sibex/spicer fork failure!!!!

[joeywv]

this is pic of my buddy gerry's fork. the fork is a spicer labeled sibex fork. it snapped at a race here in wv on sunday. the fork was about a year old. gerry is probally about 150lbs and the course was definantly not to blame. gerry skewered his arm on the fork leg and suffered a compound fracture and severed the tendons that control his fingers. he has a long hard road of recovery ahead of him. anyone else have this happen? i realy feal super bad for gerry. he is a fast dude. is the defending police games world mtb champion and finished up second in the wvmba series last year. he also a great spokesman for the 29" wheel revolution.

[Enoch]

A friend of mine snapped on at the crown race. His was less than 3 months old. He was a 170 lb. rider. Unacceptable and very dangerous.

[ihatemybike]

That is super scarey. I hope he heals up OK.

[carter1]

Holy Crap! I am sorry for your friend, our prayers will be with him for recovery.

I weigh 215 and have a Sibex on my Jake the Snake cross bike. I guess I should start looking for something else-now.

c

[jfkbike2]

I had one once, rode it once and it flexed so much it scared the hell out of me and I sold it on ebay right away. Buyer beware on this fork IMHO.

[rockhound]

Can you post a pic looking up at the crown, showing the fracture surface?

[ncj01]

I once had one of those on a bike I owned - or was in my possession to be technical. On dry pavement, I could apply the front brake and the fork would bend in-wards a good 3-4 inches. That was under firm braking, but not even enough to make the rear wheel come up. It seemed a little scary, but I took it to just be the "compliant" nature of the fork. I never off-roaded it.

[teamdicky]

Broke right at the welds on the crown. Eeessshhh!
I sincerely hope he ends up OK.
Is someone looking into these problems, or are the riders just being given new forks ( that they will never trust enough to ride)?
I almost bought a 29'er Sibex/Spicer before I went with a steel WW forks. I definitely don't regret it now.

[dRjOn]

it has to be said, not an uncommon failure it seems...tho' didnt they mention beefing up the tubes at some point? is the fork an older one?

and of course, hope the path to recovery is uneventful and short...

[CJones]

<< anyone else have this happen? >>

This is a well documented failure. Do a search on here and the singlespeed forum and there is story after story about people breaking these forks. I'm suprised they even still sell them. Sorry about your friend. His injuries sound pretty bad.

[mgersib]

Originally Posted by carter1

I weigh 215 and have a Sibex on my Jake the Snake cross bike. I guess I should start looking for something else-now.

c

That's a very good idea. I've not had the displeasure of breaking one of these forks personally, though I've heard reports of their failures in-use dating back several years. It's no secret in many circles that those forks are dangerous and unsafe.

It sucks that stuff like this has to happen to get the word out... Joeywv, I hope your friend heals quickly, and that he's back on the bike soon. That had to be a very scary couple of moments for him.

[Cloxxki]

Wasn't Spicer working with Changda in China, while Sibex is russian made?

I'm sorry about the loss and injury. Slso that it was a Spicer, not a Sibex.

[lanpope]

Not trying to defend XACD/Spicer, but I rode one of their forks for about 2 years w/o any problem. I ordered a frame (which broke) and fork directly from XACD 3 years ago and when I did I speced a larger diameter wall thickness in the fork blades and crown. Of course I have no way of verifying what the wall thickness actually was on the fork. It was light (about 630 grams cut to length) and flexy.

I rode it hard for 2 years not holding anything back and never had a problem. I traded it to a forum member who rides rigid exclusively and was curious about its perfomance. The fork did not fail under him, but I believe he sold it due to the flex.

All that said - I ride steel forks now.

I've got no hard feelings toward XACD - the whole design process was fun and it was neat to ride something that I alone designed. It sucks that their stuff doesn't hold up.

