Unscrew presta valves all the way for easier pumping to 120lb with blow joe type pumps etc.

[S-Express]

This will end up like the 'average bar width' thread if we're not careful. It will depend on things like your weight, tyre volume, road surface quality and weather conditions.

 

[rideswithmoobs]

According to that chart i have been putting in about right pressure using the old hand squeeze method and asking myself how does it feel on my arse when i ride..... about 50-55 psi in my 32mm tyres.

 

[Ian H]

I can't say I've noticed it being any more difficult to inflate a tyre with the valve lock only partially open. It does make it less likely that you'll bend the locking bit.

 

[simon.r]

So where is the sweet spot and how do you calculate it, for a given width of tyre and your average British road surface? I've been using this for some time - see attachment.

I've been using that same table for a few months, with various width tyres. I've been pleasantly surprised with the results. My personal preference is for about 5psi more than the table recommends, but it's a really good starting point I think.

 

[Sea of vapours]

I've been using that same table for a few months, with various width tyres. I've been pleasantly surprised with the results. My personal preference is for about 5psi more than the table recommends, but it's a really good starting point I think.

Hmmmm.... using that table would give me, on my 28mm (tubeless) tyres, 48 front and 75 rear (I'm currently using 65/75). The 48 front would most certainly obviate any need to unscrew the head of the valve fully.

And to be even further back on topic: I've noticed the easier inflation when the valve head is fully unscrewed too (not on my tyres - on some which require much higher pressure).

 

[raleighnut]

on the boards, presumably?

No, they're a road tyre, albeit a stupid road tyre.

 

[S-Express]

No, they're a road tyre, albeit a stupid road tyre.

Solid wooden wheels would probably give you a better ride. What are you using them for and what is the reason for such a high pressure? Either way, I didn't think Conti made the Supersonic in 18mm. 20 or 23 only.

 

[Tin Pot]

I only have that pressure in the back tyre at the moment. Not sure what to do about the front, as I guess higher pressure means a bit less rubber in contact with the road.

http://www.bicyclerollingresistance.com/road-bike-reviews

Enjoy

 

[Ajax Bay]

At 120lb of pressure I feel it is a noticeably easier ride too.

I only have that pressure in the back tyre at the moment. Not sure what to do about the front

OP: assuming you're 80kg on a 12kg bike and running 23s, 120psi is right for the rear: 90psi would be good for the front. 25s or 28s would be more comfortable at lower pressures, though, and the rolling resistance would be not significantly more (if your frame can take 28s).

 

[swee'pea99]

I feel sure that most of you on here will already know that you can fully unscrew a presta valve and it won’t drop out. I have to say, I did not know that until I tried it during the course of repairing a tube a few days ago.

I had only ever managed to get about 95lb in the tyres which was kind of ok, but the last 10lb of this was always a real struggle using the blow Joe type pump without fully unscrewing the valve. I used to have to put most of my weight on the handle to get the pressure past 90lb.

So today, I tried the new method. I attached the blow joe and managed to put the desired 120lb in with much less effort than all the other occasions. At 120lb of pressure I feel it is a noticeably easier ride too.

Thanks. I'm going to give this a go next time I use the pump. (I find it hard to get past about 90 too...I have to pretty much jump in the air then come down stiff-armed on the pump handle!.)

 

[night cycler]

My OP was about unscrewing the valve to make pumping easier, so I am pleased that my post will potentially help at least one person Swee`pea99. (By mentioning the tyre pressure that I have put in, I feel the thread topic went a bit off course). Whether inflating to just 50lb or as much as 150lb I was just trying to explain that I found the pumping action much easier with a fully open valve. Hope it has been of help to others.

 

[bigjim]

Surely rider weight is important when defining pressure. I'm 14.5 stone and run at 110 PSI on the rear. Don't feel too rough on the crap roads.

 

[Ajax Bay]

Factors:
Load on tyre (function of rider plus bike and baggage weight, factored by front/rear split 45/55% or whatever)
Width of tyre
Moderated by level of desire for comfort (but go too low and you'll get snakebites in 'normal' tyres (ie needing inner tubes)).
Increased for less rolling resistance on normal (ie decent) road surfaces on rides where time matters more than comfort.

 

[youngoldbloke]

My OP was about unscrewing the valve to make pumping easier, so I am pleased that my post will potentially help at least one person Swee`pea99. (By mentioning the tyre pressure that I have put in, I feel the thread topic went a bit off course). Whether inflating to just 50lb or as much as 150lb I was just trying to explain that I found the pumping action much easier with a fully open valve. Hope it has been of help to others.

This might well be true with most pump chucks, but with some others you find that if you undo the lock nut completely, when you push on the chuck (or screw on the adapter) you actually start to depress the valve core so that air in the tube is released and trying to pump in more is ineffective. (The solution is to screw up the locknut a little). Otherwise IME it makes very little difference whether or not you complete unscrew the lock nut right to the end of it's thread.