Suspension info
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Road Captain
Joined: Apr 2009
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From: Sunbury, PA
Suspension info
I am trying to educate myself on suspension set up and would like to find a spring rate calculator. Racetech has one but it only calculates the front suspension. Could someone provide me with a link for a spring rate calculator that will calculate rear rates?
Club Member
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From: Bedford UK
I'm not sure you will find that info! What is it you are striving to learn? Plenty of us have aftermarket shocks and forks upgrades, so can help you out - to some degree at least. Forks have longer travel than shocks, but spring rates for shocks will be similar to forks.
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From: USA
Stellar HDF Member
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From: Nor Cal
Everyone, I mean everyone in the dirt bike world does this, same with road racing, the HD world of suspension is decades behind. It’s almost comical, rebound only? 2 springs only? I run Ohlins suspension on my HD and it’s stellar, just like on all my other bikes, even with them getting good info is like pulling teeth.
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From: USA
And then there is damping. Which is often what one wants when chasing spring rates.
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From: Nor Cal
There is no one target number, nor one singular calculation. Some want a plush ride, some want a firm ride. Neither is right, nor wrong. Equally, neither is optimal because that is not a single definition.
And then there is damping. Which is often what one wants when chasing spring rates.
And then there is damping. Which is often what one wants when chasing spring rates.
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HDF Community Team
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From: USA
Oh, no doubt the spring holds you up. And with the right length, one can get a spring of any length to sit the bike in the middle of the suspension range of motion.
But the actual rate of the spring? Thats a taste thing, in many ways.
Perhaps a 350 lb/inch rate. Itll ride hard, but wont change much with a passenger or luggage, and will rarely bottom out.
or perhaps a 150 lb/inch rate. Itll be plush, especially on smooth roads. But itll bottom out easily on bumps, and require lots of preload adjustment for a passenger or luggage.
And thats without getting into the front to rear balancing. Get this too far off And you have a bike/vehicle that pitches body to tail obnoxiously. Empty pickup trucks often suffer this.
But the actual rate of the spring? Thats a taste thing, in many ways.
Perhaps a 350 lb/inch rate. Itll ride hard, but wont change much with a passenger or luggage, and will rarely bottom out.
or perhaps a 150 lb/inch rate. Itll be plush, especially on smooth roads. But itll bottom out easily on bumps, and require lots of preload adjustment for a passenger or luggage.
And thats without getting into the front to rear balancing. Get this too far off And you have a bike/vehicle that pitches body to tail obnoxiously. Empty pickup trucks often suffer this.
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Joined: Apr 2007
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From: Nor Cal
Oh, no doubt the spring holds you up. And with the right length, one can get a spring of any length to sit the bike in the middle of the suspension range of motion.
But the actual rate of the spring? That’s a taste thing, in many ways.
Perhaps a 350 lb/inch rate. It’ll ride hard, but won’t change much with a passenger or luggage, and will rarely bottom out.
or perhaps a 150 lb/inch rate. It’ll be plush, especially on smooth roads. But it’ll bottom out easily on bumps, and require lots of preload adjustment for a passenger or luggage.
And that’s without getting into the front to rear balancing. Get this too far off And you have a bike/vehicle that pitches body to tail obnoxiously. Empty pickup trucks often suffer this.
But the actual rate of the spring? That’s a taste thing, in many ways.
Perhaps a 350 lb/inch rate. It’ll ride hard, but won’t change much with a passenger or luggage, and will rarely bottom out.
or perhaps a 150 lb/inch rate. It’ll be plush, especially on smooth roads. But it’ll bottom out easily on bumps, and require lots of preload adjustment for a passenger or luggage.
And that’s without getting into the front to rear balancing. Get this too far off And you have a bike/vehicle that pitches body to tail obnoxiously. Empty pickup trucks often suffer this.
Last edited by mikes300; Nov 30, 2019 at 11:11 AM.
HDF Community Team
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From: USA
well I disagree sort of one should get the correct spring for the weight the intend to run, being one or sptwo up and with luggage does pose a issue for is , every major suspension tuner says spring for weight and valve for conditions, those 150 pound guys jumping 90 feet in SX run the same springs most any other 150 pound guy does, but with vastly different valving.
My dirt bike has a much longer suspension travel than my Harley. My dirt bike is meant to travel over much rougher terrain than my Harley. The spring rates and damping are different, because its different targets.
Those stunt riders arent landing on flat ground, they are landing on a downward slope. It greatly extends the vertical deceleration time, which reduces the forces. Were they to be targeting flat ground landings from such heights, theyd have to have completely different suspension, to meet the different needs.