Tyre pressure and punctures.

[Smurfy]

I've never understood why so many roadies have such an aversion to frame pumps. What is more of a pain, carrying a tiny bit of extra weight that will enable you to reinflate quickly to well over 100psi again and again, or riding slowly and trying to unweight the wheel on every bump all the way home?

http://roadcyclinguk.com/news/rides-news/zefal-hpx-classic-pump-and-go.html

 

[andrewsdad]

It's important not to run tyres at too low a pressure, mostly because the air pressure keeps the tyre on the rim but also to avoid pinch flats. When you hit a pothole/kerb/rock/whatever, you need to have enough pressure in there to avoid compressing the tube enough to pinch it and cause the "snake-bite" holes.

Sheldon Brown has (as usual) a good page on this : http://sheldonbrown.com/flats.html

... and here discusses optimal pressures : http://sheldonbrown.com/tires.html#pressure

I also run 25mm tyres. I'm a smidge under 100kg so total load is around 110kg. I would guess 60% of that goes to the rear and 40% to the front so wheel load at rear is around 65kg, 45kg front. I inflate to 120psi rear, 100psi front. Linking back to the OP, I carry a Topeak Road Morph which isn't TOO big but transforms into a floor pump and I can get 120 with that (with some time and effort). I can't bring myself to use CO2 because of the material waste (perhaps I'm wrong, do they get refilled ?).

One more point - check your tyre pressures before every ride. Certainly don't leave it weeks. Depending on the tube you use, they don't hold air forever and I wasn't at all surprised to hear you were down to 20/30 after such a long time - even though SittingBull is probably right. Anyway you don't need to be down by much to increase the likelihood of pinch flats a lot, especially on rough surfaces.

I use 700×25 gaterskins I put 120psi in both, would I benefit dropping the pressure in the front?

 

[Marc D]

Hi folks, can anybody tell me how much pressure I should be putting in my tyres? The tyres I have are Continental Contact 700 x 32c. I checked the pressure earlier as I noticed last time I was out they seemed a tad flat and the pressure was 60psi. After reading some comments on here I seen some people were saying the norm is anything between 80-100. When I tried inflating these I was only getting up to 80psi without putting my full body weight down on the pump and I didn't want to do this because of the fear of the bursting or something.

 

[RhythMick]

Hi folks, can anybody tell me how much pressure I should be putting in my tyres? The tyres I have are Continental Contact 700 x 32c. I checked the pressure earlier as I noticed last time I was out they seemed a tad flat and the pressure was 60psi. After reading some comments on here I seen some people were saying the norm is anything between 80-100. When I tried inflating these I was only getting up to 80psi without putting my full body weight down on the pump and I didn't want to do this because of the fear of the bursting or something.

The tyre will show a MAX pressure on the sidewall and it may also show a MIN pressure. According to this the 700x32c has a recommended pressure of 70 and a MAX of 80. Always read the sidewall (if you can).
http://www.conti-tyres.co.uk/conticycle/ti contact.shtml

Also Sheldon Brown covers this here : http://sheldonbrown.com/tires.html#pressure

Experiment with what feels right, but I generally go by his rule that "your tires should visibly bulge out at least a bit under your weight". After posting and re-reading that link I decided my rear tyre was actually deflecting a little too much and have upped it to 120psi. Perhaps the weight distribution is more like 30/70. Anyway worked well on my 55 miler yesterday.

If you're struggling to reach the right pressure, get a floor/track pump.

 

[RhythMick]

I use 700×25 gaterskins I put 120psi in both, would I benefit dropping the pressure in the front?

Experiment and see what feels right. Should bulge a little while riding. To quote Sheldon again ...

"When riding on a smooth surface, rolling resistance does decrease theoretically with any increase in pressure, but with modern, high-quality tires the rolling resistance at correct inflation pressure is already so low that the infinitesimal reductions gained are more than outweighed by the trade-offs.

In practice, riding surfaces aren't perfectly smooth, and overinflation actually increases rolling resistance, due to vibration."

Sheldon also suggests have a wider tyre on the front and I'm going to put a 28mm on to see,

 

[Marc D]

Thanks very much mate, I will leave them as they are for today to see how I get on. Getting them up to the current 80psi was with a floor pump but I just didn't fancy trying to pump any more air in with the resistance being quite hard.

 

[Marc D]

The tyre will show a MAX pressure on the sidewall and it may also show a MIN pressure. According to this the 700x32c has a recommended pressure of 70 and a MAX of 80. Always read the sidewall (if you can).
http://www.conti-tyres.co.uk/conticycle/ti contact.shtml

Also Sheldon Brown covers this here : http://sheldonbrown.com/tires.html#pressure

Experiment with what feels right, but I generally go by his rule that "your tires should visibly bulge out at least a bit under your weight". After posting and re-reading that link I decided my rear tyre was actually deflecting a little too much and have upped it to 120psi. Perhaps the weight distribution is more like 30/70. Anyway worked well on my 55 miler yesterday.

