Mt Bike Tire Talk

[Jed Peters]

XC: Ardent race or Ikon front, ikon rear. (2.3 front, 2.25 rear)

Trail/DH: Minon DHF front, DHR rear or Aggressor rear (depending on terrain) (2.5f/2./2.4r)

Conversation over.

 

[AmyPJ]

So why not let a little air out if you prefer it that way?

Well, one because I just had a pinch flat running it low like I do (although, to be fair, it's the first flat in 5 seasons, so...) and, I like them REALLY low, like, 15 in the back and 13 in the front. The whole bike feels fast and pliable and nimble and compliant and glued to the trail. If I run higher, it bounces off rocks a lot more, which is very unnerving in corners. It also bounces around a lot more while climbing rock gardens.

 

[cantunamunch]

*senses an imminent Schwalbe Procore shopper*

 

[AmyPJ]

*senses an imminent Schwalbe Procore shopper*

Was ist das?

 

[cantunamunch]

Was ist das?

It's a thing where there's an inner high pressure chamber and an outer low pressure chamber.


or you can do the Cush Core/ Vittoria Air liner foam thing.

 

[scott43]

Sheesh..I run 30 front and 35 rear...

 

[Philpug]

Sheesh..I run 30 front and 35 rear...

Yeah, thats Canadian air.

 

[cantunamunch]

Sheesh..I run 30 front and 35 rear...

*2 bars on Violin of Woe*

 

[AmyPJ]

It's a thing where there's an inner high pressure chamber and an outer low pressure chamber.


or you can do the Cush Core/ Vittoria Air liner foam thing.

Hmmm, it does sound like something I'd like.
That being said, if I haven't had an issue in 5 seasons, maybe I shouldn't worry too much? Except, I get a heaping of grief from the man friend for running them that low.

 

[cantunamunch]

That being said, if I haven't had an issue in 5 seasons, maybe I shouldn't worry too much?

Can't help you there...are your rims and the MF's gear envy worth $150ish and some hassle per wheel?

 

[Erik Timmerman]

I had a nice 30 psi in my rear tire today. No casing squirm at all, which made me actually wonder, should I drop like 1 psi so that on the limit that squirm is there to communicate with me. Does a little bit of squirm maybe increase grip?

 

[Primoz]

30 to 35psi can be super high or super low. There's just way too many factors that influence this to be able to compare these numbers just like this. It mostly depends on what tires you are running and what your (plus bike) weight is, but also trail conditions, riding style etc. influence that. For super light xc tires you need to go much higher then for heavy dh rubbers, and someone at 50kg can go much lower then someone with 100kg. I'm running Conti's Race king as rear tire and there's some 2-3psi difference between Racesport and Protection version if you want them to behave about same, and other then amount of protection, it's exactly same time. Here we are talking anything from super light xc tires to heavy trail tires so operating with numbers is pretty much useless unless we have all the other data with it (exact tire model, riders weight, riding style and also trail conditions info).

 

[AmyPJ]

30 to 35psi can be super high or super low. There's just way too many factors that influence this to be able to compare these numbers just like this. It mostly depends on what tires you are running and what your (plus bike) weight is, but also trail conditions, riding style etc. influence that. For super light xc tires you need to go much higher then for heavy dh rubbers, and someone at 50kg can go much lower then someone with 100kg. I'm running Conti's Race king as rear tire and there's some 2-3psi difference between Racesport and Protection version if you want them to behave about same, and other then amount of protection, it's exactly same time. Here we are talking anything from super light xc tires to heavy trail tires so operating with numbers is pretty much useless unless we have all the other data with it (exact tire model, riders weight, riding style and also trail conditions info).

Yep, this is true for sure. Could be that the slightly beefier XR4 tires (vs. the XR3 I was running before) can run on lower pressure.

 

[cantunamunch]

Yep, this is true for sure. Could be that the slightly beefier XR4 tires (vs. the XR3 I was running before) can run on lower pressure.

I think I'm probably misreading - was it the XR3 or XR4 that had the low pressure burp/squirm? Which tire did you run for 5 years?

 

[Tom K.]

Hmmm, it does sound like something I'd like.
That being said, if I haven't had an issue in 5 seasons, maybe I shouldn't worry too much? Except, I get a heaping of grief from the man friend for running them that low.

Just tell him what he wants to hear, and go about your business. My wife tells me this strategy works wonderfully, though I have no idea who she employs it with.

Yep, this is true for sure. Could be that the slightly beefier XR4 tires (vs. the XR3 I was running before) can run on lower pressure.

XR3 and XR4 have the same casing, though the XR4 has more rubber in the form of bigger knobs on that same casing.

I still think you were just having an "on" day, unless your good ride happened after rain. I'm always amazed at how much more supple of a ride I get on familiar trails, once our fall rains kick in. Surprising difference.

 

[cantunamunch]

I still think you were just having an "on" day, unless your good ride happened after rain. I'm always amazed at how much more supple of a ride I get on familiar trails, once our fall rains kick in. Surprising difference.

OK, I was actually dreading going out today 'coz we just had the first of our regularly scheduled Labor Day deluges. This kinda helped.

 

[AmyPJ]

Just tell him what he wants to hear, and go about your business. My wife tells me this strategy works wonderfully, though I have no idea who she employs it with.



XR3 and XR4 have the same casing, though the XR4 has more rubber in the form of bigger knobs on that same casing.

I still think you were just having an "on" day, unless your good ride happened after rain. I'm always amazed at how much more supple of a ride I get on familiar trails, once our fall rains kick in. Surprising difference.

I employ this same strategy, however, he likes to fill my tires when we ride together. So, I suppose I'll have to resort to smacking him upside the head and telling him to go away.

 

[AmyPJ]

I think I'm probably misreading - was it the XR3 or XR4 that had the low pressure burp/squirm? Which tire did you run for 5 years?

The XR3 in the back had the burp on a big, sharp rock. That's the tire I've been running until this season.

 

[cantunamunch]

The XR3 in the back had the burp on a big, sharp rock. That's the tire I've been running until this season.

OK, I see.

There is one thing that explains the known data points - tire beads get looser relative to the casing as tires age and get miles on them*.

All tires do this**. If you continue to run the XR4 in the teens it will ,at some point, do it too.


*Well, except maybe for the ones with slovenian and canadian air, those have kilometers
**even high pressure roadie ones - this is why it's much easier to get an old tire onto a tight rim.

 

[ScottB]

I ride a hard tail and tires are my rear suspension. The tires that came with the bike had to be run at 30-35 psi otherwise they squirmed and pinch flatted. I had about 15 flats in 3 seasons. I finally researched mtn bike tires and learned their casings vary from one tire model to another, and even within the same model tire. Very confusing, but from other's experience I run 2017 Nobby Nic's in 29 x 2.35" and I run them around 19 psi. Its pretty amazing that tire side wall and casing make that much difference but it does. I weigh 240lbs, so Amy running hers around 15 is pretty comparable I would guess.

I did allow a friend to pump up my tires when we were in a hurry to leave one ride, and even though I told him 19 psi, he felt he knew better and pumped them to 30 psi. I was having a bad bike day, as you might expect, and kept thinking the bike feels like the tires are too hard, but I assured myself they couldn't be because I specifically told my friend 19 psi after he questioned it. I wanted to kick his a*** when I bounced off the trail, hit a fallen tree and ruined my deraliler on a tree branch. That 's when I figured it out.

Amy, don't let your friend near your tire pump is my advice.