2021 Stumpjumper

PB Forum :: Specialized
2021 Stumpjumper
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Posted: Oct 30, 2022 at 12:20 Quote
I was too curious and could not resist.
Just have put a RS Super Deluxe coil on my Stumpjumper. I went for a ride today and noticed immediately that it has less/almost no bob while pedaling. It is what was bothering me most with air shocks. Besides that it is super sensitive and gives a lot of support. It was great so far for flat single trail and jumps. I still need to ride some steep downhill with it but I am confident i won’t get disappointed.
The downside is that it was really tight to fit. I had to remove the shock link and the seat stay bolts to install. The coil clears the side arm with about 2-3 mm but it increases under sag. And it is pretty heavy with the 600 lbs spring.

Posted: Oct 30, 2022 at 12:35 Quote
[PI=23646048
][/PI]
CristianoSebastiao wrote:
I was too curious and could not resist.
Just have put a RS Super Deluxe coil on my Stumpjumper. I went for a ride today and noticed immediately that it has less/almost no bob while pedaling. It is what was bothering me most with air shocks. Besides that it is super sensitive and gives a lot of support. It was great so far for flat single trail and jumps. I still need to ride some steep downhill with it but I am confident i won’t get disappointed.
The downside is that it was really tight to fit. I had to remove the shock link and the seat stay bolts to install. The coil clears the side arm with about 2-3 mm but it increases under sag. And it is pretty heavy with the 600 lbs spring.

Posted: Nov 1, 2022 at 10:12 Quote
CristianoSebastiao wrote:
[PI=23646048
][/PI]
CristianoSebastiao wrote:
I was too curious and could not resist.
Just have put a RS Super Deluxe coil on my Stumpjumper. I went for a ride today and noticed immediately that it has less/almost no bob while pedaling. It is what was bothering me most with air shocks. Besides that it is super sensitive and gives a lot of support. It was great so far for flat single trail and jumps. I still need to ride some steep downhill with it but I am confident i won’t get disappointed.
The downside is that it was really tight to fit. I had to remove the shock link and the seat stay bolts to install. The coil clears the side arm with about 2-3 mm but it increases under sag. And it is pretty heavy with the 600 lbs spring.

So actually Specialized says that you can't run a coil rear shock because of the angle of force created by the linkage puts too much stress on the coil shaft and causes them to break prematurely. Only EXT makes a coil shock that's strong enough to handle the torsional stress that the SJ creates.

Posted: Nov 1, 2022 at 14:15 Quote
seraph wrote:

So actually Specialized says that you can't run a coil rear shock because of the angle of force created by the linkage puts too much stress on the coil shaft and causes them to break prematurely. Only EXT makes a coil shock that's strong enough to handle the torsional stress that the SJ creates.

I wonder if that applies for the new beefed up RS coils? The press/review units were pictured mounted to SJ Evos, and I doubt the side loading is any worse on the regular SJ vs Evo

That said I wouldn't run that shock/spring with the clearance shown in the photo. Also IMO the SJ's suspension kinematics are somewhat compromised for weight savings (flexstay), so adding significant weight to try and make up for that doesn't make sense to me. I would think a SDU air or Float X with the proper tune would improve performance significantly without as much added weight.

O+
Posted: Nov 1, 2022 at 14:50 Quote
lyzyrdskydr wrote:
seraph wrote:

So actually Specialized says that you can't run a coil rear shock because of the angle of force created by the linkage puts too much stress on the coil shaft and causes them to break prematurely. Only EXT makes a coil shock that's strong enough to handle the torsional stress that the SJ creates.

I wonder if that applies for the new beefed up RS coils? The press/review units were pictured mounted to SJ Evos, and I doubt the side loading is any worse on the regular SJ vs Evo

That said I wouldn't run that shock/spring with the clearance shown in the photo. Also IMO the SJ's suspension kinematics are somewhat compromised for weight savings (flexstay), so adding significant weight to try and make up for that doesn't make sense to me. I would think a SDU air or Float X with the proper tune would improve performance significantly without as much added weight.

Agree, my EVO is a better pedaling bike overall than my SJ.

Posted: Nov 1, 2022 at 16:05 Quote
lyzyrdskydr wrote:
seraph wrote:

So actually Specialized says that you can't run a coil rear shock because of the angle of force created by the linkage puts too much stress on the coil shaft and causes them to break prematurely. Only EXT makes a coil shock that's strong enough to handle the torsional stress that the SJ creates.

I wonder if that applies for the new beefed up RS coils? The press/review units were pictured mounted to SJ Evos, and I doubt the side loading is any worse on the regular SJ vs Evo

That said I wouldn't run that shock/spring with the clearance shown in the photo. Also IMO the SJ's suspension kinematics are somewhat compromised for weight savings (flexstay), so adding significant weight to try and make up for that doesn't make sense to me. I would think a SDU air or Float X with the proper tune would improve performance significantly without as much added weight.

