Fox SLS Coil Spring: Product Review


With more and more bikes now coming with coil rear shocks, suspension manufactures are looking for every bit of performance they can find. With a coil shock, the coil spring itself is certainly something to consider. Brands like Fox have their SLS spring, Cane Creek with their Valt spring, and Rockshox's high performance steel spring. Here in this review, we are going to be taking a closer look at the Fox "Super Light Steel", or SLS, coil spring. The SLS spring is the fancy orange coil you have been seeing on all of Fox's top athletes bikes. The best part about the SLS spring is that Fox has made it available to everyone right from the get go. That way you can get all the same gear that riders like Neko Mulally and Danny Hart are riding on!

Fox SLS Spring Review - Worldwide Cyclery

SLS Spring Specifications

Fox claims that the SLS orange springs are lighter than titanium springs at a more affordable price. In the past, riders looking for a high performance spring would jump straight to titanium offerings because of the weight savings. Titanium springs come with a healthy price tag! With a little bit of tricky engineering, Fox's Super Light Steel springs are just as light as titanium springs, and come in at less than half the cost! 

So how does Fox do it? How are these steel springs lighter than other titanium springs? Isn't titanium supposed to be really light? These are all good questions. The answer is more straight forward than you might think. Fox has developed a proprietary surface treatment that is applied to the material before the coils are wound. This surface treatment and stress release process removes any residual stresses in the material, in the end allowing the springs to withstand higher stresses. Because the material can handle higher stresses than the material used in traditional steel coil springs, Fox is able to use a smaller wire diameter with less coils, creating a lighter spring

Fox SLS Spring Review - Worldwide Cyclery

Riding and Performance

The spring ridden here has been mounted and ridden on a Fox DHX2 rear shock on a Santa Cruz V10. Be sure to also check out our Fox DHX2 rear shock review!

After racing the downhill world cup venues at Fort William and Leogang, along with plenty of weekends riding at Windrock Bike Park in Tennessee, Max has put a lot of time in on this particular Fox SLS orange coil spring. Let's see what Max has to say about its riding and performance. 


  • One of the main benefits to Fox's SLS coil spring is how light they are. Even though we weren't able to get these springs on a scale, the SLS spring is less than half the weight of the traditional steel counterpart. The total weight of the DHX2 and the SLS spring is lighter than the black steel spring alone!
  • The Fox SLS springs are offered in 25lb increments allowing you to further fine tune your bike setup. All bikes use a different leverage ratio and require different weight springs, even for the same rider. Traditional black steel springs were only offered in 50lb increments. Because the SLS springs now come in 25lb increments, you are able to dial in your suspension setup much more closely to suit your particular rider weight, bike, and suspension preferences.  

Fox SLS Spring Review - Worldwide Cyclery

  • The SLS springs hold much tighter tolerances on the claimed spring weight than the previous black steel springs. When you get a 550lb SLS spring, it's going to somewhere from 540 to 560lbs. There are a lot of variables to consider in the manufacturing process, so holding such high tolerances can be challenging. These SLS springs do a much better job of this. With the black steel springs, when you get a 550lb spring you could end up with what is actually a 500lb spring when tested. In the end, you can get exactly the spring rate you want much easier with the Fox SLS springs. 
  • Out on the trail, these orange springs do exactly what you would expect. They provide a nice smooth feel and seem to be very durable. What isn't there to like?


  • After over a year of abuse, the orange finish on the spring is starting to show some wear. Some of the orange paint has started to chip off particularly around each end of the coil where the coils come in contact with each other. With that being said, this 550lb spring is still performing just like it did when it was pulled out of the box for the first time. 

What's The Bottom Line?

Fox's SLS orange coil spring is a great offering for those looking for a performance  spring at a fair price. The SLS spring performs exactly how you would expect out on the trail, giving your shock a smooth action while weighing much less. Fox claims that these Super Light Steel springs weigh less than similar titanium offerings at less than half the cost. Get one of Fox's SLS springs and get your bike looking like one of the pro's. 

Fox SLS Spring Review - Worldwide Cyclery

About Me

Max Morgan is 25 years old, and lives in Brevard, North Carolina. Max grew up in Atlanta, Georgia and started racing downhill at the age of 15. He has now been racing professionally for the last 7 years, competing in the U.S. Pro GRT series and UCI World Cup series. Check out Max's rider spotlight here! 
Instagram: @mxmorgan77

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March 21, 2018

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