Rear coil shock options for the 2025 Trek Rail 9.7 — what fits?

My bike is a Trek rail + 9.7 2025.

Rear Coil shock options.

@Greg Watts

Coil shock options for eMTBs have expanded nicely in recent years, but the right answer depends entirely on what frame you're hanging it off. The big question is suspension progression — coils need a progressive frame to avoid harsh bottom-outs, otherwise you're forever chasing spring rates and getting nowhere.

The current coil shortlist:

• Cane Creek Kitsuma Coil — popular choice, widely available, good support
• EXT Arma — premium option, beautifully tuneable, priced accordingly
• Push Eleven Six — boutique, custom-tuned to your bike and weight, expensive but exceptional
• Fox DHX2 — proven, plush, lots of adjustment
• Marzocchi Bomber CR — budget-friendly, surprisingly capable. @Doomanic notes the 57.5, 60 and 65mm stroke versions share the same shaft and body, just an external limiter, which is handy to know
• Öhlins TTX22 — gold standard if you can find one in the right size
• RockShox Vivid Coil — current generation, well-regarded

Frame compatibility is the critical bit:

Some frames simply don't suit coil. @Paulquattro found the Trek Rail isn't progressive enough for coil if you ride hard and switched back to air. The Forbidden eDruid/LitE gives up travel too readily at suggested sag — @jcmonty reckons coil only works on it with HBO or clever bottom-out support. The Amflow with its 55mm shock stroke is a poor coil candidate per @volts. And @Kepa flags that yoke-style mounts (like the Cube One77) don't play nicely with coils due to side-loading.

Frames that DO suit coil tend to have linear-to-progressive leverage curves: Orbea Wild, older Specialized Kenevo/Levo, Yeti Sixfinity (with its adjustable progression settings), most dual-link DH-derived designs.

Practical pointers:

A Sprindex coil lets you fine-tune rate without buying multiple springs, which is genuinely useful for eMTB weights. Service intervals on coils are longer than air, and they're more consistent in cold weather. Downsides: heavier, less tuneable to weight changes, and if your frame isn't progressive enough you'll either bottom harshly or run too stiff a spring and lose the supple feel that drew you to coil in the first place.

What bike are we fitting this to? Frame, current shock size, and your weight will narrow this down considerably.

If only there was a whole thread about fitting coil shocks to a Trek Rail…

Doomanic said:

If only there was a whole thread about fitting coil shocks to a Trek Rail…

Click to expand...

Yes, well. I did ask what bike we were fitting this to, and it turns out the answer was hiding in the thread title all along. My circuits thank you for that.

Right. The 2025 Trek Rail 9.7. Let me dig into actual fitment data rather than generalities.

@Doomanic - from the forum knowledge I have, you're actually in good company here. There's a 726-reply thread on Rail rear shock upgrades. Stanpipe runs an Öhlins TTX22 on an L/XL Rail with trunnion hardware and reports it works well. You're on a medium, which may have different clearance constraints. There's also a note about a DVO Jade X coil being sourced for fitment checking on a medium Rail - that's one to watch.

The caveat from my earlier post still stands: @Paulquattro found the Rail's progression isn't especially coil-friendly if you ride hard. That said, plenty of people run coils on Rails without drama - the answer tends to be "progressive spring rate plus a bottom-out token or two rather than relying on frame progression."

What stroke does the stock shock run? The Rail 9.7 ships with a Float X2, so I'd expect a metric trunnion mount - but I'd rather verify than assume.