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Why do I get punctures?

danielschipper's picture

By danielschipper - Posted on 29 August 2010

Out at Manly Dam today and got a nasty puncture on the rear tire. Double snake bite... Lucky I had just got a pump and repair kit...also had some co2 canister which made getting up to pressure easier.

I'm just getting back into riding although this reminded me that I would get punctures regularly when I was riding a 6" travel bike 3-4 years ago. I tried hard and low tire pressure and some imported tubes that were supposed to be more resistant to punctures (don't remember the brand but they were green). no matter what I did still got punctures; always on the rear tube, always snake bite- I.e. Two holes, directly opposite each other.

So my question is what am I doing wrong? I'm considering going tubeless to avoid the problem although figure if it is a riding style or simile tire pressure issue I could save some cash.

I'm riding a Giant Trance 5" travel and everything is stock.

Any suggestions?

Fatboy's picture

Not enough tyre pressure for your weight or riding style. Go tubeless. If you weigh up all the pros & cons of going tubeless the cons side of the ledger is empty.

herzog's picture

Definitely go tubeless, or ramp up your pressures to something really high like 45.

You do lose traction at high pressures though, so tubeless is the way to go.

CB's picture

I've been running tubeless for about 3 1/2 years ( on a Cannondale F1 and then a 575) and haven't had a single puncture. I run 30psi front and 32psi rear and weigh around 95kg. To me, it's a no brainer.

The only time I've used my emergency spare tube was to give it to another rider at the Fling 2 years ago.


PIVOT MACH 5's picture

Regardless of your tyre pressure you should lift your weight off the bike as you roll over objects. Try to pretend that your bike does not have suspension and you'll ride much smoother and faster. And of course minimise the risk of flattening out your back wheel on a rock.
Also go tubeless.

VC's picture

i have a similar bike and had similar probs, i dont have tubeless, and i like slightly lower pressures, so my fix.....and this is a secret.... i use a downhill dual ply back tyre (larsen ) and i love it...! i enjoy red hill and used to get lots of punctures, now i can keep my low pressure and minimize punctures.

daveh's picture

I have a Trance X2 and would continually get pinch flats. I started running at a higher pressure and whilst the number of flats definitely reduced I wasn't happy with the loss of traction. I went tubeless about a month ago and it has been great. I purchased tubeless specific Maxxis and Stan's tubeless kit and use my existing non-tubeless specific rims. Converting to tubeless using the kit was an absolute breeze (a standard floor pump was fine) and (touch wood) I have had no issues with losing any pressure at all. I run it at about 40 psi which is exactly where I want.

Yep, get more pressure in your tyres or go tubeless for sure.

Rob's picture

I notice fatboy has a notubes kit for sale in his various bits ad.

I have 2 tubeless wheelsets: 1 is ghetto tubeless (it has Stans Yellow rimtape in it now - on standard times) and the other is 'proper' tubeless (Mavic 819XM rims). Fitting 'proper' UST tyres on the Mavic rims is a dream compared to the other set.

So while someone above said there is no downside to a tubeless setup, the fitment can be a pain. Proper tubeless rims and tyres help a lot here.

daveh's picture

My first attempt and needed new tyres anyway so purchased Ignitor/Larsen LUST combo and put them on Mavic rims. Even my "practise" fitment, i.e. without liquid latex, sealed up without any loss of air. It went so well that I have been ultra sceptical and waiting for something to go wrong but a month later, still all good. I would not necessarily recommend people go tubeless but I would recommend the kit if the price is ok and you are keen to go tubeless.

Colt's picture

Well I'd like to make the point that I have a Trance X2 2009 and run with tubes at approx 45 PSI (only 5PSI more than daveh is running using tubeless) and I have had only ONE pinch flat and NEVER had a snake bite type puncture.

Everyone who is just saying "yeh go tubeless" isn't exactly helping solve the problem in the first place : that is, what's causing the punctures? As he said he's tried hard and soft psi and still got flats so obviously it's NOT an issue of too low tyre pressure.

