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a given p urpose. H owever , Sh'1pman does get into some theoreti cal stuff about periods or osc illa tio n and resonant sy ste m s. H e to sses in sen te nces lik e "Frequenc y o r it s e q u ivalen t pe riod is cri tical to a ll vehicular suspens io n systems: ' w hich is fin e if th e read er ca n be ex pecte d to kno w that , in sim ple harm onic m o tion , the freq uency is d efined as the reciprocal of th e period, but I d oub t if m o st rea de rs o f this book can be as su med to know suc h thi ngs . There is also so me d oubt in m y own mind that Mr. Sh ipman real ly underst ands suspens io n sy stem s, a t least in th eore tical terms, be cause in nei th e r his text nor hi s d iagrams does he get into the notion of damping as an en ergy ab sorption functi on with a tim e dependency. All his d iagrams sh o w a cons tan t amplitude oscillations, where in fact the whole idea is to transform a step fu nction into a damped os cill ation. His first illustration in th at ch apter is extremely poor be cause it shows so mething that simply can n o t exist. A wheel is sh o wn going up a step w hose height equals the radi us of the wheel. Un le ss there is a vertical co mp on en t to the vector vel ocity (not shown o r indica ted), that wheel has j ust slam med into a wall and will either br eak something, sh oot straigh t up, or rebou nd backwards. Further, to follow path "A" of the illustration, th e wheel wo u ld ha ve to de crease its diameter b y 20 percent as it pas sed over th e lip of the ledge, while path I" B" is sim p ly a p hysic al impossibility . Mr , Shi pman, a trials rider, co n fuses w hat apparen tly happens in such situations with w hat actually happens. In between su ch problems as I h ave noted there is some good material, such as an interesting d escription of how and why a chain tensioner works, more than y o u 11 ever want to know a b o u t floatin g brakes , sev eral neat tips, and some hard -to - com e -by informatio n. For in stance, how many riders realize that a trial s universal will provide more tracti on than a knobb y under some off-ro ad conditions? Or the ad van rag e of a two-wire kill button? As Mr. Shipman gets more and more in to th e practical mechanic al aspects of keeping t h e motorcycle running w ell, h is material gets better and better. By an d large the average read er sho uld learn quite a b it from Sh ipman on the gentle art of m aintaining hi s tra il bike . Man y re aders, o f cou rse , will buy this book to learn th e skills o f rid ing, an d if th ey live in the so u t h we st , some of them migh t h e sa tis fie d by th e 60-page sec t io n on rid in g, Bu t frankly , I d oub t it . Jf th ey live elsew h ere, I'm su re the y won 't. He sta rts h is se ction on " m ud a n d ice " (sn ow d o esn't e xis t ) by say ing, "I d on't kn ow much abut mud and ice because the y don't h appen much w her e I live:' (Ne ithe r appa re n tly d oes gr am m ar. ) In th e sp ace of three par agraphs h e proves h is st atement co n cl usivel y, bu t sin ce about 50 percent of th e rid er s in th e coun tr y sp end a con side ra b le pa r t o f th eir t ime rid ing mud and ir e (a n d sno w), w he re d o es th is h o ok lea ve the m ? Ac tuall y , th e riders wh o en co un te r mud a re j ust as we ll off wit h th is boo k as d esert rid ers, wi th res pe ct to th e riding en d, because, w hile S h ipman p rofesses t o know so me th ing abou t other asp ects of riding , an d possib ly does, he d o esn 't com m u nica te ve ry w e ll - in -t h is area.