What tyre pressure?
- commi
- Posts: 62
- Joined: Tue Jan 02, 2007 1:10 pm
- Location: Melbourne, VIC
What tyre pressure?
Postby commi » Sun Jan 28, 2007 3:53 pm
My Avanti Blade Sport comes with 700x28c all condition tyres...I remember when I first got it the tyres were rock hard. After the first 2 weeks they became a bit soft so I went to my bike shop to pump it up (they did it for me when it was getting the trip computer fitted). Now its time to pump them again. I bought a floor pump but I'm not sure how hard to pump them.
The tyre says "recommended 800KPa min/850KPa max with hook bead rim (115PSI/125PSI, 8.0Bar/8.5Bar)
Does that min 115min and 125max PSI?
The tyre says "recommended 800KPa min/850KPa max with hook bead rim (115PSI/125PSI, 8.0Bar/8.5Bar)
Does that min 115min and 125max PSI?
- mikesbytes
- Super Mod
- Posts: 22159
- Joined: Thu Dec 01, 2005 11:42 pm
- Location: Tempe, Sydney
- Contact:
Postby mikesbytes » Sun Jan 28, 2007 4:00 pm
It depends on how much you weigh. There is an optimum pressure that provides the correct size tyre patch.
If the R-1 rule is broken, what happens to N+1?
- mikesbytes
- Super Mod
- Posts: 22159
- Joined: Thu Dec 01, 2005 11:42 pm
- Location: Tempe, Sydney
- Contact:
Postby mikesbytes » Sun Jan 28, 2007 4:14 pm
On 23mm tyres that would be about 100psi front and 110psi rear.
So I guessing that on 28mm tyres, that would be about 85psi front and 95psi rear.
Michelin's tyre pressure guide
Sheldon Brown tyre pessure guide
So I guessing that on 28mm tyres, that would be about 85psi front and 95psi rear.
Michelin's tyre pressure guide
Sheldon Brown tyre pessure guide
If the R-1 rule is broken, what happens to N+1?
- commi
- Posts: 62
- Joined: Tue Jan 02, 2007 1:10 pm
- Location: Melbourne, VIC
Postby commi » Sun Jan 28, 2007 5:01 pm
I'm not sure if I'm using the floor pump correctly or not.
On my MTB, as soon as I put the valve in and lock it the gauge gives me a reading of PSI and so I could pump it up no worries...
But on the flat bar nothing happens when I put valve in and lock.
Its only when I start pumping do I see something.
So when I unscrew the cap off the tyre I then unscrew the little metal thingy, right? I can now put the pump valve thing in and lift to lock...
Have I got the steps correct?
And when I stop pumpingg (just under 100PSI) the thing is kind of hard to pull off. By the time I yank it off I'm sure I've let some air out.
I feel like such an idiot, that I can't even pump a tyre!!!
Can't wait til I get a puncture and have to change it (not that I have a spare tube or puncture kit).
On my MTB, as soon as I put the valve in and lock it the gauge gives me a reading of PSI and so I could pump it up no worries...
But on the flat bar nothing happens when I put valve in and lock.
Its only when I start pumping do I see something.
So when I unscrew the cap off the tyre I then unscrew the little metal thingy, right? I can now put the pump valve thing in and lift to lock...
Have I got the steps correct?
And when I stop pumpingg (just under 100PSI) the thing is kind of hard to pull off. By the time I yank it off I'm sure I've let some air out.
I feel like such an idiot, that I can't even pump a tyre!!!
Can't wait til I get a puncture and have to change it (not that I have a spare tube or puncture kit).
-
- Posts: 103
- Joined: Mon Dec 18, 2006 4:30 pm
- Location: Ferntree Gully
Postby tinstaafl » Sun Jan 28, 2007 5:09 pm
I actually do like the whole puncture repair process.commi wrote:Can't wait til I get a puncture and have to change it (not that I have a spare tube or puncture kit).
The secret is to carry a spare tube with you. A lot of people have a small saddle bag under the seat with a tube and tyre levers. I carry a patch kit but have yet to have a double puncture on the one ride.
It's much more fun to repair a tube at home.
Robert
- mikesbytes
- Super Mod
- Posts: 22159
- Joined: Thu Dec 01, 2005 11:42 pm
- Location: Tempe, Sydney
- Contact:
Postby mikesbytes » Sun Jan 28, 2007 5:20 pm
The flat bar has a different type of valve that is only engaged when you start to pump, therefor you don't get a reading prior like you do on the MTB
If the R-1 rule is broken, what happens to N+1?
- LuckyPierre
- Posts: 1432
- Joined: Fri Jul 14, 2006 4:37 pm
- Location: Canberra, ACT
Postby LuckyPierre » Sun Jan 28, 2007 5:56 pm
As Mike says, the 700c tube has a 'presta' valve and they often won't register on a pump's gauge until they open - ie. after you've got some air in. Mine often go way up, then the valve 'cracks open' and I start to get sensible readings. Your sequence of events seems right - well, that's what I do anyway!
Don't forget to 'unlock' the pump from the valve - but the air you hear escaping is more likely to be air in the delivery hose from the pump, rather the bike tube.
