Fat man and tyre squirm

slowmick

"I am over 1000 kg"
I have a question for the brains trust here. When hitting off camber sections on the Aneurysm trail out at Lysterfield I get a very squirmy feeling in the back wheel, I even managed to start rolling the tyre off the rim on one run. The tyre now has the cross hatching on the side of it like I am running to low a pressure.

I run a Maxxis Ardent 2.4 EXO wire bead with a regular tube on a Specialized Roval Aluminium rim at 35psi. With riding gear I am close to 120 kg.

What am I doing wrong? Do I need more pressure? thicker tubes? dual ply tyres? A diet? To harden up?

The Rovals may not be your choice of rim but it's what I've got to work with (they are only a few months old so replaceing them is off the table).
 

Static 81

Likes Bikes
Not that I'm a professional by any means But i'm running the same tyre, am tipping the scales at around 105 kitted up and riding a hardtail.
I run my front and rear at 60 psi and I'm wondering if that isn't too low. (Please note; I used to ride a bmx with pressures exceeding 110psi. So anything lower than 90 feels odd to me)

However, If you're rolling the tyre off the rim, pressure would be the key factor here. Maybe increase pressure 5psi at a time and see how it feels?
 
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Comic Book Guy

Likes Bikes and Dirt
Does sound like a pressure problem.

I'm a fat bastard and I run my rear at 50-60psi with thorn proof tubes. My experience is the thicker tubes make the tyre feel firmer.
 

outtacontrol

Likes Bikes and Dirt
Wow they are some big numbers getting bandied around... I would think an increase in pressure would definitely help, but will also reduce the traction the tyre can get. If the tyre is too hard it will just pinball off everything.

A tyre with a stronger sidewall might be a better solution?? Maybe look at UST or dual ply tyres? They will be heavier, but should allow you to run pressures that will still allow the tyre to grip properly...
 

John U

MTB Precision
Make sure your pressures are correct. I was thinking the rear of my frame was built of cheese. I purchased a topeak digital pressure gauge. It turned the pump I was using was overstating my tyre pressure by 20psi! Correct pressure solved the issue.
 

slowmick

"I am over 1000 kg"
thaks for all the suggestions guys. i'll try adding more pressure and see if i can balance grip and squirm. will also keep a look out for a dual ply on sale to try. cheers.
 

mitchy_

Llama calmer
i've got a maxxis 26 x 2.35" high roller dual ply for sale, i meant to pick up a single ply.
$30 + post
 

my02

Likes Dirt
I weigh a little over 120 RTR and have no problems running pressures in the high 20s to low 30s depending on the track. I ride a 6" trail bike and DH.

However I simply can't get away with riding single ply tyres. The trail bike is running tubeless 2.4 Ardent F and 2.25 Crossmark R. When I've run tubed, it's always been at least Freeride or DH versions.
 

Rider15

Likes Bikes and Dirt
I have a question for the brains trust here. When hitting off camber sections on the Aneurysm trail out at Lysterfield I get a very squirmy feeling in the back wheel, I even managed to start rolling the tyre off the rim on one run. The tyre now has the cross hatching on the side of it like I am running to low a pressure.

I run a Maxxis Ardent 2.4 EXO wire bead with a regular tube on a Specialized Roval Aluminium rim at 35psi. With riding gear I am close to 120 kg.

What am I doing wrong? Do I need more pressure? thicker tubes? dual ply tyres? A diet? To harden up?

The Rovals may not be your choice of rim but it's what I've got to work with (they are only a few months old so replaceing them is off the table).
Not to be a dick here but at 120kg you are putting a lot of pressure on your tyres and rims. I would suggest upping the tyre pressure slightly say, 40-45psi and maybe investing in a stiffer tyre, I believe they make an Ardent in a DH casing which should do the trick or a high roller in a 2.35 in the DH casing.

Not that I'm a professional by any means But i'm running the same tyre, am tipping the scales at around 105 kitted up and riding a hardtail.
I run my front and rear at 60 psi and I'm wondering if that isn't too low. (Please note; I used to ride a bmx with pressures exceeding 110psi. So anything lower than 90 feels odd to me)


However, If you're rolling the tyre off the rim, pressure would be the key factor here. Maybe increase pressure 5psi at a time and see how it feels?


60psi?? What kind of riding are you doing on that pressure?!
 

