Tubeless tyre pressure

defride

I've lurked a while here as I get back into riding after a couple of years out and just purchased a pair of wheels from the classified.

Its my first experience of Tubeless wheels and its started well. Tyres on and inflated without much bother. Will finally get a chance to ride them tomorrow. I'm planning on starting at 30psi and going down over the next few rides. Tyres are Spec Fasttrack LK 2.0. The riding? Cross country trails in the Chilterns so nothing extreme. Any comments on whether this sort of tyre pressure is a good start point welcome.

Cheers all

Chunkers1980

Depends how heavy you, your machine and equiptment are. 30 sounds like a good place to start though.

defride

Chunkers, thanks for the reply. I guess the following would be helpful in that case... I'm about 175lbs, hardtail Cube 25lbs-ish at a guess, XTR wheelset

Chunkers1980

Yes 30 is a good place to start but depends on the terrain you are rinding on that ride, just like suspention it's a case of tuning it, 20 would be too soft for most, 40 is about that max, I'd say you'll end up between 25-30 psi for most things.

mrmonkfinger

Chunkers1980 wrote:

I'd say you'll end up between 25-30 psi for most things.

+potato

davewalsh

For a good starting point, multiply your weight in stones x 4 and divide by the tyre width.

bennett_346

davewalsh wrote:

For a good starting point, multiply your weight in stones x 4 and divide by the tyre width.

:?

Sounds like nonsense/witchcraft.

Just set it to 25 and adjust as needed.

cooldad

bennett_346 wrote:

davewalsh wrote:

For a good starting point, multiply your weight in stones x 4 and divide by the tyre width.

:?

Sounds like nonsense/witchcraft.

Just set it to 25 and adjust as needed.

Especially if you are big enough to measure your weight in boulders.
WTF is a stone anyway? Kg's I understand, even archaic things like lb's, but measuring in rocks?

YeehaaMcgee

davewalsh wrote:

For a good starting point, multiply your weight in stones x 4 and divide by the tyre width.

I was about to call "nonsense", then I did the math, and, er... it may have some logic behind it after all. Witchcraft indeed
Where did you learn this?

bennett_346

By that calculation i should be running 15psi lol

YeehaaMcgee

bennett_346 wrote:

By that calculation i should be running 15psi lol

You must be pretty light then. Taking a 2.5" tyre (pretty damned wide) and using his formula, that would make you around 9+1/3 stone.

And if you were that light, with a tyre that wide, then 15PSI might be fine.

It's not as crazy as it sounds (although I'm not saying it isn't just a little bit crazy either )

Yacoby

9.5 * 4 / 2.2 = 18

Waaay too low

bennett_346

YeehaaMcgee wrote:

bennett_346 wrote:

By that calculation i should be running 15psi lol

You must be pretty light then. Taking a 2.5" tyre (pretty damned wide) and using his formula, that would make you around 9+1/3 stone.

And if you were that light, with a tyre that wide, then 15PSI might be fine.

It's not as crazy as it sounds (although I'm not saying it isn't just a little bit crazy either )

It was a rough calc in my head, 10 stone * 4 = 40, / 2.3 = ~15 (17 with a calc).

I'd never run it that low! It depends on what you ride and how rigid your tyres are etc.. But granted it isnt that far off

supersonic

I have a better formula: 20 to 40psi. Or press with thumb, if firm, that'll do.

supersonic

And I have to say FastTrak tyres are the worst I have ever used. Ever!

cooldad

I still don't know wtf a stone is in real terms.

Chunkers1980

14 quid.

YeehaaMcgee

cooldad wrote:

I still don't know wtf a stone is in real terms.

Aren't you from that era, though?

cooldad

YeehaaMcgee wrote:

cooldad wrote:

I still don't know wtf a stone is in real terms.

Aren't you from that era, though?

Even in prehistoric times, in the colonies we used sensible measures divisible by 10.

bennett_346

cooldad wrote:

YeehaaMcgee wrote:

cooldad wrote:

I still don't know wtf a stone is in real terms.

Aren't you from that era, though?

Even in prehistoric times, in the colonies we used sensible measures divisible by 10.

So stones then. 10 stone /10 = 1 stone.

cooldad

bennett_346 wrote:

cooldad wrote:

YeehaaMcgee wrote:

cooldad wrote:

I still don't know wtf a stone is in real terms.

Aren't you from that era, though?

Even in prehistoric times, in the colonies we used sensible measures divisible by 10.

So stones then. 10 stone /10 = 1 stone.

I was going to make a sarcastic remark, then saw Gateshead, and instead was overwhelmed by compassion.

bennett_346

cooldad wrote:

bennett_346 wrote:

cooldad wrote:

YeehaaMcgee wrote:

cooldad wrote:

I still don't know wtf a stone is in real terms.

Aren't you from that era, though?

Even in prehistoric times, in the colonies we used sensible measures divisible by 10.

So stones then. 10 stone /10 = 1 stone.

I was going to make a sarcastic remark, then saw Gateshead, and instead was overwhelmed by compassion.

I'm flattered. Really, i am. It may surprise you to know that we have mathematics up here as well. Well, around 50% of us do. IIRC a lot of your family live in Sunderland which would make them Mackems, 90% of which haven't even got past primary school.

davewalsh

YeehaaMcgee wrote:

Where did you learn this?

Stans website actually recommends dividing your weight in pounds by 7 then subtracting 1psi for the front and adding 2 for the rear, however this doesn't take into account the tyre width so I expanded it slightly.

bennett_346 wrote:

By that calculation i should be running 15psi lol

Try it, you may be surprised

bennett_346

I have tried it. Its virtually useless on thin sidewalled xc tyres on 30 mile rides. So i imagine it would be even worse if i was running tubeless.

Maybe i run it a bit closer when im on the downhill trails, probably around 20 but i have thicker tyres for that so its irrelevant.

nicklouse

anyway to answer the question a bit less than you would have used with tubes.

davewalsh

bennett_346 wrote:

I have tried it. Its virtually useless on thin sidewalled xc tyres on 30 mile rides. So i imagine it would be even worse if i was running tubeless.

So you haven't tried it tubeless then.

bennett_346 wrote:

davewalsh wrote:

For a good starting point, multiply your weight in stones x 4 and divide by the tyre width.

:?

Sounds like nonsense/witchcraft.

Just set it to 25 and adjust as needed.

So, you dismiss my calculation as 'nonsense/witchcraft' then recommend exactly the same pressure as the calculation gives but without any logic or reason behind it :?

YeehaaMcgee

Well, come on. It IS witchcraft.
If this was the dark ages, you'd have been burnt at the stake, or at least had a ride in the dunking stool by now

defride

Went out on 30psi today riding wheels that are much lighter than previously, the bike feels a great deal more skittish descending though not uncontrolably so. Climbs like a demon, I'm going up hills a couple of gears lower and took 20mins off my reg 1.40hr loop. Like the wheels, not sure on the tyres. Will try 28psi next time out.

YeehaaMcgee

defride wrote:

Climbs like a demon, I'm going up hills a couple of gears lower

:?
huh?

bennett_346

A lot of people seem to think "lower gear" refers to how low down the chain is on the cassette. Well, one person i know does.

YeehaaMcgee

I bet they make terrible drivers