If you're struggling to reach the right pressure, get a floor/track pump.

Just had a read of the pages you attached and they are very useful. I have bookmarked both of these for future purposes. Many thanks again.

 

[nickyboy]

I've never understood why so many roadies have such an aversion to frame pumps. What is more of a pain, carrying a tiny bit of extra weight that will enable you to reinflate quickly to well over 100psi again and again, or riding slowly and trying to unweight the wheel on every bump all the way home?

http://roadcyclinguk.com/news/rides-news/zefal-hpx-classic-pump-and-go.html

I used to be one of those mini pump guys....stick it in your back pocket, keeps the bike looking nice. But too many times I've punctured a long way from home, only been able to get 65psi into the tyre and had to endure a pretty miserable ride home.

So I got a topeak roadmorph. It weighs the same as my old mini pump and easily gets 110psi and has a proper flexible connector so there is minimal chance of valve damage when pumping up. I attach it to the underside of my top tube. Sure it doesn't look quite so nice but the security of being able to guarantee correct tyre pressure far outweighs that

 

[RhythMick]

I used to be one of those mini pump guys....stick it in your back pocket, keeps the bike looking nice. But too many times I've punctured a long way from home, only been able to get 65psi into the tyre and had to endure a pretty miserable ride home.

So I got a topeak roadmorph. It weighs the same as my old mini pump and easily gets 110psi and has a proper flexible connector so there is minimal chance of valve damage when pumping up. I attach it to the underside of my top tube. Sure it doesn't look quite so nice but the security of being able to guarantee correct tyre pressure far outweighs that

+1 for the Topeak Road Morph, with a caveat. It can certainly get up to pressure (though it's quite tough work at 110 psi) and it's light and attaches firmly to the frame. The caveat is that I've cursed it so many times because it catches my fingers, especially when pushing it down hard at high pressure. So much so that despite my vote for it I'm going to try a proper frame pump. The extra weight can't be THAT much. Lots of people like the Zefal HPX, but I've gone for the Park PMP-5 because I like to buy quality, Park Tools are normally good quality and it has been cleverly design to adjust the size. Will report back.

 

[Smurfy]

I used to be one of those mini pump guys....stick it in your back pocket, keeps the bike looking nice. But too many times I've punctured a long way from home, only been able to get 65psi into the tyre and had to endure a pretty miserable ride home.

So I got a topeak roadmorph. It weighs the same as my old mini pump and easily gets 110psi and has a proper flexible connector so there is minimal chance of valve damage when pumping up. I attach it to the underside of my top tube. Sure it doesn't look quite so nice but the security of being able to guarantee correct tyre pressure far outweighs that

Does that conform to Rule #30?

http://www.velominati.com/the-rules/

 

[EasyPeez]

Why bother with larger pumps like the Roadmorph though when you can get smaller, lighter, prettier pumps that'll take you up to 120psi?

Or are the spec claims of the likes of Lezyne not to be trusted?
http://www.lezyne.com/product-hpumps-hp-pressdrive.php#.VSLzMtzF-So

 

[EasyPeez]

Why bother with larger pumps like the Roadmorph though when you can get smaller, lighter, prettier pumps that'll take you up to 120psi?

Or are the spec claims of the likes of Lezyne not to be trusted?
http://www.lezyne.com/product-hpumps-hp-pressdrive.php#.VSLzMtzF-So

 

[andrewsdad]

Experiment and see what feels right. Should bulge a little while riding. To quote Sheldon again ...

"When riding on a smooth surface, rolling resistance does decrease theoretically with any increase in pressure, but with modern, high-quality tires the rolling resistance at correct inflation pressure is already so low that the infinitesimal reductions gained are more than outweighed by the trade-offs.

In practice, riding surfaces aren't perfectly smooth, and overinflation actually increases rolling resistance, due to vibration."

Sheldon also suggests have a wider tyre on the front and I'm going to put a 28mm on to see,

If Sheldon says it, then there's no argument lol

 

[nickyboy]

Does that conform to Rule #30?

http://www.velominati.com/the-rules/

Thankfully I don't give a flying f*ck about those "rules"

 

[nickyboy]

Why bother with larger pumps like the Roadmorph though when you can get smaller, lighter, prettier pumps that'll take you up to 120psi?

Or are the spec claims of the likes of Lezyne not to be trusted?
http://www.lezyne.com/product-hpumps-hp-pressdrive.php#.VSLzMtzF-So

I did a fair bit of research before plumping for the roadmorph. I'm sure the lezyne is good but my experience with true mini pumps is that you struggle to get much above 80psi. Of course they are engineered up to 120psi but it is ultimately down to the person doing the pumping. With the roadmorph it converts into a semi-track pump (you can put it vertically on the ground) and that helps a lot with getting the pressure in.Also, does the lezyne have a pressure gauge?