Unbelievable Pressure

[Scottjaeger]

So I bought a small pump with a pressure gauge from Amazon a while back, pretty quickly I became convinced the gauge was faulty as it was showing 45-50psi and the tyres felt like they were at bursting point.

Today, whilst buying oil and what have you I bought another pump, a foot pump with a gauge. I pumped the tyres to their maximum 115psi, holy sh*t, I don't think the first pump was faulty anymore!

The tyres are now completely unyielding, does anyone actually cycle at that psi? Must be properly uncomfortable right? And won't they just puncture immediately?

It's a road bike by the way, Continental GP 4000ii 28s.

I found a 150 pound tire and installedit It rode really hard. I felt like i was going to get launched into the next county.

 

[I like Skol]

I used to run my 28s at 70/60 F/R when 80kg.

I may be misreading, but are you saying you ran higher pressures in the front tyre?

Even 160psi didn't save me from a pinch puncture on a sharp-edged pothole.

Tyre pressure alone cannot prevent pinch punctures as you describe, you really need to be looking ahead and watching for such problems. Putting your tyres to such an extreme high pressure to try and avoid pinch punctures will compromise handling, grip and comfort to such an extent that it is a danger.

I am just over 2/3 your weight and run 32s even lower. I run 55 rear and 50 front, have done for 5 years and would no dream of going over 60.

I don't check the pressures with religious regularity. Those are my starting pressures, by the time I notice any significant change in feel due to reduced pressures the reading is often in the 40-50psi range. Actually, the biggest giveaway that it is time to top up the pressures comes from my cycle computer. My commute measures 21.20 miles on freshly inflated tyres but as the pressure slowly drops over 3-4 weeks that measured distance creeps up to over 21.25, no need for fancy gauges or regular checks

 

[sleuthey]

I may be misreading, but are you saying you ran higher pressures in the front tyre?

Tyre pressure alone cannot prevent pinch punctures as you describe, you really need to be looking ahead and watching for such problems. Putting your tyres to such an extreme high pressure to try and avoid pinch punctures will compromise handling, grip and comfort to such an extent that it is a danger.

I don't check the pressures with religious regularity. Those are my starting pressures, by the time I notice any significant change in feel due to reduced pressures the reading is often in the 40-50psi range. Actually, the biggest giveaway that it is time to top up the pressures comes from my cycle computer. My commute measures 21.20 miles on freshly inflated tyres but as the pressure slowly drops over 3-4 weeks that measured distance creeps up to over 21.25, no need for fancy gauges or regular checks

I just wait till the hills start to get sluggish then I know it’s time to pump up!

 

[Ming the Merciless]

I may be misreading, but are you saying you ran higher pressures in the front tyre?

You are not misreading. I mistyped, meant to be other way round.

 

[Ming the Merciless]

I too don’t pump religiously. Just redo when it feels like it needs it. At the moment on wider tyres for winter, I am going weeks between inflations.

 

[Ajax Bay]

About 67kg and [4000] 28s

they are not undersized 28s as some seem to be. In fact, they measure about 29mm on 14mm rims at my preferred pressure.

Loads of anecdata in thread above. Here's some more.
Tyre width. For me on 15mm rims, 4000S2s 28s come up at 30mm at 80psi. And you need to use 'real widths' using the graph below.
67kg + 10kg bike + 77kg. Split that 55% rear and 45% front = 42 and 35 Graph for 28mm tyres gives 69psi and 58psi. I would irrationally round that up to 75psi rear and 65psi front (Sacrifice a little bit of surface vibration for a little more snakebite assurance.)
I use the authoritative BQ article (attached) - here's the graph from that:

Regular inflation: Thumb test normally, but before a longer ride: track pump with a gauge I can trust.
Punctures happen, but for snakebites it's likely to be the rider's "fault", ime.

 

[Grant Fondo]

Loads of anecdata in thread above. Here's some more.
Tyre width. For me on 15mm rims, 4000S2s 28s come up at 30mm at 80psi. And you need to use 'real widths' using the graph below.
67kg + 10kg bike + 77kg. Split that 55% rear and 45% front = 42 and 35 Graph for 28mm tyres gives 69psi and 58psi. I would irrationally round that up to 75psi rear and 65psi front (Sacrifice a little bit of surface vibration for a little more snakebite assurance.)
I use the authoritative BQ article (attached) - here's the graph from that:
View attachment 572623
Regular inflation: Thumb test normally, but before a longer ride: track pump with a gauge I can trust.
Punctures happen, but for snakebites it's likely to be the rider's "fault", ime.

Thanks just checked mine, bang on at 90psi... so that was luck rather than judgement

 

[rogerzilla]

This thread appears to have been taken over by rulers of Mongo.

 

[Deleted User]

About 67kg and 28s

I'm 72kg and put 70 in 28 tubeless.

 

[Fab Foodie]

Same tyres, same size, 95kg, 75/85psi.

 

[Ridgeway]

GP5000 x 28mm here (75kgs)

Summer: 70r and 65f
Winter: 65r and 60f

 

[weareHKR]

Personally I can't see how 5 psi would make any noticeable difference whatsoever, are you honestly saying you can physically notice the difference? Taking into account the pump tolerance, road conditions & climate conditions, I don't believe it!
If you're using a indoor track that may be different perhaps?

 

[weareHKR]

My commute measures 21.20 miles on freshly inflated tyres but as the pressure slowly drops over 3-4 weeks that measured distance creeps up to over 21.25, no need for fancy gauges or regular checks

So if you have a day with a headwind & your time is 45.25 what pressure do you pump your tires up to?

 

[Johnsco]

On 27" x 1.1/4", Schwalbe road tyres, I run on 80psi front and back.
I'm on the lighter side.
Like a lot of things ...... I'm not too precious about it !

 

[T4tomo]

So if you have a day with a headwind & your time is 45.25 what pressure do you pump your tires up to?

distance, not time. reduced pressure -> marginally reduced tyre circumference, so need more revolutions to get there, so distance reads higher.