Fork upgrade suggestion

[wil59]

Hello everyone, current situation: rear suspension changed to a 95N / mm spring. Perfect sag of 60 mm (with maximum spring preload). Front fork not yet adjusted but has a riders sag of 70 instead of desired 63. What do you suggest: applying spacers for spring preload adjustment or changing the springs to higher spring rate (and if so which spring rate, riders weight is 102 without motorcycle gear). Suggestions are welcome.

[williestreet]

Do some math.

70mm sag plus 13mm installed preload=83mm x 0.57kg/mm(stock spring rate)=47.31kg of force

Desired sag 63+13mm installed preload= 76mm

 

47.31/76=0.6225kg/mm

 

Specs say fork travel =210mm, but if you take fork apart and measure its actual travel is only 200mm.

I would be looking for 60mm sag front and rear.

60mm desired sag+13mm installed preload=73mm

 

47.31/73=0.6481 kg/mm desired spring rate.

 

I am the same weight as you and will be ordering a set of 0.64kg springs.  I can always add some spacers later if required.

 

 

[NvNick]

I would think the spring is not enough if you have max preload.

[wil59]

@ NvNick: So if i understand correctly, an extra 12,5 mm pre-load on the front fork wil not give enough preload to reach the desired sag of 60/63? 

 

@williestreet : after looking up what you mean with the 13 mm preload and 0,57 kg/mm (both standard specs on the T700, did not know that) i now undestand what you mean.

Clear explanation. Now i know what i need. Thanx.

[NvNick]

I was talking about the rear. I used to do some suspension work and always shot for the sag to be correct in the middle of the available preload range. If your at max preload then the spring is too soft. You effectively have no adjustment except going softer.

[williestreet]

3 hours ago, wil59 said:

@ NvNick: So if i understand correctly, an extra 12,5 mm pre-load on the front fork wil not give enough preload to reach the desired sag of 60/63? 

 

@williestreet : after looking up what you mean with the 13 mm preload and 0,57 kg/mm (both standard specs on the T700, did not know that) i now undestand what you mean.

Clear explanation. Now i know what i need. Thanx.

Remember this only applies if your new springs are the same free length as the stock springs. 

Stock are listed as 423mm long, so as long as you buy springs the same length or close the figures above should be close.

I think Ktech springs are 425mm, but some other are shorter.  If buying shorter springs you may need to make some spacers to get the proper installed preload, and therefore the proper sag.

 

I am surprised you mention you have max preload on the adjuster with a 95N spring to get proper sag. 

Maybe that was a typo or maybe your new rear spring is shorter and you have less installed preload.

 

I have a 90N spring coming for mine and I expect to get proper sag with 0 clicks(minimum setting ) on my shock.  But this is using the Ktech spring which is 5mm longer than stock and therefore has more installed preload at the minimum setting.  As mentioned I am the same weight as you.