I think that 100 psi in a 28 mm tyre seems pretty high, especially if you're only low- to mid-70 kgs.
Don't forget to 'unlock' the pump from the valve - but the air you hear escaping is more likely to be air in the delivery hose from the pump, rather the bike tube.
I think that 100 psi in a 28 mm tyre seems pretty high, especially if you're only low- to mid-70 kgs.
- commi
- Posts: 62
- Joined: Tue Jan 02, 2007 1:10 pm
- Location: Melbourne, VIC
- Hotdog
- Posts: 928
- Joined: Thu Sep 28, 2006 11:00 am
- Location: North Strathfield, Sydney
- Contact:
Postby Hotdog » Sun Jan 28, 2007 9:22 pm
That's pretty much it. Over inflation reduces the suspension effect of the tyres, which gives you a harsher ride. That's not just uncomfortable as the extra juddering also reduces traction. The harder tyres also make your wheels more prone to damage if you hit a bump. Under inflation on the other hand increases rolling resistance so slowing you down, and if severe puts you at risk of a 'pinch flat' type puncture or even damaged wheel rims if you hit a bump.
Edit: Seems Bnej has been talking about these things too, over in another thread: http://bicycles.net.au/forums/viewtopic.php?p=7744#7744
Edit: Seems Bnej has been talking about these things too, over in another thread: http://bicycles.net.au/forums/viewtopic.php?p=7744#7744
- mikesbytes
- Super Mod
- Posts: 22159
- Joined: Thu Dec 01, 2005 11:42 pm
- Location: Tempe, Sydney
- Contact:
Postby mikesbytes » Sun Jan 28, 2007 11:12 pm
What happens is that the tyre feels as if its giving you less rolling resistance where in fact it is giving you greater rolling resistance. Instead of folding around the micro bumps on the road surface, it is bouncing upwards over them converting your forwards energy into wasted upwards energy.commi wrote:How would that affect the ride? Too bumpy? More prone to puncture? Control?peterrjleach wrote:I think that 100 psi in a 28 mm tyre seems pretty high, especially if you're only low- to mid-70 kgs.
If the R-1 rule is broken, what happens to N+1?
-
- Posts: 1818
- Joined: Thu Sep 28, 2006 8:38 pm
- Location: Warrnambool
Postby stryker84 » Mon Jan 29, 2007 12:00 pm
more exactly, it's actually less rolling resistance, but you're wasting energy since you're pedalling while bouncing (i.e, airborne), some of the energy you're putting into the pedals isn't converted into forward movement due to the tyre not gripping while you bounce.mikesbytes wrote:What happens is that the tyre feels as if its giving you less rolling resistance where in fact it is giving you greater rolling resistance. Instead of folding around the micro bumps on the road surface, it is bouncing upwards over them converting your forwards energy into wasted upwards energy.commi wrote:How would that affect the ride? Too bumpy? More prone to puncture? Control?peterrjleach wrote:I think that 100 psi in a 28 mm tyre seems pretty high, especially if you're only low- to mid-70 kgs.
also, related, is the slight loss of traction you get due to the bounce/loss of grip, can be dangerous if by chance you need quick precise handiling.
Return to “General Cycling Discussion”
Jump to
- General Australian Cycling Topics
- Info / announcements
- Buying a bike / parts
- General Cycling Discussion
- The Bike Shed
- Cycling Health
- Cycling Safety and Advocacy
- Women's Cycling
- Bike & Gear Reviews
- Cycling Trade
- Stolen Bikes
- Bicycle FAQs
- Serious Biking
- Audax / Randonneuring
- Retro biking
- Commuting
- MTB
- Recumbents
- Fixed Gear/ Single Speed
- Track
- Electric Bicycles
- Cyclocross and Gravel Grinding
- Dragsters / Lowriders / Cruisers
- Children's Bikes
- Cargo Bikes and Utility Cycling
- Road Racing
- Road Biking
- Training
- Time Trial
- Triathlon
- International and National Tours and Events
- Cycle Touring
- Touring Australia
- Touring Overseas
- Touring Bikes and Equipment
- Australia
- Western Australia
- New South Wales
- Queensland
- South Australia
- Victoria
- ACT
- Tasmania
- Northern Territory
- Country & Regional
- The Market Place
- Member to Member Bike and Gear Sales
- Want to Buy, Group Buy, Swap
- My Bikes or Gear Elsewhere
- Cycling Brands
- Cannondale
- Garmin
- Giant
- Shimano
- Trek
Who is online
Users browsing this forum: No registered users
- All times are UTC+11:00
- Top
- Delete cookies
About the Australian Cycling Forums
The Australian Cycling Forums is a welcoming community where you can ask questions and talk about the type of bikes and cycling topics you like.
Bicycles Network Australia
Forum Information
Connect with BNA
Brought to you by Bicycles Network Australia | © 1999 - 2024 | Powered by phpBB ®
This website uses affiliate links to retail platforms including ebay, amazon, proviz and ribble.
This website uses affiliate links to retail platforms including ebay, amazon, proviz and ribble.