- In- hi ssec ti o ri 'o n d o w n hill rid in g, for ins t ance : h e has n oth in g for the ri de r who su dden ly finds himself over his head . no ad vice on how to nego tiate turns going downhill, no ad vice on differen t ty pe s of terrain, etc. In shor t, it 's p retty su perficial. In hooks of sufficien t qual ity t o m e rit a 55 price tag, one doesn't expect pl ugs fo r p roducts, especially n ot fo r p roducts in which t he aut hor h ap p en s t o hav e an in te res t, but t he re are a n irri ta t ing number o f suc h p lu gs in this book. Also the re is the ba ld statement, "The bes t-quali fied person in the USA to teach , fast ri di ng technique is G ary Bailey who co n d uc t s . .. r acing sc hools . . ." I w ill chari t ab ly ass u m e th at Mr , Shipman is un aware of th e e xis te n ce of Rolf Tibblin, who co n d ucts th e Husqvarna training school an d who is, conservative ly, at least ten times as qualified as Gary Bailey , ha ving b een a world m o to cro ss champion at a time when Gary Bai ley , at his peak, w as merely a Ca liforni a champion, Gary is go od, but h as never won an y o f th e European events. Rolf has won d o zens o f them . The last ch ap te r of Shipman's book is the most interesting as i t is ce n t e re d a bou t a truly original idea. The ch a p ter is ' en titl ed "The Ban g-Bang Servo T e chn iqu e for Control of You r ' Mo t orcy cl e " and it describes a m ethod of learn in g to con tro l a bike based o n th e elec tro ni c ca n trol meth ods of fee dbac k an d suc cessive approxi ma tion . I' ve tri ed it - so mew ha t, and a m sti ll pl ay in g wi th it. Whether it has tbe sort of u n iversal applica tion that Mr. Shi p man se e ms to feel it does, I' m not sure , but it ca n ' t he lp but teach y o u so met hing. For a book that is supposedly a m o r e - o r -L ess co mplete treatise on off-road motorcycling, this book la cks som e important fea t u res . For instance . th ere is n oth in g o n the subjec t of dr essin g fo r co m fo rt or p ro te ction. The re is vir tuall y n o m ent io n of en viron mental matter s, whi ch is a c rime, in m y estimatio n , There is very li tt le o n em erg ency p roc edures, either t o deal wi th b ike pr ob lems o r human pr oblems, T o sum up , th e re is a wh ole lo t of inform a ti on in this b o ok, but it is not all rel evant or acc ura te, and th er e is too m u ch mi ssing f or a whole-h earted recomm endation o f the b o ok, in spite o f its very a ttra cti ve p ackage, Escape by Trail Bike by Wiltz Wagner and Bill Brokaw, $3 ,50, 1973 rev. ed., 8% by 5%, 85 pp. }'or the bulk of th e m aterial o n rid ing techn ique , I ha ve n othin g b ut p raise . Fi rs t o f all, it is w ri tten by p eople w h o kn o w both h ow to ri de an d how to write. I suspec t th at most of th e tech n ique came fro m Bill Brokaw , who is a n e xpert trail rider. That, h ow eve r, is un impo rtant ; the important th ing is that e ve r y mo tio n of eac h t ech n ique has been ca refu lly an al y zed and ex plained . But beyond t hat, t he re is a reali sti c ap proach , With d iffi cult st u n ts, th ey te ll you th e prob le ms , an d so metim es, wh at to do wh en thi ngs go wro ng, T hey/ no t on ly t ell y ou h ow to ride d own a h ill , but ho w to get off if th e b ik e starts to ge t away. The y exp la in th e re as oning beh in d various wheelie p osit ions and wh a t will h appen if you r throttl e con trol is in correc t when going o ver a log, Mos t riders co uld make a 100 p ercen t improvement in their riding ab ili ty if the y did nothing but read (an d learn ) the t echniques suggested for m akin g up h ill and downhill turns, For the better rider, the authors h av e provided some st un ts, suc h as riding bac kwards, and riding up to a wall, p utting your fron t w h eel up o n the w all and turning. Quite sp ec tac u lar reall y . In future editions of the b ook , th ere a re two o f th e ridi ng sections th at co uld .stan d a b it more elaboration : the sectio n on riding sand is a bit less expert than m ost of the book , and the re is no t hing on fast fire roadi ng . T he re is one m istake in the sect ion on sa n d rid ing . the on ly on e I was really aware of in th e who le boo k. T hey suggest th a t , in very dry w ash es , letting so m e air o ut of th e tire s mi ght help. Q ui te often th e p ro b lem , espec iall y w it h small b