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high speed blowouts and such(4 posts)

high speed blowouts and suchWoof the dog
Jan 10, 2004 4:44 PM
Say, if I have to jump a huge hole at say 40 mph, would the speed I'm at cause higher chances of blowing out a tire/tube?

And does blowing out a tire (off the rim) even happen when hopping things? I know it happens when you overinflate (tube pops, you get scared...), but say you are at your max pressure and then compress tires further by landing a jump, my reasonable conclusion is that a blowout may happen.

If a blowout happens, what is the course of your actions? Say, rear blew? I would probably jam on the front break as much as I can and try to bring it to the stop. What about a corner? One would probably lose it...

Now the front one? I dont' even know where to begin... brace for impact... try front breaking?

thanx

woof, the dog that once blew a tire by overinflation.
re: high speed blowouts and suchlaffeaux
Jan 10, 2004 6:10 PM
The amount of downward force created by landign a jump at 40 mph is exactly the same as landing one at 20 or 10 mph. The downward force is determined by your weight and the height of the jump, regardless of speed. However, if you slam into a pot hole at 40 mph, the results are very different.

Rear blow outs are not that bad as long as you're not leaning hard in a turn. Decrease your speed and come to a stop.

Front blow outs can be much more traumatic. I've had front tires blow on MTBs (luckily never a road bike) and have sometimes saved it and sometimes crashed.
blew front at 25 mph, crashed hardbm
Jan 10, 2004 7:19 PM
i blew my front at 25 mph. not from hopping; i hit something in paceline. i lost control in the front without traction, so i braked. don't know if that was the correct action, but i ended up going over front handlebars and hit concrete.
Beloki doesn't let you sleep well? ;)cyclopathic
Jan 11, 2004 8:56 AM
yes you have higher chances of blowing at higher speed; most likely when you miss end land into pothole. Second, it is much less forgiving when you land at higher speed, there's no margin for error. It is enough to loose control just a bit and you'd be all over the road, possibly down. I had a pleasent experience of landing rear tire on angled RR track at ~35mph, and though I've survived and didn't go down, if there were any riders within 5' buble there were a lot of broken bones, bikes and grind meat.

Rear blow out is actually o'k. It takes several seconds for tire to deflate, and though bike becomes unstable, it is manageble. What to do? you scream to warn other riders, and use both brakes to descelerate. Do not try to take corners (unless they're really really gradual), just keep in straight line and look for soft landing spot for run off. Pretty much what LA did in his cyclocross advanture in '03 tour (also if you remember Jan running off in '01)

Sorry can't help you much with front one. The only time I had it happen when was riding in group with wheel overlap. Unfortunately for me tire poped off the rim, wheel locked and went over the bars at luckly low (~20mph) speed.

The worse case scenario if you blow front your tire goes off the rim and locks front wheel. To avoid it try to shift weight back, use rear brake only, and keep bike in straight line as long as possible.

One of MTB tricks is to avoid endo is to clip and step out over the bars into running. Works well at low (8-15mph) speeds, I wouldn't try it 40mph. Just be mentally ready if front washes out or gets locked by tire good luck.

CP

PS The best piece of advice on front blow out I had heard from old (55yo) retired racer. He said what you need to do is to stand up, bend backward and kiss your ass goodbye.