If you’ve not heard of I Chu Technologies, it’s probably because they’ve been behind the scenes winding coils for Fox, Rockshox and others’ rear shocks. Lately, they’ve been developing new XLS Springs, which promise insanely long life and titanium-like weights, all for the price of a steel spring.

Affordable lightweight coils spring update for mountain bike rear shocks

The new I Chu XLS cool on the left compared to a standard steel coil on the right.

Well, the price of a premium steel spring, but still about 1/10 the cost of a titanium spring upgrade. Their new XLS coils qualifies as SAE 9254 steel, but I Chu uses different trace elements in there to create a high tensile strength steel that’s as light as titanium. Because the steel is so much stronger, they can not only make the wire diameter thinner, but they can spread the pitch a lot further, reducing the total number of coils by roughly 25%. All told, it adds up to massive weight savings.

Lightweight steel coil spring upgrade for Fox Rockshox and DVO rear mountain bike shocks are as light as titanium but much less expensive

They make the traditional springs for Fox, Rockshox, Ohlins and others, but DVO has already jumped on board to offer the new one as an upgrade option. And they’re in talks with Fox and Rockshox.

They’ll be selling them aftermarket, too, with distribution already in Europe, and the US market is coming soon. As for the name, technically, it’s “I Chu” as the words, but most people write it as “Ichu” in case you’re searching around the Interwebz for them.




    If I’m not mistaken Fox already offers a spring like this, its the SLS (super light spring). I have a couple and they are a definite improvement over the standard steel spring in terms of weight and feel.

    From Fox site:
    SLS (Super Light Steel) springs are now available from FOX for DHX and VAN rear shocks. These SLS springs are a lighter weight steel spring option offered in addition to our standard steel springs. The new SLS springs from FOX are lighter than titanium springs at more affordable prices. A proprietary surface treatment and stress relief process removes residual stresses from the spring, allowing them to withstand higher stresses. Each spring is optimized by using a smaller wire diameter and fewer coils, creating a lighter spring.


  2. Brad Comis (@BradComis) on

    ” I Chu uses different trace elements in there to create a high tensile strength steel that’s as light as titanium.”
    Sorry guys this is impossible. 1 cubic centimeter of steel (any alloy) cannot be as light as 1 cubic centimeter of Ti. It certainly seems to me that it is possible to design a lighter steel spring, but that’s not the same as material weight.

    • Brad Comis (@BradComis) on

      Further to that it is quite possible that the rate of the spring as it compresses might vary in a different way to a standard spring which could alter the feeling of the suspension. That alteration might be good or it might be bad, but no information is provided to confirm this.

    • Veganpotter on

      “IF” it’s stronger, they can use a thinner gauge(exactly what they’re doing), and a less tight coil(also what they’re doing). So they’re using less metal. They aren’t really claiming their metal is lighter per cubic centimeter.

      • JBikes on

        All steels have essentially the same elastic modulus. The only way to make them lighter is to decrease material…via diameter or winding as the article states.
        This will ultimately cause the spring to operate with higher stresses.

        The benefit of the higher strength will be to counter the higher stresses, hopefully providing a satisfactory endurance limit for the performance/cost.

        Ti is about 55% the weight of steel, but has a youngs modulus 60%. Contrary to popularly stated opinion, both steel and Ti alloy have fatigue limits (although steel seem to have a more define endurance limit where Ti seem linear…i.e. Ti will eventually crack. Steel…theoretically yes but often not seen). Moot point though as I think bike rear springs seemingly fall into fatigue operating regions.

  3. Sorry, not sorry on

    Only people that seem to be complaining are the people that shelled out for titanium springs. Not upset that they spent more money, but upset they don’t get to feel all superior anymore.


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