A moment's inattention this morning, and I hit a nasty wee pothole, going at a fair lick, and got a snakebite puncture, two little slits in the tube, maybe 6mm long and 5mm apart – not something I've experienced before.
Try as I may, I can't visualize exactly what happens inside the tyre to produce this effect. Anyone enlighten me?
Snakebite puncture
-
NATURAL ANKLING
- Posts: 13780
- Joined: 24 Oct 2012, 10:43pm
- Location: English Riviera
Re: Snakebite puncture
Hi,
Tyre folds flat at point of impact with sharp edge of object.
The inner tube also deforms flat but wider than the norm, like flattening an cardboard tube.
So the rim pinches the tyre and tube against the offending object!
Hence the two slits.
Check your tyre for damage.
More air and keeping eyes on the road in front normally helps, I realise this is not always possible in traffic / bad weather.
There was limit to how little air you have in a off road motorcycle as to not get the same, go below at you peril.
I myself dont deflate tyres below max at all, there is the question of comfort with less air, and you pays the price
Tyre folds flat at point of impact with sharp edge of object.
The inner tube also deforms flat but wider than the norm, like flattening an cardboard tube.
So the rim pinches the tyre and tube against the offending object!
Hence the two slits.
Check your tyre for damage.
More air and keeping eyes on the road in front normally helps, I realise this is not always possible in traffic / bad weather.
There was limit to how little air you have in a off road motorcycle as to not get the same, go below at you peril.
I myself dont deflate tyres below max at all, there is the question of comfort with less air, and you pays the price
NA Thinks Just End 2 End Return + Bivvy - Some day Soon I hope
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.
Re: Snakebite puncture
Hard to believe the OP has never had a snake bite before. I imagine @nirakora is only 6 stone wet through. At my weight I’ve had more than I can remember.
Whatever I am, wherever I am, this is me. This is my life
https://stcleve.wordpress.com/category/lejog/
E2E info
https://stcleve.wordpress.com/category/lejog/
E2E info
Re: Snakebite puncture
It used to be called a pinch puncture (an accurate description). it wasn't until the 80's that I heard the American description of snake bite, which is quite an apt description.
Re: Snakebite puncture
I had a couple when I ran 20mm tyres, but since going to 23mm, I've had none.
Never had them before the 20mm, and never since.
It's a very very rare occurrence IME.
Never had them before the 20mm, and never since.
It's a very very rare occurrence IME.
Mick F. Cornwall
-
NATURAL ANKLING
- Posts: 13780
- Joined: 24 Oct 2012, 10:43pm
- Location: English Riviera
Re: Snakebite puncture
Hi,
On a motorcycle yes, on a bicycle no.
Well I did my Devon and Cornwall coast ride, Actually on the shakedown trial just before I did the ride, I was on a cycle path not too bad there was a concrete step over a small bridge, I knew it was there but I'd forgotten about it temporarily, when I hit it at speed probably about 15 20 miles an hour there was two bangs as both wheels hit the step.
To my surprise no flats and also no damage to the rims.
On the actual ride proper I had to ride down tracks with stones and rocks in the dark, plenty of green laneing, but despite putting no air in for the whole week I'm coming home with probably about 75 psi in each tire I didn't have a single flat in the 640 odd miles I did.
Part of that is avoiding things that you know will damage, but I think it's more about not letting out too much air from the tires when you start.
So 120 psi To start on 23 Mil tyres.
I see that Sheldon Brown says that wider tires are better than more air, that's less likely to get snake bites.
If you can't fit wide tires then putting more air in, that's the max recomended, seems like common sense to me.
With the right frame hard tires make little or no affect on comfort.
Off-road motorcycling without letting the tires down that's reducing air to sometimes a third of what is recommended, You would simply be left behind and you would find some conditions impossible to get through, lesser more rubber in contact so better grip, snake bites here would be very common and I had a few.
Devon is full of potholes, but if you can't avoid them you should reduce your speed to a snail's pace when you drop in and out of them.
On a motorcycle yes, on a bicycle no.
Well I did my Devon and Cornwall coast ride, Actually on the shakedown trial just before I did the ride, I was on a cycle path not too bad there was a concrete step over a small bridge, I knew it was there but I'd forgotten about it temporarily, when I hit it at speed probably about 15 20 miles an hour there was two bangs as both wheels hit the step.
To my surprise no flats and also no damage to the rims.
On the actual ride proper I had to ride down tracks with stones and rocks in the dark, plenty of green laneing, but despite putting no air in for the whole week I'm coming home with probably about 75 psi in each tire I didn't have a single flat in the 640 odd miles I did.
Part of that is avoiding things that you know will damage, but I think it's more about not letting out too much air from the tires when you start.
So 120 psi To start on 23 Mil tyres.
I see that Sheldon Brown says that wider tires are better than more air, that's less likely to get snake bites.
If you can't fit wide tires then putting more air in, that's the max recomended, seems like common sense to me.
With the right frame hard tires make little or no affect on comfort.
Off-road motorcycling without letting the tires down that's reducing air to sometimes a third of what is recommended, You would simply be left behind and you would find some conditions impossible to get through, lesser more rubber in contact so better grip, snake bites here would be very common and I had a few.
