Mountain Bike Reviews Forum banner
1 - 20 of 31 Posts

·
local trails rider
Joined
·
12,300 Posts
Discussion Starter · #1 ·
Just saw a report from yesterday's easy group ride that one of the guys had a pretty serious mishap when his RS Reba came apart on an easy trail at about 20mph. Fortunately it was in a place that the ambulance could reach quickly.

Anybody want to speculate on how that could have happened?
 

Attachments

·
Registered
Joined
·
3,159 Posts
perttime said:
Just saw a report from yesterday's easy group ride that one of the guys had a pretty serious mishap when his RS Reba came apart on an easy trail at about 20mph. Fortunately it was in a place that the ambulance could reach quickly.

Anybody want to speculate on how that could have happened?
Snap ring not properly seated.
 

·
local trails rider
Joined
·
12,300 Posts
Discussion Starter · #4 ·
Update from hospital:
broken jaw and his teeth went through his upper lip. He cannot remember anything about what happened...
 

·
local trails rider
Joined
·
12,300 Posts
Discussion Starter · #6 ·
At least his neck, spine and teeth are OK....

Apparently, the fork had lost damping and they'd increased pressures to make the bike ridable. As I recall from riding with him a few times, he's not at all a heavy guy (like me...).

Those Wednesday rides are sort of "official" newbie/recovery rides, so they mainly stick to the easier trails and keep the pace relaxed.
 

·
Registered
Joined
·
9,592 Posts
Can somebody give even more info on exactly what failed

I've never imagined my (1) Reba or my (2) Revelations or my (1) Pike could ever separate like that. Is it just that fatigue of some parts takes its toll? Is there something that can be checked periodically to avoid this?
 

·
Super Moderator
Joined
·
20,810 Posts
xcguy said:
I've never imagined my (1) Reba or my (2) Revelations or my (1) Pike could ever separate like that. Is it just that fatigue of some parts takes its toll? Is there something that can be checked periodically to avoid this?
the snaprings that Ratt and I are talking about are the ones shown in these images of the Service Guide

 

·
Registered
Joined
·
9,592 Posts
So that little bitty snap ring is all there is?

That's what's holding the whole fork together? That one little part fails and your stanchions pull out from the lowers? Isn't there the moral equivalent of "lawyer tabs" somewhere in there?
 

·
Super Moderator
Joined
·
20,810 Posts
xcguy said:
That's what's holding the whole fork together? That one little part fails and your stanchions pull out from the lowers? Isn't there the moral equivalent of "lawyer tabs" somewhere in there?
well...in a way, yeah.....the 2 of them would have to break and the rebound and air rod have to pop out... very hard but definitely possible. that's probably the loss of damping that perttime's friend noticed before it happened...

actually when I got my Pike one of them was broken..and I only noticed because the lockout didn't work as the oil went into the lowers...
 

·
local trails rider
Joined
·
12,300 Posts
Discussion Starter · #12 ·
I don't feel like asking a lot of questions (these guys are not like "friends", just guys I sometimes meet on the trails) but I've been seeing some stuff here that probably contributed.

I found a thread at a local forum where he had taken a Reba SL apart, after spotting some wear marks on the stanchions about two months ago (pic in post 8 here: http://www.fillarifoorumi.fi/forum/showthread.php?t=30524 ). Sounds like he has the right tools and does his own oil changes and such.

- There was a problem with damping now.
- They increased pressures (beyond spec???) to make it "semi-rigid".

now the guesses: things were under a lot of tension inside the fork - you have a little bump (there's always some) - one thing fails - the next thing fails - fun is over...

Lesson one, I think:
- If your fork is not working as it should, stop, find out what it is, fix it. Dont rig something to get "just one more ride".
 

·
Registered
Joined
·
8,308 Posts
perttime said:
I don't feel like asking a lot of questions (these guys are not like "friends", just guys I sometimes meet on the trails) but I've been seeing some stuff here that probably contributed.

I found a thread at a local forum where he had taken a Reba SL apart, after spotting some wear marks on the stanchions about two months ago (pic in post 8 here: http://www.fillarifoorumi.fi/forum/showthread.php?t=30524 ). Sounds like he has the right tools and does his own oil changes and such.

