BLADDER FORK MYSTERIES: MR KNOW-IT-ALL
FORK BLUES
Dear Mr. Know-It-All,
I recently bought a used 2013 KTM 450SX, and coming off an Asian non-button starter, I couldn’t wait to hit the hills and hammer. The bike starts and runs stellar, but the fork is miserable. I’m a trail rider who occasionally rides tracks, and the front end on this bike is harsh and pumps my arms into cement. I bleed them prior to the ride, have tried going up and down on the compression adjuster and nothing seems to make a difference. I read that this WP fork is a closed-cartridge design and uses an air bladder. Is the air bladder something I need to adjust? I don’t even know where it is. Help, please!
James Read
This is one of those mysteries that few riders, and even aficionados, know exists. The WP twin-chamber fork on the majority of ’07–’14 KTMs was fit with an air bladder that pressurizes the inner chamber to keep the air from mixing with oil. Both Showa and KYB dampers use a spring called a pressure spring to achieve this identical state. If your air bladder has more than the recommended 17 psi, your fork could react to terrain in a harsh fashion. Slavens Racing has a video series on suspension service that can be helpful.
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