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Tire pressures

Old 11-30-18, 12:02 PM
  #1  
GeorgeAz
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Tire pressures

Got a new and my first 29er and I really like it. I feel like I can bulldoze over everything. Quick question about tire pressures. I converted to tubeless and no issues so far. I run about 40 psi, I told some other riders my tire pressure on the trails I was on at the time, mostly hardpack single track. Like very hardpack, almost roadlike quality. I was riding pretty fast and I am not uncomfortable at 40 psi on these trails and I was looked at like I was an idiot. I was "informed" the tire pressure was way too high. It was recommended to 20-25. which to me would feel like I was riding on a flat tire.

I think if I was in a a rutted trail area with a bunch of roots and stuff, I might back off, but only to around 30psi. I run my road bike at 100 psi with 25c tires on the road, sometimes the road is chip sealed, but I rarely have an issue. Coming from a 26 mountain bike, the 29 is awesome. It is a hardtail and the tires are pretty compliant and I am a bigger guy. Am I wrong for running 40 psi? These are 2.1 tires.
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Old 11-30-18, 01:06 PM
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Have you tried 25psi with tubeless? It doesn't feel flat

Tubeless changes how low psi feels and gives you more... give. I would recommend trying out different psi. Personally I run between 12psi and 22psi depending on trail and conditions.
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Old 11-30-18, 06:40 PM
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Originally Posted by GeorgeAz View Post
It is a hardtail and the tires are pretty compliant and I am a bigger guy. Am I wrong for running 40 psi? These are 2.1 tires.
How much do you weigh?
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Old 11-30-18, 07:51 PM
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205. I got a lot of miles in on the road this summer and have lost some weight. Target for me would be 200.
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Old 12-01-18, 06:42 AM
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You aren’t wrong for running 40psi, however you will benefit more from tubeless by running a lower pressure.
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Old 12-01-18, 08:36 AM
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Run what feels good to you. It'll annoy all the rest of us . Do though, at least try a few runs on some lower pressures. Trails are smooth where I live too, and yet I can't think of anyone who runs 40 psi. I run 20 and 25 psi on my 2.25" 26er tires, and that's with tubes in them. Or maybe it's 15 and 20 psi. I forget. Whatever I have them at, I won't go lower due to tire squirm.

At the end of the day though, ride what you feel good about riding.
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Old 12-01-18, 08:51 AM
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Originally Posted by GeorgeAz View Post
205. I got a lot of miles in on the road this summer and have lost some weight. Target for me would be 200.
Assummng you are running even modest quality tires, you can definitely go lower and will experience benefits with no loss in speed unless you are on something litterally as smooth as pavement.

However, at your weight, and with 2.1” tires, 20-25 seems too low, particularly in the rear. You might not get pinch flats, but you could definitely get rim strikes.

I weigh 175, run 2.3” tubeless, and have settled on 23 front, 27 rear. Other people might even go a bit lower.

In your case I would definitely try going lower. I would try something like 28/33 F/R. I think if you give it some time, you will likely find that works better on dirt. If so, try going a little lower bit by bit. At some point you might feel rim strikes or it may feel squirmy in corners. Then you know you went too low.

Also, you can pretty much always run lower pressure in the front. Not as much weight on the front end.

Interested to know what you find.
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Old 12-01-18, 09:04 AM
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I'm about 185lbs and run my 29er HT at 30psi on trails with tubes. 2.2" tires.

On pavement I'll put them up to 40psi. Every year when I get back to trail riding, my friend will chide me about my pressures being to high. I'll say they aren't, but he's always right

Trust me that you will be faster if you drop your pressures down slightly. Pump them up to your 40psi, but once on the trail try bleeding them down gradually.

The best way for me to judge good tire pressure is on hard cornering, and ruts. Too high of pressure will cause your front to feel unsure, and your back will be bouncing.

Drop your front pressure by doing a couple taps on the valve to burp air. Then take some corners and repeat. This should start to make the front feel very sure of itself, you feel it grab predictably - keep your eyes past the apex of the turn, not down at the tire.

Drop your rear until the thumps become "dulled".

It's in your mind that the tires feel "flat", trust me I was the same way, doing far more road riding then mtb. It's incredible to realize your mtb speed will increase, because you'll have more shure footing and less bounce that will translate into less speed loss in corners and rough terrain.

Running tubless you have nothing to worry about when it comes to low pressures, unless you go crazy low like 12psi, which you'll know
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Old 12-01-18, 10:53 AM
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recently took off my tubed 29x2.25 riddlers but if I remember correctly I was very happy with 25psi front / 35 psi rear & I currently add a decent 240lbs w clothes, trunk & water bottles, etc to the weight of the bike. I used the bike on a mix of surfaces & love the width & speed of the riddlers. recently mounted up some 29x2.0 studded marathons which are yet to be tested. it's a lower volume tire so I may try 40 front 50 rear today

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Old 12-01-18, 05:19 PM
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Originally Posted by GeorgeAz View Post
Am I wrong for running 40 psi? These are 2.1 tires.
I think that's more pressure than you need to run, but you do you. My advice would be to take a pump and a gauge with you and experiment. You might find that 35 is a sweet spot. Or 27. You'll never know until you try.
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Old 12-01-18, 05:41 PM
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If it works for you-good. But like everyone else is saying, experiment. I hate low pressures on asphalt after riding trails and must pump up before heading home. But a lot of times when it's been dry out, I'll leave the pressures up that I used to reach the trails just so I don't have to muck with it. The ride is a lot harsher on the trail though and traction isn't always the greatest at higher pressures. And if you hit deep sand with high pressure you will really notice the difference. Good luck,
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Old 12-16-18, 02:24 AM
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I'm 175 and run 24 F and 26 R on a short travel (100mm) full-suspension. 40 is sort of high, even at 205. Try this formula:

Rider Weight in pounds divided by 7 = x
x - 1 = Front tire pressure in PSI
x + 2 = Rear tire pressure in PSI
Example: 185lb rider
185/7 = 26.4
Front tire pressure: 26 - 1 = 25 PSI
Rear tire pressure: 26 + 2 = 28 PSI

(Only good for riders 150+, below is too low tire psi)
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Old 12-16-18, 04:55 PM
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Optimally for best off road traction and handling, you should run them down to just before they start feeling like they are wobbling side to side on corners. Depending on bike geometry, your weight, your riding style, and the particular tire, and terrain, it can vary as much as 10-12lbs. I weigh about 205, ride 27.5, trail bike with 2.25 Maxxis Ardent tires and enduro bike with 2.4 Maxxis Minion tires, and both with tubes. I run the trail bike at 25lbs and the enduro bike at about 22lbs. I find that on soft, sandy trails, both seem too hard, but on hardpack with rocky technical sections 22lbs on the enduro bike can seem too soft. Experiment and find what works for you.
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Old 12-17-18, 03:52 AM
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Hi There -

I wight something around 55 - 60KG And run 29 - 31 PSI on Maxxis Minion 2.5
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