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I recently asked a question about how to make a lockable suspension last longer. There zenbike told me about the “blow off” feature. Now, I am curious about how the whole system works.

So, can anyone tell me about how a lockable front suspension works, together with features like “remote-lock” and “blow-off”.

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I did google, and just want simple and understandable explanation. – Starx Mar 20 '12 at 18:10
up vote 11 down vote accepted

Modern suspensions have a valve inside, and when the suspension moves, the valve moves inside oil, and the oil is forced to pass a very narrow opening.

The size of this opening is different depending if the suspension is compressing or returning. Usually, there is a spring which lets the oil flow more when it compresses, and less when it rebounds (the spring closes the so-called lip-valve), thus damping the oscillations and giving the rider more comfort and control.

Then on these modern suspensions, there is a knob that shuts the valve close, so that is impossible to compress the fork at all (some models), or the suspension locks close to the bottom and keeps some of its travel (some other models), and so on.

The blow-off feature is one that allows the system to auto-release when you hit a very hard bump, because the oil pressure rises so much that it activates an auto-release system. Some extra-super-fancy models allow you to adjust how hard the hit needs to be in order to release the lock.

As far as I remember, some cheaper models have mechanical locking system, which lock the suspension the same way you lock a door (some metal slides inside and blocks the suspension), but this might be considered a not very elegant solution.

Remote lock means the knob you turn is mounted on the handlebar, so you can activate it without taking your hand from the handlebar. I guess this is actually NEEDED only for high-end mountain-bike racers, but you know, mountain-bike is a very fashion-oriented activity...

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