LP

[Fastskiguy]

It always gives me pause when I see something like that and especially to hear about the injuries, yikes! Lots of times I think "gee, lightweight this" or "super trick that" but then I see a pic of something broken and think....hmmm, maybe the KM fork for this 200 pounder might just be the best. stout. firm. prolly will bend before snapping. what's the failure mode of carbon fiber? Now you've got me worried about my road bike!

Best wishes to your buddy, if hope from strangers can help I am sure he's got a lot coming his way.

[Rainman]

I've seen a few of those forks broken. Not nice. I hope that the guy heals up quickly.


R.

[TheRedMantra]

Thats why when I ordered mine from XACD I asked for thicker walls. 150g+ but peace of mind (and surprisingly no upcharge).

[mvi]

Aren't Manufacturers insured for things like this?

[Soupboy]

Originally Posted by mvi

Aren't Manufacturers insured for things like this?

They should be but if they're foreign it may be a hornet's nest. The next dude in line to get sued is the distributor/LBS, Spicer, which I'm sure carries some form of liability insurance but then all of a sudden you're suing a little shop for a faulty product they re-sell. A significant negative outcome for them may result in premium increases than render their business model moot.

Difficult spot for everyone. Best wishes to Gerry on a fast and full recovery. As bad as he's hurting, just looking at that fork it could have been much worse.

At my weight, not even in my drunkest moment would I plausibly consider a Ti or CF fork. Also, I'm so slow I've got another built-in layer of self-defense.

[Disco_Inferno]

But I have to point out, there isn't one drop of blood on that fork or frame, not even a skin shaving on the fork tubes much less a plug of meat from where fork tube "skewered" his arm. No hair, no bone fragments, no clothing fibers, no nuthin. Compound fractures bleed HEAP BIG, and any piece of jagged metal that rips the flesh deep enough to sever tendons and bust bone will have visible signs of DNA hanging all over it.

Nothing disrespectfull, just an observation.

[dRjOn]

what? for goodness sake that is just crap. if he fell and compound fractured the bone is much more likely to have done the severing...what an inane (not insane) thing to say....

[SanAnMan]

I had heard the XACD forks had been improved since a rash of failures a few years ago. This pic date is from May 2004. I have no idea who’s fork or bike it is in this pic.

[None]

Originally Posted by Disco_Inferno

But I have to point out, there isn't one drop of blood on that fork or frame, not even a skin shaving on the fork tubes much less a plug of meat from where fork tube "skewered" his arm. No hair, no bone fragments, no clothing fibers, no nuthin. Compound fractures bleed HEAP BIG, and any piece of jagged metal that rips the flesh deep enough to sever tendons and bust bone will have visible signs of DNA hanging all over it.

Nothing disrespectfull, just an observation.

30 years ago I had a motocross wreck that left me with a compound fracture of both bones on my right arm and a broken wrist That memory still hurts! However there was just the slightest amount of blood loss that could have been cleaned up with a Q-tip!
I too (being a gore seeker) looked for signs of DNA refrence the "skewered" statement and just assumed it was uhhh...PG'd for everyones sensabilities.
FYI, I ran one of those Spicer forks on my 26er ss for a couple years and it does sorta make you wonder with the amount of movement that thing has. It never failed on me and was sold with the bike. Wonder it the current owner is still running it? I hope not!

[joeywv]

Originally Posted by Disco_Inferno

But I have to point out, there isn't one drop of blood on that fork or frame, not even a skin shaving on the fork tubes much less a plug of meat from where fork tube "skewered" his arm. No hair, no bone fragments, no clothing fibers, no nuthin. Compound fractures bleed HEAP BIG, and any piece of jagged metal that rips the flesh deep enough to sever tendons and bust bone will have visible signs of DNA hanging all over it.

Nothing disrespectfull, just an observation.

there is blood in the left fork leg, not visible on the pic. my wife looked in the fork after the race and made a comment about the corrosion in leg, it wasn't corrosion it was a large amount of dried blood. my buddy andy was riding with gerry at the time of the incident and said gerry was bleeding profously. i do not think the fork went clear through his arm but rather inserted into his arm breaking the bones and cutting the tendons.