The Evo comes stock with a coil on some models so it's definitely ok. The SJ applies different loads to the shock structure due to the nature of the flex stay pivot system.

Posted: Nov 1, 2022 at 22:59 Quote
seraph wrote:
The Evo comes stock with a coil on some models so it's definitely ok. The SJ applies different loads to the shock structure due to the nature of the flex stay pivot system.

The side loading issue is a result of the extended yoke mount that connects to the rear shock eyelet. This is not unique to a specific model, nor just specialized: https://www.ridefox.com/fox17/help.php?m=bike&id=1138

The Evo and the SJ use an almost identical linkage, really the only difference is the use of a flex stay rather than a horst pivot by the dropout. The flex stays do effect the kinematics, but they aren't gonna cause any more side loading than the Evo. If Specialized says the regular SJ isn't compatible with coils its likely because they don't clear the sidearm, the kinematics aren't optimized for it, and because the shock will experience the same side loading as the Evo or Levo.

The LTD model that was initially specced with the older SD coil was changed almost immediately to ship with an SD air. There are currently no Evos that ship with coils, but I bet the new beefed up SD coil would survive on an Evo. I have the new SDU coil on my Enduro and it's amazing

Posted: Nov 2, 2022 at 3:37 Quote
There is a lot of theories around the coil - stumpjumper combination.
Some factors that should also be considered is the rider weight. At 70 kg I am applying much less load to the system then a 90 kg rider. Another aspect on this set up ist the shock/shaft length. Again in theory it would have less leverage forces applied to the shaft / system. For me it is obvious that spz and the shock manufacturers would tell to avoid coil shocks to have warranty potentials reduced.
The new RS also doesn’t fit this frame officially as you won’t be able to install it without removing the shock extension and seat stay bolts.
I had a 2021 super deluxe air tuned for me and bike and the shock felt either like a soft couch or very harsch. I was never able to get support and small bump compliance. Maybe it was not tunned right. In fact the coil set up rides better for jumps and downhill.

The clearance does bothers although it increases in sag.

Posted: Nov 2, 2022 at 10:05 Quote
lyzyrdskydr wrote:
seraph wrote:
The Evo comes stock with a coil on some models so it's definitely ok. The SJ applies different loads to the shock structure due to the nature of the flex stay pivot system.

The side loading issue is a result of the extended yoke mount that connects to the rear shock eyelet. This is not unique to a specific model, nor just specialized: https://www.ridefox.com/fox17/help.php?m=bike&id=1138

The Evo and the SJ use an almost identical linkage, really the only difference is the use of a flex stay rather than a horst pivot by the dropout. The flex stays do effect the kinematics, but they aren't gonna cause any more side loading than the Evo. If Specialized says the regular SJ isn't compatible with coils its likely because they don't clear the sidearm, the kinematics aren't optimized for it, and because the shock will experience the same side loading as the Evo or Levo.

The LTD model that was initially specced with the older SD coil was changed almost immediately to ship with an SD air. There are currently no Evos that ship with coils, but I bet the new beefed up SD coil would survive on an Evo. I have the new SDU coil on my Enduro and it's amazing

Mmmm no, it's definitely something else. A lot of companies make coils that are small enough diameter to clear the arm. I've seen coil shocks buckle and collapse on regular SJs. I ran a coil shock on a Top Fuel that literally cleared the frame by 1mm, and it didn't void the warranty due to limited fitment.

O+
Posted: Nov 2, 2022 at 12:32 Quote
seraph wrote:
lyzyrdskydr wrote:
seraph wrote:
The Evo comes stock with a coil on some models so it's definitely ok. The SJ applies different loads to the shock structure due to the nature of the flex stay pivot system.

The side loading issue is a result of the extended yoke mount that connects to the rear shock eyelet. This is not unique to a specific model, nor just specialized: https://www.ridefox.com/fox17/help.php?m=bike&id=1138

The Evo and the SJ use an almost identical linkage, really the only difference is the use of a flex stay rather than a horst pivot by the dropout. The flex stays do effect the kinematics, but they aren't gonna cause any more side loading than the Evo. If Specialized says the regular SJ isn't compatible with coils its likely because they don't clear the sidearm, the kinematics aren't optimized for it, and because the shock will experience the same side loading as the Evo or Levo.

