Inner Tube / Flat Help

Biomech

Hi,

I was wondering if you could cast your eyes over this

I had my first ever puncture on a road bike the other day and I did my first ever road side repair! So that was fun.

I put the spare tube in and used a CO2 cylinder, but the top of the tyre nearly exploded (couldn't take a photo at the time). The points around the tube swelled right up as did the tyre itself. It was the correct size tube for the tyre/wheel. I'm wondering if maybe the CO2 went in too fast? Is that a thing/issue to watch out for? I pulled it off before it caused any damage. Once home, I tested the tube to see where the problem was, this is the tube, I took a photo so that you can see the swelling (mildly here)



Image 2 is the replacement tube. Two things here: 1; is the valve point always constructed on inner tubes?
and 2: I put this in, it lasted me about 5 miles before it started going down. When tested, it had two holes in it, inconsistent with anything in the tyre. What are the failure rates of tubes out of the box? Do you think something got into the tyre and fell out when I got the bike home and investigated?



Image 3 is a piece of glass I found in the tyre when I got home. It's consistent with the location of the hole in the original flat but NOT with the holes in the replacement. The glass didn't appear to go all the way through and I brushed over it twice thinking it was just torn rubber it was that small. I'm 99% sure this is what caused the first flat - but do question it due to the size and that the 2 holes in the replacement were no where near where this glass was and the 2 holes where about 30cm apart.



My conclusion is that the glass caused puncture 1 and some foreign body caused the 2 in the replacement tube (despite the size of the glass and it apparently not piercing the replacement tube)

I thought I'd see what you guys thought Thanks!

EDIT: No sorry it won't let me upload the pictures - sorry for all the white, but it won't let me upload pictures unless they are EXACTLY 640 x 480 and upright (which wasn't a problem before)

wishitwasallflat

Tubes are always that shape round the valve when inflated out of tyres.
Sounds like the tyre bead wasn't properly seated when inflated with the co2 and thats why it bulged.
Little bits of glass embed in tyres and can be missed best way to find them IME is fold the tyre flat and run your finger around the inside pressing and waiting to get cut!
Never had tube damaged out of the pack but as with all things its possible. Nothing else to offer re the two holes other than if it was me I would check that tyre carefully again in case there was anything else stuck in there I missed .

ai_1

The tube size is not critical. The tube is only there to provide airtightness, not structural strength. The tyre contains the tube. Inflating the tube out of the tyre doesn't really tell you anything except whether there's a puncture.

When it "nearly exploded" did the tyre come off the rim or are you saying it bulged? A tire should never bulge unless it is damaged. If it came off the rim, I would assume it was simply that it had not been seated properly.

If there was a piece of glass inside the tyre after the second set of punctures and no evidence of further holes in the tyre then look no further. Why would you expect any other culprit? The shard of glass would no doubt have moved around as the tyre flexed and pressure changed. The only other likely cause would be if the tyre had been under-inflated after the repair and you got a pinch puncture or two. Pinch punctures usually look like thin slits and you'll most often get two side by side as either side of the rim creates a similar cut.

I reckon this is simply a case of inexperience with puncture repairs. No reason to suspect any failure on the part of the tube or tyre as far as I can see.

Biomech

Thanks for the replies.

Indeed, there's certainly a lot of inexperience involved. It's a bit more involved - and easier/quicker/more fun - than patching a tube as a kid :P

run your finger around the inside pressing and waiting to get cut!

That was my plan , I used the back of my finger and waited to get cut (which I didn't)

My tyres are 25's from the rim, when it bugled it went to around 35 but only to the immediate left and right of the valve (like in the picture). The tyre ran up the rim a bit from the bulge but I don't recall it actually coming off at all 0 the tyre was clearly stressed.

I mentioned the glass as it was embedded very firmly in the outside of the tyre, even before taking it out I couldn't see that it had broken the inside (but, as you say, riding and the pressures could have caused that). So for the second tube, I'm assuming something else got into the tyre when I was fixing it at the road side which later fell out when I got home and took the wheel off as the holes in the second tube didn't match where the glass was.

Great info though, thanks

Monty Dog

Suspect that the tyre wasn't seated correctly on reinflation and that the glass was the cause for both punctures - I was with someone who punctured 5 tubes before I found the shard of wire embedded in the tyre that was rubbing holes in the tube - you could just feel it with a fingernail.

JayKosta

If the 2 new punctures are on the 'sides' of the tube and directly across from each other, then they are probably 'snake bites' from hitting a large bump and having the tire deflect so much that the inner tube gets pinched between the top of the rim and the sidewall - usually caused by low pressure in the tire.

