Cycle News - Archive Issues - 1970's

:! ." en Q. ... N THE MAN/MACHINE INTERfACE.... HANDLING ell ui . > ::0 ~ w Z with some thoughts on The Great American Motorcycle W ..J U >- U By La ne Cam p b ell (rep rin te d from Cycle Ne ws D ixi e ) T h is article is not an a tte rnp t t o explain handling. It's more of a n attempt to explain wh y handlin g is so hard to e xplain. If a n y th ing , when you 're d one , you'll kn ow why m otorcycle riding is still more a rt form than scien ce. Real ly , o f all th e man /machine relationships we have tod ay , motorcycling is m ore akin to the ear ly days of Ily in g than anythi ng else. Sure, the b u ilde rs of the first aircraft und ersto od wh y their creatio ns SIIOU LD ff y an d eve n cou ld c ome up wi th rea ms of detai led d raw ings a nd co lumns of figu res to support th eir theories . Yet gelling o ne of the cran ky contraptions to h eave itself aloft and stay th a t w ay for a while - this w as largely a seat-of-the-pan ts skill th a t w as the exclusive domain o f a few "natural' Flyers. It took a he avy injec tio n of technol ogy (a nd tw o wars) to make airplane design and airplane h andling in to exact sciences. Man v o f the REAL right answers didn't begin to come until the engineers started as k in g th e rig h t q uestion s ab o u t a thin g th e tech n o c ra ts n ow ca ll 'The ~I an /~l ach i n e Interface.' Surprise ! I t' s the same way with mot orcy cl es. Fo r the beauty o f it, , v e'r e luc ky n obody h as su ccessfully made a w ar m achine o u t o f a rac ing bike (o r a sp o rts car, fo r th at mailer). So high -pe rforma n ce riding/drivin g still rem ains fin e arl o and the on ly e nginee rs reall y probing th e matte r a re usuall y poverty -strick en enthusiasts with no access to free com p u te r time . Mu ch o f wh a t is the real truth of m otorc y cle rid ing lies embedded in the bones of the greatest livin g riders : and few if any have the intense tec hn ical training needed to tran slate their gu t fee lings into h ard n u mbe rs. The average rider ge ts th is thing of man and m ach in e interactin g w it h each o the r p ou n ded into h is h ead - b y lan ding o n it. Le t' s lo ok a t a few cas es in p oin t : Eve r w o nd er (w h ile rubb ing yo ur bruises) ho w so me European mo tocross s ta rs manage to go so b loody fast with so lillie ap paren t effort, wh ile th e rest of us bust o ur hu mp s a t h al f the speed ? I go t an inkling of this a fe w years ago, wh en a d eal er frie n d brou ght b ac k some excelle n t film footage of the lI o u st on Inter-Am to run in his shop projec tion b o oth . T he re w as th is one fast down hi ll st re tc h, wh o op-de-do c s with a badly ripp led surface in be twecn. You know . th e ki nd t ha t sets bi kes a n d bods gy rati ng every w hich w ay. It really h ad m an y riders allove r their machine s, figh tin g just to stay on top. Then, al ong cam e J oel R obert on hi s CZ , CUll in g through the slo wer rid ers like a h ungry shark through a sch o o l o f herrin g. The firs t tim e I saw the footage, it was amazing. The second time, I n oticed so me thi n g. You c o u ld have d rill ed a steel rod th ro ugh R ob ert' s knees an d th e m oto rcycle : it wou ldn ' t h ave m ad e any differen ce. T he CZ w as b u ckin g like an un tamed b ro n c, h ut Joel's knees were pinp oin ted at th e ce n ter o f gyrati on . His arms were pumping aw ay with th e p lungin g h andlebar s, bu t th e re st o f h is b ody w as in a state of relative cal m. Now - stop and think a minute, I. I F th e footpegs h ad be en pl aced any w h ere bu t where th ey wer e; o r. 2 . IF th e fron t an d rear sprin g an d d amp ing rat es h ad be en different : o r, 3 . I F J oel h ad no t th e correc t sta nce o n th