Why Do I Have A Flat?





#1
I haven't had a bike flat in the last 2 1/2 years. Then, yesterday, I got the bike back from the dealership after they did the 8K service, rode around for a couple of hours and parked in the garage for the night. Got all ready for the gym this morning, walked out to the garage and psshh, first flat. Uhhhgg!

So, I searched the tire all over and found nothing - no punctures, tears, gashes or slashes, with plenty of tread - only have maybe 2000 miles on this back tire... can still see the blue marking from when it was new.

I got to thinking... yesterday had a high of 105 degrees where I'm at... and the shop, according to the service receipt, put the back tire at 41 psi (max 42 in cold).

Any chance the tire burst from too much pressure?

I filled it back to about 38 psi and am monitoring it.

What should I do? Fix-a-flat? Do I need to replace it? Would like to ride today, but no one is open on Sunday!

Thanks in advance...
 
#2
Maybe when they checked the tire pressure during the service, the tire valve didn't seat properly...it's happened a time or two on my tires.

Squirt some dish detergent on the valve and see if it bubbles.:whistle:
 

outlawbusa

1 wheel up aero testing
Donating Member
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#4
Also spray around the bead and the base of the valve to make sure it's all still seated properly. Check for cracks in the valve itself...most shops don't ever change them unless asked to do so or if they visably see something wrong.

Are you using heavy valve caps (such as the skulls)? Over certain speeds they tend to bend the valves and cause cracks if they are dried out a bit.
 

outlawbusa

1 wheel up aero testing
Donating Member
Registered
#5
PS...touching on the valve stem thing...get metal valve stems, they are much safer and very cheap...plus if you do track days or high speed runs such as Maxton, some places require them.
 
#7
Also spray around the bead and the base of the valve to make sure it's all still seated properly. Check for cracks in the valve itself...most shops don't ever change them unless asked to do so or if they visably see something wrong.

Are you using heavy valve caps (such as the skulls)? Over certain speeds they tend to bend the valves and cause cracks if they are dried out a bit.
If it is not seated properly (looks fine to me), am I able to reseat it (wiggle it around??) and fix it?.. to the point air will not leak anymore? I guess it would be fairly obvious if the valve was not seated correctly (sitting at angle or something). Is it common to have to change the valve? I suppose they could've cracked it when they checked/changed the air pressure.

I just use the plastic caps that came with the bike.
 
#8
Don't use fix a flat unless you absolutely have to it's not good for extended use
Agreed. Wasn't planning on it, but thought I might need to to get it up to the shop. It does seem to be holding air well enough after a couple hours to not need it.

Hoping I dont have to replace the tire since I don't see any damage and it is so new!
 
#10
Hahaha... ok, sure..

Thanks..
He is serios, use dish washing liquid, my favorite is windex or 409, but anything that will produce bubbles will work. If you do not find any bubbles at first bring the tire pressure up to 45-50 pounds and re-spray and recheck for bubbles.

It is very, very rare (I have only seen it once), but the wheel could have a crack in it. Good luck and I hope it is a cheap/easy fix.
 
#11
He is serios, use dish washing liquid, my favorite is windex or 409, but anything that will produce bubbles will work. If you do not find any bubbles at first bring the tire pressure up to 45-50 pounds and re-spray and recheck for bubbles.

It is very, very rare (I have only seen it once), but the wheel could have a crack in it. Good luck and I hope it is a cheap/easy fix.
Nah, I know...

Yeah, I may have to raise pressure up, bc I didn't see anything at 38 psi.

BTW, 2 hours ago I raised it to 40 PSI, 1 hour later it had fallen to 36, now close to 32, so not that slow of a leak.

Thanks... I kinda wished i'd seen tire damage, cuz this has me all befuddled!
 
#12
Nah, I know...

Yeah, I may have to raise pressure up, bc I didn't see anything at 38 psi.

BTW, 2 hours ago I raised it to 40 PSI, 1 hour later it had fallen to 36, now close to 32, so not that slow of a leak.

Thanks... I kinda wished i'd seen tire damage, cuz this has me all befuddled!
Sorry, I thought, that you thought he was kidding.
 
#14
If it is not seated properly (looks fine to me), am I able to reseat it (wiggle it around??) and fix it?..
Yes. They unscrew with a simple tool and can be removed easily. Sometimes they can get cocked a little and not seat properly. Just give it a push down.

I guess it would be fairly obvious if the valve was not seated correctly (sitting at angle or something).
The quickest way is to spit on your finger and put the spit in the vavle stem filling it up and look for bubbles. If you find that offensive a soap and water mixture will suffice.

2 hours ago I raised it to 40 PSI, 1 hour later it had fallen to 36, now close to 32, so not that slow of a leak.
Sorry to hear about that. Did you check your vavle stem for leaks?
 
#15
Yes. They unscrew with a simple tool and can be removed easily. Sometimes they can get cocked a little and not seat properly. Just give it a push down.

The quickest way is to spit on your finger and put the spit in the vavle stem filling it up and look for bubbles. If you find that offensive a soap and water mixture will suffice.

Sorry to hear about that. Did you check your vavle stem for leaks?
OK, if they unscrew, maybe I should screw it on tighter? I guess I would have to let the air out of the tire first - or maybe even take the tire off first. I did push it down... wasn't any room to go down any further. It really does look fine.

Yes, I tried soap/water, 409 etc... didn't see any leak at the valve stem (where you put the air in).

Perhaps I missed the tire damage, though I looked it over quite thoroughly.. maybe someone punctured it with a compass. ;)

Thanks for all the help, btw.
 
#16
OK, if they unscrew, maybe I should screw it on tighter? I guess I would have to let the air out of the tire first - or maybe even take the tire off first. I did push it down... wasn't any room to go down any further. It really does look fine.

Yes, I tried soap/water, 409 etc... didn't see any leak at the valve stem (where you put the air in).

Perhaps I missed the tire damage, though I looked it over quite thoroughly.. maybe someone punctured it with a compass. ;)

Thanks for all the help, btw.
What I did notice is that unlike with the front tire, when I screw the cap on with the back tire, it does not completely go flush with the rubber stem cover - there is about .5 " gold stem left... I tried hand tightening that a little ... felt like it might have turned a bit - couldn't exactly tell.

Sorry to be over retentive with this, just obviously don't know wth I am doing ;)
 
#17
Leave the valve stem cap off and see if it still leaks.

You need the tool if you want to screw it on tighter. I wouldn't suggest inventing one. They are cheap at kragen.
 

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