# CRASH! front brake locked up



## Marko Polo (Feb 5, 2005)

Does anyone have an idea why the front brake on a dura ace brifter would lock up when going over a bump in the road?
Here's the scoop. I recently bought a new road bike, a Gunnar Roadie with a full dura ace set up. I bought the frame and components from the LBS and had them assemble it. The components were a take off from a new bike, supposedly never ridden, they look new. The frame is brand spankin' new.
I was on a group ride, cruising along about 20 mph or so when I hit a bump in the road. My front brake locked up and put me over the bars. No apparent damage to my bike but the front brake was locked up solid. When I got home, after a trip to the ER, I pulled the bike out of the van the brake was still locked up. I moved the shifter and squeezed the brake and then the brake worked fine. 
I'm going to be off the bike for a while, but now I question the shifter and what recourse I have. The bike only has 160 miles on it.

-Mark


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## andulong (Nov 23, 2006)

Are you saying that you never even applied the brake? Or are you sayin' that you applied the brake and then it locked up? I don't see how the brakes would lock up just riding over a bump. Maybe you have a defective/sticky mechanism? Not sure what sort of liability there might be? Might want to talk to an attorney if it is mechanical failure.


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## Marko Polo (Feb 5, 2005)

I never applied the brakes, I was riding on the hoods, hit the bump and I was airborn. The bump was nothing out of the ordinary, it wasn't even a pothole, just a small dip and rise in the asphalt. I think it's a defect.


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## Kerry Irons (Feb 25, 2002)

*Lockjaw*



Marko Polo said:


> I never applied the brakes, I was riding on the hoods, hit the bump and I was airborn. The bump was nothing out of the ordinary, it wasn't even a pothole, just a small dip and rise in the asphalt. I think it's a defect.


Please explain in more detail. For example, were the pads clinched on the rim and the cable slack, or was the cable taught and the lever slack? Is it possible the pads are adjusted to "high" and they grabbed the tire? What did you do to free up the brakes? Have you been able to detect any stickiness in the lever action? Can you reproduce the lockup?

It is rather hard to envision how a defect in the levers could spontaneously apply enough force to the brakes to put you over the bars. Where would that force come from? What you experienced sounds a lot more like picking up some road debris and having it jam between the tire and fork.


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## cosmo333 (Oct 5, 2005)

Since you hit a bump while on the hoods at the same time the brake locked the most likely cause would be the shift lever sliding down on the bars, the cable tightens as the lever moves down and the housing holds tight under the bar tape. Doesn't take much movement if the brakes are set tight. More common on carbon bars with a slick finish but if the lever wasn't tight enough and/or an odd placement this can happen on an alum bar too. When you moved the shifter the tension was released and the brake opened, probably nothing wrong with the shifter or brake. There's most likely a good mark on the bar from the clamp nut-inspect it.

At our shop we put carbon assembly paste under all bar clamps (carbon or alum bars) to give some extra grip and torque to spec. And check the spec for both the bar and clamp-you be surpised the varience in min and max spec for bars and shifters out there. Some bars have a max torque below the min spec of the shifter.


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## Marko Polo (Feb 5, 2005)

Kerry, when I picked my bike up off the road the brakes were locked up tight on the rim, the wheel wouldn't move and if memory serves the lever was tight. When I dropped my bike off at my house I pulled it out of the van and the brake was still locked. My front deraillieur was in the big ring but the chain was off, I shifted to the small ring and put the chain on and squeezed the brakes and they were fine. I'll admit I didn't do any real troubleshooting as I was in some pain. Tomorrow I'll go back over to my house and take a better look and see if I can recreate the problem.

Cosmo, I do have carbon bars, so I'll check for lever movement/marks.

I've built a few mountain bikes, all single speeds, and fixies in the past but this is my first "real" roadbike that's why I had the LBS build it up.

thanks for the info


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## Henry Chinaski (Feb 3, 2004)

cosmo333 said:


> Since you hit a bump while on the hoods at the same time the brake locked the most likely cause would be the shift lever sliding down on the bars, the cable tightens as the lever moves down and the housing holds tight under the bar tape.


From what he described that would be my initial guess as well.


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## Camilo (Jun 23, 2007)

cosmo333 said:


> Since you hit a bump while on the hoods at the same time the brake locked the most likely cause would be the shift lever sliding down on the bars, the cable tightens as the lever moves down and the housing holds tight under the bar tape. Doesn't take much movement if the brakes are set tight. More common on carbon bars with a slick finish but if the lever wasn't tight enough and/or an odd placement this can happen on an alum bar too. When you moved the shifter the tension was released and the brake opened, probably nothing wrong with the shifter or brake. There's most likely a good mark on the bar from the clamp nut-inspect it.
> 
> At our shop we put carbon assembly paste under all bar clamps (carbon or alum bars) to give some extra grip and torque to spec. And check the spec for both the bar and clamp-you be surpised the varience in min and max spec for bars and shifters out there. Some bars have a max torque below the min spec of the shifter.


