Puncture minimisation tips

Road cycling & upcoming rides
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geoff m
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Postby geoff m » 13 Aug 2012, 23:20

Given a number of punctures on the Sunday combined C25/28 ride its worth sharing a few tips.

WARNING: IF YOU FOLLOW THESE TIPS YOU MAY RENDER YOURSELF OUT OF CONTENTION IN THE 2012 FLAT TYRE COMPETITION

Always take 2 inner tubes. Often the offending piece of glass/wire stays hidden in the tyre wall - only to get a flat in the same spot. If you need to borrow a tube, these are not cheap. Always ensure you bring a new tube the next week for your club colleague who saved your bacon, or pay $10 or whatever it is they paid for their tubes.

If you get a flat, don't forget to take off your tyre, invert it inside out, and check the inner walls. Often the glass/wire is still there, waiting to do the same thing to you in 200 metres!

Ever noticed someone refitting their tyre onto the wheel and aligning the tyre brand just under the valve?? Well there's a good reason. If, you are unable to find the offending glass fragment in the tyre wall, but know where the hole was in the inner tube by reinflating the tyre, its easy to know which part of the tyre wall the puncture pentrated from. This is because your tyre is always fixed to the same position relative to the valve (ie. the Brand Logo). Then go back and look closer, and often the offending piece of glass can be found on closer inspection. Or hopefully it's no where to be found, which means you are pretty confident you won't reflat in the same place.

Lastly, after each ride, or before your next ride, get a small nail or object with a sharp point and slowly spin your wheels around and check for glass fragments embedded in your tyre. Then carefully pick these out. After every ride I average about 2 or three fragments. If not treated, these stay in the tyre, and get pushed down the more your ride, or as you hit potholes, and then punctures the inner tube. They are main offenders for punctures. By taking these out I reckon you will reduce your punctures by 50%.

Ignore the above tips, and you may have a better chance of a high score in the Flat Tyre Competition.

timothy_clifford
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Postby timothy_clifford » 13 Aug 2012, 23:24

Or buy some tyre liners.

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geoff m
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Postby geoff m » 13 Aug 2012, 23:25

Or buy some tyre liners.
Mr Tuffy are good brands for inner liners

Eleri
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Postby Eleri » 14 Aug 2012, 06:49

And pump your tyres up! Not only will you ride easier, but you are less likely to puncture. Double bonus.

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weiyun
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Postby weiyun » 14 Aug 2012, 15:13

1) (Without saying) Watch the road for debris.
2) Back off on power and let the bike coast should one rides through a debris field.
3) Regularly examine tyres and pick out embedded glass fragments.
4) Tyres always pumped to the recommended pressure. Too high and too low will both increase puncture risk.

Lizanne
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Postby Lizanne » 14 Aug 2012, 15:50

new tyres!
if you've chewed through the rubber, it aint gonna protect the tube

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mikesbytes
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Postby mikesbytes » 14 Aug 2012, 17:01

Don't ride with me

rhys
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Postby rhys » 14 Aug 2012, 19:59

Avoid crap pieces of road. And never run more than 90psi, especially if you weigh under 70kg.

shrubb face
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Postby shrubb face » 14 Aug 2012, 20:15

Im not convinced about that last one Rhys. Whats the logic behind that?

Im under 70kgs....

rhys
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Postby rhys » 14 Aug 2012, 20:39

Only from personal experience. I am 85kg on a 'light' day, and I've never run more than 90psi. If helps you stick to the ground better, and as your tyres have more give, you're less likely to have glass inject itself into your tyre and more likely to just roll over it. This may explain why I have had two punctures in the last three years, but that may also be down to luck and the smooth roads I tend to ride on.
A few friends of mine who at a guess would weigh 60-70kg each used to run 110-120psi in their tyres and riding behind them on rough road, they would be bouncing and shuddering all over the place. Imagine riding heffron with 120psi as opposed to 90psi, there would be a massive difference in comfort, as well as grip when cornering. It's especially important when you run harder compound tyres like Gatorskins, which can be quite slippery and unpredictable in some conditions.

