myisland

I would like to know if sudden front tube failure at the valve of my front 700x25 tire could have caused my over the handlebars crash. Originally I thought that I applied the front break too hard but now I've noticed the tire is flat and I discovered that the valve is half separated from the tube. The tire and wheel are fine. I had slowed down to about 5 mph when it suddenly stopped and it pulled towards the right as I went down, breaking my hand and ribs.

WhyFi

Ouch, sorry to hear about the accident.

I think that the most simple way of explaining it is your original assumption of braking too hard and that the additional damage happened in the tumble.

If I were spit-balling ideas on other ways that it might be explained, given the valve, the only thing that I could think of is - braking hard, the tire was under-inflated enough that the tube/tire slid around the rim enough to shear the valve, rapid deflation, hello ground.

Classtime 

Much can happen during the couple months between the crash and the valve stem failure.

Sy Reene

Interesting hypothetical, perhaps made more likely to occur if tube was talced, and/or any of the talc inadvertently got on the hook/bead area where tire is engaged with the rim?

topflightpro

A flat can cause a crash. A crash can also cause a flat. So, it's hard to say whether one caused the other.

RiceAWay

If you have disk brakes and you have clincher tires that you allowed to get too soft (they often ride fine) it is very likely that pulling the brake on too hard and too suddenly will spin the tire and tube on the wheel pulling the filler out. Over the bars is almost NEVER because of a flat which would normally slide out.

eduskator

Broken hand & ribs? You were very unlucky.

As for the cause, there are a few possible scenarios... You are saying that your bike came to a sudden stop at 5MPH without you applying more pressure on the front lever?

Did your front tire hit something on the ground? Any pictures of the damage?

79pmooney

I look at this as a reminder to consider everything on a bike from 6" behind the head tube forward as critical. Everything. Failures there can be life threatening.

I say this and I am a walking example of what not to do. I rode a Lambert until the fork broke. (5 day coma, seizures, loss of education and 7 years of recovery.) I've had front wheels come off twice. First is still a mystery. Slight downhill on perfect pavement, Campy skewer in quality Japanese hub. Probably operator error but I've known the importance of tightening front QRs a long time. Front QR again. This time after a domestic dispute and I forgot I hung the bike hastily to leave the house while I was working on it. That one cost me massive soft tissue damage to my shoulder, collarbone, ribs and collapsed lung. Yep, I paid.

I've also broken handlebars. Old school soft metal GB bars. Hit a pothole and one side bent down 30 degrees but stayed in one piece. Had one start to crack in the same place. I could hear the crack working when I stood. I was riding 2 miles to the velodrome to watch some races. Got there, passed word to the announcer that I had bike issues and needed a ride home. (I did NOT want to ride back down that hill with its stop at the bottom on those bars!)

Two more forks. A cheap steel fork of unknown history simply broke mid-blade. I happened to notice it a mile from home. Seemed I'd been riding it with no issues so I just rode it home. (And went to the bike shop and bought a used bike for its fork and frame.) Then year 3 of my custom with its nickle plated gem of a fork. I got lucky. Or the bike was looking after me. Or some God-thing. I was on a 40 mile ride with 2000' of climbing and descending, At the high point, no descending yet. This was my fix gear that I regularly stopped and flipped the rear wheel for unscrewed the cog to do big hills. Screwed on the tiny cog and could not get the chain to behave. It kept going tight, then loose. I finally elected to just ease the bike down the hills in the big gear with a very slack chain that would be easy to throw off. Meant that I eased around the corner I love to come into really hot, brake hard, and take fast. Down on the flat I felt the front of the bike start bucking when I touched the front brake. Turned out both fork blades were about to break just below the fork crown. (Warning - if you ever nickle plate high strength steel; ie any quality frame tubing, make sure it is heat treated afterwards!)

I am planning to return to sewup tires as I wear out my current rims; yes for the joy of riding them but also to be on tires that stay on after blowouts. (Glue doesn't care what happened to the tire. You can have a samurai shred it, cutting right down to the rim and it is still glued on.)

My mom rode all her life.. Wasn't the best on maintenance and care. Let a bungee (we think) get caught in her front spokes, Concussion, damage to teeth and permanent damage to her lips meaning she could never again get a pure flute tone. (I grew up spoiled. I've known what perfect tone on that instrument sounds like since I was knee high.)

