Coil compatibility question

So I'm farting around with spring weights on my little Bomber CR, and starting to think I should try a heavier rate... Is there any reason I shouldn't put a 38mm ID Rockshox spring on a Fox/Marzocchi body?

I'd obviously want a spring clip adapter like Sprindex ship with (and are annoyingly hard to find). 

Rockshox coils are cheaper, more available in the relevant length/stroke, and come in red.

I think if you can find the right adapter and correct free stroke length, you should be OK. Have you used up all the appropriate pre-load on your current spring before trying something heavier?

Posted by: shoreboy

I think if you can find the right adapter and correct free stroke length, you should be OK. Have you used up all the appropriate pre-load on your current spring before trying something heavier?

Cheers. 

It's the mid- and end-stroke I'm after, adding preload is just raising the sag point. 

I've been swapping between a 550lb linear and a 525-610lb progressive. The progressive doesn't have the mid support I want, and the linear gets to the bottom too easily. A 550+ progressive would probably be best, but a 600lb linear is a cheaper experiment.

When I was looking for a coil last year, the Rock Shox coils per given spring rate and stroke were physically longer than some of the other options, I think about 10mm too long to fit onto my CCDC.

I ended up just ordering a Nukeproof light steel spring from CRC which included the adapter as well.

Posted by: UFO

When I was looking for a coil last year, the Rock Shox coils per given spring rate and stroke were physically longer than some of the other options, I think about 10mm too long to fit onto my CCDC.

I ended up just ordering a Nukeproof light steel spring from CRC which included the adapter as well.

Good heads up, I'll be sure to check the free length first if I go for RS.

Thanks to Srams enormous spare parts pdf I found some handy details to just leave here.

00.4118.200.028 SPRING, METRIC COIL, RED , LENGTH 134MM, SPRING TRAVEL (47.5-55MM), 600 LB

Now to find a pair of in-stock 35-38mm adapters...

After recently installing a sprindex, I'd put my vote in for that. They're not cheap, but it's been awesome being able to hone in on the perfect rate, and then also have the ability to bump the rate up tiny bit for more burly types of rides. I was pretty close with a 500lb spring, but dialing up to 510 turned out to be PERFECT. And Sprindex comes with the adapters for everything.

Me and a few homies run the springdex coils. The adjustability is amazing. I would recommend it over fafing about with standard coil.

Thinking I will grab a Springdex as an upgrade later this year. I have a 2023 SD Ultimate coil, currently running a 550lbs RS steel spring which is a touch stiffer than I was expecting (27% sag). I actually ordered a 600lbs thinking the 550 might be too light but in reality I probably want 525ish. Was debating some of the third party Ti springs but the Sprindex isn't much more at $200CAD and the adjustability seems pretty cool, plus it's still 110g lighter than my RS 550# (561g).

The bike came with a Sprindex, but I find myself winding it full hard (560lb). I like it for bracketing in to find the rate, but less so for long term use - using fewer coils means the spring fatigues faster, and the plastic section wears the paint off the spring, leading to rust.

I think of it like a Shockwhiz. Use it for setup, then move it along to the next rider.

Posted by: mammal

After recently installing a sprindex, I'd put my vote in for that. They're not cheap, but it's been awesome being able to hone in on the perfect rate, and then also have the ability to bump the rate up tiny bit for more burly types of rides. I was pretty close with a 500lb spring, but dialing up to 510 turned out to be PERFECT. And Sprindex comes with the adapters for everything.

2nd

Posted by: velocipedestrian

Using fewer coils means the spring fatigues faster. 

That's an interesting take. Looking at mine, it's got 5 usable coil windings, and the Sprindex rotates a half turn. So between using all the coils and minimal coils, the difference is 5 vs. 4.5 (10%). I wouldn't think that would cause an increase in spring fatigue, to the point where one would worry about wearing it out too quickly.

Posted by: velocipedestrian

The bike came with a Sprindex, but I find myself winding it full hard (560lb). I like it for bracketing in to find the rate, but less so for long term use - using fewer coils means the spring fatigues faster, and the plastic section wears the paint off the spring, leading to rust.

I think of it like a Shockwhiz. Use it for setup, then move it along to the next rider.

Once I found the spring rate I wanted I haven't touched my coil shock.

I had used a Sprindex for awhile to dial in the right rate but found a lot of side deflection when cranking it up and was rubbing on the shock body. I've also found that it has a wall of a progression spike about 80% into it's stroke that was causing some rebound issues with the shock tune I was using at the time. It also tested at a lower rate than advertised range, the 610-690 lb./in is really 590-640 lb./in according to the graph I saw posted.

I ended up with 2 springs, an Ohlins 434 lb. for natural trails with a lot of smaller hits and a DVO 420-500 progressive for berms/jumps like most man-made trails