[None]

Originally Posted by joeywv

there is blood in the left fork leg, not visible on the pic. my wife looked in the fork after the race and made a comment about the corrosion in leg, it wasn't corrosion it was a large amount of dried blood. my buddy andy was riding with gerry at the time of the incident and said gerry was bleeding profously. i do not think the fork went clear through his arm but rather inserted into his arm breaking the bones and cutting the tendons.

SEE!!! It was better when I did'nt know that!!! Best wishes for a complete and speedy recovery!

[paqrat]

That was me. The fork was also about 3 months old, and that happened while riding over a logpile - no freeriding. Luckily, my injuries were only a mild scab on my knee. People were quick to blame rider weight, but 2 other locals with the same vintage fork broke theirs shortly after mine (and one weighed 140 lbs). I thought it was possibly a quality control problem at XACD.

Before I shipped it back to Gene, I had the resident metallurgist at work check it out - his guess was a contaminated weld (oxygen got to it). Gene Spicer was excellent with customer service, so I have no complaint against him. But I wouldn't put a lot of faith in XACD after seeing this issue creep up again 2 years later.

A little trivia - the van in the picture is also on Matt Chester's website gallery. I'm one of the few left on his queue for a 29"er Mutinyman.

[jowale]

so I'm confused, are these spicer forks contracted out to china, or the russian made sibex forks, PLEASE CLARIFY thanks a lot, hope he has a quick recovery

[2xPneu]

Oops, double post.

Trying to get my count up.

[2xPneu]

Originally Posted by paqrat

I'm one of the few left on his queue for a 29"er Mutinyman.

There's more of us than you think...

Regarding the fork, James of Black Sheep has the ti fork thing worked out pretty well, a lot of people are riding them, including me (I've got 2) with absolutely no problems that I know of. I hammer mine as hard as I can take it with no issues at all.

Plus he'll have it to you in far less than three years.

[MtotheF]

Originally Posted by jowale

so I'm confused, are these spicer forks contracted out to china, or the russian made sibex forks, PLEASE CLARIFY thanks a lot, hope he has a quick recovery

the spicer forks are made by XACD in china, not sibex in russia. as has already been mentioned elsewhere in this post and others, there are different thickness fork legs available from XACD, and there is a wide variety of length options as well. however, there are more than a few documented failures of very light XACD forks. enough to make people nervous.

for my part, i ordered a suspension corrected fork from gene spicer, as light as he was comfortable going. 470mm axle to crown. my rider weight at the time being about 180lbs. gene went so far as to tell me that he wasn't entirely comfortable with the length at that light weight a tubing, and that i shouldn't get too gung ho about bunny hopping or jumping. at gene's end, the service and delivery and communication was first rate.

but the fork was scary. it tracked like a drunk squirrel, flexed backwards far enough under brakes that the front wheel would almost contact the downtube, and after about five rides had taken a 6mm reduction in rake. titanium has to be bent a hell of a long way to take a different set, and that alone scared me enough to relegate the fork to mantlepiece curiosity. i wouldn't say that anything was XACD's or spicer's fault in this matter. i was testing the envelope of how light i could safely go. and i found the edge without getting hurt, fortunately.

so, pay attention folks. for each and every one of us, given our different riding weights, riding styles, types of terrain, and types of bikes, there is a limit to how much weight we can shave, or how geeked out we can get in pursuit of bling. going beyond the known and sensible, it gets easy to cross that invisible line and go straight to victim...

[snowdrifter]

Spicer, and or Sibex @ 600 grams is stupid light for any serious offroad ripping.

[F5000sl]

What's interesting is that both pics so far show very similar contours/waves to the breakage, and they both even show similar breakage contours in relation to the area of the fork.

Here's to best wishes that your buddy heals fast.