ikes, is too much tr ac t ion , an d letting the air o u t j us t a ggrava t es th e p rob lem , There ar e two las t p o in ts which readers of this book may appreciate . First , the aut h ors do not "write d o wn" t o th e readers as d o so man y m otorcycling wr iters. Second , the y don't engage in - any o f wh at I call theore t ical b .s, It might b e inter esting to a m ath or p hysics st ud ent, an d ev en n ecessary to a design engineer. to kn o w w h e t he r c e n trif uga l f or c e o r " gyro scop ic" force k eeps a m ot orc y cle upright, bu t it's o f ze ro practical va lue to th e ave rag e bike rid er. It is an eve n worse d isservic e to the reader t o in clude s uc h stuff , and th en analyze it superficially or incorrectly , as is done in Shipman's book, Mercifully , t his sort of n on s e n se d o es not exist in the Wagn er-Brokaw book, T his one is h igh ly recommended. Then let Rolf Tibblin and Micke y Quade improve your d irt-ri d ing skill - tune you r bod . Beginners to pros. All makes of bikes accept ed - rentals availab le. T uit ion fee of $1 75. 00 covers all. Cont act : fED Husqvarna InternationaI Training Center 933 So . Santa Fe Ave" Vista, CA 92083 714-724-8091 Roge.. Bull supports.. . M.O.R.E. non profi t Can you do any ....?..e ",0. I M.O.R.E. ~ ~J of California 1129 N. 11th sr. Sacramento , CA 95826 This book, a lso no w in its sec ond edit io n, co vers material so simi lar to th e Boonie Book that i I seemed appropriate 10 review it at thi s time, e ve n th ough it has b een revi ew ed by others previously, be cause frankl y, it is a much better book, But let's be gin with its sh o rtco mi n gs. Escap e by Trail B ik e is a small book , an d n ot nearly as , attractively p ack aged as the Bo onie Boo k. It's printed on thin co a ted st o ck so it appears to be even skinnier than it actually is. The photos range from small to tiny, and in te chnical quality from adeq ua te to mediocre, But before I leave y o u w ith a wr ong impression, let m e sa y that , wh ile the photo s a re not going t o thrill an y An sel Adams fan s, the y a re extremely well th ought-out in terms o f illust rating th e p oints the a u th o rs a re tryin g t o m ak e and the y are much more than ade q ua te as teac h ing ai ds . Th er e is o ne seq ue nce sh o w ing a rider on a ver y small bike goi ng ove r a ve ry lar ge log (bo th correc tly and inco rrec tly) th at will have most riders doing an in credul ou s d o uble-t ake. This book is d evoted alm o st en ti re ly to riding techniques. Onl y a t th e ve r y en d d o t he aut ho rs d ev ot e a few p ages to th e se lec t ion o r ridi ng gea r and com pa nio ns , so me ver y elem en tary m ain tenan ce, and, thankf'u ll y , to so m e o f the social an d e nviron mental r e s p o n s i b ilit ies tha t ride rs should assum e w he n th e y ra ke to t he trails. Their sect io ns o n trail m an ne rs an d rid in g companions are go o d , bu t the y co u ld profi ta bly spend a few mo re pages on th e subjec t of emerge ncy re p airs and p rope r ridi ng gear. Walk before you run $10 a year prevents bad laws and gets you a ll the state news. Trans AMA Qualifier $1200 Purse Top U.S. Motocross Stars 250cc - 500cc Sunday, May 19th A mechanic for dirt bikes On e of the m o re d ifficult problems faci ng dirt riders is find in g me chani cs wh o want t o take the time to help w ith od d ba ll d irt bike prob lems. There ' s a n ew sh op in tow n whi ch is go ing t o specialize in th is sort o f th in g a nd th e q ua lity of th e w ork is ass ured by a supe r auto mec ha ni c , J ohn Gregory , wh om m an y o f yo u h ave seen goi ng away from y o u on th e d esert. T he n e w pl ace is cal led S cott 's S coo ter Se rvice, an d Scott Fo rwa rd is th e imp resa rio . G ive him a try if yo u live o u t G len dale way at (2 13 ) 249ยท6 75 6 . Ron Schneiders -A a u (vent mte r All classes Saturday, May 18th No A ffiliation req 'd. Deschutes Cycle Park Bend, Oregon 503 389-1479 15