My puncture repair process:
1) Remove punctured tube and entire tire from the rim.
2) Examine the tube for the puncture location. Examine the tire (inside and out) and remove all pointy bits. Something caused the puncture!
3) Mount 1 side of the tire on the rim, insert the new/repaired inner tube - making certain the valve stem is straight, not tilted.
4) Mount the other side of the tire, making certain that the inner tube is fully inside the tire and not pinched between the rim and tire.
5) Closely examine both sides of the tire so verify that the tube is not pinched, and that the tire is mounted evenly all the way around the rim - typically there's ridge on the sidewalls that can be used as a guide with the top of the rim.
6) If the valve stem is not straight, then massage the entire tire gently around the rim to straighten the stem.
7) If the stem is threaded, then install the nut finger tight - using the nut helps keep the stem in the proper position for inflating.
8) Inflate to get the tire to full size, but moderate pressure - then inspect again for pinched tube and position on the rim. Adjust if needed.
9) Inflate to full pressure and tighten the stem nut a little more.

I carry 2 spare inners..... and a patch kit!

Jay Kosta
Endwell NY USA

Biomech

I tell you one of the mistakes I made; I did a "proper job" when I got home and left the wheel off to test the pressure the next day (I'd never taken a rear wheel off and thought it was a lot more complicated with the derailer etc)

Then I tried to put it back on, forgetting that the inflated tyre wouldn't fit heh. So I'm glad I hadn't used another CO2 on that. Although my rear brakes are soft now and need tightening - are there micro adjustment screws for the brakes?

dj58

Biomech wrote:

Then I tried to put it back on, forgetting that the inflated tyre wouldn't fit heh. So I'm glad I hadn't used another CO2 on that. Although my rear brakes are soft now and need tightening - are there micro adjustment screws for the brakes?

Do you mean is there a way to open the brake caliper so that you can replace the wheel without deflating the tyre?
If so yes, there should be a quick release lever on your brake caliper arm, where the cable is clamped to the arm.
Item 6 in the exploaded diagram.

http://cycle.shimano-eu.com/publish/con ... _road.html

http://cycle.shimano-eu.com/media/techd ... 820619.pdf

Ben6899

DJ58 wrote:

Biomech wrote:

Then I tried to put it back on, forgetting that the inflated tyre wouldn't fit heh. So I'm glad I hadn't used another CO2 on that. Although my rear brakes are soft now and need tightening - are there micro adjustment screws for the brakes?

Do you mean is there a way to open the brake caliper so that you can replace the wheel without deflating the tyre?
If so yes, there should be a quick release lever on your brake caliper arm, where the cable is clamped to the arm.
Item 6 in the exploaded diagram.

http://cycle.shimano-eu.com/publish/con ... _road.html

http://cycle.shimano-eu.com/media/techd ... 820619.pdf

Or if you're running Campagnolo, it's on the brake lever.

Biomech

No I found that one

I mean is there a way to tighten the brakes without having to losen the nut and pull the cable through more etc?

Ben6899

Biomech wrote:

No I found that one

I mean is there a way to tighten the brakes without having to losen the nut and pull the cable through more etc?

Yes. Turn the barrel adjuster where the cable enters the caliper.

ai_1

Biomech wrote:

I tell you one of the mistakes I made; I did a "proper job" when I got home and left the wheel off to test the pressure the next day (I'd never taken a rear wheel off and thought it was a lot more complicated with the derailer etc)

Then I tried to put it back on, forgetting that the inflated tyre wouldn't fit heh. So I'm glad I hadn't used another CO2 on that. Although my rear brakes are soft now and need tightening - are there micro adjustment screws for the brakes?

In case you're not aware, CO2 is really only suitable for inflating tyres as a temporary measure when you're in a hurry. i.e. in the middle of a ride, especially an event. It's not and shouldn't be the "normal" method of inflation. Use a pump. If you have a bike, get a track pump. Mini pumps are not up to the job.
CO2 will permeate the tube far faster than air, so your tyre will likely deflate significantly between rides.

Biomech

Yes. Turn the barrel adjuster where the cable enters the caliper.

Excellent, thank you, I found that - although it only seem's to work one way, the other way it just spins down the thread and nothing moves - I also find that the quick release lever works, but doesn't open up the pads enough to fit an inflated tyre through - is this normal?

CO2 will permeate the tube far faster than air, so your tyre will likely deflate significantly between rides.

I normally use a big pump that I have at home and CO2 for on the road. But that's a thought, I never considered the difference in the gases, I would have left the CO2 in after a repair, but sounds like a good idea to release it and replace with O2 - thanks!

agent nomad

A lot of people do this when fitting tyres

If you look at the tyre there is a label with the make and model on it if you move this round until it is centred over the valve hole fit inner tube and use wheel as normal.

When you get a puncture remove the inner tube blow up the inner tube with a pump (not CO2) and find the hole now lay the inner tube next to the wheel and tyre vale next to the tyre label and still in line with valve hole if you have it the right way around you now know where to look for the glass, flint, or whatever has found it's way into the tyre.

Hope I have put something so simple into works you can follow (too cold in the garage to take photos etc.)

Another tip is to dust the inside of the tyre and the inner tube with talcum powder, this helps when fitting the tyre and inner tube as they move around and stay in the tube, and don't get trapped under the bead as easily.

Pre dust spare inner tubes that you carry as spares.

lapavoni10

I put my spare tubes in nitrile gloves with talc. Makes the tube easy to fit, and you have a glove if you have to mess with the drivetrain.