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Old 11 Hours Ago
Tom68's Avatar
Tom68 Tom68 is offline
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Originally Posted by OMC View Post
Well, sometimes it pays to ask a curly question. Thanks for the explanation Lukey, I didn't study physics but I will sleep well tonight. Now I just need to figure out how I can apply this newly acquired knowledge to my real life...
Start setting up long travel off road racers and it'll become part of your life.
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Old 4 Hours Ago
numroe numroe is offline
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Originally Posted by Arctra View Post
Now, I am an ex-auditor, so I've had it drummed into me that you need to find corroborating evidence to support any opinion.
There is no factual evidence. Paul T's book is just another opinion. Suspension and bike setup is mostly done by opinions and personal preference.

I agree with Grant Hay (and Terry and Paul T) that the rider sag matters most. Ride height of the bike at each end is a primary tuning variable and perhaps the the most important thing of all. But if the spring rate and static sag are way out of range, then we can have big issues with traction and control, So they both matter.

Originally Posted by Blas'e View Post
Dynamic vs Static.....some get it, some dont.
Soooooooo many influencing factors unless you understand whats happening in your own head its no point listening to others.
That's a really good point. And generally I agree - get some understanding before trying to decipher opinions. The catch is that to a large extent we need to learn from others to understand in the first place. So it's usually a iterative learning cycle. Listen/read, try/ride, feel/experiment, repeat ... Making mistakes as we go is necessary.

So many influencing factors is right. 102 or 105mm is just a number. Either can work, depending on other things. But if we are outside of a sane range (like 100 to 110) then it suggests something can be improved in the setup and maybe improved a lot.

Originally Posted by Jakobi View Post
Another question that could be asked... is there any specific advantage/disadvantage to running a spring with more/less preload, given both rates in their setups achieve the desired geometry (race sag)?

Ie 5.2kg/mm 100mm race, 25 static, vs 5.4kg/mm 100mm race 35 static.
I believe there is a matching spring rate, spring preload and reb damping curve. The preload impacts the reb action a lot near full extension (top of stroke) so it has a large impact on traction.

Different damping curves, especially rebound, can also effect the rider sag setting that seems to work best. Because rider sag is measured stationary but the rear wheel is usually ridden over bumps. I think that setting our rear sag to some recommended number makes no sense if not also considering static/free sag, damping settings and the entire front end setup of the bike.

Last edited by numroe; 3 Hours Ago at 01:32 PM.
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Old 4 Hours Ago
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tonyg tonyg is offline
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Originally Posted by tonyg View Post
2014 ktm 350 excf

Progressive spring

Static Sag = 38
Rider Sag = 130

How's my spring rate looking as a starting point?

Hanna Somatics

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