If you've been eyeing a coil shock for your mountain bike lately, you've likely seen the mrp spring pop up in just about every forum thread or gear review. It's one of those upgrades that seems simple on the surface—after all, it's just a coiled piece of metal—but it can completely change how your bike behaves on the trail. Most of us start out on air shocks because they're easy to tune with a shock pump, but there's a certain point where you start craving that "stuck to the ground" feeling that only a coil can provide.
The thing about switching to a coil is that it's not just about the shock itself; the spring you choose is what's doing the heavy lifting. MRP has carved out a pretty specific niche here, especially with their progressive rate options. It's a bit of a rabbit hole once you start looking at spring rates and stroke lengths, but honestly, it's one of the most rewarding tweaks you can make to your setup.
Why go with a coil setup anyway?
Before we dive into the specifics of the mrp spring, it's worth asking why people bother with the extra weight of a coil in the first place. Air shocks are great, don't get me wrong. They're light and highly adjustable. But they have a few inherent flaws. As the shock compresses, the air pressure builds up exponentially, which can feel "harsh" at the end of the stroke. Plus, air seals create friction, often called stiction, which means the shock isn't as sensitive to those tiny little bumps that chatter your teeth.
A coil shock, on the other hand, is almost entirely friction-free. It moves the instant your tire touches a pebble. This creates a level of traction that air just can't match. When you're pinning it through a technical rock garden, a coil keeps the rear tire glued to the dirt. The mrp spring is often the go-to choice for riders making this switch because they offer more than just a standard linear rate.
The magic of the progressive rate
This is where things get interesting. Traditionally, coil springs are linear. That means if it takes 400 pounds to compress the spring one inch, it takes exactly 800 pounds to compress it two inches. While that's great for consistency, it can be a problem for bikes with "linear" suspension designs. If your bike doesn't have a lot of built-in ramp-up, you might find yourself bottoming out a standard coil shock way too easily on big drops.
The mrp spring (specifically their progressive line) solves this. It starts out at one rate for the first part of the travel to give you that supple, small-bump sensitivity we all crave. But as you get deeper into the stroke, the spring rate actually increases. It's like having the best of both worlds: the plushness of a coil with the bottom-out resistance of an air shock. I've talked to plenty of riders who felt their bikes were too "linear" for a coil until they swapped in a progressive MRP spring, and it suddenly felt like a whole new machine.
Finding the right weight for your style
Choosing a spring rate can feel like a math test you didn't study for. You'll see numbers like 350, 400, 450, and so on. This is where you have to be honest about your riding weight—including your helmet, shoes, and that hydration pack full of snacks. If you pick a mrp spring that's too light, you'll be sagging too deep into your travel, which messes up your bike's geometry and makes you strike your pedals on everything.
If you go too stiff, you won't get enough sag, and the bike will feel harsh and tall. Most people find that the "sweet spot" is right around 28-30% sag for an enduro bike. One of the cool things about the MRP options is that they offer increments that allow for fine-tuning. It's not just about the big jumps; it's about how the bike sits in a corner. A properly sprung bike feels balanced—neither diving in the front nor wallowing in the back.
Compatibility and those pesky spacers
One of the biggest headaches when buying a new spring is making sure it actually fits your shock body. Different brands use different diameters. Fortunately, the mrp spring is designed to be pretty universal. They usually have a 38mm (1.5-inch) internal diameter, which is a bit of a "standard" in the industry, but obviously, not every shock is built the same.
To get around this, MRP sells adapters. So, whether you're running a RockShox, a Fox, or even a Marzocchi, you can usually make it work. It's a small detail, but it saves you from having to buy a brand-specific spring that you can't take with you if you decide to buy a different shock later. Just make sure you check the "stroke" of your shock. You never want to put a spring on that has a shorter travel than your shock, because the coils will bind together (coil bind) before the shock finishes its movement, and that can lead to some pretty expensive damage.
How it actually feels on the trail
Let's get away from the technical specs for a second and talk about the actual ride. When you first drop into a trail with a fresh mrp spring, the first thing you notice is the silence. Because there's less friction and better damping control, the bike just sounds quieter. It doesn't "clatter" over roots; it thuds. It's a very composed feeling.
In the corners, a progressive spring gives you something to push against. Some linear coils can feel a bit "dead" in the middle of the stroke, making it hard to pop the bike off side hits or pump through rollers. Because the mrp spring builds support as it compresses, you still get that "poppy" feeling that makes trail riding fun. You aren't just sinking into a bottomless pit of travel; you have a platform to work with.
And then there are the big hits. We've all had those "clank" moments where you misjudge a landing and find the end of your suspension's rope. With a progressive coil, those moments are much softer. Instead of a harsh metal-on-metal feeling, it feels more like a controlled deceleration. It gives you a lot more confidence to try lines that you might have avoided on a standard linear setup.
Weight savings without the sacrifice
Usually, when you hear "coil," you think "heavy." And yeah, a steel spring is never going to be lighter than a canister of air. But the materials used in a modern mrp spring are a far cry from the heavy pig-iron springs of ten years ago. They use high-grade steel that allows for fewer coils and thinner wire, which sheds a significant amount of weight.
Is it still heavier than an air shock? Yes. But for most of us who aren't counting every single gram for an XC race, the performance gains far outweigh the few hundred extra grams. The bike feels more planted, you have more grip in the wet, and your rear end stays composed under heavy braking. To me, that's a trade-off worth making every single time.
Final thoughts on the upgrade
Switching to a coil setup is a bit of a commitment, but it's one of those things where once you do it, it's hard to go back. The mrp spring really bridges the gap for riders who want the coil feel but are worried about losing the "playfulness" or the bottom-out support of their air shock.
It's not just a component; it's a tuning tool. It lets you keep the bike active and sensitive without sacrificing the ability to go big. If you're tired of fiddling with air pressures and volume spacers every time the temperature changes or you head to a new bike park, a coil might be the answer. It's consistent, it's durable, and honestly, it just looks cool. There's something undeniably "pro" about seeing a high-quality coil tucked into a frame. So, if you're looking to level up your suspension game, definitely give these springs a look. You might just find the traction you've been missing.