Garcon

Hi, today my inner tire exploded, came out of the outer tire, wrapped around the rear axle, and almost ripped off the brakes and would have killed me if it had happened a few meters further down the road where there is a 45% grade hill.

Why did this happen?
How can I prevent this from happening again?


my bike is a front suspension walmart "Road Warrior".

thanks
Frank

Al1943

This type of blowout usually happens when some part of the inner tube gets pinched between the tire and rim during installation.
Also be sure your tires are fully inflated before each ride. Under-inflation can cause the tire's bead to unseat.

Al

Garcon

hi Al, thanks for answering.
and that brings up another question:
when I try to pump air into my tires, the pressure goes straight up to about 40PSI on 1 single pump actuation, and the tire does not inflate at all. Whats wrong with my air pump?

BikeWise1

You're not getting the pump fully seated on the valve.

Chris_W

One important tip - don't buy a bike from Walmart.

Chris_W

I would say that he is getting it sealed, but the valve is not opening to let the air into the tube. However, it is hard to diagnose why over the internet.

vintagefuji

Also, sell the walmart bike and buy a nicer bike used. youll be much happier.

Garcon

how can I tell whats a nice bike?
thanks again

Garcon

why would my tire blow out only 20 minutes after I used the bike last, and it was fine at that time?

LesterOfPuppets

If you have some innertube pinched under the tire bead, it can blow out at anytime.
It might blow as soon as you inflate the tire, or the next day.

griftereck

tyres and wheel rims flex and move about as you go over bumps.

for extreme example of that, watch trial biking videos on youtube.

so its possible that the tube can work its way into a bad position

Ive had a few blowouts on the road. ussualy several miles away. So I had to walk far with the bike

Mondoman

There's also the possibility, if you were doing sustained rim braking on a long stretch of steep downhill, that the rim heated up and caused the inner tube to warm up, increasing the air pressure inside and causing a blowout.

JanMM

A 20% grade is a very steep hill. A 45% grade is an exaggeration.

DX Rider

For comparison, Mt Snow in Vermont claims to have the steepest ski slope in New England and it's only in the 30's, a think it's either 31% or 34%, but I don't remember for sure. Anyway, I've skiied that slope and it's pretty steep, not something I would attempt to bike down. Although, I think that in the summer and fall they offer "Mountain Biking", which is really mountain coasting since they only ride one direction, down.

kabersch

Actually it's probably 31 or 34 degrees. A 45 degree slope is a 100% grade - 1 foot down for 1 foot forward. Most roads aren't steeper than 8% or 9% (9 feet forward for 1 foot up) and that is considered steep. You will find some over 10%, but I've never seen a road with a grade greater than 12%.

dvs cycles

There are plenty of roads steeper than 12%.
There is one on with a sign of 22% in Laguna Beach that I ride by, not up , all the time.

bigbossman 

Come to CA. We have a lot of them.

coldfeet

Another thing to check, look at the brake pad position. If it was rubbing against the tire, it could have rubbed thru it and caused that, is the tire sidewall damaged?

iluvfreebeer

Kill the bike!

I wouldn't take that @#$% from some two wheeled terrorist!!!!

intx13

Go to a local bike shop and let them guide you through the process of finding a bike that's good for you. Go to another local bike shop and do it again, to get a different opinion on it. Repeat as much as you need. Come back here and maybe you can find someone who rides the same bike you're interested in and get some first-hand information. When you're satisfied, break out the wallet

Be prepared for sticker shock though. A WalMart bike might run you $100 tops, but a real bike is going to at least break $300. But with a real bike, you're getting a legitimate form of transportation that can outlive you.

That said, this problem probably isn't bike-specific. But if you're using your bike for anything other than chaining to your porch to rust, ditching the WalMart bike for a real bike is always a good idea

Dan The Man

Mount Nebo Arkansas averages 18% for 4 miles.

MilitantPotato

I'm going to chime in by saying my wife bought your exact bike over a year ago. The tires where too large for the rim, and would come off for no reason, causing the tube to explode. Nearly caused her to wreck towing our toddler. Those bikes have terrible quality control. We wound up returning it.

That being said, unless your bike is having the same issue, a tube blowing out like that can come from a pinched tube, tire not being seated properly, or under inflation. If the tires slip very easily onto the rim, with little to no effort, the tires where made too large.

If you're wanting an inexpensive bike, you can find a very decent used bike for under $200, which should be of a much higher quality build. Good luck, I hope it doesn't happen again.

Retro Grouch 

That'll have you looking for your granny gear.

FBinNY 

As others have said, your tire was probably not properly seated, and at some point the pressure pushed it off far enough for the tube to bulge through and explode.

Improperly seated tires are a time bomb waiting to go off, but it can happen at any time. Possible the action of the brakes warming the rims, or the rolling action of the wheel slowly worked a section out enough for it to finally blow.

It's hard to say exactly what happened, but blowouts are easily prevented by making sure the tire is uniformly seated with no low or high spots when mounted. Use the molded lines as an indicator, spinning the wheel slowly as you check.

High spots are where they blow, but low spots are also important, because they mean there's some extra slack elsewhere on the tire, even if you don't see a high spot immediately.

As far as your pump goes- always let a dash of air out of the tire before pumping. Sometimes the valve gets a bit sticky after staying closed a while and that little blast ensures that it'll open when you try to pump it.

UBUvelo

wal-mart bike....scare them and mention the word 'sue'