Page 1 of 1

Standard Shock/Spring Performance and Measurement

Posted: Tue Jun 29, 2021 12:04 am
by kmisterk
Hey all!

In the hopes that I'll be able to ride 2-up soon-ish, I have been wondering the best method (is there a standardized one?) for "measuring" the performance of your shocks/springs. How much "Sag" is to spec, how do you measure it, etc.

My brother helped me in measuring the sag, and as best I can tell, the numbers (for the back spring) are a bit high (in terms of how *much* sag is expected, compared to bike alone on its wheels, no center stand).

Those numbers look like this:

Myself alone: 1 1/8" sag
Myself plus 2-up partner: 2 1/8" sag

The reference points used to measure were the lower spring bolt in a straight line perpendicular to the ground up to the frame supported by the shock. It's a Hagon spring, but I can't for the life of me find any numbers or info on the spring. I'm 280lb, and my 2-up is 175lb. I have virtually no info on the weight of the rider for who the spring/rear shock was purchased, but based on this sag info, is it safe to assume that I am heavier than them?

This leads me to my next question: I presume I can keep the existing shock body, but need to replace the spring. If this is true, how do I go about determining what I need, and where do I get it?

Re: Standard Shock/Spring Performance and Measurement

Posted: Tue Jun 29, 2021 12:08 pm
by Seth
I would think that with the 2 people you mention (455#), the bike would be over capacity.
Based upon this site, the limit is 397#, so almost 60# overloaded.

https://www.motorbikecatalog.com/moto/1 ... 100_t.html

Even if you stiffened the shock, you'd still have to deal with the capacity of the tires, then the frame and wheels.

Re: Standard Shock/Spring Performance and Measurement

Posted: Tue Jun 29, 2021 12:57 pm
by kmisterk
Seth wrote: Tue Jun 29, 2021 12:08 pm I would think that with the 2 people you mention (455#), the bike would be over capacity.
Based upon this site, the limit is 397#, so almost 60# overloaded.

https://www.motorbikecatalog.com/moto/1 ... 100_t.html

Even if you stiffened the shock, you'd still have to deal with the capacity of the tires, then the frame and wheels.
Ahh. Whelp. Looks like we need to lose some weight then. Lol.

Thanks for pointing that out.