right tyre pressure

by Shanefutcher   August 5, 2013  

Hi I've been riding for about 2 years now and always have my tyre pressure at 105psi.should I have more in there

19 user comments

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NO. Not unless you are on 23c's and weigh 100kg. Follow this PDF, it's science. Anyone else is wrong.

http://www.bikequarterly.com/images/TireDrop.pdf

Your arse, hands and times will thank you.

I was told there would be Cake. Luckily there's http://TestValleyCC.org.uk

KiwiMike's picture

posted by KiwiMike [474 posts]
5th August 2013 - 23:42

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It depends a little bit on the tyres you're using but as a rule the front should have 10 less than the rear and as above 105 is probably high.

Personally I think the article suggests pressures that are a bit low for my liking (round about 80/90psi for me) but it's in the ball park. I'd also say I add 10 for good surfaces (racing crits, riding in France) and another if I'm on my race tyres as they're extremely supple.

posted by racingcondor [109 posts]
6th August 2013 - 7:04

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very interesting, one thing I have noticed is my tires after a 80k ride drop pressure from 110psi to 85psi, that measurement I gave taken the last three 80k rides I have done.

proving the point that you should alwsys check your pressure at least before anything over 20k

posted by billyman [122 posts]
6th August 2013 - 8:24

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Ha -answer is 'it depends'

105 sounds reasonable, I'd you feel reasonably comfortable and quick then it's right. Worth experimenting though.

Otherwise..

Follow manufacturers guidelines for your weight (if specified), take into account road surface you're riding on that day -lower pressure for rough surfaces - and type of riding (I always go higher for TT's)

Clinchers will also have a specified max for the wheel, tubs can go loads higher. I've had anything from 100 - 160, depending! But I'm quite heavy..

posted by 700c [556 posts]
6th August 2013 - 11:13

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Read this, worked out what my bike would need ...... and
found the front would be below manufacturers recommended
minimum (rear is just on the limit !!)

still on the 3rd switch-back of Bwlch !

posted by therevokid [698 posts]
6th August 2013 - 12:12

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Vittoria do an app for their tyres, I think on the open corsa I ended up running 120/115 in dry smooth conditions and 5-10 lower in wet/rough

posted by SammyG [295 posts]
6th August 2013 - 12:14

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Hi KiwiMike,
According to this I'm running my tyres with way too much pressure; combined weight of rider and bike is around 79kgs and, on 23mmm tyres, I run 100psi in the front and 110psi in the rear. Manufacturer recommends 115 to 125psi, so I'm below that already. Any idea why the manufacturer specifies such high pressures?

posted by Al'76 [126 posts]
6th August 2013 - 21:54

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Get the Vittoria Ityre pressure app, gives you ideal pressure based on the tyre and conditions. It is intended to work with vittoria tyres, but you can get it to work pretty well for other brands

posted by pdows47 [103 posts]
6th August 2013 - 23:09

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Al, I'd suggest your pressures sounds about about right for your weight. You and Shane should try 10 psi either side of what you run now and see how it feels, establish what suits you.

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posted by Simon E [1946 posts]
7th August 2013 - 14:10

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KiwiMike wrote:
NO. Not unless you are on 23c's and weigh 100kg. Follow this PDF, it's science. Anyone else is wrong.
http://www.bikequarterly.com/images/TireDrop.pdf
Your arse, hands and times will thank you.

+1

That's definitely the best method available, at least as a starting point but it seems like science isn't very much in nowadays Wink

Please stop blindly following manufacturers' recommendations people.

I don't follow trends. Trends follow me.

posted by BBB [180 posts]
7th August 2013 - 23:49

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BBB wrote:
KiwiMike wrote:
NO. Not unless you are on 23c's and weigh 100kg. Follow this PDF, it's science. Anyone else is wrong.
http://www.bikequarterly.com/images/TireDrop.pdf
Your arse, hands and times will thank you.

+1

That's definitely the best method available, at least as a starting point but it seems like science isn't very much in nowadays Wink

Please stop blindly following manufacturers' recommendations people.

As a roadie noob I can also say I feel more comfortable following the pressures in this guide and haven't noticed any loss in speed.

The difference when applying the drop to my Bad Boy is much more pronounced and was a bit of a revelation for me. Much smoother and noticeably quicker than using mfrs recommended pressures!

posted by goldtop [12 posts]
8th August 2013 - 15:10

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According to that, I'm supposed to have 9.5 Bar in my tyres. Only problem is, my Conti 4000 S tyres say max pressure of 8.5 bar...

Wonderful...

posted by Hector Ch [52 posts]
8th August 2013 - 19:29

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Here's an online calculator based on the 15% drop method: http://www.dorkypantsr.us/bike-tire-pressure-calculator.html

Works well IME

posted by Mr Will [88 posts]
9th August 2013 - 15:35

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Hector Ch wrote:
According to that, I'm supposed to have 9.5 Bar in my tyres. Only problem is, my Conti 4000 S tyres say max pressure of 8.5 bar...

Wonderful...

What this is clearly telling you is that you need wider tyres.

I don't follow trends. Trends follow me.

posted by BBB [180 posts]
9th August 2013 - 21:25

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It says that you should change the tyres.i slid off my bike with giant p-slr tyres and think they're awful in wet conditions

posted by Shanefutcher [110 posts]
10th August 2013 - 19:20

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Shanefutcher wrote:
It says that you should change the tyres.i slid off my bike with giant p-slr tyres and think they're awful in wet conditions

What is it that says I should change my tyres?

I have only done 800 miles on them and they are almost worn down to the indicator, so will change them in the next few months anyway. Going to get Conti GP 4000S, having seen good reviews.

I have just worked out what my pressures should be using the 15% drop chart. It saysvI should have my front at 90 and my rear at 140. Considering tge max is 120 I wont be going to 140.

posted by Sensible [60 posts]
11th August 2013 - 19:22

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I am 86 kg and have an 8kg Giant TCR Advanced. I have 23c Giant P-SLR 1 tyres. (Giants top tyres with different compound front and rear) The max pressure is 120psi and I have been running at 110 psi. A few months ago I came off the bike in the wet when the rear end slid away from me. Still recovering from a wrist injury. Are my tyre pressures too high?

posted by Sensible [60 posts]
11th August 2013 - 19:30

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I'm bemused by the science and the calculator. Sad

I currently inflate both tyres to 90. What am I doing wrong?

posted by paulfg42 [374 posts]
12th August 2013 - 23:31

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Calculator is all well and good if you have decent tyres which will handle , for example, 140 psi on the rear, but when that exceeds the manufacturers recommendation, or even that specified for the rim, it's probably not a good idea

Handmade tubular type with high thread count will work, but not much else

And no, I don't think going up to a bulging 25 or 28 is what I want to do when I've spent loads on an aero wheelset!

Still,, seems to justify my high pressures for the rear, though says my front needs to be reduced

posted by 700c [556 posts]
13th August 2013 - 11:46

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