First Puncture - But why!?

nbuuifx

Just went out for a quick ride before dark tonight, 3 miles from home there was a loud bang followed by a short hiss. My rear inner tube

My friend cycled home and got my car and came back for me.

I expected to see a big rupture from the very loud bang it made but all I can find is a small horizontal 4mm slit in one side of the innertube.

I've closely examined the tyre and there isn't a single nick or puncture mark in it (they've only done a few hundred miles).

I pumped the tyres up before I left. I inflated to 125 but lost a little as I removed the pump. The max pressure is stated as 120psi.

At the time I was doing 20mph down a steep bank, approaching the junction at the bottom. I was heavy on the brakes. The road was fairly smooth at the time of the bang, but I had gone over a rougher patch further up the bank.

The tyres are 700x23 gatorskins.

Just wanted to know what would have caused it?

harkmeadow

too much pressure. 95-100 tops is max you need for a road bike. Oh and just because it happens.
ps - no spare tube / puncture repair kit?!

nbuuifx

I tempted fate with my post on this thread only 4 days ago:

viewtopic.php?f=40020&t=12871519

I've never had a puncture so stopped carrying all the kit! Will have to start again I think!

I thought the idea was that the higher the pressure the less likely you are to get pinch flats etc?

I think I'll carry a spare inner tube and a couple of levers from now on, can't be bothered with fixing punctures at the side of the road.

To be fair though I think given the situation I'd have done the same even if I had the tube/repair stuff. The sun was setting, it was only 3 miles. By the time I'd faffed swapping the tube and inflating it would have been dark anyway.

ShutUpLegs

The most i've ridden on a puncture is 5 miles. Think Lance won a race with the final 15 miles punctured.

nbuuifx

ShutUpLegs wrote:

The most i've ridden on a puncture is 5 miles. Think Lance won a race with the final 15 miles punctured.

So can you actually continue without knackering the tyre/rim? Is it safe?

I went about 20 yards, it did seem to handle normally though - I imagined falling off as I heard the bang!

antfly

You will get plenty more flats and there might not always be someone to pick you up. Everyone gets flats occasionally, replacing a tube takes 15 mins tops and some people do it in under 5. If you are 30 miles from home alone it's the only option so just keep everything you need on the bike so it's there when you need it and you don't have to go home just cos you flat. 125 psi is too hard.

GSJ

This is slightly off topic but my tyres say 100-145 psi which is ideal for me? I'm a light rider at just under 10stone

simon_masterson

nbuuifx wrote:

I tempted fate with my post on this thread only 4 days ago:

viewtopic.php?f=40020&t=12871519

I've never had a puncture so stopped carrying all the kit! Will have to start again I think!

I thought the idea was that the higher the pressure the less likely you are to get pinch flats etc?

I think I'll carry a spare inner tube and a couple of levers from now on, can't be bothered with fixing punctures at the side of the road.

To be fair though I think given the situation I'd have done the same even if I had the tube/repair stuff. The sun was setting, it was only 3 miles. By the time I'd faffed swapping the tube and inflating it would have been dark anyway.

With practice you should be able to change the tube over and pump it up within a couple of minutes.

That logic is basically correct. With higher pressure rolling resistance should be reduced and the likelihood of pinch flats also reduced. However, the risk of punctures is increased, so the honourable gentleman who pointed out the factor of pressure has a point. This is a divisive issue, but nevertheless you do have the pressure pretty high. It could be that you could reduce the risk of puncture.

The maximum pressure can be a good starting point - and indeed may work very well - but don't take it as gospel. The tyre companies aren't going to give you an exact number because there isn't one. They also don't want to be sued. The pressure that you should use will be determined by your tyre and its size, the terrain on which you ride, the desired ride quality and traction, and the weight of the rider and any luggage on the bike.

Sheldon Brown, as ever, has plenty of good stuff to say on the subject.

http://sheldonbrown.com/tires.html#pressure

120psi happens to be the rough figure he gives for a 23mm tyre, so chances are you may not need to reduce it by that much. Perhaps try 110 or 100 and see how you get on.

I'd love to be more helpful as I have Gatorskins on my favourite bike, but they're 27x1 1/4 (32mm), and I run them at a very ordinary 85psi, which - for what it's worth - is the maximum pressure. I haven't punctured them yet.

simon_masterson

GSJ wrote:

This is slightly off topic but my tyres say 100-145 psi which is ideal for me? I'm a light rider at just under 10stone

See the Sheldon Brown article I linked to.

If you're just under 10 stone (I wish I still were!), 100 will probably be fine. I definitely wouldn't go up to anywhere near 145 unless this is a track bike we are talking about! What tyre is it, and what size?

nbuuifx

Thanks for that link, there was also a link from that page to another which suggested that for my weight (88kg) I should be looking at around 100-110psi Max.

I still can't figure out what caused the puncture though. It shoudln't be a pinch flat as they usually occur if under-inflated. For over inflated everything says you get a puncture easier from sharp objects etc, but surely this would have punctured the tyre as well?

