[Closed] Small changes to tyre pressures ,,Really noticeable?

around your preferred sweetspot, Yes.
same with suspension

Agree. A few psi can be enough to take you out if the sweet spot and turn a great tyre into a pig.

Yes, and the lower you go the more noticeable it gets.

Depends on the tyre as well, couple of PSI difference on the WTB trail boss I have on at the minute makes a massive difference as the sidewalls aren't as robust as say a minion for example, so it's really noticeable when corning.

yep definitely, and it depends on the tyre, the surface and the conditions.

There was an article someone linked to on here a while back, where an industry veteran talked about doing controlled customer tests on how various components affected ride quality. Stuff like frame material, fancy wheels, tyres, bars, stem, etc was all very marginal. The one thing that riders consistently noticed the effect of was dropping the pressure by 5psi.

Stuff like frame material, fancy wheels, tyres, bars, stem, etc was all very marginal. The one thing that riders consistently noticed the effect of was dropping the pressure by 5psi.

Cool, that's what I've always thought. That said, I am a squeeze and go type. But I have got a gauge on order.

Yes, particularly at lower pressures on a very supple tyre. Especially as the one I'm thinking of is quite lightly treaded in quite a hard rubber compound, it's very much a balancing act between grip/not bouncing off things and squirm.

Softer rubber with a bit thicker sidewalls isn't so sensitive but still noticeable, and at higher pressures the same applies, you're not treading that line.

Meh, i have no concept of what mine are.... I'd guess on a given ride it could be 5-10psi different depending on whether i remember to stick a few pumps of air in or not.

Depends what you mean by small. Certainly I would not trust my thumb to give good reliable results though others may be better calibrated! 5psi can make quite a difference.

For road cycling, basically everything from hard to rock hard is ok IME, if you can push in significantly it's probably far too flat 🙂 (tubeless on rough roads is a whole different ball game though)

What's a good/reliable Presta gauge then guys ? my track-pump is miles out.

@weeksy

https://www.amazon.co.uk/dp/B00070KA5I/ref=cm_sw_r_cp_awdb_t1_Ze5MBbRR214NP

Different pressure ranges available. Cheap, accurate, and the valve unscrews for cleaning if it gets clogged with sealant.

Edit: don't think that's the presta one I linked. If you can't find it I'll look up the model I got later.

my track-pump is miles out.

I think the actual measure is probably not as important as consistency.

I can certainly notice, climbing grip on the rear changes and cornering grip on the front.

What is a small change? 2 psi? When running low pressures, 14-20 psi, then yes I can notice 2psi difference. I cannot notice 1-2psi difference with the thumb test though.

Most folk don't even realise where to put their thumb to check presure. Thumb will get you close. Then ride a corner and adjust as required.
**** taking a pressure gauge out on a ride

Depends on your riding / starting pressure - there's probably not much difference between 80 and 100psi on a road bike on smooth roads, but as a light rider it makes a huge difference between 20 and 25psi on 2.4s off-road.

Same with handlebar width, a few extra cm helps compensate for my lack of ability and upper body strength - am a lot quicker on 80cms vs 70cm bars.

Most marginal changes won't make much difference at the recreational end of the sport, ability and fitness are what makes people fast.

slight deflection of topic:

I've been running my rear Hans Dampf (and the Fat Albert on the HT) a little harder than anticipated (around 30psi, according to my imprecise and inaccurate trackpump) as it just feels really squirmy when at the pressures you read about. I find the tyre fine really, nice predictable grip, never had a puncture, but is it a sidewall support issue and would I be dumbstruck at the improvement were I to change over to a better supported rubber run at lower pressures?

n.b. pretty sure the FA would be better on much wider rims - it's a while since 19mm was wide for MTB 😀

IME some tyres are more fickle than others. My WTB Vigilantes has very narrow sweet spot. Too high and they don't grip & bounce around. Too low and they fold in cornering. This sweet spot was about 0.5 psi.

Other tyres are more forgiving, but I still notice 2 psi difference out of about 22.

Most marginal changes won’t make much difference at the recreational end of the sport, ability and fitness are what makes people fast.

No but it's not about speed (why do people keep acting like it is?).  Your bike feels much more comfortable with cushy lower pressures, but it's no fun cornering on squirmy tyres.  The right pressures gives a more pleasurable ride, I've no idea if it's faster or not.

As above it varies by tyre.  I had Specialized Butcher/Purgatory combo on my rigid bike - they bounced at anything below 30psi which was quite hard to ride with.  With Racing Ralphs there's no bounce or squirm even down to 20psi, and that drop really helps over rough ground and rocks.

The closer you are to soft/squirmy/snake bite or rock hard pingy the more you will notice I guess.

With tubeless I tend to end up with it probably slipping 5-6psi before it feels like a problem and top up. If I was starting out 3-4psi lower I'm sure I'd notice the difference faster.

Did ride with a lad who complained his tyres were a bit hard now he was carrying no water at the end of the ride, cue much piss taking about measuring accurate intake and outflow from the body and how many PSI for a good dump.