e m otorcy cle t o pl ace hi s k nees at the exact cen ter of gy ratio n; o r, 4. I F th is 'gyrocenter' had been at so me pl ace where J oel coul dn ' t p ossib ly p ut hi s k nees, J oel R obert w o ul d h ave been in as mu ch tro uble as every on e else. Now , wh at's th is prove ? J oel R ob e rt is a great rid er. He knows intui t ivel y h o w to rid e fast over rough grou nd , and h e has th e fr ee dom to tell th e factory exactly h ow h e wan ts his machin e set up . But pi c ture some po o r b loody e n gin ee r (e specially a n on -ride r) faced w ith trying _ to simulate J oe l' s rough rid e on a com p u te r and comin g up with specs for a suspension that w ould cop e . T he ch arac te rist ics of the m o to rcy cl e and the grou n d are easy enough to h an g n u mbe rs on, b ut wh at about J o el R ob e r t ? lie' s m o re th an 5 0% of w ha t makes the system go . So so me how our erstwh ile engineer has to measure Joel Robert ( in whole and in p art ) to co m e up wi th a set o f numbe rs describin g a system of jointed be ams con nec ted b y co m p lex sp rin g/ d am pe r com bos th a t w o uld (h o pefu lly ) represent Joe l's sta nce o n th e m o to rcy cl e. Spea kin g as all engineer, I can say - ' Fer git it!' It's so much easie r (and cheape r) to h ire Robert , h ave hi m ride your b ike and tell you the sw ing a rm 's to o sho r t : th e forks need L ESS dam pi ng, n o t m o re : the foo tpegs need to be moved, the tank na rr owed ah here! and th e h an d leba rs a lillie wider. Yeah . Th at 's exa c tly wh at Suzuki d id (w it h com m e n d ab le results ) , an d it lo o ks like Yamaha is ge tti ng into the ac t. also . Oh , y eah , keep in mind th at the example I just ci ted w as sim p ly for a motocrosser going in a straight line; the rest o f the performan ce envelope hasn't been tou ched. Road bikes a re n ' t th at simple , e ithe r. F'rin st ance - wh at d o yo u d o to lay a bike o ver in to a com er: just lean righ t ? Part righ t. Y 'se e , at speed , yo u ' re play in g with a coup le o f gyroscope s. Y ou know , th ose kid's to y s th e y u se t o make ICB~l' s shoot straigh t. A sp innin g top is a gyro and so are th e wh eel s of yo u r moto rc ycle a t any speed above a fas t w alk. (Wh ich e xp lains wh y a top-heavy b ike ge ts mo re sta b le as th e speed rise s. ) Now what a lot o f folks don 't know is how a gyro reacts when y ou tr y to push it o ut of line . Try thi s. Ta ke a bicycle wheel, gra b the e n ds of th e spindle , a nd h ol d it o ut in front o f you, spin ning in a ' ro lling forward " d irectio n . Now tr y to turn it le ft. Yo u 'll get a reactio n out of it th a t ' Il make it want to BANK (no t turn ) righ t. T h is always h appen s, an d th ere' s a lot of h airy math th at sa y s wh y ; b ut in a nuts he ll , a gy ro always gives a reacti on a t 90 degrees to any tw ist p u t on it. N o w make th a t bicycle wh eel th e fro nt wh eel of yo u r moto rcycle , se t firm ly b etween th e fo rks, Le tting your b o d y rid e wi th th e machine , you pu t pr essure in to th e han d lebars as if to tu rn le ft. You'll get a reactio n fro m the fro n t whee l forcin g th e m achine to b an k. As lon g as you ride w ith it. not resist ing th a t ban king m omen t, an d as lo n g as you maint ain that p ressure on the bars, the machin e will con tinue t o crank over until you fall off. T he re's one catc h . These ideas are pretty sim p le-m in de d , taken al o n e. But yo u d o th em all togeth er in e x actly th e righ t measure , wi thout eve n thin kin g. It 's suc h a n atu ral, see m in gly effo rt less thin g, it 's both grea t fun and als o n early im possible to hang numbe rs on . Th e aver age m otorc y cle ride r does a t least three thin gs to change