worst designed bike ever?

Thias":buh4iilk said:
And you say, the suspension is working less the more the bb is traveling? (has to travel)

No. I'm saying that the further the BB would have to travel for the suspension to work, means the less likely it is that it could travel with the weight of a (let's say) 13 stone rider preventing it from doing so.

Because the point at which the rider is applied to the system is that much further away from the pivot.
 
By my very rough calculations, the BB would have to travel a little over 60% of the distance of the rear drop out.

So 6" of travel of the rear wheel would mean the BB travels backwards and upwards 3.7".

(Obviously Mantras were never designed for that sort of travel).
 
But that was not the point. Sure the bb travels more with a higher pivot. But the "responsiveness" while standing is not affected by pivot height or (relative) bb movement. That is what I am trying to say.

If I understand the physics (witch I might not...) the responsivenes is all about the lever length. Horizontal distance from pivot to the left or right.
That is also the difference between standing and Sitting. If one would draw a straight line from the saddle through the pivot and further down with a length of 2*(distance saddle->pivot) and the bb would be at the end of that line, there would be no difference between standing and sitting.
Because the lever length would be the same. Right?
 
Thias":lbyne263 said:
But that was not the point. Sure the bb travels more with a higher pivot. But the "responsiveness" while standing is not affected by pivot height or (relative) bb movement. That is what I am trying to say.

If I understand the physics (witch I might not...) the responsivenes is all about the lever length. Horizontal distance from pivot to the left or right.
That is also the difference between standing and Sitting. If one would draw a straight line from the saddle through the pivot and further down with a length of 2*(distance saddle->pivot) and the bb would be at the end of that line, there would be no difference between standing and sitting.
Because the lever length would be the same. Right?

Maybe. But then it couldn't compress. It has to be forward or rearward of the bb otherwise any hit would try and force a solid piece of steel directly back into the pivot.
 
Re:

Still not the worst design ever no matter what physics/engineering arguments you throw about. They are cool and they work well enough for XC 8)
 
Adruzzz":1d94ss1e said:
velomaniac":1d94ss1e said:
If you've never seen a URT then you must be blind, are you perchance typing with a braille keyboard :shock:

Admittedly you mainly see them as BSO's today but that makes them the single most common suspension bike design there is !

I haven't got a clue what URT is to be honest... thought it was a type of milk, but having googled it I did see this:

764d3a8ea46d48540464f78b6b3c32f6.jpg

I love it !
 
Re: Re:

velomaniac":2vu9rdkt said:
Still not the worst design ever no matter what physics/engineering arguments you throw about. They are cool and they work well enough for XC 8)

Maybe the heavier you are, the worse they are.

As I'm 16 stone, then maybe that's why they're worse for someone like me.
 
Thias":36u02h27 said:
But that was not the point. Sure the bb travels more with a higher pivot. But the "responsiveness" while standing is not affected by pivot height or (relative) bb movement. That is what I am trying to say.

If I understand the physics (witch I might not...) the responsivenes is all about the lever length. Horizontal distance from pivot to the left or right.
That is also the difference between standing and Sitting. If one would draw a straight line from the saddle through the pivot and further down with a length of 2*(distance saddle->pivot) and the bb would be at the end of that line, there would be no difference between standing and sitting.
Because the lever length would be the same. Right?

There are multiple levers in play, but if you discount the front one, an URT system is a basic upside down second class lever. The distance between the fulcrum (pivot) and the load (bb) vs. the load (bb) and the force (rear axle) have a much higher effect than they do in a first class lever.
 
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