My take - that end of the bike should be treated as sacred. Worshiped and attended to. Easy to do less. All that stuff is so reliable, so forgiving of inattention compared to the fussy (and far more expensive) rear ends of bikes. But when the front end does want our attention, it doesn't just bite us in the a**, it takes our head in its mouth like an alligator.

Ben

banerjek

Beyond unlucky. Broken ribs really suck.

This is a weird crash -- I wouldn't have guessed it would be possible to go over the bars at 5mph. I'm basically on board with WhyFi's theory.

The sudden stop sounds more like something getting caught in the brake calipers or fork.

RiceAWay

Because of the outside possibility of losing a front wheel I now keep the "Lawyers Lips" on the forks and put up with the inconvenience of having to open the quick releases for a half hour before the wheel will extricate itself from the fork.

RiceAWay

I was riding my cyclocross bike on a very steep downhill. Coming the other way was a long string of MTB's on the hard part of the trail. Since I am very experienced and it was pretty clear that most of those guys weren't I pulled into the soft dirt on the right side of the trail. I was continuing down and looking forward to pulling over soon since the tail end charley was a Hispanic kid who was obviously a beginner. I was moving pretty fast and had hydraulic disks with a flat bar. Suddenly my front wheel dropped into a deep rain gutter and covered over with dust. When I hit the other side it rocked me hard forward and trying to hold on I pulled the brakes on hard enough to stop the front wheel.

This rotated me right over the bars on a steep downhill putting me over 6 feet above the ground. Luckily this allowed me time to rotate from head first to on my side and landing in the deep dust was relatively painless. But then CRASH! the bike fell on top of me. This Hispanic kid had stopped upon seeing that. "Uh, are you OK?" "AM I OK????) echoed for several seconds off of the surrounding hills. Kicking the bike off of me I got up. The bike falling on me had caused some minor cuts and abrasions on my left hand fingers and they were bleeding pretty good. But the immediate shock prevented any pain. So I told the kid I was OK and continued down the hill this time on the hard pack. At the bottom I rode another couple of miles to a bike shop and used their toilet to clean everything up and wrap it in some gauze. That sufficed until I could get home and treated it properly. Some pain for a couple of days and sore for a week. Believe me, disk brakes are nothing to take lightly. And you should always have some antibiotic cream in the medicine cabinet along with Band-Aids and gauze for minor injuries like that.

myisland

I ride a traditional road bike with properly inflated 700x25 clincher tires, alloy wheels, rim brakes
Crash occurred on a clean flat cement bike path.
I was applying both bakes, slowing down, beginning to stand up getting ready to swing my leg over and then it happened in a flash.

myisland

Nothing got caught in the brakes calipers or fork. I learned that lesson 30 years ago when a loose bungee cord grabbed my wheel and I flew full speed.

RiceAWay

That is certainly not the situation that could lead to an over the handlebars crash from a sudden flat which would simply slide you to a halt at that speed. You had to have hit something that shifted your weight forward.

CliffordK

Standing up does shift the weight forward.

I haven't really thought about dismounting much. I will unclip early, but it is more of putting the foot down and scooting forward off of the seat.

A blowout will have an audible bang, and typically either blows a hole through the tire, or blows the tire off of the rim. Even with the crash, a blowout should have been noticeable.

I agree, this sounds a lot like a wheel falling into a hole or crack, or something caught in the spokes.

I'd carefully inspect the back side of the fork, and bottom side of the downtube for signs of something being jambed between the tire or spokes and the fork/downtube.

Also look for bent spokes and damage to the rim. Out of true?

79pmooney

I've never filed lawyer's lips off, but I also have never owned a bike that had them (at least, not after I made it ride-able). Only bike that came with them was a Peugeot I picked up "as is" after a run-in with an SUV. Fork was trashed. I never looked twice at it. Just went out and picked up a used fork to replace it. No lips.

Ben

79pmooney

Was the concrete poured in "blocks" separated by gaps? I have dropped my front tire into one of those on a MUP and gone down. (And been "bad". I haven't gone and hollered at the city planners. That spill, which was no big deal for me; a routine fall I've known how to take with zero injury a million years, could be an expensive suit for the city if a well heeled citizen breaks bones and has complications.)

