Levo Gen 2 Are you running a FOX X2 on a Levo? then read this

[Zimmerframe]

It's effectively the same setup, with a solid mount at the bottom that, therefore, makes the whole yoke effectively a solid part of the shock and, in turn, gives the rest of the rear end more leverage to "bend" the shock. Using your bike pump analogy, imagine welding on a 4-6" bar on the end of the pump and grasping that. It would snap even faster, no?

Yes and no .. This is what I mean with the is it better or worse - would it cause a different failure ?

If you welded you bar onto my pump (my poor pump ) ... Yes, you'd have more leverage and could boomerang it far easier. So yes, definitely by making it longer, you're applying a higher leverage force which if the "pump" wasn't designed for that, it would fail sooner.

If we attached your bar onto my pump with a hinge instead (like the levo clevis) It would be harder for you to snap the pump because you'd just be bending at the hinge as you tried to boomerang it . BUT !!!!

If we first used your welded bar, with the bar on the floor, standing vertically, and hit it with a sledge hammer downwards - it would most likely just compress the pump. The further off vertical it is, the more effect your bar will have on causing a fail rather than compress.

If we used the hinged one, for starters it would want to flop over on the hinge - so we can't even try to hit it to make it fail - because it can move .. But if we supported it temporarily them hit it, the pump/shock/clevis would flex at the hinge, the bottom of the pump would hit the floor off to the side - the same distance as the length of your hinged bar extension and the pump would probably snap as it wouldn't have the forces controlled vertically through it. The welded bar I see as the Kenevo linkage, the hinge as the Levo.

There is an advantage to welding the bar in one situation, which also works as a disadvantage in the other situation.

There is an advantage in hinging it in the first situation, but that works as a disadvantage in the second situation.

Do I win the rambling rubbish award yet

 

[Zimmerframe]

It's effectively the same setup, with a solid mount at the bottom that, therefore, makes the whole yoke effectively a solid part of the shock and, in turn, gives the rest of the rear end more leverage to "bend" the shock. Using your bike pump analogy, imagine welding on a 4-6" bar on the end of the pump and grasping that. It would snap even faster, no?

Ok, so visually this angle shows what you're saying and makes it easier to understand (for me anyway) :

The FSR Linkage results in increased leverage forces to the bottom eyelet.

With the Clevis (Pinned through) , the shock can swing left/right at the bottom eyelet, but if you try to compress the shock, it will try to resists, which means there's a huge amount of vertical twisting/snapping force being applied to that bottom shock eyelet by the FSR linkage.

If the shock wasn't designed for that, you can see why it would fail. You can also understand where component weight is a hugely important factor, why you wouldn't specifically design your shock to handle those loads/stresses/forces if it wouldn't generally get mounted like that.

 

[CjP]

The only possible way that’s going to move around is if the linkage bolt is loose. Otherwise every shock would fail.

 

[KennyB]

Maybe this is why, for the Gen2 Levo, the user manual tells you to hand tighten the lower mounting bolt, install and torque the upper bolt and then torque the lower bolt. It also tells you to grease the shaft of the bolts.

 

[Bigtuna00]

If we attached your bar onto my pump with a hinge instead (like the levo clevis)

I see! This is the fundamental misunderstanding. The lower eyelet on a Levo is NOT a hinge. The Levo flip chip does *not* allow the shock to rotate. It's torqued way too high to be a pivot, and there's no bushing anyway. It's not intended to allow the shock to move. This is why I said it's effectively the same design as the Kenovo. I realize it's a different implementation (duh!).

When people talk about the "clevis mount" on an FSR bike, they're referring to the whole yoke, not the bottom eyelet.
The only way it becomes a "hinge" is if you add a bearing or bushing, like Push does.

Ok, so visually this angle shows what you're saying and makes it easier to understand (for me anyway) :

This is a photo of the BikeYoke adapter, which *does* allow the shock to rotate. But this is not the default implementation.

 

[CjP]

Maybe this is why, for the Gen2 Levo, the user manual tells you to hand tighten the lower mounting bolt, install and torque the upper bolt and then torque the lower bolt. It also tells you to grease the shaft of the bolts.

I over torque that bolt, I’m surprised I haven’t snapped mine yet. Still no shock failures on my bikes.

 

[escrs]

So i spoke to someone at Silverfish (FOX Importers) as they also have a service centre for FOX there and his is what they said

Obviously any comment I make is without the benefit of inspection of the shock but in general it is possible that wear found to damper shafts and localised marks and scuffs to the inner air sleeve can be caused by side loads applied to the shock by the frame. These loads are affected by a number of influences including the condition of interconnecting bearings and type of usage.

 

[Zimmerframe]

This is a photo of the BikeYoke adapter, which *does* allow the shock to rotate. But this is not the default implementation.