Mywifesirrational

I however am very normal. Trust me.
I'm between 105-110kg and are having no troubles running lower pressures - usually 25 psi (F) - 30 psi (R), I am actually thinking of going 2-3 psi lower.

For myself rim selection and tire choice was the most important factor, a wider rims like a Stans Flow Ex seems to support the side walls really well, coming from rims with either 19 to 21mm internal the width difference with the same tires was instantly noticeable + tubeless ready tires with a sturdy sidewall. I'm running tubeless and plowing through anything and everything without any problems, the bike has awesome traction, no dings and very confidence inspiring.

High pressures are not your friend, once you can reliably run low pressures it's a real eye opener in cornering and traction.
 

Static 81

Likes Bikes
60psi?? What kind of riding are you doing on that pressure?!
I don't exactly call it riding........ I like to call it Falling, with style.
Having read many posts in this thread, I think I may knock a few pounds out of my tyres and see how that goes for me.

So there you have it Slowmick, I am certainly no professional......... Good thing I never claimed to be. :eek:hwell:
 

slowmick

"I am over 1000 kg"
Thanks for all your help guys. Just placed an order for some dual ply high rollers and Minion DHRs from Pushy's $10 Maxxis sale (sorry Mitchy).

Will play with pressures on the weekend then have a go with the dual ply tyres. I think I still have downhill tubes in the garage from when I used run folding tyres and roll them off the rim. Maybe it's time to put down the pies...

Static - you're in good company - the blokes I ride with describe me as like being followed by someone dragging a tool box... :becky:
 

tasty.dirt74

Likes Bikes and Dirt
Lighter tyres and larger riders = no no.

Hi Static.. Im generally at 100kg with gear,backpack etc... and generally run under 30psi... Sometimes i have noticed with lighter tyres under hard cornering a squirm, or sidewall deflection, which is quite unnerving.
As was mentioned, stronger sidewalls gives more support and consistency with cornering. Not wanting to blatently advertise, but Pushys.. http://www.pushys.com.au/bike-tubes-and-tyres/26-inch-tyres.html are doing a wide selection of Maxxis tyres under $10 !!!:high5::high5:

Also the Specialized tyres(not sworks) are pretty good.

Dammit slowmick, not so slow eh !!
 
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Bermshot

Banned
So that's how my tires come about with that pattern.

I guess the o'l thumb test doesn't apply anymore!

(Never had a puncture or a blow out since T-less)

Mass slow and fat at 83kegs.
 

mitchy_

Llama calmer
Thanks for all your help guys. Just placed an order for some dual ply high rollers and Minion DHRs from Pushy's $10 Maxxis sale (sorry Mitchy).

Will play with pressures on the weekend then have a go with the dual ply tyres. I think I still have downhill tubes in the garage from when I used run folding tyres and roll them off the rim. Maybe it's time to put down the pies...

Static - you're in good company - the blokes I ride with describe me as like being followed by someone dragging a tool box... :becky:
Not a problem! Wish I saw that sale before I just bought tyres...
 

jackass'd

Likes Dirt
I have a question for the brains trust here. When hitting off camber sections on the Aneurysm trail out at Lysterfield I get a very squirmy feeling in the back wheel, I even managed to start rolling the tyre off the rim on one run. The tyre now has the cross hatching on the side of it like I am running to low a pressure.

I run a Maxxis Ardent 2.4 EXO wire bead with a regular tube on a Specialized Roval Aluminium rim at 35psi. With riding gear I am close to 120 kg.

What am I doing wrong? Do I need more pressure? thicker tubes? dual ply tyres? A diet? To harden up?

The Rovals may not be your choice of rim but it's what I've got to work with (they are only a few months old so replaceing them is off the table).
I ran around 37 - 40 psi in a Maxxis Highroller 2.35 dual ply wire bead with a standard tube on my FR bike and found that worked well for me when I was at the 120kg riding weight.

To get to that number, I just kept adding a few psi before every ride until I found it worked for me. Obviously ever ssetup with be different due to tyre type, tubed/tubeless etc.
 

Bermshot

Banned
I ran around 37 - 40 psi in a Maxxis Highroller 2.35 dual ply wire bead with a standard tube on my FR bike and found that worked well for me when I was at the 120kg riding weight.

To get to that number, I just kept adding a few psi before every ride until I found it worked for me. Obviously ever ssetup with be different due to tyre type, tubed/tubeless etc.
In'it the medium? 2kg tires ain't for me.
 
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