The LTD model that was initially specced with the older SD coil was changed almost immediately to ship with an SD air. There are currently no Evos that ship with coils, but I bet the new beefed up SD coil would survive on an Evo. I have the new SDU coil on my Enduro and it's amazing

Mmmm no, it's definitely something else. A lot of companies make coils that are small enough diameter to clear the arm. I've seen coil shocks buckle and collapse on regular SJs. I ran a coil shock on a Top Fuel that literally cleared the frame by 1mm, and it didn't void the warranty due to limited fitment.

you just bolded one of the reasons listed, all three are why it isn't.

Posted: Nov 2, 2022 at 14:22 Quote
newbermuda wrote:
seraph wrote:
lyzyrdskydr wrote:


The side loading issue is a result of the extended yoke mount that connects to the rear shock eyelet. This is not unique to a specific model, nor just specialized: https://www.ridefox.com/fox17/help.php?m=bike&id=1138

The Evo and the SJ use an almost identical linkage, really the only difference is the use of a flex stay rather than a horst pivot by the dropout. The flex stays do effect the kinematics, but they aren't gonna cause any more side loading than the Evo. If Specialized says the regular SJ isn't compatible with coils its likely because they don't clear the sidearm , the kinematics aren't optimized for it, and because the shock will experience the same side loading as the Evo or Levo.

The LTD model that was initially specced with the older SD coil was changed almost immediately to ship with an SD air. There are currently no Evos that ship with coils, but I bet the new beefed up SD coil would survive on an Evo. I have the new SDU coil on my Enduro and it's amazing

Mmmm no, it's definitely something else. A lot of companies make coils that are small enough diameter to clear the arm. I've seen coil shocks buckle and collapse on regular SJs. I ran a coil shock on a Top Fuel that literally cleared the frame by 1mm, and it didn't void the warranty due to limited fitment.

you just bolded one of the reasons listed, all three are why it isn't.
I meant to only bold the first part of that sentence.

Edit: you're right, I apparently only read the first part of the sentence as well. But my point stands, that one of the reasons why the coil isn't supported for the SJ is that they have a tendency to break because the shafts aren't strong enough for the SJ's suspension design.

O+
Posted: Nov 20, 2022 at 15:56 Quote
Yes coils are not supported or recommended on the current SJ platform whether that's an EVO, LT, ST, Levo or anything in between. This is purely because of the side loading issues causing accelerated wear to the shaft and in some cases snapping them.

I run a DHX2 on a 2020 EVO which came as standard equipment. This was before they figured out the issue. I am fairly lightweight and have yet to break a shaft but I have replaced a shaft as part of a damper service to be on the safe side. It was quite polished on one side, likely because that side of the seal had more force applied to it during compression therefore "polishing" one side of the shaft.

Fox or Specialized might state they "cannot accept" a coil shock but the reality is, the frame's can. There are a few limiting factors to bear in mind however:

Due to the sidearm, there is limited space for a shock body. Care needs to be taken to ensure there is no risk of the body fouling the sidearm for obvious reasons. This is not only limited to coil shocks. Fox X2 have issues with adequate clearance with alloy frames however just fit on some carbon frames. Only way to know is try it out and look at the clearance throughout the stroke.

Stroke length and eye to eye, technically, you could run slightly longer/shorter eye to eye but this will change other geometry and potentially cause clearance issues. Same with overstroking. I removed a 5mm limiting spacer on my DHX2 to gain some extra travel and this can also be done with airshocks but you need to check clearances to make sure the rear triangle doesn't foul on the seat stay or your in for a bad time. I'm probably being a bit tight and risky with my clearance but I haven't had any issues yet touch wood. Depends on your appetite for risk.

Just want to set the record straight. Yes its possible to run a coil. they fit and mount up fine however there are things to know. I have run both a coil an air shock. Due to the kinematic design of the SJ, they are more suited toward an airshock but they do feel great with a coil also. They feel like two different bikes. Air shock will make it feel like an energetic trail bike that gives lots of feedback, a coil will make the SJ feel a little more dull but smooth.

If you want to use a coil, I would recommended a Cascade Components link to help remedy the leverage ratio issue, a progressive spring to introduce even more progression into the design and if possible, a shock with hydraulic bottom out as they have a tendency to blow through the travel even with the link and progressive spring.

Posted: Nov 26, 2022 at 2:36 Quote
hi all

i need help plz im looking to replace my headset bearings on my 2021 stumpjumper comp ally anyone no where the best to buy it from on the website plz

thanl you

Posted: Dec 21, 2022 at 19:29 Quote
I know this is ‘21 model thread, but any comments about running a coil on the ‘22 alloy frame?

New toy Shorter travel trail bike for the collection Specialized Stumpjumper Alloy Ohlins suspension Magura brakes. Drivetrain upgrades coming
Before the fork swop. M2 is going to another bike bumped to 170. This one will be running a RXF36 EVO with a 150mm M2 air spring,


 
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