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Old 07-01-04, 09:27 PM   #1
unrelated
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Tire pressure?

Can someone kinda explain which condition do I use lower pressure and higher pressure?

Say for eg ascending slope with lose rocks, will lower pressure be better or higher?
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Old 07-01-04, 09:39 PM   #2
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Well, for overall control and speed, (depending on rider weight) you should keep your tire pressure between 35 and 45 psi. Generally under 40 is best. This will give you a good compromise between traction and control and since you are riding off-road will help you roll over loose soil.

Many people believe that if they overinflate their tires they'll roll faster. Not necessarily true. If the trails are HARDPACK conditions then yes, but if you have any roots or any varied soil conditions less air will be faster. A softer tire will provide grip over roots. Overinflated tires will skate across the tops. In loose soil, a softer tire will allow the wheel to stay on top of the loose stuff by spreading the load. A hard tire will cut through like a knife. A softer tire will absorb rock and roots and give some inherent suspension. A hard tire will bounce like a pinball.

You should experiement. I usually overinflate my tires at the trailhead/truck and then stop every few minutes and "burp" some air (quick little burst) while I'm waiting for friends to regroup. Once I feel my speed increase. Yes, increase! I leave it be. When I get back to the truck, I'll put a gauge on it to verify the pressure. Then next time under similar conditions, I'll start just a few psi above that level.

I'm a big boy, (250 lbs) I need a bit more psi than you skrawny toothpick riders. (really I'm just envious). So I usually start at 50 psi and work down from there!

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Old 07-01-04, 09:53 PM   #3
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I start the day off at the max my tires will allow (~80) and bleed it off as the conditions require.
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Old 07-01-04, 09:59 PM   #4
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How much do you weight Jas? at 80, you're starting WAY too high. Unless you're starting with a 10 mile section of riding on the road to get to the trails.

I'd start at 45 if you weight under 200 lbs.

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Old 07-01-04, 10:02 PM   #5
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Originally Posted by a2psyklnut
How much do you weight Jas? at 80, you're starting WAY too high. Unless you're starting with a 10 mile section of riding on the road to get to the trails.

I'd start at 45 if you weight under 200 lbs.

L8R


I weigh 200lbs, and I do ride the road to the trails which is why I start so high. I cannot stand powersapping. The first section of the trails are also very dense hardpack.


Once I get to the looser/rootier section of the trails I generally bleed down to about 50ish.
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Old 07-01-04, 10:14 PM   #6
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50 pounds...thats insane. It really is incredible how different people are with pressures. I run 35 almost all the time. If on skinnies or wet I probably run 25 to 30ish...
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Old 07-01-04, 10:25 PM   #7
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I just have this serious problem with powersuck. I'm not a weight weenie, but I just hate feeling my pedal strokes being wasted.
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Old 07-01-04, 10:58 PM   #8
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I can see that. I suppose I do (if I take the time) run higher air pressure to get to the trail.
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Old 07-01-04, 11:01 PM   #9
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I can see that. I suppose I do (if I take the time) run higher air pressure to get to the trail.



I think how much pressure you need to run to avoid power-sapping is related to how you pedal.




I'm on the anarobic side of the spectrum, and have very powerful legs. I think the large surges of power with each stroke I feed to the wheels will make the sapping effect worse than someone who spins at a high RPM keeping the pressure very smooth.


Maybe someone has experience with that?
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Old 07-01-04, 11:35 PM   #10
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I torque, I don't spin much. Trails here don't allow for much high rpm unless you wear clipless. That and at 270...I just mash
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Old 07-02-04, 03:11 PM   #11
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What about say i ride in the city? Traction isn't as important, so I will think higher pressure reduces the contact surface area = less friction. Of course with off-road tires you get more vibration this way.
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Old 07-02-04, 04:50 PM   #12
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i pump mine pretty high, too. sometimes i lose traction if i'm on dry loose dirt, but it makes me feel like i've got more control with the added rigidity.
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Old 07-04-04, 04:08 PM   #13
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I am 200#s give or take and I agree,I hate loosing enegy on a climb so I keep my rear at appr.45 and front at appr.35.I had a frame that was harder to climb with than the one I ride now so maybe geometry plays a bit too.my setup works well for me overall.
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