MTB Specific: What Tyre Pressures

[Jako De Wet]

@Dirt Tracker how do you rate the Eliminator up front?

 

I am switching to a an 2.3 Aggressor R and want to fit either a 2.5 Assegai or a 2.6 Eliminator on the front.

 

EDIT: Read your comments on the other tyre thread Eliminator it is.

Edited October 8, 2019 by Jako De Wet

[Captain Fastbastard Mayhem]

@Dirt Tracker how do you rate the Eliminator up front?

 

I am switching to a an 2.3 Aggressor R and want to fit either a 2.5 Assegai or a 2.6 Eliminator on the front.

 

EDIT: Read your comments on the other tyre thread Eliminator it is.

Cuan rates it over teh Mary, and that's high praise. TBH I don't think you can go wrong with either. If matchy matchy is your thing then get an asseguy Exo Plus for the front. Otherwise - whichever is cheaper. 

[Dirt Tracker]

@Dirt Tracker how do you rate the Eliminator up front?

 

I am switching to a an 2.3 Aggressor R and want to fit either a 2.5 Assegai or a 2.6 Eliminator on the front.

 

I really like it a lot. I've always had a thing about grippy tyres not going well and fast rolling tyres not giving enough grip (or having a deal breaking flaw somewhere in them). 

 

To say it's a tyre you can fit and forget is the biggest compliment. It's the one thing I don't want to be thinking about, I want to be looking down the track to the next thing not in front of me wondering if it's going hold in / squirm / break traction on those roots / wash out in the corner / sneak a death gap moment on me. 

 

To date it's been as grippy as I needed at alot of places and rolls well enough that I wouldn't be cursing it at the more pedally places here and on the garden route. Puncture wise it's been perfect, side wall stiffness on the grid casing up front is good. Tbh I'll most likely get another because with hindsight it's been faultless and I trust it but you do wonder if that grass over the hedge is greener. 

[Captain Fastbastard Mayhem]

"starting to think" = a slight dash of sarcasm.

the theory has been around for years but the volue increase is very negligable. volume is often touted as the benefit but it is really almost purely the mechanical support as you rightly say. 

 

the issue is the common language always describes wider as better due to the volume increase and I see many illustrations in marketing that shows of this gross exaggeration. I'd like to see the dialogue return to science and talk about how much more supportive a wider rim is for the tyre. Same in cars and motorcycles, wider base of support gives a less squirrely tyre.

 

using low profiles on a car as an example, the volume there is drastically reduced but the side walls support the tyre more effectively and the car handles better. Any additional volume is really gained from a bigger tyre. For Enduro, big volumous tyres wide rims = happiniss is.

XCO/XCM wider to a point so that 2.2 to 2.35 tyre is well supported is where a limit exists till they start to make the tyres more round. I also run my tyres harder to achieve that more round profile at the contact patch and thus actually reducing the size of the contact patch and get better feel and grip from the tyres. Played around with tyre pressures a few weekends ago (after dinging my carbon rim) and found that sweet spot is really the point at which the tyre doesn't rebound uncontrollably.

 

In closing, there's little difference in performance between a 23mm rim to a 27mm rim and again from 27 to a 30mm

But ay of those is a huge leap forward from a 19mm internal width rim.

I agree for trial/ AM/Enduro 30-35mm is perfect if tyre is 2.5 and over.

For 2.0 to 2.5 23-27 is great .

 

BUT , tyre pressure is where the real performance can be unlocked. I see far too many under-inflated XC tyres. An 80kg rider running 18psi front 20psi rear is way too soft IMO.

 

Tyrewiz is another useful tool that rider should play around with. Too expensive to justify ownership for me ....

100% agreed. 

[Straight Line]

100% agreed. 

Spot on with the observation that performance is dictated by tyre pressure. Tyre sidewalls flex (distort) progressively more as pressure is reduced. This gobbles up rider energy and increases rider fatigue which is exponential in long rides or difficult terrain. It's also destructive for tyre tread and casing.

Work on the premise that if you increase your tyres pressure from "too low" (ie. below 1.5 bars nominally) to the hardest you're comfortable with, you'll conserve energy and be able go faster for longer. Do it incrementally and give each pressure enough riding time to get used to the change in handling. You'll eventually find the "Sweet spot" DieselinDust is talking about. You'll ride better and your tyres will last longer.