Funny, I was coming to a stop to adjust clothes early in a ride when I did this. Just like the OP except I don't do the stand and swing. Never thought about it but probably for the better.

Ben

Kabuki12

I had a situation a couple of years ago on an asphalt road that had recently been repaved. They left a ledge right near the white stripe with very little shoulder to ride on. I let my front tire drift too close and before I could blink I was face down with multiple injuries . The bar end shifter buried itself in my leg , my cheek bones was broken in 4 places, my orbital bone was broken, my left outer metacarpal yup broken! All this at 12mph , glad i was wearing a helmet. Then there was the road rash..... Joe

ridelikeaturtle

Hitting any small stone can stop your forward momentum enough - and that energy has to go somewhere. If you were in the process of standing up at exactly the right time, it sounds like you may have simply overcame the threshold needed to go over the bars.

Very odd way to crash at low speed on a road bike. Sounds like bad luck to me, and I wouldn't overthink that flat tyre too much.

RiceAWay

He said that he was only rolling at 5 mph. Crashing hard at that speed is VERY hard since you can step off. Flat tires cause you to slide at that speed. None of it makes sense. I was estimate that he had to have hit something or had a blowout that dropped the front wheel flat on the road almost instantly and that he was JUST standing up so that he still had a forward momentum and his weight was forward. Innertube fillers do not break off except when the tire is rotated and the tube sticks to the tire. I have seen them tear enough to cause an unrepairable leak but never torn completely off so this was pretty unusual conditions.

So either he had a blowout at EXACTLY the wrong time or he hit something with very soft tires or he had some very powerful brakes and something occurred to make him apply then too hard. Certainly the torn filler would have to be an after the case event.

AdkMtnMonster

Weird- I would hav3 used their sink to clean my hands, but you do whatever works best for you.

myisland

I believe that I applied the front break too hard and the flat remains a mystery. Because of neck pains I've ridden with my drop bars turned up for 30 years with no problems but my research has revealed the following post:


"In this scenario I assume the rider usually operates the brake levers with palms. A situation that calls for even just moderate application of the brakes (and/or grabby brakes) could cause the rider's weight to fall still harder onto the brake levers and result in a positive feedback loop that eliminates all possibility of any brake modulation. Worst-case scenario would be an endo. For the performance-minded there are many reasons not to turn up drop bars like this--not the least of which is the risk of un-weighting the front tire, but I think if levers can be installed in front of the handlebars to prevent the aforementioned feedback loop then for utility riding you might as well give this a shot."


So the cause is explained by physics. I will need to reposition my brakes keeping a handlebar height comfortable for my neck. May require new handlebars or a riser of some sort.

alo

I am heavy, and I find tires do slide around on rims, when braking, and even peddling hard. I have never had a valve stem tear from a tube, but it is not unrealistic. This happens to me with standard 26 inch mountain bike wheels. Obviously it happens more if the tire is at low pressure.

RiceAWay

This was more or less the problem I had with my disk brake bike. I was thrown forward and trying to push myself back and grabbing onto the brake handles and applying the brakes bringing the wheels to a dead stop and me so far up the air that I could see the entire Redwood Canyon. Well, not quite but it sure felt that way at the time.

79pmooney

Joe, I discovered a tire three years ago that might have bailed you out. The Vittoria Corsa G+. The "G" means it has the new graphene in the thread so for a given rolling resistance they have more grip but probably just as important, they have the ribbed tread that was common 40 years ago. (Thin parallel ribs running in line with the tire.) Best tread ever for climbing out of ruts, cracks and back onto pavement. (I love having it back! Never got why it disappeared.)

Story related to yours. 43 years ago. Extremely wet race, late miles, speed building. I was moving up on the left side of our lanes of a divided highway so the median on my immediate left. But this median was sunk about an inch below the road surface and paved with cobbles. Got distracted and rode onto it. Jarring! Well I had to get back onto the road. Now I was riding orange colored tread tires. Very slippery wet. But ribbed tread. I rode up to the pavement edge and just went for it. Tires climbed back onto the pavement like it was no big deal.

Ben