Can't inflate Presta valve

magicbastarder

so yeah, you might need 120psi if the bike is carrying 120kg on 25mms.

ED E

Specialized:

700 x 23mm, PSI 110-125, approximate weight 285g
700 x 25mm, PSI 110-125, approximate weight 315g
700 x 28mm, PSI 85-95, approximate weight 350g
700 x 30mm, PSI 85-95, approximate weight 400g
700 x 32mm, PSI 85-95, approximate weight 430g

Conti

Article ETRTO Dimension Technology Color/Sidewall/Bead TPI BlackChili g PSI
0101626
32-622 700 X 32C Vectran Breaker black/black Skin foldable 3/330
295 85-100
0101625
28-622 700 X 28C Vectran Breaker black/black Skin foldable 3/330
250 95-115
0101624
25-622 700 X 25C Vectran Breaker black/black Skin foldable 3/330
220 95-120
0101623
23-622 700 X 23C Vectran Breaker black/black Skin foldable 3/330
205 110-120

tomasrojo

ED E wrote: »

Yeahhhhhh....no.


Mini pump fans: Do you manage 120psi? Or is it roll home on a soggy 80?

Oh yeah, I wouldn't use that compressed-air canister. I can't see it appealing to a very large section of people who cycle either.

I think I can get up to about 3 bar with a mini-pump. Maybe I could get further, but it's a perfectly tolerable ride at that pressure (for utility cycling till i get home anyway, which is all I need it for). When I get home, I use a track pump to get up to 5 (bakfiets) or 6 bar (everything else).

tomasrojo

As a matter of interest, are all these charts of what pressure to use based on tyre deflection?

https://janheine.wordpress.com/2016/03/09/tire-pressure-take-home/

Much of it depends on the tires you run. Berto measured the tire drop (above; how much the tire deflects for a given load and pressure) for dozens of tires. He then averaged the values, and drew his chart for a tire drop of 15%.

magicbastarder

ED E wrote: »

Specialized:


Conti

i'd be very curious as to how many riders run 110psi on a 25mm tyre nowadays, especially anyone under 100KG in weight.

Fighting Tao

magicbastarder wrote: »

i'd be very curious as to how many riders run 110psi on a 25mm tyre nowadays, especially anyone under 100KG in weight.

Over 100kg and I ran 110psi on 25mm contis for over 4 years.

I changed to Vittoria Corsa G+ 25mm and I run 125psi front and 135psi rear.

jamesd

I got a minipump that also takes co2, so I use the co2 side if in a rush or otherwise just pump manually - handy to have the option.

C3PO

magicbastarder wrote: »

i'd be very curious as to how many riders run 110psi on a 25mm tyre nowadays, especially anyone under 100KG in weight.

Always run 115psi on 25mm at 85kgs kitted out! Basically always inflate tyres to maximum indicated pressure. Probably should reduce but rarely get punctures!

Duckjob

C3PO wrote: »

Always run 115psi on 25mm at 85kgs kitted out! Basically always inflate tyres to maximum indicated pressure. Probably should reduce but rarely get punctures!

I'm also 85kg and used to pump religiously to 120psi on my 700/25s until I realised I was losing lots of power due to bouncing up and down on some of the very knobbly roads in my locality. These days I do 100psi max and find it makes for a far easier and more comfortable ride.

magicbastarder

i'm 72kg, and run at 80psi. have had two punctures in the last 15k km or so, and one was definitely a pinch flat from leaving the tyres too long without topping up, i reckon it was about 50 or 60psi at the time.

triggermortis

I pump my commuter tyres to 105 psi (front and back) at the start of my shift and re-check then halfway through my shift as I can’t be bothered checking every day ( around 85kg on Durano max tyres). If I go out on the good bike I always check before I go and put in 100psi (conti tyres) in both. Last year I only had 1 puncture - in a conti

C3PO

That's very interesting lads - you've persuaded me .... but I'll be back to you if I start getting punctures!
I'll reduce to 100psi and see how I get on.
What about 28s GP4000s on carbon rims ... about 90psi?

ford2600

C3PO wrote: »

That's very interesting lads - you've persuaded me .... but I'll be back to you if I start getting punctures!
I'll reduce to 100psi and see how I get on.
What about 28s GP4000s on carbon rims ... about 90psi?

Pressure recommendations would depend on rim width and surface quality.

I've used 28mm gp4000 for years on 19-20mm internal width on predominantly really poor quality roads and zombie roads. At 83kg with a 10kg bike 75/65 is my typical rear/front split. Over 70 on front feels horrible now

That's exactly what I used for Paris Roubaix sportive.

If I was riding on really nice tarmac there probably would be an advantage to higher pressure but then I'd have to share that road with cars and it would probably be boring and flat...

Brian?

Did that tyre ever get inflated?

doozerie

Re tyre pressure, another benefit of lower pressure is potentially better grip. A tyre pumped to very high pressure will typically deflect far less then one at significantly lower pressure, and while it's easy to focus on the effects of this when rolling along a straight road, don't forget to consider too what happens when you are leaning into a bend at speed.

A lot depends on your tyres of course (tyres with stiffer walls will deflect less, etc.), and some of it on your tubes (latex tubes deflect more than butyl), and on how much you like to lean into bends in the first place. But certainly for me I feel a lot more confident pushing my bike into bends on 25mm tyres with latex tubes at 85psi then I've ever felt at higher pressures on the same tyres, on narrower (23mm) tyres at 100psi, or even when using butyl tubes.

And when you are feeling more confident you use your brakes less, so you maintain more speed or basically you effectively go faster. So whatever about the science, of which there is quite a bit on this topic (not all of it reliable though, I reckon), perception plays a big part too. I perceive significant benefits for me from all of the options of slightly wider tyres, latex tubes, and lower pressures. And if I'm wrong, well at least I am happy in my ignorance as I "feel faster"

Amouar

OP here. I just wanted to update this thread that I managed to solve my issue by buying a Presta adapter (Like this one) and my mini pump worked like a charm when I switched the pump's rubber valve from Presta to Schrader

Mickiemcfist

Amouar wrote: »

OP here. I just wanted to update this thread that I managed to solve my issue by buying a Presta adapter (Like this one) and my mini pump worked like a charm when I switched the pump's rubber valve from Presta to Schrader

I bought one of those recently for the saddlebag, just in case my minipump broke or something I could still get sorted at a petrol stations pump.

tomasrojo

I carry one of those because one of my bikes has Woods valves, and to use a mini-pump with those, you need to use an adapter and the Schraeder part of the pump head.