RockShox Reverb bent

[Redman]

So my 150mm Reverb stopped going back up by itself. And, took much efforto to go down. Anywho, I took it to my LBS and they discovered that the post is bent. Rockshox is going to warranty no ques asked.

I'm just curious if anyone else has experienced a bent reverb dropper. Or, any dropper post for that matter.


thanks!!!!

 

[Mikie]

Not I...
I own the Gravity Dropper and works awesome...

 

[knucklebuster]

I've not heard of a dropper (any brand) being bent before either. I have 2 reverbs, one is 100mm and other is 125. Have had other issues but not bent.

I'd say that's pretty good warranty service being no questions asked for a bent post.

 

[Varaxis]

Only have 125mm versions. Not much leverage nor force from my skinny ass to bend anything, short of some seat rails. Post being dropped is more of my "default" position, with it only going up if I know there's a long enough stretch of easy pedaling, so even less likely to bend.

 

[MCB2K]

Fox DOSS... no complaints or issues.

 

[Redman]

strange. the bike that this is on (a 14' newmad) only has about 70 hours on it. never been layed down. no tumbles. i store the bike tires on the ground, leaning against a wall. when i wash the bike, i clamp the post loosely. I weigh about 190lbs packed down. so, i'm baffled as to how it got bent.

theories??????

 

[Mikie]

You are a badazz mountain biker. Only force I foresee to bend a post is a slam on some negative "G's"...

 

[Daddy Dirtbag]

Any chance you have your saddle mounted so the clamp is more toward the front of the saddle? That would allow a fair amount of leverage on the post, not to mention the saddle rails. Whenever someone says they continually bend saddle rails, more often than not, they have the saddle mounted like that. If your seatpost/saddle clamp has some rearward offset, that only compounds the issue.

 

[Runs with Scissors]

Or maybe it's just a defective post.

 

[Varaxis]

Just what I found on the first page of results on a google search:

X-Fusion upper tube bent (2 total for this guy): <a class="postlink" href="http://singletrackworld.com/forum/topic/what-dropper-seatpost-1#post-3845835" onclick="window.open(this.href);return false;">http://singletrackworld.com/forum/topic ... st-3845835</a>

Gravity Dropper upper tube failure: <a class="postlink" href="http://www.bermstyle.com/gravity-dropper-classic-adjustable-seat-post-long-term-review/" onclick="window.open(this.href);return false;">http://www.bermstyle.com/gravity-droppe ... rm-review/</a>

Reverb upper tube bend, reports 210 lbs foot came uncliped mid-air, landed hard on seat resulting in failure: <a class="postlink" href="http://www.amazon.com/review/RJVQMPRI1ILDY/" onclick="window.open(this.href);return false;">http://www.amazon.com/review/RJVQMPRI1ILDY/</a>

Science. Aluminum tubes bend, especially with a force applied in that direction.

Tried to dig up dirt on the Fox DOSS, but came up empty.
- This guy said he crashed on a 20' jump which bent the saddle, and the DOSS came out unharmed: <a class="postlink" href="http://www.bikerumor.com/2014/02/19/review-foxs-ultra-smooth-d-o-s-s-dropper-post/" onclick="window.open(this.href);return false;">http://www.bikerumor.com/2014/02/19/rev ... pper-post/</a>
- This guy bent his DOSS remote twice, with it mounted on top: <a class="postlink" href="http://bicyclingaustralia.com.au/2013/03/latest-dirt-fox-doss-dropper-seat-post" onclick="window.open(this.href);return false;">http://bicyclingaustralia.com.au/2013/0 ... -seat-post</a>

I busted my Reverb remote a little too (it's almost $100 to replace). The rectangular button/cap on the lever rotated on a slow speed crash (I fell, slowing down behind slow XC guys at Big Bear on a descent), and now it spins with only a little resistance and rattles a bit. Was mounted on top. It was one of those bails where you just drop the bike and the front turns into the ground.

Just in case someone wants to chime in with their "favored post", being proud that it's not listed above...

There was reports of KS dropper post issues too. I recall many talking about the seat rail clamping bits failing and other talk about sag.

Reports of Command Post losing air (return spring force) over a very short time, needing more frequent fill-ups than their tires.

Can see where the weight goes in these posts, with the weight of Fox going towards durability/reliability and RockShox trying to trim weight to offset all the internals jammed in there.

 

[Redman]

Any chance you have your saddle mounted so the clamp is more toward the front of the saddle? That would allow a fair amount of leverage on the post, not to mention the saddle rails. Whenever someone says they continually bend saddle rails, more often than not, they have the saddle mounted like that. If your seatpost/saddle clamp has some rearward offset, that only compounds the issue.

My seat is pushed back. but not to that extreme. and there is not set back on the saddle clamp location.

The LBS did mention that it seemed the post was bent to the side. not directly back, in line with the bike. But, they weren't sure as they had the post removed from the seat tube when they realized it was bent.

 

[Varaxis]

You are a badazz mountain biker. Only force I foresee to bend a post is a slam on some negative "G's"...

Almost missed this. Surprised this came from someone working on aviation related stuff. Unless I misunderstand how you used the term negative Gs, and mean what typically happens after experiencing negative Gs (usually positive Gs). Hucking to uphill might result in 4+ Gs, which is effectively 4x his weight, and hitting the seat with that instead of it going through the BB/rear and fork means the thin seatpost tube eats it.

A suspension system typically is tuned store/damp 300-450 lbs of force (1350-2000 N) assuming conservative sag (25-30% rear, 20-25% front), with the Newmad tuned more on the progressive side to allow for deep sag or big hits. Still 4Gs for him would be 800 lbs, which should be split up evenly and stored in the spring of each side, to be handled graciously. A big difference compared to a lighter rider, 140 lbs putting out only 560 lbs of force in the same scenario.

Off-topic, but somewhat related, 1350 N ain't enough for my skinny ass. Have to reduce the volume in my shock's air spring quite a bit to get the spring rate curve to ramp up enough. Should probably pay attention to the forces chart a bit more:

Nomad, big hit monster:

Enduro 29, plush trail/AM machine:

SB5c, balanced trail/AM machine:

Forces chart is basically what the suspension model looks like after you combine the shock rate (AKA leverage ratio) curve with the stock shock's spring rate curve. Surprisingly, the industry finds the majority of casual riders actually are more comfortable on the "wallowy" mid stroke, demanding damping to handle the resulting wallow, as opposed to a more linear stroke (see Jekyll, designed for Enduro racer instead of riders used to susp designs of old). In these charts, 25% sag is set for a 175 lb rider, on a AM bike with 60/40 rear/front balance (or 20% sag for a XC/trail bike). Gotta say the SB5C curve is sweet, only going to get better with the EVOL air spring for those that care more for support than plushness.