RaceTecH .9kg/mm fork springs, 15w oil and R100GS fork gaiters

One thing which is a given on any BMW motorcycle – the stock fork springs will be far too soft for best comfort or handling. Given the difficulty of finding the White Power fork springs, I chose to try the RaceTech fork springs. The stock fork springs are .55kg/mm in spring rate, and RaceTech makes from .7kg/mm thru .9kg/mm springs for the K11’s. My instinct was to run the .7kg/mm springs, since that rate represented a modest increase in spring stiffness from stock without sounding too harsh. RaceTech STRONGLY advised running the .9kg/mm springs, and with some misgivings I agreed to try them. They also recommended running 15w oil in place of the stock 7.5w. RaceTech was absolutely correct in their recommendations.

Turns out that the stock fork springs run far too much preload (45mm), in an attempt to compensate for the soft rate. Using the RaceTech .9kg/mm springs, 25mm spring preload, and the 15w fork oil, the ride is much more plush than stock, yet much more controlled.

While I had the forks off the bike for the spring installation, I also installed a set of fork gaiters originally designed for the BMW R100GS. This will ensure that my fork tubes don’t get nicked during a ride and cause a cut fork seal/oil leak.