In that case, is it not more feasible that he has an issue with his spokes protruding through or something along such lines? Has another rear rim been tried to see if it has the same issue?

The complete devotion to tubeless (and clipless for that matter) by members of this site, to the exclusion of all else, does make me chuckle. Sometimes tubeless isn't the fix for everything. LOL. Smiling


hawkeye's picture

pinchflat and snakebite punctures are the same thing.

What causes the puncture is the rim compressing the tube into the ground on a hard hit.

Spokes protruding through as you suggest or rim tape drifting out of place and exposing the sharp edges of spoke holes are definitely worth examining, but given that he's had the same issue on two bikes now I'd be looking at the common element, which is probably riding technique and/or line choice.

Hit something hard enough and you'll get a pinchflat no matter how high the psi. I had my first ever pinchflat last week on 90psi road tyres. Sad

Colt's picture

Thanks for the correction Hawkeye... I was under the impression that snakebite was dual holes while pinch flat was ANY split caused by a pinching of the tube. You learn something new everyday... Smiling

And as you said, the issue at hand has been on two bikes and, as he said, on various PSI levels, and thus one has to invesigate the common element.

I just had to point out what everyone else seemed to have completely missed... that his issue was not PSI related and thus all the going on about tubeless rims was about as helpfull as suggesting he use wooden wheels.


hawkeye's picture

I wouldn't be so quick to dismiss 'going on about tubeless' as monomania. There's a lot of years of accumulated experience on the board here. And there is a lot of sense to the tubeless suggestion:

1: You take the problem of punctured tubes out of play by removing the tube
2: Proper UST or tubeless ready tyres have heavier sidewalls, so are less likely to allow the rim to compress all the way to the tread

You do create a risk of a different nature - burping the tyre off the rim - but this tends to be prevalant only with non-tubeless tyres running on inadequate pressure. It is a rare occurrence with UST rubber on UST rims.

And I believe wooden wheels are making a comeback in some quarters when teamed with singles. Laughing out loud

Fatboy's picture

Guys, going tubeless doesn't explain why he has problems but will pretty much eliminate flats.

One sure way to get great advice in sport or business is to ask the guys at the top of their game. I know you won't get any elite Cross Country riders defending tubes. Most have probably forgotten how to fit them.

Scottboy's picture

was at Canberra racing track at Stromlo earlier in the year and I think it was Gordo racing, he was bringing his tubes back with him & grabbing another one coming thru the finishing line or he was being a courier for other riders out there I don't know.

daveh's picture

I am not sure that it is a devotion to tubeless, it is just a problem that others (myself included) have had and have solved it by going tubeless. All anyone can do is provide a reason within their own experience and knowledge. I think that several people have actually said what the problem is according to their experience and then provided the solution that worked for them. I had pinch flats and, as I said, running at a higher pressure reduced the frequency but I still got them. I have gone tubeless and that problem has been eliminated.

muvro's picture

My guess is it's a line/technique issue. I run around 38psi in my freeride bike and very rarely get a flat. The only times I get a flat is when I haven't checked the tyre press before I ride and it's gotten a bit low @ around 25-28 psi.

On my XC I run tubeless and run my pressure at different levels depending on the track and conditions, anywhere between 30-40psi.

I was a tube man, but since getting my XC bike and now running tubeless, I'm a convert. The decreased rolling resistance, the lighter weight and no flats are all reasons for me never to go back to tubes on the XC rig.

ps's picture

I used to get regular pinchflats riding the terrey hills trails. Usually only happened on particular rocky downhill sections where speeds were higher and I was hitting rocks with sharp edges. Upgraded to a pinchflat resistant tyre, checked the tyre pressures before every ride and no punctures. After wearing out that tyre I replaced it with a tubeless that the LBS told me was better for resisting pinchflats. Again no punctures when running approx 35ps in the rear on a hardtail.
I went tubeless this year because there is a smaller chance of a pinchflat related mechanical delays. Most people who want to avoid pinchflats go tubeless. At a recent 24 hr race there were at least 5 pinchflats on the first lap. The experienced guys run tubeless and didnt get flats. My brother went into the race with a rim problem and ended up with a slow leak on the second lap so we put in a regular tube. It lasted another 5 hours before he pinchflatted it on a rocky section. We put my tubeless on his bike and he didnt have another problem for the rest of the race. I got two more flats running his tyre with tubes.
Bottom line is that tubeless works better on rocky trails.
There are riding style influences as well as line, tyre pressure, rim and tyre influences however the major factor is tubes dont survive hits on sharp rocks.