Lesson one, I think:
- If your fork is not working as it should, stop, find out what it is, fix it. Dont rig something to get "just one more ride".
OK, so he worked on his fork, that answers part of my question.

Not to mention that the snap rings are part of a rebuild kit. If you take it apart often, you should replace those, as they are not meant to be taken on/off many times.

BTW, the wear marks on the stanchion is another factor that points to something being wrong with the fork that could have compounded this over time. IIRC, I have never seen any reports of that issue other than 5yo forks from almost any mfg, which this Reba isn't. It is most likely indicative of a bushing wear issue that would have caused significant forward play in the fork.

Hope he is OK.
 

·
Super Moderator
Joined
·
20,810 Posts
perttime said:
- There was a problem with damping now.
- They increased pressures (beyond spec???) to make it "semi-rigid".

now the guesses: things were under a lot of tension inside the fork - you have a little bump (there's always some) - one thing fails - the next thing fails - fun is over...

Lesson one, I think:
- If your fork is not working as it should, stop, find out what it is, fix it. Dont rig something to get "just one more ride".
Agreed!

my guess: since the lost of damping is from the right leg...it could be that the right circlip failed first (losing damping) and then the higher air pressures sure put even more strain on the left circlip....add a couple of bumps and BOOM..
 

·
Registered
Joined
·
6,762 Posts
The first indication that...

something was wrong was unusual wear on the stanchions. The mistake was likely made in reassembly after taking it apart for inspection. Those snap rings are directional. They have a beveled outside edge and a flat sharp edge on the oposite side. The sharp edge should always face out towards the lowers, the beveled edge in towards the damper or spring. If you get it backwards with the beveled edge facing out the pressure from the springs and the resistance of the compression damper could cause the rings to work their way out of the slot they are in. From there the second and biggest clue to STOP was the loss of damping. I would say the damper side ring had popped out and allowed the damper rod to extand beyond the bottom of the stanchion and drop all the oil into the lowers. Now you only have one c clip holding the whole fork together! The BIG mistake was in increasing the air pressure to compensate for the lack of compression damping. That put even more stress on the spring side c clip, and probably pushed it to the failure point.

CharacterZero, no the foot nuts wouldn't need to strip out. They're likely still bolted to the lowers and in fine shape. The only thing that holds the camper rod and the spring piston rod ini the bottom of the stanchion are those c clips. If the clips fail the rods are fee to pop out of the bottom of the stanchion tubes and remain attached to the lowers. They'll be sitting inside the lower legs still botlted on!

But rest assured that Rock Shox and Marzzochi have been using the c clip retention system for the srping and damper rods for many many years. I've only seen two instances of seperation like this ever in many years of riding. And both were the result of getting those clips in backwards!

This was most likely caused by a series of errors, both technical, and a couple of errors in judgement. .

I'm not bagging on the guy it happened to. I'm glad he's going to be okay, and I hope he heals fast. Not a good thing to happen to anybody.

The bottom line is don't get paranoid over your RS fork. If you do your own maintenance work then just make sure you get those c clips back in the right way, and PAY ATTENTION to what your fork is telling you as your ride. If it ain't acting right, RIDE OUT SLOWLY!!! Get it home and find out what's going on. It's better to suffer a busted ride and some down time than it is to break your neck!

Good Dirt
 

·
local trails rider
Joined
·
12,300 Posts
Discussion Starter · #16 ·
That makes sense to me, Squash.

I started this thread in hope that there's a lesson to be learned in this mishap. Clearly there is.
 

·
Registered
Joined
·
1,610 Posts
I wonder how come the front brake cable didn't keep the lowers from separating? Too long maybe. Also, I'm surprised that the stanchions aren't bent backwards if he went down at 20mph.
 

·
local trails rider
Joined
·
12,300 Posts
Discussion Starter · #20 ·
A couple of more details:
The fork was pumped up to around 130 to 150psi.
It was making clunking or rattling noices just before the crash.
 
1 - 20 of 31 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top