What tyre pressures are you using off road?

Dirtydog11

Brassknocker wrote:

I'm ~75kg and run my panaracer XC firepros at a min of 50psi + on the rear and about 45-50psi on the front - but I'm a HT lycra lad that prefers the ups to the downs.

It doesn't make any difference, read this

http://www.bicicletta.co.za/Downloadabl ... trated.pdf

Brassknocker

Hi Dirtydog11, thanks for that, that's a useful read - and possible thread ender!

It doesn't make any difference, read this

http://www.bicicletta.co.za/Downloadabl ... trated.pdf

I've always assumed that the higher the pressure - the lower the rolling resistance! - obviously I've been wrong all along!

I'll have to eventually replace my 1.9s with 2.1 and lower the pressure from over 50psi down to low 30s then!!!
(however, I often ride >25miles on road to get the the MTBing - so perhaps wasn't too far wrong on the road)

I expect to be much faster this summer now(but hopefully no snakebites!!)
Cheers!

bails87

Does that article basically say this:

bails87 wrote:

But with rock solid tyres off road, every time you hit a bump the wheel is forced upwards, with softer tyres the tyre deforms over the bump and the wheel itself keeps moving forwards.

?

supersonic

There is a limit to this - basically each tyre has an optimum pressure for a certain weight and terrain. Go lower still and the rolling resistance will get higher.

Hercule Q

i stick between 25-30psi plenty of grip from my minion and highroller

stubs

bails87 wrote:

Does that article basically say this:

bails87 wrote:

But with rock solid tyres off road, every time you hit a bump the wheel is forced upwards, with softer tyres the tyre deforms over the bump and the wheel itself keeps moving forwards.

?

Yep you are right bails. Think I will experiment at the weekend with dropping my back tyre from about 30 ish to 25 ish must remember to take a pressure gauge

calummcgoff

i run about 17 psi front 20 back but then i do have a dh bike and insane japanese tyres

robertpb

When I first started out riding MTBs in the mid 80's, the people I rode with Geoff Apps, Dave Wrath-Sharman rode around with only 15psi in their Nokia Hakkapeliitta tyres on a 650B rim.

So I have always used lower pressures, but after reading several threads on this site last year about tyre pressures and seeing that many to me were using pretty high psi, I did some investigating.

I e-mailed most of the past and current world champs and found the highest psi was 29 and lowest 23, these riders were all between 69 and 80kg

Recently I found that LA on the Leadville 100 was running 26 front 28 rear on 2.2 tyres and he weighs 75kg.

So these guys are all looking for speed and grip so the Bicicietta article seems confirm this.

Also I found an article which I can't find now that Maxxis testers start off testing at 27psi.

Hope this helps.

bike-a-swan

I've always gone with centre tread blocks shouldn't quite compress all the way in for general all-round work.

For really ragging it round somewhere techy I just drop the front as low as it'll go before the tyre starts to roll into the corners (sometimes takes a quick test to get this right!) and the back harder (I run a hardtail, it stops pinch flats and I don't generally care what the back end is doing as long as the front is where I want it). Not very precise, but it works for me

lock1981

i run about 29 to 30 psi on my bonty mud x's they feel like there dragging to much any harder

i pumped them up to 35 when i got them cos i ride abit of road and fire road inbetween moor in the winter, thinking it would help on the climbs!!!

but nnoooooo

richg1979

im 95kg and run 30psi rear and 25 front and 40psi-35psi if its quite rocky, and higher pressures actually drag more offroad than lower pressure as the tyres is bouncing over things and not rolling over them.

Northwind

Just sort of whatever feels right. 30-ish generally but I don't stress too much, they end up running down a little over time so they're probably mid 20s most of the time.

captainfly

It depends on the bike and what I'm doing. But for general off road 30ish on the front and a bit more on the back, for sand about 20psi or less with 2.35 SP swampthings and kenda downhill tubes, the jump bike varies depending on surface and how much of run up I can ge.

CycloRos

I run anywhere between low 20's to 30 psi depending on conditions.

I'm with the guys that think anything higher than 30+ is crazy, I've yet to come across a tyre/condition that works well at that high a pressure without sacrificing grip/comfort.

85kg rider btw

Anonymous

Thing is though, my tyres specify a minimum of 35 (Maxxis Ignitors). Surely there's a reason for them saying that?

I went up to 40 on mine as I thought I was under inflating and also I want to avoid pinch flats. 40 is a bit firm though so I may back off to 35.

schmako

I'm like 9.5 stone so 40psi is perfect for me, quick on the ups and the downs!

rudedog

bails87 wrote:

Does that article basically say this:

bails87 wrote:

But with rock solid tyres off road, every time you hit a bump the wheel is forced upwards, with softer tyres the tyre deforms over the bump and the wheel itself keeps moving forwards.

?

Not just that though - it was interesting to read what they had to say about wide vs thin tyres. According to their research, wider tyres roll faster than thinner tyres (offroad) and the inreased weight of fatter tyres is actually negated by this performance increase!!

incredible if true and thanks to the poster who posted the article, one of the most interesting things I've read regarding biking in ages.