Eleri
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Postby Eleri » 15 Aug 2012, 12:54

A few friends of mine who at a guess would weigh 60-70kg each used to run 110-120psi in their tyres and riding behind them on rough road, they would be bouncing and shuddering all over the place. Imagine riding heffron with 120psi as opposed to 90psi, there would be a massive difference in comfort, as well as grip when cornering. It's especially important when you run harder compound tyres like Gatorskins, which can be quite slippery and unpredictable in some conditions.
Umm, I ride Gatorskins and weigh somewhat less than 60kg AND I run 100-110 in my tyres. Someone please tell me if I'm bouncing all over the road because I wasn't noticing it. A chap did tell me I should run 80psi and would have a more comfy ride but I ignored him :-)

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weiyun
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Postby weiyun » 15 Aug 2012, 14:49

Umm, I ride Gatorskins and weigh somewhat less than 60kg AND I run 100-110 in my tyres. Someone please tell me if I'm bouncing all over the road because I wasn't noticing it. A chap did tell me I should run 80psi and would have a more comfy ride but I ignored him :-)
Micro bounce, one that breaks contact, loses grip and loses efficiency. By the time a rider notices it, it's too late. :mrgreen:

Seriously, there's good evidence that suggests more is not always better. For cycling, we are constantly balancing the risk of pinch flats with that of "bouncing". Sheldon Brown has a recommendation table that has been widely accepted and adopted. Coming into 21st century, tyre pressure can be further reduced with tubeless tyres (as the risk of pinch flat is no longer there). I use 100/105psi for my 63-65kg weight. Been scientifically convinced that I should go to 90psi but haven't, all due to a fixated old practice. I suspect many are in the same boat.

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Philip
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Postby Philip » 15 Aug 2012, 15:51

The physics is interesting. If you are riding on a perfectly flat surface then the harder the better, less rubber on the road = less friction. Whereas if there is any kind of roughness to the surface then that same high pressure becomes less efficient. Assume your tyres were solid and had no give at all, every bump no matter how small would require the bike to change direction on the vertical plane to get over the bump. Every vertical movement robs energy from your horizontal momentum. Where as a softer tyre will absorb the small bumps allowing the bike to stay in a horizontal path. Also saving ones butt from the torture of the road. All this assumes two things though. One, that the bike is completely stiff and doesn't it self absorb any of the road bumps. And two, that I have any idea what I'm talking about, which may be doubtful.

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Adrian E
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Postby Adrian E » 15 Aug 2012, 15:55

A few extra tips...

* Keep an eye out for rim tape failures. If the puncture is on the non-tyre side of the tube this is the most likely cause. They will keep happening unless you fix the rim tape around the spoke hole.
* Be kind to your valve. Valve failures can happen before you go for a ride and during a puncture repair. If you're on the road and a group is waiting, don't rush the job when you pump up your tyres. Your friends will be more annoyed if they have to wait for you to put in another tube in.
* Don't use tyre levers to put the tyre back on (unless you really have to). You may repuncture. To just use your hands, hold the wheel on the ground with valve at a 6 o clock position in front of you. Starting with both hands at the 12 o clock position, push the bead into the 'well' of the rim, and holding this tension, work both hands around the rim in a continouous movement untill your hands meet at the 6 o clock position. With a bit of luck, the tyre will pop straight into the rim with very little effort.
* Pump your tyres up at the race. If you're driving to a race be careful leaving high pressure tyres exposed to the sun in the back car. I've seen/heard them blowup driving to races on several occasions. It can be quiet unnerving.
* Read Sheldon Brown. He know's everything: http://sheldonbrown.com/flats.html
* If you've never learnt to change tubes (successfully), come along to one of the City of Sydney's free bike maintenance courses http://sydneycycleways.net/courses

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mikesbytes
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Postby mikesbytes » 15 Aug 2012, 16:13

The physics is interesting. If you are riding on a perfectly flat surface then the harder the better, less rubber on the road = less friction. Whereas if there is any kind of roughness to the surface then that same high pressure becomes less efficient. Assume your tyres were solid and had no give at all, every bump no matter how small would require the bike to change direction on the vertical plane to get over the bump. Every vertical movement robs energy from your horizontal momentum. Where as a softer tyre will absorb the small bumps allowing the bike to stay in a horizontal path. Also saving ones butt from the torture of the road. All this assumes two things though. One, that the bike is completely stiff and doesn't it self absorb any of the road bumps. And two, that I have any idea what I'm talking about, which may be doubtful.
Good definition Philip. I'll add from another angle.

If you had 100% solid wheels, then each micro bump will convert forward kinetic energy into upwards potential energy, but this does not necessarily covert back to forward kinetic energy when the wheel comes down. Now with a pneumatic tyre, the tyre folds around the micro bump and gives you less upwards loss, while adding a small amount of rolling resistance.

The deceptive thing is that the harder tyres actually feel faster, then they are not.

So what's the optimum pressure? There are different views on this. 15% drop is a popular guide.

Now back to punctures, if you tyres are too soft, you get flat spots when you hit some of the features of Sydney roads. Too much pressure and you get more objects piercing the rubber, where the tyre may of just folded over it and left it where it was.


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