Replacing rear spring
I've got a Jamis Dakar Sport with the steel coil over shock, and want to upgrade to something lighter. First thought was a titanium spring, but I'm not sure how to interpret the specs.
The spring is marked 400x1.78. 400 is the spring rate, what's the 1.78? Free length is 3 3/8", and travel is 1 1/4" (measured between the shcok body and the bumper).
the 1.78 is the stroke length of the coil before full compression. It's fairly normal to have a spring that is about .25" longer than the stroke. Your shock has a 1.5" stroke (the space the bumper takes up is part of the stroke). So you'll want a spring that is about 1.75" stroke length.
Now, let me ask you something....
The shock on your Dakar Sport is probably a Fox Vanilla with no adjustments. This is a sub $200 shock at best. Does throwing another $200 for a ti spring seem a little excessive?
For a little more you could get a Fox Float R brand new for $250 and it will be half the weight of your current shock. If you check the MTBR classifieds, you can probably find a lightly used one for less than $150. Seems like the better way to go to me.
Thanks for the help! You're right, my budget's more like $50. Saw a bunch of ti springs on ebay for that much too, though didn't know what to get. You've given me some good advice. I'll check the classified too.