the shocking truth about shock absorbers... (noob questions as asked by myself)

Originally Posted by ThEGr33k

I find it hard to imagine what he says about springs becoming 'coil bound'. Surly the springs and forks are setup in souch a way that the springs are no where near this point even at Maximum travel!?

unless you have his progressive spring

Boyz boyz boyz ... think about it ...

if instead of a spring we had a sponge sat on top of a crusty loaf of bread, what would happen when we put weight/books on top of them??

With a light book, the sponge would deform first, the bread pretty much unaffected ... put more force (books) on and the sponge gets even more deformed ... only at the point the sponge is fully squidged will we start squashing the loaf ... as the loaf if 'arder

A progressive spring works in exactly the same way ... until the 'softer' part becomes coilbound there is no way the harder part can/will start deforming ... as the softer bit will be easier to move/deform and take up the energy ...

[yorkie_chris]

Why?
f = kx
So to squash the first softer spring there must be some reaction force on the harder part, which must deform it by some amount. This appears to be why the dual rate springs act effectively the same as progressive ones.

Originally Posted by yorkie_chris

Why?
f = kx
So to squash the first softer spring there must be some reaction force on the harder part, which must deform it by some amount. This appears to be why the dual rate springs act effectively the same as progressive ones.

what would happen if you put 2 different rate springs on top of each other with washer between them?

[Paul the 6th]

I'd crash

[yorkie_chris]

Originally Posted by zadar

what would happen if you put 2 different rate springs on top of each other with washer between them?

Depends on the rates. If there's a major difference in rate then one could go coilbound before the other one has moved by any real amount. If similar then same thing applies. Say one has 1kg/mm other one has 2kg/mm, applying 2kg will create 3mm deflection.

Edit: does a dual rate or progressive spring work any differently?

Originally Posted by Blue_SV650S

A progressive spring works in exactly the same way ... until the 'softer' part becomes coilbound there is no way the harder part can/will start deforming ... as the softer bit will be easier to move/deform and take up the energy ...

that is not correct.both will compress but part with less space between coils will bind first making that part of spring useless.

[yorkie_chris]

Yeah best tag that onto end of my reply ... will behave like I said above untill one part of it binds

Originally Posted by zadar

that is not correct.both will compress but part with less space between coils will bind first making that part of spring useless.

Yes, I didn't really give an example that matches the sorts of rate differential we have in springs ...

The loaf will have deformed, but by such a small amount it is not really important ..

same with springs if they were equally different rates.

In reality, the dual hagon springs are 6.5 for about the first 1/3 and then 9.5 for the rest - you will get deflection in the 9.5 part as you add weight (that is deflecting the 6.5 part more) ... only at the point where the 6.5 part becomes coilbound will you be on the full 9.5 rate and the 'dive' slow ... if the 6.5 never became coilbound, then we wouldn't get a 'progressive' nature to the spring ...

I actually rang the manufacturer of Hagon and voiced my concerns about it being dual rate i.e. that 'switchover' point would be sudden (not-good) ... he said it was technically a dual rate, but its really hard to build a spring that deforms equally ... therefore in practice/experiment it actually gives a 'nice' progressive type rate curve as different parts of the spring give way/deflect different amounts at different pressure/weight. But technically is has 2 rates - he just can't build it 100% that way, which actually helps in this instance!!

He actaully builds springs with distinctive dual rates - says it is useful in things like trials bikes, where the rider uses the spring to store energy for a 'hop'

[dizzyblonde]

Tell ya wot Paul, come and have a ride of Suzy (if the electrics are fixed before your over) shes got hagon progs in with 15w oil, and if you can wait while I swap batteries then you can ride Dave with Ohlins linears with 15w oil.....
Slightly different to pointy,granted, but you may get the jist..perahps



or maybe just have a go on the SRX for a horrendously handled bike....and no ya can't have a go on the Raptor