neo Posted December 3, 2009 Report Share Posted December 3, 2009 Hi All, In the recent news articles on the new Ossa, according to Ossa engineers, the lighter a bike gets the more weight should go towards the front of the bike? What do you thinks about this theory?...get as technical as you like Best of balance (front or back) Neo Quote Link to comment Share on other sites More sharing options...
ham2 Posted December 3, 2009 Report Share Posted December 3, 2009 This maybe more to do with my lack of talent and I can't give a technical answer but I've owned a 2001 Sherco which was very light on the front (compared to other model years) and the thing would understeer all day and pitch up the front wheel with very little warning. I also spent some time on most of the 315 Montesas and the one with the lightest front end ,2001,understeered and pitched up too easily as well. I had a '98 315 with a very heavy front end and I loved to try out steps, hanging back, whilst not putting the front wheel down (I wouldn't have dared to on the aformentioned bikes ). Maybe I just need more counterbalance for my fat ar5e. Quote Link to comment Share on other sites More sharing options...
copemech Posted December 4, 2009 Report Share Posted December 4, 2009 Obviously there must be some relationship in the CG of the rider and his ability to alter the attitude of the bike while working against the CG of it. I seem to recall years back either Scorpa or Beta claiming a near 50/50 ratio with weight on the wheels. Yet I am totally unsure if that fact alone would neccessarily make it easier to manipulate the bike, as the riders CG and points of contact and force imput to the bike may disagree. Then you can get into the rotational forces of the flywheel and all, and its effect upon the bike. Nothing in ideal relationship here. Seems all this science is important, yet none can agree, as there is no standard perfect bike! Quote Link to comment Share on other sites More sharing options...
axulsuv Posted December 4, 2009 Report Share Posted December 4, 2009 50 / 50 weight distribution is Ideal , but hard to acheive ... As the controlable ballest on our bikes (the rider) , if the bike is moving our weight is being driven down and back thru the footpegs most of the time . The bike is actually pushing our weight with the rear wheel . Under hard throttle application the rear suspension compresses and the front extends . Starting with a balanced bike makes controlling the inertia and ever changing geometry of the bike much easier . Then you can get into the details of where the footpeg and handlebar positions apply outside forces (our weight) to the chassis . And how the rear spring rate will make major changes to how the bike reacts ... To much technical info to go into deep detail here , But try to think in automotive chassis layout handling traits for a moment . Front engine rear wheel drive vs. front engine front wheel drive vs. mid engine rwd vs. rear engine rwd. The layouts that provide 50/50 weight dist. generally provide the best handling whether accelerating or decelerating and the best even wear patterns on brakes and tires . Because the center of gravity and the inertia of the vehicle is easier to control . But it all basically gets down to simple physics ... "for every action there is a equal and opposite reaction " Which in trials bikes kinda means the least effort you have to put into controlling the basic movement of the bike ,will require the least input to change its direction ... Maybe ? Something like that ... Just my morning ramblings !! Glenn Quote Link to comment Share on other sites More sharing options...
zippy Posted December 4, 2009 Report Share Posted December 4, 2009 axulsuv Posted Today, 07:11 AM mid engine rwd vs. rear engine rwd Just keep Ralph Nader away from my trials bike. Right now it is a mid engine model, if he gets involved it would end up with the engine over the front tire and front wheel drive........and anti-lock brakes, and a seat belt (but no seat.....well that's the safety police for ya) Quote Link to comment Share on other sites More sharing options...
axulsuv Posted December 4, 2009 Report Share Posted December 4, 2009 (edited) I've owned a few corvairs over the years ,(favorite was a monza turbo spyder ...) and a Lotus Europa JPS... And TRUST me the lotus was a much more enthralling ride ! Even at about 1000lbs less weight and 50hp or so . It was like a trials bike (or a formula ford...) versus a cb360 in the dirt . And I never had much use for Ralph Either !!!! But then again a 911 can be controlled quite well at speed once you learn how to steer with your foot too ! but look how well a stock subaru with a front weight bias can go too , although awd ... Glenn And we are getting way off topic now ......................! Edited December 4, 2009 by axulsuv Quote Link to comment Share on other sites More sharing options...
neo Posted December 5, 2009 Author Report Share Posted December 5, 2009 (edited) I've owned a few corvairs over the years ,(favorite was a monza turbo spyder ...) and a Lotus Europa JPS... And TRUST me the lotus was a much more enthralling ride ! Even at about 1000lbs less weight and 50hp or so . It was like a trials bike (or a formula ford...) versus a cb360 in the dirt . And I never had much use for Ralph Either !!!! But then again a 911 can be controlled quite well at speed once you learn how to steer with your foot too ! but look how well a stock subaru with a front weight bias can go too , although awd ... Thanks Glenn, Although not being an expert on fast cars I'm finding all this a little hard to cross correlate against the dynamics of a Trials bike. Keep em coming gents...there's lots of food for thought here....don't leave it all to the manufactures to think about.....we're doing this stuff too Best of balance. Neo Edited December 19, 2009 by Neo Quote Link to comment Share on other sites More sharing options...
garyc Posted December 17, 2009 Report Share Posted December 17, 2009 I think maybe they are considering the moment (or torque) due to the bikes weight about the rear wheel? This is the weight of the bike multiplied by the distance of the center of gravity from the rear wheel axle. To keep the moment constant as the bike gets lighter, the center of gravity is shifted forward. This moment is important, because it determines how easily the front wheel lifts off the ground, but I really don't know what the best setup would be is. I'm guessing Ossa are assuming it's currently about right and so making the bike lighter would indeed need the centre of gravity shifted forward. Quote Link to comment Share on other sites More sharing options...
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