Can anyone advise, where do i measure the preload on the rear showa shock , is it the visible threads above the locking ring? if so i have 12mm rather than 17mm, would that account for some running wide on corners? also what size spanner do I need to adjust this? and where to get one? Cheers peeps.
For correct "preload" you need to set the "static sag" first. That is more accurate than a measurement on the actual shock absorber itself. Correct sag might correspond to a certain measurement, but it won't be the same for every bike/shock absorber, it's best done on an individual bike basis. Obviously this assumes you have the correct spring fitted in the first place & if you set it for yourself, it would need changing if carrying a pillion.
Something like this, https://www.ebay.co.uk/itm/251700871771?hash=item3a9a8a825b:g:AqgAAOSwBahVXGi3, or this, https://www.ebay.co.uk/itm/224083809997?hash=item342c6f96cd:g:y-8AAOSwC-xasohL. You will need two to unlock the two adjuster nuts. Spring pre load is a function of free length over the amount of compression. With both adjuster nuts fully wound out, the spring is still under a small amount of compression that I’d ignore. Measure the depth of the two nuts from the root of the thread at the top of the shock. Add this figure to your pre load and measure from the root of the thread at the top of the shock to the nut spring interface. As to your understeer, could be a combination of front and rear settings. Andy