[pimpbot]

Originally Posted by joeywv

this is pic of my buddy gerry's fork. the fork is a spicer labeled sibex fork. it snapped at a race here in wv on sunday. the fork was about a year old. gerry is probally about 150lbs and the course was definantly not to blame. gerry skewered his arm on the fork leg and suffered a compound fracture and severed the tendons that control his fingers. he has a long hard road of recovery ahead of him. anyone else have this happen? i realy feal super bad for gerry. he is a fast dude. is the defending police games world mtb champion and finished up second in the wvmba series last year. he also a great spokesman for the 29" wheel revolution.

So how's your bud doing 9 months later?

Hope he's recovering.

[Secret Squirrel]

I also hope your friend recovers fully and quickly. I had my credit card in hand for one of those things but my local shop talked me out of it. If you do a little looking, you can find a number of similar pictures out there. Each one will scare you a little more and the next thing you know you're back to steel.

[John_Biker]

I used to import XACD product under the name "Vanguard Titanium." The frames were safe, mostly to my design and using .9mm straight gauge titanium. The forks were another story. We got two forks from XACD, of their design. Very light and flexy. One of our customers broke his at the crown race area, JRA. We recalled them both ASAP. XACD denied it ever happened, even after I sent the fork back to them. I ride a Waltworks steel fork now. I'm pretty firm in my belief that steel is a better fork material than titanium.

[Chest Rockwell]

I wonder if the forces exerted by a disc brake may have been a contributing factor. With the front brake engaged, the tendancy for the fork would be to "curl" under the frame, putting a tremendous amount of stress/strain at the end of the tubes at the weld.

Would a linerar pull have the same effect? I wonder...

[MtotheF]

Originally Posted by Chest Rockwell

I wonder if the forces exerted by a disc brake may have been a contributing factor. With the front brake engaged, the tendancy for the fork would be to "curl" under the frame, putting a tremendous amount of stress/strain at the end of the tubes at the weld.

Would a linerar pull have the same effect? I wonder...

the rearward force on the fork is a result of the bike trying to overtake the front wheel after the brake is applied.you should be able to generate the same amount of axle deflection, provided the traction is the same, with either a rim or a disc brake...

[juansevo]

Neither fork company seems to have a very good reputation for reliability. I'd steer (no pun intended) clear of either companies product. Especially when Pace, White Brothers, and On-One make nice carbon models with no failures to date.

[Secret Squirrel]

I would disagree with you there. With a disc brake, all of the forces come into play at the end of the fork near the dropouts. With a rim brake a good deal of the stress would occur at the point where the brake bosses are mounted to the fork, that is the hub would push the dropouts toward the rider, and the rim/brake interaction would pull the bosses away from the rider resulting in a reduction in the amount of torque applied to the crown since a good deal of the force is applied at point much closer to the crown itself. I'm not an engineer, but thats how I would see it.

[Chest Rockwell]

I'm not so sure about that.

I'm not JPL scientist, but I believe that the torque exhibited at the crown of the fork will be significantly higher with a disc vs cantilevers.

Assume for the sake of argument:
18.5 inch (470 mm) long fork
71 degree head/fork angle.
The same force (F) will be needed to slow or stop the rider using either brake
Disc forces acting at bottom of fork
Canti forces acting 350 mm from bottom of fork

The braking force necessary to stop the rider will be the same, so it is a simple matter of moment arms and torque.

1) Imagine a line 470mm long at an angle of 71 degrees.

2) Drop a plumb line straight down from the top, creating a triangle with 90, 71, and 19 degree angles.

3) Measure the side opposite to the 71 degree angle. The length of the side from the top of the "fork" to the floor should be 290.7mm. This is the moment arm of the disc brake.

4) Along that 470mm long line, mark a point 350mm up from the bottom of the line.

5) Now draw a line that will intersect the plumb line at a 90 degree angle. You will notice that the new triangle has the same angles and is only a smaller version of the first.