Noel's picture

Dear Daniel,

I bet you have your rear shock too hard, and your rear tyre too soft.

Maybe stay away from super thin tubes like maxis featherweight tubes, use lots of talc in your tubed tire, keep your rear closer to 35 than 25 psi, set your sag closer to 30% than 20% and if you're over 100kg you might un-weight the rear end more often when you expect it to impact something hard. Also, if those Nevegals (in the pic) are the skinny ones, and you plan on staying with tubes, maybe get something with a bigger bag, like a 2.35 or something. I'm sure somebody will have a 2nd hand 2.35 one laying around. A slightly worn Nevegal runs fine on the back, save your fresh new tacky one for the front. I think the thinner tires pinch flat easier at they just don't seem to have the give.

Lots of love,


PS: I have tried to think of various things that could contribute to it.

danielschipper's picture

Hi all,

Thanks heap's for the feedback. I'm fairly certain that technique is the root cause. I'm a bit of a speed nut so tend to barrel down anything steep as fast as possible. Speed does tend to make up for bad technique until you either come off or get a pinch flat, and I tend to do both.

I weigh in a bit over 80Kg's (hopefully under 80Kg's by summer now I have my new bike) so I don;t think it's a weight issue as such. I don't always tend to pick the best line and certainly get the odd jolt when the rear picks up a rock or a root. I guess I could slow down but I like the speed too much.

Will have a look at some of the non-tubeless options to start with but think I will give in eventually. I do like the option of never having to sit on the side of a trail with sandpaper and glue again.

Fatboy's picture

Yes Smiley Gordo flatted a few times. Once he had the first and put a tube in he kept having problems with tubes. He certainly never started the event with a tube in. He runs heavy tubeless small block 8's but as you know Stromlo has sidewall ripping granite which will rip anything if you hit it the wrong way especially at speed.

Gordo runs normal tyre pressures at technical tracks like Stromlo but very high pressures (>45psi) at the enduros like the Fling and he's tens of kilos lighter than most of us (well rotund middle aged blokes like me anyway). Not that he does that to prevent flats as he does it for rolling resistance but he does alright with his slightly different view on tyre set up.

Noel's picture

I think carry a spare tube instead of repairing it on the trail.

First flat = use the tube, and go to higher pressure
2nd flat = use your mates spare tube
3nd flat = get out the repair kit

You can leave fixing tubes for something to do at night as a batch, and do a few at once.

Discodan's picture

In all seriousness is it really worth repairing them these days? I get cheap and cheerful tubes for $5 from Big W, it's a quick and easy swap. Compared to frigging around with repair kits and then not being convinced it still doesn't have a slow leak (I know, trust your workmanship) it's a no-brainer for me. I keep the old tubes for a rainy day but that's it. I patched a tube on the weekend just to teach my son how it's done but that was an exception

Rob's picture

Well, it's up to you, but $5 for a new tube (which if it's from Big W I'm guessing isn't going to last that long) versus 50c for a patch and some glue?

Sure, it takes some time to fix a flat but what else you gonna do on a Sunday night? Eye-wink

CharlieB's picture

My $$ is the line/technique angle being the issue. I am happy to run tubed at >45psi – and still get pinch flats on my SS hardtail. It does sound like I ride like you, what I give away in technique, I try to make up with bravado. Unfortunately it is a poor substitute! I personally blame my dual sus riding for encouraging me to take what among my riding buddies are considered ‘interesting lines’. Going back to a hardtail is reminding me a few things – however they are seemingly forgotten on a fast bit of trail. Once one goes, I am likely to do another couple – then I take care, but there is no fun in that! So my advice – take more tubes, and get fast at changing them.

