MetinUz

So, we are just riding along main street, and my friend's 1980 Trek 610 suddenly decides to stretch into a low-rider. Did I mention that this was at mile 250, just steps away from our overnight stop, having descended over gravel and potholes all day, hitting 40+ mph? If this had happened during a descent, my friend would be in the hospital, or worse.





It is quite possible that this started as a hairline crack and grew slowly until it suddenly broke apart. I would like to believe that it could be caught with regular cleaning and inspection, but I am not sure. In any case, give those forks a good inspection every now and then.

U5512

Wow! Glad your friend is OK and wasn't injured.

DVC45

Be glad it was a steel fork. If it was carbon, it would have just snapped.

oddjob2

Glad no one was injured!

Looking at the dirt, it appears that the fork bearings haven't been serviced and there is a lot of rust at the fork crown. That rust didn't build up in only a few months.

repechage

The lack of bright shiny metal at the tear indicates to me that it was cracked for quite a while.

So yes, there is a reason to clean a bike periodically and inspect things.

An interesting failure for sure. As both blades appear almost equally torn, the problem began with the mfg.

kunsunoke 

Kinda hard to tell what caused this without having the fork to see the progression of the metal failure. Looks like there was a pre-existing crack at the juncture between the blade and the investment crown, and that the ninja-style riding you guys were doing that day was too much for the fork to handle. As others have already stated - if this had been carbon your bud would need new teeth.

SJX426 

I agree with @repachage concerning the bright metal and age of the crack. Hard to state what inititiated the failure. If the reason was a faulty casting of the crown, there would be some indication of a stress riser. I would not expect uniformity between both sides! there should be some bright metal showing to indicate how far the crack propagated prior to the failure. Comparing both sides would be interesting too.

This is not the Tange crown found on '84 610 Treks. Can someone confirm this is a Trek fork of 1980? Come to think of it, its a stupid question as the paint looks original and only one application!
Is there any paint discoloration around where the initial crack might be?

Dave Cutter

Nice to read I am not the only cyclist out here that washes his bicycles. I think that the washing/inspecting is the only way I'd ever catch any damage or defect that doesn't make noise.

Bummer to see the damage. Glad no one got hurt!

Chrome Molly

Did the casting break on one side, and the blade pull away with no casting break on the other side? It's a little scary to have two kinds of failure on the same fork. If so, the left side was probably holding it together for years based on the discoloration.

Considering 1980 was almost 35 years ago, that's reasonably decent service life. Not saying it shouldn't last a lifetime, but that's a lifetime for most bikes these days. Your friend was very lucky that it didn't come apart at full speed. I wonder what the true service life will be for full carbon forks.

The Golden Boy 

I'm glad your friend wasn't injured.

The Golden Boy 

According to the Vintage Trek catalogs- there wasn't a 1980 600 series bike- they came about in 1981- and the fork and crown were Ishiwata.

bikemig 

That could have been a heck of a bad accident. This is the reason why I don't opt for the lightest possible frame or handlebar or stem for that matter.

jbchybridrider 

Check your frames - it's not just carbon that breaks!

Olympia's don't break they just go faster!! .......... Glad no one was hurt.

StanSeven

Carbon snaps after it's damaged. In other words it would have been in a prior incident which sends up a flag. So if you have a carbon fork and know its history, it just wont snap.

jimmuller 

Frightening failure. Glad no one was hurt.
This quote makes an interesting point. Apparently your friend has been mistaken about the bike's identity for a while. Of course anyone can misremember a bike's age (I only think I remember when I bought my UO8), but if he is not the original owner then whoever sold it to him may have mislead him accidentally or on purpose. Which is to say it behooves us all to take an active interest in our bikes' histories. And do the maintenance of course.

SJX426 

... and inspect all purchases, during and afterwards for the details. It is surprising what you didn't see at the purchase time that you find when you tear down after taking it home.

Based on my long time interest in Jeep Cherokee's, I have created a list of over 50 items to check when looking at a perspective purchase. Even though the model was produced for something like 15 years, there are certain years where there are problems you should expect to find, i.e. 1998 - all the power windows work from the drivers seat but not from each door! Problem is a solder joint that fails on the PCB in the drivers door. Touch it with a solder iron and its good. Getting to the joint is the challenge! Might be more fun in Washington and Colorado, but will take longer!

repechage

My position is no used carbon. For just that reason, one does not know the history.

I would not have considered carbon for a fork before they industry evolved to using a tapered steerer, I did not like the concept of a 90° abrupt turn to the fibres.
If you notice the distance from the axle to the crown race seat on a typical recently designed carbon fork/frame set extends the distance between the tire and the bottom of the head tube.
Everyone is learning.

kc0yef 

You Tore through the lug impressive

brianinc-ville

Yikes! Glad nobody got hurt.

rowebr

Is that the Ishiwata CCL fork crown? I think @thebulls described a similar fork failure on a Trek with that fork crown, maybe he can chime in and tell us.

jeirvine 

Yup. Here:
https://www.bikeforums.net/long-dista...l#post15322546

"AVOID '81 Trek 610/613/614 and '82 Trek 613/614 because the Ishiwata CCL fork crown does not have a proper lug point so it is a failure vector."

Edit: the knowledge base here never ceases to amaze me. Thanks.

John E

I have broken three steel frames, never catastrophically, but fortunately never any part of a fork assembly. Yes, it is good practice to inspect framesets, rims, hubs, seat posts, handlebars, stems, etc. for hairline cracks or even deep scratches.

thebulls

I think the bike in the OP's photo is an '81 600 series Trek -- the '82's and '83's were not made in that color, and the headtubes were painted a contrasting color, which this isn't.

The failure mode looks exactly the same as my '82 Trek 614.

My statement about "does not have a proper lug point so it is a failure vector." is a little cryptic. If you look on the inside of the leg on any well-made bicycle, the fork crown lug either has a lug point that extends down the leg, or is at least semi-circular. That's to prevent a stress-riser at the fork crown. On those Ishiwata CCL semi-sloping fork crowns, the lug is perfectly horizontal on the inside of the fork leg. That creates a stress riser, which results in more metal fatigue at that point, increasing the likelihood of eventual failure. That's what it looks like on the left leg of the bicycle in the OP's photo--horizontal tear in the leg. We can't see the inside of the right leg, but I bet it looks the same.

On my Trek 614, I was riding to work and the front end felt like it was more "flexy" than usual when I stood on a hill, and I found the crack before it caused a problem. I rode home and took the front wheel off and discovered the crack. I tore one of the fork legs off by hand but left the other there so you can see how the crack developed. You can see that there is some rusting inside the leg, but the rust is not a contributing factor, it's just surface rust. The crack had developed for some time, as you can see in DSCN1251 to the inside-rear of the torn-off right leg. But the metal is still bright in the front of the crack and all around the outside of the leg.

SJX426 

AHHH DESIGN Defect! Repeatable too!

JohnDThompson 

It's not a cast crown, but a stamped, folded, and welded crown. The failure looks like it may have been caused by overheating during construction. FWIW, those forks were brazed in Japan, not Waterloo, and shipped to Waterloo unpainted to be mated with frames. All the Waterloo built forks used investment cast crowns.