Could it also be the bar clamp on the stem? It's a fairly common mistake to undertighten those, and when you hit a bump with weight on the brifters, the bars will rotate downward.


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## ericm979 (Jun 26, 2005)

Camilo said:


> Could it also be the bar clamp on the stem? It's a fairly common mistake to undertighten those, and when you hit a bump with weight on the brifters, the bars will rotate downward.



That won't cause the brake to come on.

It's the brake lever clamp. Oops.


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## Marko Polo (Feb 5, 2005)

Ok, I have looked at the bike. Both shifters are scraped up as expected. It looks as though the rear assembly stayed in place, maybe pushed up a bit. The front assembly definitely moved, down. I moved the thing up, down, in and out and the brakes work fine. I cannot get the problem to show up. 

I guess my main concern is more for piece of mind. Is this going to happen again? I don't really understand how it's possible to go from apparently functioning well to locked up tight without doing anything other than hitting a bump in the road. 

I ride about 3500-4000 miles a year on the trails and the road and have not had a road crash until now. I could see if it was something obvious, like a huge pothole or a sewer grate, or even tangling with another rider but a bump in the road? come on I live in Wisconsin, after this winter and spring the roads are crap, there is no such thing as a smooth road.


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## Henry Chinaski (Feb 3, 2004)

Marko Polo said:


> Ok, I have looked at the bike. Both shifters are scraped up as expected. It looks as though the rear assembly stayed in place, maybe pushed up a bit. The front assembly definitely moved, down. I moved the thing up, down, in and out and the brakes work fine. I cannot get the problem to show up.


What do you mean by "assembly"? The brifter? If so, it sounds like what Cosmo described above--did you understand what he was talking about? I'm gonna refrain from a huge anti-carbon rant, but you need to make sure the brifters will stay in one place.


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## Marko Polo (Feb 5, 2005)

Yes, I mean the brifters. If I understand Cosmo, shouldn't I be able to recreate the brake lockup by moving the brifter one way or the other? I have tried moving the brifters around every which way and if I move them 15 or 20 degrees outward from straight I see the brakes tighten up a little bit. What I experienced was a total lockup of the brakes. No matter how I move the brifters I cannot get the brakes to lock the way they did, not even to the point of the pads touching the rim. 

The bump I went over, I would equate the force to the equivilent of popping a wheelie maybe 3 inches high.


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## mohair_chair (Oct 3, 2002)

Do you KNOW that your brakes locked up, causing the crash, or are you making the ASSUMPTION that because you found them locked up AFTER the crash, they must have locked up to CAUSE the crash. Because those are totally different things. 

It would not be unusual to find your wheel doesn't turn after a crash for a variety of reasons. This could be because the brakes are locked up, perhaps due to the cable housing slipping out of a cable stop somewhere. But that doesn't mean that is what caused the crash.


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## FatManOnaBike (Nov 1, 2007)

Something must be missing. The calipers are held open by a spring. If the brake pads 
( with no debris under them ) are "clamped" to the rim so tightly as to cause the effect you described, there had to be tension on the cable substantially greater than the opening force of the spring. It appears that the bump, however minor, was enough to allow the brifter to slide down the bars driven by your body weight on the hoods. I'm simply trying to clarify what others have said. The brifter is simply a lever and a cable. IMHO it _can't_ fail the way it has appered to.


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## msohio (Feb 23, 2004)

*bar tape on or off*

When trying to duplicate it, the bar tape has to be on and tight. That's what causes the brakes to tighten when the brifters shift. The tape holds the casing and the brifter sliding forward pulls the brake cable.

When I was getting new bars set up right, it happened to me. I thought I had them set right and taped the bars. Then when I rode, they needed to be a bit lower. I loosened the clamp and slid the brifter down and forward a slight bit. Tightened it back up. re-mounted and started to pedal. Nothing. Brakes locked from the forward movement. The good news is that no one saw me do a tip over before got got my cleats out !!


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## Marko Polo (Feb 5, 2005)

Mohair, the brakes locked up to cause the crash. Usually when I see a bump I kind of unweight the bike to float over it. I unweighted and the next thing I knew I was slammed over the bars, no nose wheelie or anything. The bike just flipped over.


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## Marko Polo (Feb 5, 2005)

My LBS is closed today, so I'll head down there later this week and see what they come up with. I'll post their diagnosis...


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## Bocephus Jones II (Oct 7, 2004)

Marko Polo said:


> Mohair, the brakes locked up to cause the crash. Usually when I see a bump I kind of unweight the bike to float over it. I unweighted and the next thing I knew I was slammed over the bars, no nose wheelie or anything. The bike just flipped over.


you sure a stick or rock didn't get caught in your wheel? I really can't see how a brake could spontaneously lock up without the brifter being depressed or something getting stuck in the brake.