Stevo_666

40 psi for XC sprints and fast trail work: 35psi for slightly tougher going. Have gone down to 30 when it gets muddy.

philrw

Something arpund 30 PSI.

I've run tubeless for last 4 years sopinch flats not a concern

Buckled_Rims

35psi on my main off roads, but I tend to stay will 45ish on my Bell tyres (cheap from ASDA) that I sometimes commute with but are excellent for dry off roads.

NatoED

i run 50 PSI in 2.0 tyres. i don't find it to rough . i feel more part of the bike and quicker timed run than when I'm lower pressure. I find that lower pressure really does not help with corners as the tyre wants to roll off the rim . I f also find breaking a lot better at higher pressures and the tyre will dig into the ground more rather than trying to slide round the rim. well that's what i found in my XC riding.

Doing DH i would run 45 PSI on my hard tail and be faster than some guy on a 6 ich DH bike (back in the late 90's) . In mud i'll run 60psi to cut down into the lower layers (why do you think tractors have narrow tall wheels on them when in the forest logging) . It can get skittish on roots and rocks but then you just have to think more than just blindly bouncing over rocks.

capoz77

i read a similar question on MTBR a while back and everyone was reccomending 25-28 for off road, a lot were shocked at the thought of 35psi LOL

NatoED

got to say if that link says wide is better why are they still making 2.0 tyres? looks more like an advert. surely a narrower lighter tyre is going to be faster to accelerate than a heavy wide tyre due to rotational mass and forces involved ?

When it comes to lower pressure deforms hence better ,why do you think we have suspension.?

Anonymous

NatoED wrote:

When it comes to lower pressure deforms hence better ,why do you think we have suspension.?

Isn't the deformation more to do with surface contact though? After all, off-road it's more about grip, though depends on conditions whether you need it.

NatoED

deforming tyres can also lose you grip as the knobs that dig in are closed up as the tyre compresses . this stops them from biting into soil . Rally cars will run a similar pressure to road going cars (about 35psi) . I used to work in a hotel where the Pug works rally team would stay every year for the RAC rally Wales. They show me a lot about how tyres react to different surfaces. on lose rocky surfaces they would run a lower psi but on hard packed or soil roads (Norway for example) they were up in the mid 30psi to 40's for the knobs to bite into the hard pack and corners.

Suspension was designed to give that surface contact with out the closure on the tyre tread. When set up properly it should allow the tyre to be in constant pressure against the trail surface thus giving you the needed grip . When it's set up with too slow a rebound then you lose traction as the forks are not extending fast enough to apply the needed pressure after hitting a bump . Same goes compression to fast and the wheel will un-weight the tyre too fast and you lose traction.


all in all you ride what you feel comfortable with. but people saying oh low pressure will always be faster , or high always being faster isn't always right. Just as I find i ride faster with high pressure , some one else may find it better with low pressure on the same trail because of riding style. I like having higher pressure it makes me think more ride smoother and helps with the mud round where i live.

rudedog

NatoED wrote:

got to say if that link says wide is better why are they still making 2.0 tyres? looks more like an advert. surely a narrower lighter tyre is going to be faster to accelerate than a heavy wide tyre due to rotational mass and forces involved ?

When it comes to lower pressure deforms hence better ,why do you think we have suspension.?

I think it would have been a good idea for you to have read the article before commenting on it.

When you have higher pressures and hit a bumb or patch of uneven terrain, part of your forward momentum is transfered upwards resulting in energy loss - with lower pressures, the tryre is more likely to deform aound a bump which reduces this effect.

Suspension doesn't transfer this upward energy back into a forward direction - it soaks it up and it is therefore lost.

pseymour

Ned Overend recommends 37psi for most leisure riders in his book "How to mountain bike like a champion." That's good enough for me as he seems to know what he's on about. There are obviously lots of variables though depending on what type of riding you are doing on what surface. But generally, low pressure = pinch flats.

NatoED

but it is when the fork extends back to full travel . This is one reason why suspension bikes have slacker head angles. the suspension compressing does allow the wheel to roll over the obstacle in the same way as deforming would , that's where small bump sensitivity comes into play . I did read the article and tough it was interesting it didn't take into effect rim width which has a massive impact on the shape of a tyre and it's footprint .

It just looks like another piece of corporate jargon gumph to sell products. it also didn't mention cornering stability at lower pressures which is a concern.

rudedog

NatoED wrote:

but it is when the fork extends back to full travel . This is one reason why suspension bikes have slacker head angles. the suspension compressing does allow the wheel to roll over the obstacle in the same way as deforming would , that's where small bump sensitivity comes into play . I did read the article and tough it was interesting it didn't take into effect rim width which has a massive impact on the shape of a tyre and it's footprint .

It just looks like another piece of corporate jargon gumph to sell products. it also didn't mention cornering stability at lower pressures which is a concern.

you really aren't getting this at all - by the time the upwards energy has transfered to the suspension, its already been lost - suspension forks are designed to soak this energy up (dampening), not transfer it back into forward motion - what you are describing is a pogo stick.

Why would it be corporate jargon to sell tyres?

projectsome

Depends really. If the mud is wet and soggy then it's 30 psi. In the dry summer around 40 psi.