A Brief History:
Last fall I converted my bike to coil suspension. I bought a Fox Vanilla RC and, on the recommendation
of both Fox and Rocky Mountain, an 800# spring. This seemed high to me, but I deferred to the 'experts?'.
Turned out the ride was too firm. I decided to do my own research to come up with a calculator that would
provide some insight into what would be a more appropriate spring rate for different riding conditions. Also,
my bike has three travel settings and I needed to know the effect of moving from one setting to another with
the same spring or what alternate springs I might need.
This calculator, the latest ( final? ) is the end result of that research. I have added units in inches or
millimetres, three travel settings in one calculation, optional spring rates for varying degrees of preload
and a couple of extra useful links. Being honest about your riding style ( weight distribution, sag level
and preload ) in the input parameters is key to finding the correct spring rate. Also, it is a common practice
to have more than one spring.
There will always be some controversy over what is a correct spring rate. This calculator has helped me to
better understand what would be a single compromise spring rate for all three travel settings and what three
unique spring rates would be appropriate for each of those travel settings.
I now understand where that 800# recommendation came from and why I didn't like it. I prefer about 30% sag
and a 600# spring with about 2 turns of preload works well in the 4.5" travel setting. However, I prefer the
geometry of the 4.0" travel setting but ordering multiple springs from the Canadian Fox distributor was just
too expensive. Luckily, Cambria still had some Mountain Speed rear springs in my sizes at only $25 USD.
To any web designer: My apologies for the less than elegant coding. I had to find a way of keeping the whole page
under 100K bytes. That's the limit for mtbr posts. I had to load the page into Visual C++ and remove all the indenting.
This reduced the page by 30%! To restore the formatting load the page into Frontpage and save.
michael
-->
Last fall I converted my bike to coil suspension. I bought a Fox Vanilla RC and, on the recommendation
of both Fox and Rocky Mountain, an 800# spring. This seemed high to me, but I deferred to the 'experts?'.
Turned out the ride was too firm. I decided to do my own research to come up with a calculator that would
provide some insight into what would be a more appropriate spring rate for different riding conditions. Also,
my bike has three travel settings and I needed to know the effect of moving from one setting to another with
the same spring or what alternate springs I might need.
This calculator, the latest ( final? ) is the end result of that research. I have added units in inches or
millimetres, three travel settings in one calculation, optional spring rates for varying degrees of preload
and a couple of extra useful links. Being honest about your riding style ( weight distribution, sag level
and preload ) in the input parameters is key to finding the correct spring rate. Also, it is a common practice
to have more than one spring.
There will always be some controversy over what is a correct spring rate. This calculator has helped me to
better understand what would be a single compromise spring rate for all three travel settings and what three
unique spring rates would be appropriate for each of those travel settings.
I now understand where that 800# recommendation came from and why I didn't like it. I prefer about 30% sag
and a 600# spring with about 2 turns of preload works well in the 4.5" travel setting. However, I prefer the
geometry of the 4.0" travel setting but ordering multiple springs from the Canadian Fox distributor was just
too expensive. Luckily, Cambria still had some Mountain Speed rear springs in my sizes at only $25 USD.
To any web designer: My apologies for the less than elegant coding. I had to find a way of keeping the whole page
under 100K bytes. That's the limit for mtbr posts. I had to load the page into Visual C++ and remove all the indenting.
This reduced the page by 30%! To restore the formatting load the page into Frontpage and save.
michael
-->