I wanted to start a forum for current, future, or potential Stumpjumper 15 owners to compile questions, answers, tips, problems, etc.
Below is overarching information about the bike and our coverage of the bike thus far.
▪️Overall Details
- Carbon models
- Alloy models
- 145mm of rear wheel travel // 150mm fork (160mm compatible)
- S1/S2 - mixed wheel only // S3-S6 - 29-inch (mixed wheel compatible with aftermarket link)
- FOX Float with Specialized patent-pending GENIE shock on most models
- Coil models available (FOX & Öhlins)
- S1 - 210x52.5 shock // S2-S6 - 210x55 shock
- S1/S2 - 180mm PM // S3-S6 - 200mm PM
- 63, 64.5, or 65.5-degree head angle
- Two-position bottom bracket adjustment
- Size-specific chainstay lengths
- SWAT 4.0 downtube storage ( alloy & carbon)
- 30.9mm dropper post // 38.6mm seat post clamp
- 12x148 Boost rear hub spacing
- Alloy frame + GENIE = 1.47 kg (3.24 lbs) heavier than carbon
- Carbon frames = internal routing for brake/dropper
- Alloy frames = internal routing for brake/rear derailleur/dropper
▪️Geometry finder gives you numbers for each size in each geo position.
▪️Specialized suspension calculator, which is a good place to start for setup. 30% sag is recommended in the rear.
▪️FIRST RIDE Review
I was a fan of the bike when it launched. You can read my First Ride article HERE. TLDR—below is how I would compare the SJ15 against the Stumpjumper models it has replaced, along with my 'What's The Bottom Line?' I think it pretty well sums up SJ15 if you don't want to sift through all the marketing hype on the Specialized website to understand what the bike is about.
To close out the different ways the Stumpjumper 15 rode with different GENIE spring curves, here is how I would break down the bike's descending vs. climbing abilities, along with the previous Stumpjumper variants for reference:
- 2021 Stumpjumper: 50% climbing, 50% descending
- 2021 Stumpjumper EVO: 35% climbing, 65% descending
- 2024 Stumpjumper 15: 30-45% climbing, 55-70% descending
If you've been riding the current Stumpjumper, I think you can achieve a similar all-around feel with the Stumpjumper 15; you might just have to push a bit harder to reach a similar average speed. If you really prioritize efficiency and don't want to give up the light, agile, hammer-on-the-pedals vibe, I'd look at the new Epic EVO instead of the new Stumpjumper. It's light, it can still get rowdy, and it's more fun to pedal. If you previously rode the Stumpjumper EVO, or want a more descent-focused trail bike, the new Stumpjumper will surprise you with how hard it can be ridden.
What's The Bottom Line?
The Stumpjumper 15 picks up right where the previous models left off and continues to move the needle forward when it comes to capability and adaptability. The tweaks and updates are subtle, but they're in all the right places. The geometry is still spot-on, the frame is stiffer, the frame details are refined, and the on-trail performance is as versatile as ever. Planted, snappy, calm, or lively—it's a bike with multiple personalities. Riders should look past the fact that it has only 145mm of travel, and take into consideration the possibilities available with the geometry adjustments and new GENIE shock. With a few simple changes, you can recreate either Stumpjumper of the past, or achieve descending abilities that surpass the outgoing EVO.
▪️Riding Three Years of Stumpjumper 15 and GENIE Shock Development in Two Days
We had the opportunity to run through the development of Genie and SJ15. This video dives into why Specialized created the shock, how it coincided with the development of the SJ15, how different Genie setups feel, and how Genie compares to riding the bike with a coil and traditional air shock.
▪️Tuning, Shock Anatomy, and Other Details
Jason, this was just fantastic. Thank you for this granular look at suspension curves and air springs. Would love more of a "so what" at the end so we can start thinking about how this applies to bikes other than the SJ.
First time in a long time I shared a bike tech thing with some friends!
Have you taken the genie shock to your preferred suspension service centre for a full rebuild? How did it go?
I have a 2023 SWorks Evo. I bought a Genie to see how things go. May as well post about it here!
Considering the only difference between the Genie and a "regular" shock is the outer air sleeve, and the rider should be able to pull it apart to swap volume bands themselves, I don't see why anyone would have an issue servicing it.
I just added this video to the main forum post, but I'll drop it here as well so everyone above gets notified. We had Chance from Specialized run through adjusting volume spacers, what parts on the GENIE make it unique/cross over with other FOX shocks, and some general tips and tricks for using the shock. This isn't a service video, but hopefully, it helps answer some questions about what serviceability will look like in the long term.
I suspect people will hate the idea of the Genie shock less and less as they're exposed to them in real life, on friend's bikes and on their bikes. This will be a great contrast to many other proprietary Specialized forks and shocks, which people hated more and more as they were exposed to them in real life, on friend's bikes and on their bikes.
Whoa whoa, what is that yellow piece at the top of the upper eyelet, above the end stroke spacers???
Is there changes to the tune or hard parts to deal with the extra stored spring energy?
https://tech.ridefox.com/bike/service-procedures/2867/specialized-genie-shock-tuning-kit-installation
Interesting🤔
Mine went belly-up after a handful of rides. Was quite enjoying the bike and the shock until that. Feels like air in the damper. Local Fox warranty center is a month out on repairs. Two local certified service centers can’t get rebuild kits. Bought a RS SDU as a holdover and it feels absolutely trash on the bike. Currently not super-stoked.
hey- recommend calling Specialized Rider Care and explaining the situation. SBC has a small inventory of complete shocks to help with situtations like this to keep you rolling. if they can't help for whatever reason DM me and I'll help you get it sorted.
there is a floor to the amount of volume we felt was acceptable after the band cuts of the extra volume. the permananet eyelet spacer helps ensure a rider can't tune themselves into a bad spot.
Thanks for that. That was my first contact. I was advised they could not help me. I offered to buy a shock and was told they had no inventory.
DM'd
The rebound tune is progressive. Meaning at slower speeds shaft speeds it produces low damping, and as shaft speeds increase so does the rebound force. This helps the shock feel lively and responsive where the rebound forces/shaft speeds are not super high, but creates a "high speed catch" where return forces are high and it generate a higher shaft speed.
It is also worth noting that the extra spring force at the end is not exponentially higher than a "normal" spring. The first stage of the spring is softer than your traditional spring, then the extra ramp at the end brings forces back up to only slightly higher force than a traditional spring. This means we are not having to tune around forces that are very far from the norm.
My concerns around shocks like this are more about exactly what @Blatant described - the average rider is going to struggle to get proper support for these, as has been the trend for every proprietary shock in history. I checked in with the NZ distributor and I also cannot get dedicated parts or tools for these, so will yet again need to explain to people why I can't help with their shock when they were led to believe by specialized that servicing would be straighforward.
I just reached out to Fox to better understand why you can't purchase the parts and the singular "special" tool to work on the damper. What you know, but maybe not everyone reading this is that most Fox shocks have an unique tool for this type of operation. So yes, unique to our shock, but not unique in the Fox aftercare/service world. I'll let you know what Fox comes back with and if we can't get it sorted quickly, assuming you actually want to work on these shocks, I'll ship you the tool. Just DM me your address. With that part and a standard Float damper service / air spring service kit you can sort 99% of any issues a rider might encounter.
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