10/10 for spotting the bike yoke ! Only chose that one due to angle of picture ..

I did say I didn't have a clue

Thanks again for clarifying that, I'd always assumed it WAS a hinge and could move !

Well, I don't care what anyone says, I'm pretty sure NO ONE has ever had this issue on the Levo Hardtail.

 

[Bigtuna00]

Well, I don't care what anyone says, I'm pretty sure NO ONE has ever had this issue on the Levo Hardtail.

Squelching and harshness coming from the rear end? Sounds like a hardtail to me

 

[escrs]

So ive emailed Spesh UK asking them if what TF tuned and the FOX warranty manager at Silverfish are saying is correct and the Yoke design is the cause of the wear

If that is the case then the 2022 Levo's could see the same issue shortly

 

[RickBullotta]

Motorcycles often use a heim joint (rod end bearing) to accommodate a bigger range of movement, and I wonder if these could be applied to yoke-style shock mounts to mitigate the effects of side loading, flex or slight misalignment. The other thing I've seen a few times is shock mount bolts overtightened and/or bushings seized or sloppy leading to some of these kinds of wear issues. I do think a heim joint would be an interesting engineering consideration for MTBs and eMTBs.

 

[Bigtuna00]

I do think a heim joint would be an interesting engineering consideration for MTBs and eMTBs.

As I've said (at least twice) this is what Push already does. EXT did it on the V1 shocks but switched back to bushings. I asked, but never got an explanation why.

 

[RickBullotta]

As I've said (at least twice) this is what Push already does. EXT did it on the V1 shocks but switched back to bushings. I asked, but never got an explanation why.

I knew I should have learned to read instead of just learning to write. Dammit.

 

[Zimmerframe]

I knew I should have learned to read instead of just learning to write. Dammit.

Your subconcious could have been tuning it out .... BIG TUNA .. that sounds fishy .... ignore ...

 

[Zimmerframe]

Well .. it looks pretty inside .. (before we gave one to @escrs anyway )

2015 ! Video ...


But it was completely re-designed in 2021 :

23 ish seconds "Improved structural rigidity and reduced hysteresis"

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[Mikerb]

Thanks to @Bigtuna00 for all the extra information. Maybe he can comment on my question on the yoke, acting as he has explained, as a fixed extension of the shock ........viz whether there is a point of the rear triangle assembly upward travel, where the raising of the rear of the yoke goes beyond being matched by the front shock fixing allowing the shock to match its angle of attack ( ie directly in line). More specifically, could that point be exceeded by the shock having a longer travel than was originally specified ( 52.5).

 

[jbodnar]

Interesting thread…

Could this be applicable to an SL?

I’m running a 2020 X2 55 mm on my SL, and a CCDB Coil IL 55 mm on my FF (upside down, so the end of the shaft that snapped for some is at my top shock mount - I’m probably tempting fate).

I believe I torqued the bolts to spec (but when I first started swapping shocks, I didn’t realize how much tighter the bottom bolt needed to be torqued). I had the top right, but not the bottom. I guess the larger bolt should have been a clue.

Seems like an under torqued lower shock bolt could cause an issue.

I didn‘t put any grease on the shock bolts (didn’t seem like there was any when I first took them out)…is this important?

 

[Bigtuna00]

Could this be applicable to an SL?

I’m running a 2020 X2 55 mm on my SL, and a CCDB Coil IL 55 mm on my FF (upside down, so the end of the shaft that snapped for some is at my top shock mount - I’m probably tempting fate).

The issues regarding increased stress on the shaft due to a fixed lower mount apply to any bike that uses a fixed lower mount. Fox has an article on it here:

Information on "Strut-mount" bikes and FOX/Marzocchi coil shocks | Bike Tech Help Center | FOX

www.ridefox.com

Regardless of how you have it mounted, Cane Creek does not recommend the IL for Levo at all: Which Coil Shocks Are Supported on Turbo Levo? - EMTB Forums

 

[Rusty]

A couple comments - having been a test rider with the original Fox air shocks for MX back in the 70's and also being fortunate to test the Kayaba units a few months later ... then using air forks and shocks on my MTB since they first came out.

Firstly, I have had some grit get under a seal and cause a leak on my very first ride .... shit happens. Had a similar thing happen but after a few rides with Rockshox unit and a riding buddy had it happen with a low hour Ohlins.
Next, one of the reasons I dislike the Spesh suspension design (and a lot of others) is that in my opinion it puts lateral force on the shock which can allow what is really quite thin material to flex. Would love to see someone actually do some in-depth stress testing to either prove or disprove.
Further to the above - I believe Spesh uses a 52.5 to help relieve this issue and fitting a 55mm would probably exacerbate the issue.