Cycle News - Archive Issues - 1990's

WORKBENCH· By Brian Catterson Countersteering explained urn left to go righ t. and vice versa. Ho w many times have you trie d to exp lain this littl e bit of wisdom to a begi nni ng rid er? Sure, he nodded as tho ug h he understood, bu t will he remembe r wh en it comes time to employ this practice in a panic situa tion ? And even if he does man age to avoid th e o nco ming car or wha tever, does he truly understand what he did? Or wh y it works? This little bit of ph ysics goe s by the name of cou ntersteering. If you've bee n following Workben ch in recent weeks. you 'll be familiar with the theories of rake, trail and gyroscopic precession, and -thee ffects they have o n straightline stability. But how abou t cornering? Wh y does this turn-left-to-goright thing work? We were afraid yo u' d ask that. By momentarily turning th e handlebars in the direction o ppos ite the way you want to go , the cent rifug al force of ihe sp inn ing wh eel and the phe no me no n kn own as gyroscop ic precessio n will ca use th e whee l to turn in the correct directio n. Remember our exa mple of holding a bicycle wh eel by its axle? If you turn a spi nn ing whee l sudden ly in o ne direction, it has a natu ral ten den cy to tu rn itself back to the other direction. The im portant po int to kn ow here is that gyroscopic precession relies mo re on the sharpness of the movement tha n on its extent. T herefore, a quick, yet sligh t, forward/downward push o n the bars is all tha t's req uired . \0 i nitiate a turn, rather than a co nscio us effo rt to "steer" in the opposite di recti on . The reason a mo torcycle leans when it turns is to bal an ce the centrifugal for ce of turn in g (whic h mak es the bik e want to stand up and fall ou twa rd) with the gravitatio na l effect of the bik e lean ing (wh ich mak es it want to fall inward ). This is wh y a Grand Pr ix roa d racer achieves such remarkable lean angles - the h igh corne ring sp eeds genera te so mu ch cent rifuga l force that the rider nearly has to lay the bike over on its side to prevent th e cen trifuga l force from heavin g him into th e next county . (Of course, this sometimes occurs nonetheless - it 's called "highsiding .") On ce a bik e is put into a turn, th e effects of rak e and trail com bine to keep it there. The distan ce bet ween th e steeri ng head and the grou nd depends not o nly o n th e lean ang le, but o n th e posi tio n of the handlebars as well. Thus, if you turn the bars whi le leaned over, the steeri ng head wi ll rise or fall accord ingly. T he self-centering effect of the front whee l ca used by trai l then results in th e steer ing head fallin g to wha t is its lowest posi tio n, tha t is, into the turn. Ho wever, th is is co unteracted by the effects o f gravity and centrifugal force, as mentioned above . T he " feel" of a bike's steering is also largel y dictated by the degree of its ra ke a nd trai l. G iven th e same size/ weig h t wheels and tir es, th e rul e of thumb is th at the more rak e/trail you have, th e heavier the steering will feel. On e fin al not e: Countersteer in g works on ly at speed: during parkin g lot man euvers. its best to keep your bod y upright and conscious ly lean the bike into th e turns to maintain slowspeed stability. T 9TH ANNUAL ITRONATIONALS AUGUST 4 5 sr & Cecil County Dragway Rising Sun, MD t>.t\S o r B E ONE! see \he 180 mpl)_ ... o ii-2 ' wheels! V $5.00 IMPORTS S favorite HARLEYS Our Y cheer ALL RID ELcoME ERS W 1/2 PRICE SPECTATOR TICKETS AVAILABLE at Cycle Shed, Rt. 40 Elkton, MD and Ripken Cycles - Rt. 40 Joppa, MD vs INGS eo n l DA PRIZE DRAW CA N WIN! CAsH OUR TICI

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