Flynny's picture

Just letting the rear wheel smash into stuff isn't going to help. With a bit of travel on the back if you're feeling it kick then you wheel certainly is too. Are you denting your rim?

Things to try.

Tyres with sidewalls not made out of paper. Not sure what you're running but try a UST tyre, even if you use tubes, just to get the thicker sidewall

Pressure. depends on the width of the tyre. a 2.35 will need a lot less pressure not to pinch flat than will a 1.95. I'm a tad over 90kg and run 25psi in the back of my DH bike with 2.5s and 35 in the back of the XC bike with 2.1

Tooobs. If you stick with tubes try talcum powder in the tyre. In theroy (and I used it for a while with seeming success) this allows the tube to slide rather than stick to the inside of the tyre so instead of pinching it slides out of the way. I know some desert safari riders who oil up their tubes on their motor bikes to help ensure against pinch flat.

delicious's picture

You're all missing something here...
Giant's Maestro suspension has an interesting way in which it goes through its stroke. Unfortunately, very rarely do people have their bikes' suspension set up correctly, and that includes the all important correct chain length...
Briefly, the suspension is designed to run a lot of sag, and at that point the rider has a nice pedalling feel in middle and big chain rings and a little mushy when in the granny. When taking a hit ( of any type ) the stroke starts slow then speeds up. The inherent progressive nature of an air shock counter acts the faster shock rate ( easier leverage ) and the overall feel is one of smoothness and a nice even stroke all the way to the end.
Now, the first thing to flex on a modern bike is the tyres. So, if an innocent Giant rider defaults to the all too typical perspective of increased shock pressure ( thus less sag ) equals better pedalling/ride quality then a) he or she is very wrong and b) that person will get pinch/snakebite flats all day every day. Why?
One's suspension is designed to react to bump force. Over inflation of the shock will cause it to resist bump force yet the tyre will still compress and more so than if the shock ( and for that matter, tyre ) pressure were correct. Compress all the way to rim contact and....
There is definitely a dedication among the followers of this site to use tubless tyres. Go for it. A tubeless set up will obviously remove the snakebite issue. However, before the confused and bewildered gets all fired up to do the conversion, put some effort into setting up your bike effectively. Chances are you've paid a good deal of brass for it. Don't you think you deserve to get the most out of it?
A note on tyre pressures; Low pressures are not automatically a way to increase performance. Grip is obtained from the rubber compound. Always keep pressure within the manufacturers minimum and maximum and for the love of God work out for yourself what works best for you. Everyone weighs differently and rides differently and carries different amounts of crap in their backpack. Experiment and don't forget the relationship between tyre presssure and suspension pressure. Follow the advice of the manufacturer; they know better than you.
Really low pressures will increase the chance of flats and wear tyres and tubes faster.
Higher pressures will help in getting over obstacles and debris and assist in breaking traction, for those who like to ride like Nori Haga...

ADZA's picture

Delicious is quite correct about the suspension characteristics, however another thing to consider is this...
make sure you have the right size tube for the Tyre you are putting on, i.e don't think.... ah i might just go for bigger tyres say 2.25 from a standard 1.75 or 2... because i guarantee you that although the tube will expand to fill the space, and will seem ok.... effectively what you have now done is reduce the rubber thickness of the tube proportionate to the now increased surface area and you have now also put extra stress tension on the rubber... example take a rubber band and stretch it...notice how the rubber gets thinner the more it is stretched... well that is what will happen to your tube and if anything hits it then the thin and already stressed rubber will simply split.

this is exactly what happened to me, afterwards i went to a set of 2 - 2.5 tubes and ride my nevegal 2.25's and it hauls my fat ass (125kg) around manly dam without any issues on the rear, even a few times when i hit something hard on the rear and i feel it really compress i think uh-oh not a flat.. but no it just bounces back and keeps on rolling

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