Devon is full of potholes, but if you can't avoid them you should reduce your speed to a snail's pace when you drop in and out of them.
NA Thinks Just End 2 End Return + Bivvy - Some day Soon I hope
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.
Re: Snakebite puncture
Paulatic wrote:Hard to believe the OP has never had a snake bite before. I imagine @nirakora is only 6 stone wet through. At my weight I’ve had more than I can remember.
Do other people find them common?
I'm quite heavy and can only recall having two, one on a fast decent where I'd seen the pothole but couldn't avoid it due to a passing car and the other my own fault for running on a tyre I knew was soft but hoped would wait till I'd got home...
I'm methodical about maintaining tyre pressures, I know what suits me and the pump is kept by the bikes, if a bike hasn't been ridden for a few days they get topped up.
-
Ride-sleep-repeat
- Posts: 382
- Joined: 24 Nov 2020, 11:58am
Re: Snakebite puncture
Used to get them all the time on the MTB when running low pressures,24psiF/28psiR on 2.35" tyres.It was a trade off to having better grip.That's why tubeless caught on quite quickly with MTBers.
Never had one on a skinny tyred bike.
Never had one on a skinny tyred bike.
Re: Snakebite puncture
Had a few pinch punctures over the years. First had them on my MTB due to running low-ish tyre pressures.
Have had a couple on my road bike and again probably needed some extra air in the tubes.
Running wide tyres on narrow rims a common cause along with not enough air pressure.
Usually shows up as two punctures either side of the tube but I have had it just on one side once.
Have had a couple on my road bike and again probably needed some extra air in the tubes.
Running wide tyres on narrow rims a common cause along with not enough air pressure.
Usually shows up as two punctures either side of the tube but I have had it just on one side once.
You'll never know if you don't try it.
Re: Snakebite puncture
I did a trip through the cheviots last year and got several in one day.
My own fault - I had 28mm tyres with insufficient pressure. There were lots of cattle grids and other sundry surface debris/ imperfections.
Up until then, I had never heard of pinch flats (I'd not ridden a road bike with thinish tyres before), and was new to the sport.
They are not fun to repair, as the holes are large and doubled up, so tough to patch successfully. Once repaired, the small pump I had with me is a struggle to blow up to the necessary 80-100psi to avoid it happening again.
I am now very circumspect on castle grids in particular.
My own fault - I had 28mm tyres with insufficient pressure. There were lots of cattle grids and other sundry surface debris/ imperfections.
Up until then, I had never heard of pinch flats (I'd not ridden a road bike with thinish tyres before), and was new to the sport.
They are not fun to repair, as the holes are large and doubled up, so tough to patch successfully. Once repaired, the small pump I had with me is a struggle to blow up to the necessary 80-100psi to avoid it happening again.
I am now very circumspect on castle grids in particular.
Last edited by Pendodave on 26 Mar 2021, 12:33pm, edited 1 time in total.
Re: Snakebite puncture
A lot of mine have been MtB and road incidents have usually been caused by catching a roadside stone of above 40mm.
Remember @PH we build roads with rocks up here (route 74) none of that fine gravel.
Remember @PH we build roads with rocks up here (route 74) none of that fine gravel.
Whatever I am, wherever I am, this is me. This is my life
https://stcleve.wordpress.com/category/lejog/
E2E info
https://stcleve.wordpress.com/category/lejog/
E2E info
Re: Snakebite puncture
Yes - quite common - on a particular corner with accumulated gravel close to home at the bottom of a hill.
Spa Audax Ti Ultegra; Genesis Equilibrium 853; Raleigh Record Ace 1983; “Raleigh Competition”, “Raleigh Gran Sport 1982”; “Allegro Special”, Bob Jackson tourer, Ridley alu step-through with Swytch front wheel; gravel bike from an MB Dronfield 531 frame.
Re: Snakebite puncture
Yes, I'd say snakebite punctures are usually a sign of under-inflation. Or very nasty potholes, cattle grids etc.
I do find the tyre pressures suggested in some posts on this forum frighteningly low. E.g. I would never put less than about 6 bars in my front 28mm tyre, and if I did am sure the rim would bottom out on cattle grids. (But then I am on the heavy side at nearly 14 stone).
I do find the tyre pressures suggested in some posts on this forum frighteningly low. E.g. I would never put less than about 6 bars in my front 28mm tyre, and if I did am sure the rim would bottom out on cattle grids. (But then I am on the heavy side at nearly 14 stone).
-
brianleach
- Posts: 635
- Joined: 14 Jul 2007, 2:10pm
- Location: Winchester, Hants
Re: Snakebite puncture
Does a snake bite have to be two slits?? I had two identical rear flats on Sunday which both had just one slit of perhaps 3mm just offset from the centre of the tube. They were Conti 25-32 tubes in 28 tyres. First tube inflated to 98psi but with a small pump not sure of the pressure in the second. In neither case was I aware of any potholes or other road surface issues although the back roads of Hampshire are pretty terrible at the moment hence my winter ride of 35 tyres on a gravel bike. Unfortunately the Genesis has a max of 28 otherwise I would look to scale up to 32.