6) Measure from the top of the "fork" to that point of intersection. That distance should be 74.6mm. This is the moment arm for the cantlever brakes.

Disc arm = 290.7mm (11.445 in ~ .954 ft)
Canti arm = 74.6mm (2.937 in ~ .245 ft)

The moment arm for the disc is 3.9 times greater than that for cantilever brakes.

Using 150 pounds as a stopping force, the resultant torque at the top of the "fork" is going to be the moment arm times 150 pounds.

Disc: 150 lbs * .954 ft = 143 lbf torque
Canti: 150 lbs * .245 ft = 36.8 lbf torque

If I am wrong then I will humbly admit it, but I really think that I'm correct.

[MtotheF]

i've lost plenty of arguments on this front, so if i'm wrong, i'll humbly take it. but for now, i'm gonna stick to my guns.

if we are talking about the REARWARD deflection a fork is subject to under braking, then i don't think it matters one bit where the braking action is occurring. the things to take into account are the contact patch and amount of traction, the flexible length of fork (in this case the bit between crown and axle), and the fulcrum point (the axle).

all the decelerative force is being channeled through the tire contact patch. all your forward momentum is being pushed through the fork crown. the place where things are going to move is the axle, regardless of where the brakes are positioned. the fact that a rim brake is operating from further up the leg doesn't change the decelerative force, nor does it change the tire contact patch or the position of the axle.

again, i'll gladly sit down and shut up as soon as enough of you call me an idiot...

[Law]

Originally Posted by snowdrifter

Spicer, and or Sibex @ 600 grams is stupid light for any serious offroad ripping.

Black Sheep ti forks are in the low to mid 600's. I have yet to see any of those broken. I have had one for about a year. I quite like it. DIfferent type of crown though than what is on this broken fork--not segmented.

[Thylacine]

100g of Ti is a lot of Ti, especially in a unicrown as opposed to segmented which is by it's very nature heavier and weaker.

[mward]

But sexier.

[okie_calvin]

Originally Posted by MtotheF

i'll gladly sit down and shut up as soon as enough of you call me an idiot...

You're too damn funny too damn often and right almost always. Please continue!

[monogod]

Originally Posted by MtotheF

i've lost plenty of arguments on this front, so if i'm wrong, i'll humbly take it. but for now, i'm gonna stick to my guns.... again, i'll gladly sit down and shut up as soon as enough of you call me an idiot...

i wouldnt take your seat just yet...

i rode one of these for a VERY short time. basically just long enough to be scared to death by the "drunk squirrel" handling while hauling balls, and also to actually touch (more like slam) the front tire to the downtube under extreme braking.

my sibex ti fork was v, not disc. the curvature/disfigurement of the legs while flexing during braking was enough to cause the trailing edge of the brake pads to rub on the sidewall of the tire, which very clearly demonstrates the force acting upon the fork legs was NOT originating from the point on the fork at which the v-brakes were mounted.

as to the fizucks of it.... a bicycle fork is a first-class lever. that is, a lever in which the fulcrum is located between the input and output force to act upon a load. the fork legs are the levers, the crown is the fulcrum, and output force directed to the steer tube (which is stabilized by the headset) which tries to act upon a load (bike and rider).

input force is applied at the axle causing the lever (fork legs) to bend when they cant overcome the resistance of the load (lifting the bike/rider up) at the fulcrum (crown) as the output force is applied to the steer tube via the fulcrum (crown).

the brake merely acts upon the wheel to decelerate it (regardless of where it is located) and the resulting force is then transfered to the lever (fork leg) via the axle (end of the lever).

it breaks at the crown because the force being applied to the lever is not great enough to act upon the load (the bike and rider) but is greater than the material's structural integrity at the fulcrum. under breaking the force load upon the lever is so great that it causes the lever to bend, which is why the frickin front wheel tries to hide under the bottom bracket on these wet noodles. the repeated force being applied to the fulcrum overcomes the structural capability of the material at this point resulting in fatigue and failure.

