Rear shock spring specification?

[yanto]

I'm looking to upgrade the shock spring only (cannot afford to go the whole hog) as I think a number of you have already done. I want a heavier/stiffer spring to cope with 2 up with luggage riding (although in truth only 20% of my riding is 2 up).
Can anyone give me the specification of an appropriate spring so that I can go get one? I'm aware of the hyperpro spring but a dealer told me that that spring is a direct replacement. Any help gratefully recieved. If there is a dealer in the states I can get to ship one to the UK I'll also consider that.
thanks

 

[dduelin]

I believe a 900 lb spring is stock and many owners upgrade to a 1300 lb spring if they are heavier or ride two up alot. You may check with Hagon there in the UK. There is a US distributor that brings in Hagon shocks with an upgraded spring. It is possible Hagon sells the spring alone? In the US Race Tech and Hyperpro are popular spring upgrades.

 

[wjbertrand]

Race Tech recommended a 1200lb sping for my ST13. There's a spring calcuator at their site. www.racetech.com .

 

[dduelin]

Jeff,

I have visited RT site before and had them rebuild my OEM rear shock 15,000 miles ago. While I do not doubt their recommendations I am curious about the rear spring recommendation for my weight. Free sag and rider sag numbers indicate the stock spring is a good choice for my weight and riding load. If your Showa preload adjuster works good, ie., starts adding preload after a couple of clicks, how much preload does the 1200 lb shock take for your weight?

 

[wjbertrand]

I've got the preload screwed in maybe 4 turns?? I haven't had anyone over to check the sag (can't seem to get it by myself) so I've tuned it where I like the feel. Race Tech re-filled the preload adjuster when the revalved the shock and installed the new spring.

With gear on my weight is in the 230 range (I'm working on that though)

 

[dduelin]

One thing I did with the OEM shock and again after RT revalved mine was to calibrate sag to the preload adjuster so I could repeat settings. It does take help to measure and record the sag. You can do it with one other person if you have a sturdy wheel chock. My daughter helped me. I weigh about 155 without gear, 180 with, and I take a little more for normal solo riding - 12 to 16 clicks or 6 to 8 turns of the adjuster. This setting will give about 30 mm static sag and about 7 or 8 mm free sag. I like it best between 25 and 30 mm - I raised the front ride height when I changed the stock fork preload so less rear sag helps sharpen the relaxed frame geometry from losing 11 mm sag in the forks.

The thing I was curious about is that Race Tech's Paul Thede's article on spring rates http://www.sportrider.com/tech/146_9510_tech/index.html indicates the stock spring is good for me. The one recommended on the RT site would be about 30% stiffer and another light rider that went with that spring felt it was much to harsh so I opted to retain stock. It works for me but I realize alot of ST riders two up and I never do.

 

[yanto]

thanks for the comments/advice and I'll speak to hagon. However, if I'm going to speak to a 'spring maker' what details do I need to give them other than asking for a 1200lb for a pan euro??