I'll keep them between 100 and 110 for now and see what happens

blackhands

ShutUpLegs wrote:

The most i've ridden on a puncture is 5 miles. Think Lance won a race with the final 15 miles punctured.

But he was most likely using tubulars. Different altogether.

cookeeemonster

on my vredestein fortezza tricomp tyres the minimum pressure is given as something like 115 psi and the max I think 160 (possibly more...checked last night but memory like a goldf-what was I talking about?)

anyway I pumped it up to halfway between that as it seemed pretty high...what to do now? trust tyre manufacturer or t'internet??

harkmeadow

Just stop worrying. Pump to 90-100 PSI, go and ride. Job done. Chances are you will be fine. Chaps i know who get / got loads of punctures were always around 120. Pump, ride, enjoy. And accept that punctures are a fact of life. Obviously if you are getting loads them do the usual, inspect tyres, rim tape etc.

GSJ

Simon Masterson wrote:

GSJ wrote:

This is slightly off topic but my tyres say 100-145 psi which is ideal for me? I'm a light rider at just under 10stone

See the Sheldon Brown article I linked to.

If you're just under 10 stone (I wish I still were!), 100 will probably be fine. I definitely wouldn't go up to anywhere near 145 unless this is a track bike we are talking about! What tyre is it, and what size?

Tyre is Vittoria rubino pro's at 700x23 I normally pump upto 120

richh

I'd take the pressures being mentioned here as guidelines rather than hard fact. What you should be using is specific to your weight (not someone elses) and your preference for a bone jarring ride vs a little compliancy. It will also dpeend on what size tyres you're using as there's no point in using the same pressure in your 23s based on a recommendation from someone that's running 25s.

For me, at 90-95kg, 90psi in 23c tyres feels ridiculously soft to the point where it doesn't really feel safe at higher speeds or in corners. Through trial and error I now use 115psi front and rear and I don't find that too jarring and I don't think I experience any more punctures than anyone else. If I was 70kg though I'm sure I would be hating that setup!!

The best thing you can do is to try a variety of pressures from 90psi up to 115-120psi and see what works for you.

plowmar

Purely rule of thumb but I tend to take the max. tyre pressure and reduce it by 10psi and take that as the rear tyre pressure and then reduce that by a further 10 psi for the front.

This doesn't stop punctures but feels like good balance between comfort and forward motion.

nbuuifx

I swapped the tube today - so much easier than MTB tubes/tyres! Put it back on with just my thumbs.

As I put it on the bike I noticed one of the rear pads was sitting higher than the other and was very close to the tyre when the brakes were full on, I can't see that it's marked the tyre at all but the horizontal slit would have been just about this point, I'm just wondering if it could have been heating the tyre etc?

nbuuifx

Well today I got my 2nd puncture - Same tyre.

This time the sidewall gave, the inner tube bubbled out and then popped. So I'm guessing I was right about the brake pad rubbing the tyre the other day. When I checked it the other day the sidewall was fine. The brakes haven't been anywhere near the tyre today. I had both tyres at 100psi, the rear had a brand new continental inner tube. The tyre now has a buldge in the side. I replaced the inner tube whilst out, and rode home carefully with it at low pressure.

So I need to get a new tyre now as well

I've just done a bit of reading and noticed lots of complaints about the gatorskins having very weak sidewalls which fray quickly.

Is there a similar tyre which offers good puncture protection, but with stronger sidewalls?

I've borrowed a spare tyre for the minute, but could do with getting a replacement ordered today.

nbuuifx

Just noticed I can get a gatorHardshell for about £3 more which offers bead to bead protection, but weighs an extra 30g.

Anyone tried them - are they worth having a go at?

rubyrider

Aren't the brakes supposed to act on the rim and not on the tyre? Did you smell burning rubber?

nbuuifx

rubyrider wrote:

Aren't the brakes supposed to act on the rim and not on the tyre? Did you smell burning rubber?

Haha, thanks for that

They were on the rim, just the one pad was sitting a bit high, not sure if I knocked it though as I'd only checked all the brakes about 2 weeks ago and all pads were sitting in the correct place. Strangely all the pads are in about the centre of adjustment, as was this one but now I've had to move it right down, not sure if something else has moved?

But no - no smell of burning rubber, I think if it was touching it was only just touching. I couldn't see any wear on the sidewall after the blowout, but now it has given you obviously can!

rubyrider

Well my brake pads were mysteriously uncentring themselves, even overnight! .. and I had a weird few ghost changes between 3rd and 4the gear, and it was a little noisy but only in those gears and only when I was riding it... it turned out to be my rear bearings - just needed tightening. Have had no probs since, but of course I'd been twiddling with brakes and gears thinking they were the culprit

nbuuifx

Gear changes are all OK (on the rear anyway), just not sure about the brakes. Rear bearing feels good though, no play with the wheel etc.

Found the regular gatorskin tyres at Halfords for £17.59 which seems pretty cheap compared with everywhere else. They don't seem to do the hardshell ones though. I might give the regular ones a try at that price.