F2 swingarms-why are they not longer?

[Stevieweavie]

In the design of solos, one of the main criteria is to get the swingarm as long as possible, within the limits of wheelbaes of course, with gearboxs becoming stacked and the swingarm mount rammed right up againts the gearbox. This apparantly helps traction out of corners. On F2 sidecars that I've seen unclothed, the swingarm stops well short of the gearbox, why is this? Does the rider get in the way, or is there some other reason?

[alanw]

In my opinion keep the swingarm as short as possible on a sidecar whether its a long or a short bike, cornering forces completely different to a solo, especially on left handers. Only my opinion mind.

[steve-e]

Out of curiousity, why would it help traction? I can understand the relationship between the pivot and the force of the chain pulling the sprocket lifting the swing arm/digging the back end in, but how would the length help with traction?

[Stevieweavie]

I think with a longer swinarm it reduces the effects of the sprocket acting the lift the wheel off the ground. Can't visualize it in my head at the moment tho. I know the position of the pivot of the swingarm relative to the gearbox sprocket and wheel has the biggest effect on it, but often read that designers strive to get the swingarm longer for traction

[sidecarf11]

Think its more to do with the way the chain acts, if you think about it the ideal position is for the pivot of the swingarm to be level with the drive sprocket as over the bumps there would be no change in tension on the chain, where as if the pivot is before or after the drive sprocket the chain tension changes and these forces must go somewhere ?

[paul33]

P m sent

[alanw]

Be interested to hear your point of view Paul cos I regularaly race against one of your bikes, it looks to handle really well especially on left handers.