[Dicky DQ]

Spot on with the observation that performance is dictated by tyre pressure. Tyre sidewalls flex (distort) progressively more as pressure is reduced. This gobbles up rider energy and increases rider fatigue which is exponential in long rides or difficult terrain. It's also destructive for tyre tread and casing.

Work on the premise that if you increase your tyres pressure from "too low" (ie. below 1.5 bars nominally) to the hardest you're comfortable with, you'll conserve energy and be able go faster for longer. Do it incrementally and give each pressure enough riding time to get used to the change in handling. You'll eventually find the "Sweet spot" DieselinDust is talking about. You'll ride better and your tyres will last longer.

If you are riding gravel travel maybe. But on rough technical riding softer is better to a point. Tyre deforming over obsticals is better than having to bounce over. Softer also leads to better traction in general. To a point of course. I find that anything over 1.6 Bar (106kg me) is too hard and I start to loose traction and grip. But maybe that is just me.

[DieselnDust]

If you are riding gravel travel maybe. But on rough technical riding softer is better to a point. Tyre deforming over obsticals is better than having to bounce over. Softer also leads to better traction in general. To a point of course. I find that anything over 1.6 Bar (106kg me) is too hard and I start to loose traction and grip. But maybe that is just me.

1.6bar without describing the tyre dimensions and riding style isn't helpful. For your weight an xc tyre of 2.25 width would be grossly under inflated even if you're a chasing cut off time marathon rider. If riding an enduro tyre then that might very well be within the "sweetspot". The discussion can be a bit like talking about saddles. There's always an "it depends" in there

[Lance Stephenson]

1.2 and 1.1bar  (70kgs)

[DieselnDust]

1.2 and 1.1bar  (70kgs)

 

 

....but you can ride....

[RaymondC]

1.2 and 1.1bar  (70kgs)

Same this side for our side of the world. 68 kg & 2.25 width "Stellies & Grabouw" 

[Lance Stephenson]

....but you can ride....

relevant and irrelevant point.  I worked my pressure down slowly over time until I found the lowest possible pressure I could run without faults such as: tyre rolling off the rim and tyre squirm.  Once I found the right pressures I have fantastic mechanical grip.  

[DieselnDust]

relevant and irrelevant point.  I worked my pressure down slowly over time until I found the lowest possible pressure I could run without faults such as: tyre rolling off the rim and tyre squirm.  Once I found the right pressures I have fantastic mechanical grip.  

 

 

I hear you. the result is a pressure that works for your way of handling the bike, suspension set up and terrain and arrived at through extensive on the bike and trail testing to ensure you don't have broken rims or other unsafe conditions

[V18]

1.1 and 1.2! At 70kg? Holy smokes! Surely that pump must be off or you're barely hitting corrugated gravel with your bike.

[Captain Fastbastard Mayhem]

1.1 and 1.2! At 70kg? Holy smokes! Surely that pump must be off or you're barely hitting corrugated gravel with your bike.

Nah, this Lance guy can hustle.

[cadenceblur]

1.6bar without describing the tyre dimensions and riding style isn't helpful. For your weight an xc tyre of 2.25 width would be grossly under inflated even if you're a chasing cut off time marathon rider. If riding an enduro tyre then that might very well be within the "sweetspot". The discussion can be a bit like talking about saddles. There's always an "it depends" in there

At 104kgs I run

1.6 bar on the front - 2.3 tyre with an insert on a 30 inner diameter rim 

1.9 bar on the rear - 2.3 tyre with an insert on a 30 inner diameter rim

 

This feels firm when squeezed - people often comment that it feels hard, could well go lower.

Tokai trails

[LOCO4360]

At 104kgs I run

1.6 bar on the front - 2.3 tyre with an insert on a 30 inner diameter rim 

1.9 bar on the rear - 2.3 tyre with an insert on a 30 inner diameter rim

 

This feels firm when squeezed - people often comment that it feels hard, could well go lower.

Tokai trails

I'd have to admit that I am a tad heavy ha ha ha, at 89 kg and run Foamo front and rear at 1.5 Front and 1.6 rear for riding Conties (incl. DH), Hoogies etc. and then around 1.60 Front and 1.7 rear (maybe a tad higher) when hitting the Skillspark or the jumps. 

 

Running DHF 2.3 Front and Aggressor 2.3 Rear on 19mm rims with Foamo inserts (would love to upgrade to at least a 24mm internal width but alas, it shall not be soon.