like so m e of hi s ri val s, Schwantz wa s co n vince d o f th e AP ca rbo n -carbon brakes' effect iveness a ll th rough th e season. After usin g a set o f 320in m AP- Lockheed steel di scs in th e fir st two GPs in J apan and Au stralia, he conseq uen tly stuc k with th e ca rbons . Th e h eat-ret ainin g ca rb o n -fibe r sh ro uds th en didn't a p pear on th e Suzuki until three more GPs had go ne by, since La guna Seca , Jerez a nd Misano ar e a ll hard o n brakes, a nd kept th e temperatures up in th e o p tim u m 650-1300°Fahrenheit ra nge, even withou t th e sh ro u ds. As it turned out, I got th e chance to sa m p le th e bike both with th e steel di scs and with th e ca rbo ns . My first reacti on as I went o u t to begin with on th e steel d iscs was - where's the brakes? Schwantz likes a very lo ng lever, which co mes back almost to th e bar before th ere 's maximum braking effect, a nd tho ug h they do obvious ly work very well , I wasn't totally ena mored o f .the feel of th e steel di sc setu p . You do ge t a fair bit o f sensiti vit y, so th at o n the entry to Russell s, for instance, you just stroke th e lever to knock off a bit o f excess speed before la yin g it into th e left-h and entry, but th e instant effect isn 't th ere. It p rob ably could be dialed in eas ily en o ug h, th ough. Then , a fter a IO-minute stop wh ile th e en tire brake system was chan ged to th e ca rbo ns, I went o ut gingerly for a co u p le o f slo w laps with AP Racing enginee r Ra y Bailey's words o f ca u tio n rin ging in my ea rs: " Warm th e br ak es up properl y, but don 't dra g th e lever in to turns, or else th ey'll grab o n yo u as th ey did with Wa yne Gardner at Laguna Seca (in practice, not hi s serio us ra ce cras h.)" There's no question yo u have to alter yo ur riding style co ns idera bly with th e ca rbon brakes. In fact, you ac tua lly hav e to brake a little earlier at th e end of a lon g stra igh t, to get some heat into th e brakes before they start to work a t 100 % efficien cy. H owever , once th ey start offeri ng maximum braking effect, it's lik e ru nning into a brick wa ll. You have to learn to squeeze th e lever har d at a ll times - no gentle touches to knock off a little speed - and to cope wit h th e unusual feeling whereby the lever actuall y gets harder a nd comes back on yo u as th e brakes servo themselves into max -stop mode, co m m ens ura te with th e increase in temperature. It tak es a wh ile to get used to the strange feel, and for guys lik e Kevin a nd Eddie a nd both Wa yn es who live at th e o u ter rea ch es o f machine co ntrol, I ca n understand how it must be a big decisi on wh ether or n ot to go with th e ca rbo n br ak es. But having once m ad e that move, I can't see how a nyone would want to go ba ck again , if o n ly be cause th e differen ce in technique is so great, an d re-programing o nese lf to use steel dis cs again is as big a job as go ing in the other directi on. About th e on ly pl ace you might think twi ce is a t a superspeedway like Daytona - those lon g stretches on the ba nking would rea lly test the sh ro uds' efficien cv-s- but since they don't ru n G Ps on banked tracks , I recko n the ca rbon brakes a re here to stay. In terestin gl y, th e effectiveness o f the ca rbo n brakes added cred ibili ty to th e beli ef th at th e weigh t distribution of th e Suzuki is abnorm al by current standards. With th e gripping power of th e AP di scs working in fu II-on m ode a t th e end of th e

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