direc tio n, an d th e great o nes p ro b ably d o th ree or fo u r m ore. Kel Ca rru the rs will ne ve r b e replaced b y a bl ac k b ox . Not in thi s generatio n. Sometim es even our mo st earnest efforts, and the best engineering.., Whil e yo u' re main t aining th is pressure on th e h andlebar s as if to turn left, yo u ' re actually tu rning the b ar s to th e RI GH T , to track with th e m achine' s new curved p ath. (If you d idn' t , th e bike w ould track righ t o u t from under yo u.) S o let 's reca p, To lay your road bi ke into a righ t tum. you: 1. Lean, h iki n g your b ody ' s C. G . to th e in side to ge t th e mo ti on going. 2. Put a ge n tle L EFT tum pres sure into the bars, forcin g th e fr on t wheel to help lay y ou o ve r. (No te th at th e rear wheel, being a gyro al so, will RESIST all this.) Her e ' s ano th er. G oin g b ack to m oto cross and taking th at gy ro scop ic precessi on thin g with th e fro nt wh eel. Now y ou ca n figure th ose c razy R oger DeC o st er-st yle jumps with th e b ik e a ll crosse d up in m id- air. With b oth wh eels off th e grou nd , it m ak es little d ifference which way the fro n t wh eel is p o in ting (u ntil you land) so DeC ost er c ra? ks th e h andlebar s to th e RIGIIT, causing th e machine to bank LEFT. Wh en h e lands, he's all se t up fo r th at le ft -h ander off the end of the jump, and properly c ro ssed up, to b oot, ( D on' t you wish ' y o u cou ld d o that w ithout fallin g o f f?) One last o ne , You remember the n ap gen e ra te d in this and o ther public ations ab o u t the earl y Ka w asaki Threes an d th e ir rath e r spacey handlin g? I sa w one ar ticl e in which a coup le of as tu te California ty pes tamed th e Wild Kaw. by paying cl o se a ttenti on to o ne sim p le en gineering detail. T ol e ran ces. They fo und th at th e fac tory-spec to ler an ce for th e fro n t fo r k sliders were too lo ose, as w as the lo catin g effect of th e rubber sw ing-a rm b u sh . So th e y now m anuf a ctur e close- to le ra nce replacemen t parts to h elp th e m ach ine go wh er e it's poin ted . I m en ti o n t his exa mp le to prov e so me th ing; n am e ly that adme n and mar ketin g ty pes can't tell a foreign-born engi neer h ow to specify p arts that will asse m b le in to a grea t motorcycle. The typ ical J ap an ese engineer often gets a d ist orted view of th e American market and build s wha t h e' s told t o build. The en d result o fte n loses so m e th in g in tr an slation. This isn 't a n ew idea : but anyone wh o e xpec ts t o build th e Great American Mo torcycle in T aiwan had better think abou t it. Because unless the y hire Phil Read o r Dick Mann o r Barry IIiggin s to go to T a iw an with the righ t kind of p roto type hardware and say, 'H ere , Mr. Ch ain g, c op y THESE: th e G.A.M . mi gh t better b e built in Ameri ca by Americans who ride. Or it'll be something le ss than great. Like I said ea r lie r , it ' s still more art-form th an science ; a n d like good art, it doesn 't tr an slate very well through language (w h ich is a symb ol-forming m ode o f com m u n ica t io n ) o r through n u m be rs: o n ly through fee ling s. Great rid in g is still eve ry bi t as much seat-of-th e-p ants as ge tting a S opwith Camel t o n y st raig h t an d level. You want to really unde rstand motorcycle h andling? f irs t rid e . Ri de an d becom e great. Then MAYBE - if yo u 've got a go od engineeri n g b ack gr ound a n d are extremely a r ticu la te, you 'll write that definitive b ook o n the su bjec t, Until th en, gu ys like me will con ti n u e to fall off by day and pe ck aw ay at the problem over a cool o ne at nigh t. Little by little , we'll learn so me thi n g.

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