[Thylacine]

And to think even to this day I still find myself defending the importance of Design.

[Slimon]

Originally Posted by Chest Rockwell

I'm not so sure about that.

I'm not JPL scientist, but I believe that the torque exhibited at the crown of the fork will be significantly higher with a disc vs cantilevers.

Assume for the sake of argument:
18.5 inch (470 mm) long fork
71 degree head/fork angle.
The same force (F) will be needed to slow or stop the rider using either brake
Disc forces acting at bottom of fork
Canti forces acting 350 mm from bottom of fork

The braking force necessary to stop the rider will be the same, so it is a simple matter of moment arms and torque.

1) Imagine a line 470mm long at an angle of 71 degrees.

2) Drop a plumb line straight down from the top, creating a triangle with 90, 71, and 19 degree angles.

3) Measure the side opposite to the 71 degree angle. The length of the side from the top of the "fork" to the floor should be 290.7mm. This is the moment arm of the disc brake.

4) Along that 470mm long line, mark a point 350mm up from the bottom of the line.

5) Now draw a line that will intersect the plumb line at a 90 degree angle. You will notice that the new triangle has the same angles and is only a smaller version of the first.

6) Measure from the top of the "fork" to that point of intersection. That distance should be 74.6mm. This is the moment arm for the cantlever brakes.

Disc arm = 290.7mm (11.445 in ~ .954 ft)
Canti arm = 74.6mm (2.937 in ~ .245 ft)

The moment arm for the disc is 3.9 times greater than that for cantilever brakes.

Using 150 pounds as a stopping force, the resultant torque at the top of the "fork" is going to be the moment arm times 150 pounds.

Disc: 150 lbs * .954 ft = 143 lbf torque
Canti: 150 lbs * .245 ft = 36.8 lbf torque

If I am wrong then I will humbly admit it, but I really think that I'm correct.

I dont work at JPL either, but I do have 2 engineering degrees....I didnt check the math, but the theory is sound. He's right, Discs make a difference, its all about the momemt arm.

Reading about this crash scares the crap out of me. Good luck in the recovery.

[themanmonkey]

So with those calculations does it matter that the braking forces are mainly distributed up one leg with the disc and equally distributed between the two legs with the V-brakes? In my mind the force acting on the right side of the fork crown on the disc fork would be almost astronomically higher than the force on the crown from the V-brake fork.

I've ridden ti forks in the past and found them really squirrelly even when overbuilt. I've never ridden a ti fork with a disc brake, but the twisting that happens in lightweight steel forks I find kinda sketchy. Add that twisting flexing force to a material that loves to twist and flex and I don't see good things.
best,
MonkeyB

[Chest Rockwell]

It is true that there would be more force exerted on one leg than the other, but my point was not that discs caused the problem, but could have been a contributing factor to a greater degree than cants.

Clearly the material failed and there are almost an unlimited number of things that could have contributed to that failure at that point. Mine was only a simple supposition regarding the resultant forces of the two braking types.

After all that I just hope it does not happen to anyone else.

[monogod]

Originally Posted by Chest Rockwell

my point was not that discs caused the problem, but could have been a contributing factor to a greater degree than cants.

Clearly the material failed and there are almost an unlimited number of things that could have contributed to that failure at that point. Mine was only a simple supposition regarding the resultant forces of the two braking types.

its understood what the supposition was, however the error in the supposition was that the braking force was applied at the location on the fork of each different type of brake.

all of your calculations are sound IF the brake force was applied to the fork at the respective location of each brake. however this is precisely where the formula errs because that is simply not the case. the formula that was used does not find the variant braking force. its a sound formula, just the wrong one to determine variant braking force.

no matter where on the fork the brake is located or how it acts upon the wheel, the braking force applied to the fork legs is the same and it is applied at the axle.