Depends what you mean by small. Certainly I would not trust my thumb to give good reliable results though others may be better calibrated! 5psi can make quite a difference.

Yep but my thumb can tell the difference of the feel between a Magic Mary and Racing Ralph... which seems to be closer to how the tyre is going to behave than my crap track-pump.  Seems easier to me to test with my thumb, go for a ride and then use the (slightly) better gauge on my mini-pump ???

I guess what I'd really like is an accurate gauge that does presta and shreader and tyre/shock pressures or is that moon on a stick??

I guess what I’d really like is an accurate gauge that does presta and shreader and tyre/shock pressures or is that moon on a stick??

Gauge accuracy is in the range it's intended for so something that does 25 and 300 well will probably be very expensive 😉

My current track pump starts at 20(+/-3) PSI due to a tubeless explosion so it's kind of guess work at the moment, also when I found 2 identical Joe Blows reading 5psi different the thumb method tells me a lot more than most random pumps.

I've a low range gauge for my fat bike tyres where 0.5psi change can be a big difference, one for normal MTB tyre pressures and one for shocks. Having just one to cover that range, in this case 3 - 300 psi, is a tall order in a consumer item.

As above absolute accuracy isn't necessary just that the gauge is consistent between readings.

My Topeak digital gauge does Presta/Schrader tyre/fork/shock.. No idea if it's accurate but it seems to be repeatable which is the main thing.

Actually, I did use it on car tyres straight after using a garage's tyre machine and it read exactly the same so it's not far off.

For road cycling, basically everything from hard to rock hard is ok IME, if you can push in significantly it’s probably far too flat

I think people are moving away from that idea now, because there seems to be good evidence that larger diameter tyres at lower pressure can actually be faster than old school narrow rubber pumped as hard as possible. I'm running 28mm tyres at 70 psi (tubes) for a lot of my riding these days, including long Audax events, and don't notice any loss of performance compared to the higher pressures I used to use. I notice that Hunt were talking about one of their sponsored riders at the ToB racing on tubeless at 60 to 65 psi!

I think people are moving away from that idea now, because there seems to be good evidence that larger diameter tyres at lower pressure can actually be faster than old school narrow rubber pumped as hard as possible.

Anecdote time...

Did tour o the borders on 40mm at about 55psi, then belted around the warwickshire roads at a very brisk pace with no issues. Seems like we need to try some different things, was very surprised to be easily keeping what I thought was pure hard road tyre pace

It's not rocket science.

Pump tyres up,  harder than usual.

Ride.

Reduce pressure 'till it stops feeling overly harsh. Make a note of the pressure.

Keep reducing pressure until things get squirmy or you get a snakebite puncture.  Make a note of the pressure.

You now have a range of workable pressures.

Play about inside this range until  you find the compromise that suits.

No need to overcomplicate anything.

Same with suspension, although the potential for shysters to sell pointless toss to idiots and the subsequent profit generated is much greater.

🙂

I picked up a cheap pressure gauge a few years ago, settled on what pressure worked for me and stuck with it. That gauge has started to get a bit tired so I ordered one of the Topeak ones the other day. Recently moved back to full suspension, with slightly wider tyres and rims so I should be able to drop a little pressure now.

http://www.wiggle.co.uk/topeak-smarthead-digital-gauge-d2/?sku=5360389283

I really rate my topeak d2..

Thought the recent STW article was a bit unfairly written as they said it was more expensive than what it is (they quoted RRP rather than the lower price it actually sells for) and then marked it down because it was gummed up with tyre sealent  Hardly a fair test..

Gum them all up with tyre spunk and then retest lol.

I guess what I’d really like is an accurate gauge that does presta and shreader and tyre/shock pressures or is that moon on a stick??

If only someone would do a group test of these things...

Just ordered one. Thanks.

Depends on many things, and air pressure absolutely will make a difference to tyre performance. This is so proven in every other group using pneumatic tyres that there’s no basis for imagining it might not affect mountain bikes.

What becomes more fraught is whether a gauge is more consistent, repeatable and informative than your thumb. Mechanical disasters caused by my hamfisted self sold me on when to use a torque wrench years ago so this is a no brainer for me.  In particular, the higher volume tyres run at lower pressures off-road  (plus typically below 15psi, full fat typically below 5psi) the difference between 13 and 15 psi can be so huge that the thumb is a blunt instrument.

As always, whichever way you decide use one measurement consistently. Different gauges and different thumbs are not necessarily calibrated the same way!

I have to agree with Rusty... too much bull spouted to make money and complicate things for your average rider. OK... at high stake riding small changes may make the difference but in the real world for recreation purposes I suspect his suggestion is good enough for most incl certainly myself !

When you look at it as a percentage 1psi isn't as tiny as it looks when you're talking 30psi as a normal upper limit for MTB tyres, it's quite easy to think 2-3psi would be noticeable to most.

Wouldn't surprise me if the pros are working to tenths of a psi.