The first thing in setting up a motorcycle for a particular rider is installing the correct shock spring rate for the combination of motorcycle and rider. Often customers who purchase an aftermarket shock or purchase a motorcycle with an aftermarket shock installed, will ask if it has the correct spring rate for their weight. This question normally leads us into a question of "What spring rate do you have installed?" Most customers don't know they can look for info on the spring itself or they reply “there are numbers on it but I don’t know what they mean”. Today I'm going to explain the numbers printed on the most common spring we see, an Ohlins shock spring.
Let’s take a look at the spring in the picture at the top of this page. It has the printing;
To begin with there are four sets of numbers that provide information. The first set of numbers “01092” reference the series of the spring. The series is the actual nominal dimension that this spring is designed and manufactured. In this example a "01092" series spring is made to a 57mm Inner Diameter (ID) and has a Free Length of 170mm. Besides using this number to order the correct spring that fits the shock you have, you can also use this series info to determine how much preload is currently on this spring. Your suspension guy will want to know this preload number when determining the correct setup for you.
To find the preload on your spring top out the rear suspension. Meaning lifting the rear wheel off the ground with the swingarm in full extension. After that has been done, measure how long the spring is as mounted in your shock. This measurement is your "Set Length". Let’s say you measured the spring in your shock at 158mm. Using the free length of the spring series in the above example, you can subtract your Set Length from the Free Length. (170mm-158mm=12mm). You can then let anyone know, suspension tuners or buddies,how much preload you are running on your setup. This is a quick calculation, but remember there is a little bit more precision that we haven’t accounted for, but that’s an explanation for another day.
The second number that screams out info on the above spring is the "-24". This represents a part number code designation to the spring rate this spring has as manufactured. In this example the number 24 is the code designation that Ohlins uses for a 80 Newton (N) spring rate. Ohlins also prints this rate directly on the spring so you don’t really need to know the code conversion. The actual rate is found right after the code designation 24 and is printed after the forward slash “/". In the image above, this spring has an "80" spring rate. If your suspension tuner asks, ”what spring rate do you have on your bike?” Now you can quickly look at it and say, “ I’m running an 80 N” (N = newton = unit of force).
I can hear it now... “the guys on the forum say I need a 100 spring for my motorcycle and my weight. What's the part number I need” Now that you have the info above you can just about find the correct part number to call me, Ohlins, or scour the web and order the correct spring with the correct rate. You know you need the “01092” spring series but what is the rate code designation for a 100N spring. Easy, below are the codes for the most common spring rates used on Ohlins shocks;
24=80 26=85 29=90 31=95 34=100 36=105 39=110 41=120
In this example you would call me, Ohlins or scour the web and order a 01092-34 spring. All shock spring series use the same rate code. If you have a spring series "21041" and need a 95N rate, you'll order a 21041-31.
The last number on this spring we have not talked about yet is the portion printed at the end and barely visible in the image above “L2218”. This is a Lot Number. This Lot Number is a code back to Ohlins, or any other manufacture that uses them, of when, what materials, and methods used in making this part. If Ohlins had a problem with a couple of springs from the same Lot number the management in Sweden could go back to the methods and material used to manufacture the springs from that Lot number. They would investigate why they are having issues with these spring and take corrective actions and/or make changes to manufacturing or supply to make their product better. It has no bearing on your suspension setup and you don’t need to worry about it.
That’s it! I hope you gained a little more knowledge about your suspension and can go show off your smarts when someone asks "What do these numbers mean on my Ohlins spring?"
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