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## android (Nov 20, 2007)

cosmo333 said:


> Since you hit a bump while on the hoods at the same time the brake locked the most likely cause would be the shift lever sliding down on the bars, the cable tightens as the lever moves down and the housing holds tight under the bar tape.


Ding, ding, ding!!

He wins the prize. The shop didn't tighten the levers tight enough.


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## andulong (Nov 23, 2006)

I have also seen wheels lock up after a crash because the calipers are knocked off center. This will cause one brake pad to rub the rim. Maybe the levers slid down during the impact causing you to go over the bars and it locked up during the impact by the calipers being knocked out of alignment??????


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## DrSmile (Jul 22, 2006)

I suggest you strap a video camera to your handlebars, point it at the caliper, and go for a vigorous ride until the problem replicates itself. Why? Because I need some entertainment!


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## MWPDX (May 29, 2008)

DrSmile said:


> I suggest you strap a video camera to your handlebars, point it at the caliper, and go for a vigorous ride until the problem replicates itself. Why? Because I need some entertainment!


... +1


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## bike_guy (Mar 26, 2002)

android said:


> Ding, ding, ding!!
> 
> He wins the prize. The shop didn't tighten the levers tight enough.


That is my thought. Similar thing happened to me, but I didn't go over the bars. I was trying to avoid a chasing dog when I hit a pothole and the front brake locked. After coming to an abrupt stop the entire shifter had moved just enough to take up the slack in the cable causing the caliper to lock. Checked the other shifter and sure enough it was not completely tight either. I later read that some people leave their shifters a little loose in case of a crash so the lever will turn when it hits the pavement hoping that it won't completely destroy it.


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## android (Nov 20, 2007)

Marko Polo said:


> Yes, I mean the brifters. If I understand Cosmo, shouldn't I be able to recreate the brake lockup by moving the brifter one way or the other? I have tried moving the brifters around every which way and if I move them 15 or 20 degrees outward from straight I see the brakes tighten up a little bit. What I experienced was a total lockup of the brakes. No matter how I move the brifters I cannot get the brakes to lock the way they did, not even to the point of the pads touching the rim.
> 
> The bump I went over, I would equate the force to the equivilent of popping a wheelie maybe 3 inches high.


Just turning the STI levers typically won't lock up the brakes. You have to push them DOWN the handlebars while the cable housing is wrapped in tape. Think about it mechanically. That is the equivalent of squeezing the lever. You have shortened the inner cable in relation to the housing.


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## Marko Polo (Feb 5, 2005)

*gratuitous carnage picture*

First photo post, I hope it works...

Here is a picture of my knee after the crash...


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## cmg (Oct 27, 2004)

post a photo of the brakelever on the bars without the tape. we're looking for scratch marks that indicate that the brifter has moved. The photo of your knee looks bad. recommend cleaning with epson salt and water 1:4 twice a day and keep in wrapping. i landed on gravel, saw the knee cap, lots of blood, nasty fall.


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## bahueh (May 11, 2004)

*oh, that little knee injury is..*

nuthin'....wear your scar proudly.  buy some tagederm, slap it on, and forget about it for two weeks. you'll be fine.

as for the bike..is your front wheel still true? I've never heard of a brake closing so tightly that it would put someone over the bars...I have seen wheels go VERY badly out of true and press pretty tight against a caliper though...


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## thadcombs (Mar 23, 2008)

Could the front wheel have shifted in your fork ends on impact with he bump? Enough maybe to move the rim into the brakepads?


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## Marko Polo (Feb 5, 2005)

I've looked at the bike some more and I would have to agree with Cosmo, the brifter moved and caused the brake to lock up. I went down to the LBS and explained what happened and what I thought was the problem. His response was " I've never heard of that happening, are you sure you didn't put the brakes on?" He's going to check into it with Shimano...

As for the loose wheel, bent wheel questions. The wheel is still perfectly true and locked in the fork just fine.


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## Henry Chinaski (Feb 3, 2004)

Marko Polo said:


> He's going to check into it with Shimano...


What is Shimano going to say? If they talk to anyone it should be the bar manufacturer. It's a combo of slippery carbon bars and a mechanic who didn't torque the brifter on properly. Did you talk to the shop owner or service manager?


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## Marko Polo (Feb 5, 2005)

Henry, I think the owner would talk to shimano to find out if the slipping brifter could cause the brake to lock. I don't really know. I'm giving him the benefit of doubt, although I felt as though he's giving me the runaround. And yes, it was the owner and not the service manager.


