24 replies to this topic

[Bjørge]

Local workshop had an SV 650 in the other day,  both forks had progs the opposite way round....    cancelling each other out = linear!  

 

The most important aspect would be how forces applied onto lower end of the spring is transferred to the top nut. Okay, there are factors like different weight in both ends, and the aforementioned hydrodynamics of coils dipping into the fork oil, but my belief would be that these play a minor role.

 

Two unlinear springs opposite to each other definately don't constitute a linear one....

[drewpy]

I was always told that  the tightly coiled springs are at the top because it reduces sprung mass, ie the "heavier" tightly coiled springs at the top don't move up and down with the forks 

[the969]

OK I spoke to Paul Adams at Racelab who kind of knows his way around a set of suspenders....

 

Turns out that an awful lot of the last few posts (mainly including my own) are, unsurprisingly, complete bollox.  Bjorge's first sentence was closest.

 

Here are some actual facts.  

 

1) It doesn't matter whether the external force is applied at the top of the forks (courtesy of rider weight plus front brake application) or at the bottom (by the road).  Because that force is going through a spring, all parts of the spring will be involved in controlling the force. Therefore it doesn't matter which way round progs go in, it makes no difference to the ride.

 

2) The reason Hyperpro suggest the tighter coils go at the top is because their springs taper - if you put them the wrong way round, your going to have firment issues, especially when a cartridge is in situ. That is the only reason.

 

3)  If you fit them one up, one down (like the SV guy did) , they don't become effectively linear, but they don't function properly as progs either. 

 

4)  Obviously you can control default damping by oil weight and air gap, but this doesn't change the fact that linears are ultimately more predictable.

 

5) A dual rate spring is what the TDM 850 has as the OE rear shock. Kind of a halfway house between a linear and a prog.

 

Erm... thats it.

Edited by the969, 15 August 2019 - 04:54 pm.

[dandywarhol]

Engine valve springs are always fitted with the close coils to part which moves and the open ones at the cylinder head end.

 

Progressive springs are used with shitty damper rod suspension to make the damping feel better - that's why linear springs are fitted when cartridge conversions are fitted

[the969]

 

Progressive springs are used with shitty damper rod suspension to make the damping feel better - that's why linear springs are fitted when cartridge conversions are fitted

 

 

Shitty damper rod suspension, tell me all about it...

 

I've always preferred linear, pretty much irrespective of what else is inside the fork. Damping is more of a function of oil weight / air / and  valves than spring choice, at least its been that way for me, and I've ridden some utter shite. I've also been on some decent  suspenders and the main difference is always the quality of the damping.  Then again I quite like weirdo front ends, had a 1300s for a while, loved the duolever but you have to recalibrate the brain.