RE: Interested in the science behind frame design.
Ask Drew - he's got loads of text.media on this topic
Ask Drew - he's got loads of text.media on this topic
Or like Repsol are still having with the frontend of the RC212?Eclipze said:Quite interesting about how the stiffness plays an important part to a motorbikes suspension. I remember one of the top MotoGP riders had trouble with their frame being too stiff a couple of years ago.
In a perfect world the shock would fully absorb the bump and the head stem would remain static I think. There would be serious torque forces on the frame constantly. Which is why they would deisng them for as little deflection as possible.Humbug said:But isn't deflection predictable? Its just undampend springing isn't it?
Picture this scenario. The bike is at full lean on a corner. The road sudenly jumps in hieght, lets say 3cm. As the front wheel runs over it, the tyre will deform, then slowly lift the wheel up towards 3cm directly vertical. the front fork I would imagine would compress abit causeing the front wheel to change line of track... as its travel is not perpandicular with the road.
at the same time it will then have to lift the head stem verticaly 3cm, while the rear wheel is still 3cm lower. so that should introduce a tourque on the frame wouldn't it? And that would be un damped wouldn't it?
I wonder if i was able to explain that right? :S
Other way around, because you're not concerned with absorbing bumps etc so much on a race track (no speed humps and rider doesn't give a shit about comfort) you can make the frame stiffer, which makes the bike handle better, but also means that the rider has to be better to catch it if anything does go wrong.Humbug said:how can the forces be irrelivent if stiffness and overal wieght contribute to overall handling? If there are zero forces. there is zero deflection right? ofcourse, if the forces on the road are too great, you would have viabration comming from the road, through the chassis, causing traction loss from lack of dampening etc right?
so in the design of a frame, lets say a crash, it should be able to protect more delicate parts like the engine/petrol tank etc right?
therefor street frames are probably overkill in size strength and arnt required for a nice smooth race track?
I have no idea what I am on about :S