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## msohio (Feb 23, 2004)

*It shifted forward*

MP.....I can assure you the lockup was caused by the levers not being tight enough, and when you hit the bump, they slid forward. Because the outer protective cable was held in place by the bar tape, and maybe electrical tape under the bar tape, the shifter moving forward by half an inch caused the inner cable to pull outward and would be no different than pulling the brake lever to cause one half inch of pull in the inner cable and thus the brakes tighten.

You are by no means the first person this has happen to. As I said in a previous post, if you want to prove it, secure the outer cable with bar tape firmly wrapped and then loosen the shifter and slide it forward about one half to one inch. re tighten it in the new location. The brakes will probably be locked, if not the "free pull" before contact to the rim will be reduced very significantly. It has to happen that way pure and simple.


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## roadfix (Jun 20, 2006)

cosmo333 said:


> Since you hit a bump while on the hoods at the same time the brake locked the most likely cause would be the shift lever sliding down on the bars, the cable tightens as the lever moves down and the housing holds tight under the bar tape. Doesn't take much movement if the brakes are set tight.


I believe this is exactly what happened.


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## Henry Chinaski (Feb 3, 2004)

Marko Polo said:


> Henry, I think the owner would talk to shimano to find out if the slipping brifter could cause the brake to lock. I don't really know. I'm giving him the benefit of doubt, although I felt as though he's giving me the runaround. And yes, it was the owner and not the service manager.


If the owner knew anything about bikes he would know that of course a slipping brifter could cause the brakes to lock if the brakes were set tight enough. 

I wonder if these bars come with any special instructions--torque specs for brifters, etc., and if so, were they followed?


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## il sogno (Jul 15, 2002)

Marko Polo said:


> I've looked at the bike some more and I would have to agree with Cosmo, the brifter moved and caused the brake to lock up. I went down to the LBS and explained what happened and what I thought was the problem. His response was " I've never heard of that happening, are you sure you didn't put the brakes on?" He's going to check into it with Shimano...


They never heard of this happening? They should keep up with the bike racing scene cause the exact same thing happened to Lance Armstrong in the Dauphine a few years ago. 

He went over a storm cover on a descent, brifters slipped down on the handlebars, brakes locked up, he crashed.


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## evershadow (Aug 2, 2005)

*Not to mention.....*

Not to mention all that turning of your brifter on your hb......you should probably replace it. Unless you completely loosened the bolt you probably put some nice slices in the carbon. Most shops.....coming from working in one for 11 years....never touch the clamp bolt on the shifters....bummer!! You could also take your front wheel off and take a look underneath the caliper to make sure you don't see a major scratch. If there is then you might have gotten something locked in between the tire and the brake (i doubt it thought, if you did you probably wouldn't have gone over the bars.....) What brifters and hbar do you have. Have you loosened the right brifter clamp bolt? If not then you should get a torque wrench and see what it is at? That would probably indicate what the LBS had it tightened (or not tightened) to. 

Here are the torque specs for Shimano, Campy and Sram.
Pretty much most carbon manufacturers have agreed that there is no real way of stating what the torque rating should be when clamping on or to carbon. So go with some assembly paste on any carbon application and the component torque.

Shimano - 6-8 Nms or 50-70 in.lbs
Campy - 90 in.lbs
Sram - 53-70 in.lbs

If it ends up that it was the shop's mistake i think you should negotiate some settlement for the medical costs and so forth. Again, from working on bikes for 11 years I have seen way too many underbuilt rigs. Too many shops are worried about spitting out stuff to be profitable when they forget the velocity of what the bike will be doing. Hope all goes well in the end. :thumbsup:


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## evershadow (Aug 2, 2005)

Shimano is going to dodge the bullet as well. I can guarantee it. Not to mention he will probably talk to someone who has only worked there for 3 months. Again i would check the torque of the right shifter....don't tighten it just check the torque (if you didn't readjust prior to riding) that way you can see what the torque is. I would also suggest going in the shop, asking the owner who built the bike and then asking the guy that built it what the torque spec is for that shifter (just play stupid and act like you just want to know) that way you will know whether or not that guy knew....i bet he won't. (Sorry i don't have much compassion for my fellow bike mech.'s)


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## anax.mananagat (10 mo ago)

android said:


> Ding, ding, ding!!
> 
> He wins the prize. The shop didn't tighten the levers tight enough.


"To the LBS" would have been my first response. They built it and should be answerable for it.


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## DrSmile (Jul 22, 2006)

2008 thanks you.


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## Lombard (May 8, 2014)

anax.mananagat said:


> "To the LBS" would have been my first response. They built it and should be answerable for it.


I doubt the mechanic who worked there 14 years ago is still there.


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## No Time Toulouse (Sep 7, 2016)

Lombard said:


> I doubt the mechanic who worked there 14 years ago is still there.


Yeah, he probably completed his engineering degree, went into aerospace, got fat, and now curses at roadies who run lights....


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