Your method of setting correct tyre pressures
09-21-17 | 09:31 PM
#26
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+1. Since experimenting with the Frank Berto recommendations years ago, I have not been disappointed. No pinch flats, and the ride is much more comfortable than when I simply aired up the tires to the max pressure rating.
This calculator makes it easy: Bicycle tire pressure calculator (I use the "Weight of (Fully-dressed) Rider & Bike" option and select the 45%/55% weight distribution regardless of the style of bike.)
This calculator makes it easy: Bicycle tire pressure calculator (I use the "Weight of (Fully-dressed) Rider & Bike" option and select the 45%/55% weight distribution regardless of the style of bike.)
MTB is a whole different story, though. Basically I go as low as I can until I start getting pinch flats (with tubes) getting rims strikes (tubeless) or feel the tires squirming in corners.
09-21-17 | 09:32 PM
#27
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There's no such thing as correct tire pressure. Optimal pressure depends on the specific conditions, including the tire itself, the rider's weight, road surface, weather, and rider's personal preference about ride quality.
So instead of thinking about numbers, think about how pressure affects the ride.
Lowering the pressure will make for a softer ride, which is nice, especially on bumpier roads. But it increases friction and slows you. It can also allow you to bottom on bumps, causing pinch flats and denting rims.
Higher pressure lowers friction which is nice, plus makes for very crisp handling. But less friction, also can mean less traction, especially on wet roads or when cornering. It also makes for a harsher ride, especially if the road isn't glass smooth.
So start at some arbitrary pressure, say 90% of the tire's max. Ride that a while and think about the ride. Then add 10psi and ride that a while making not of what's better or worse. If it felt better overall, try 10psi more, and do this until the good isn't getting better, but the bad is getting worse. You now have an upper limit.
Repeat the process going down from where you started until you find your lower limit. IME the lower limit tends to be more obvious.
So you now have a band, probably 20-30 psi wide, and have a good sense of where within it you're happiest. As you gain a sense of how pressure effects ride, you'll make small adjustments based on specific conditions.
So instead of thinking about numbers, think about how pressure affects the ride.
Lowering the pressure will make for a softer ride, which is nice, especially on bumpier roads. But it increases friction and slows you. It can also allow you to bottom on bumps, causing pinch flats and denting rims.
Higher pressure lowers friction which is nice, plus makes for very crisp handling. But less friction, also can mean less traction, especially on wet roads or when cornering. It also makes for a harsher ride, especially if the road isn't glass smooth.
So start at some arbitrary pressure, say 90% of the tire's max. Ride that a while and think about the ride. Then add 10psi and ride that a while making not of what's better or worse. If it felt better overall, try 10psi more, and do this until the good isn't getting better, but the bad is getting worse. You now have an upper limit.
Repeat the process going down from where you started until you find your lower limit. IME the lower limit tends to be more obvious.
So you now have a band, probably 20-30 psi wide, and have a good sense of where within it you're happiest. As you gain a sense of how pressure effects ride, you'll make small adjustments based on specific conditions.
Best reply in the thread.
09-21-17 | 10:33 PM
#28
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The process I usually follow on the road is to use the Berto method to get the rear tire pressure, then subtract about 10psi for the front. I don't want to use the actual weight distribution because this usually makes the front tire too soft for out of the saddle riding. Then when I notice the handling suffer a little, I reinflate to the original number plus about 5psi. With my 38mm and 42mm tires, that means adding air every 2-3 months. With really supple tires, don't loose much speed.
09-21-17 | 11:07 PM
#29
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Ride through dust.
Then ride on pavement.
Look at contact patch.
Looks okay? Good.
Feels fast enough relative to effort? Even better.
Comfortable? Harsh. Adjust 5-10 psi until it feels right for road conditions.
That works with Schwalbe Ones.
Not so great with Vittoria Zaffiros. To be fast those need to be inflated until they feel harsh. To be comfortable on chipseal and rough pavement, I need to reduce pressure until they're sluggish. But, heck, they cost only about $10.
With my fatter hybrid tires I just guesstimate even more loosely. Anywhere from 45-65 psi, depending on terrain.
Then ride on pavement.
Look at contact patch.
Looks okay? Good.
Feels fast enough relative to effort? Even better.
Comfortable? Harsh. Adjust 5-10 psi until it feels right for road conditions.
That works with Schwalbe Ones.
Not so great with Vittoria Zaffiros. To be fast those need to be inflated until they feel harsh. To be comfortable on chipseal and rough pavement, I need to reduce pressure until they're sluggish. But, heck, they cost only about $10.
With my fatter hybrid tires I just guesstimate even more loosely. Anywhere from 45-65 psi, depending on terrain.
09-22-17 | 06:28 AM
#30
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+1. Since experimenting with the Frank Berto recommendations years ago, I have not been disappointed. No pinch flats, and the ride is much more comfortable than when I simply aired up the tires to the max pressure rating.
This calculator makes it easy: Bicycle tire pressure calculator (I use the "Weight of (Fully-dressed) Rider & Bike" option and select the 45%/55% weight distribution for any road-style bike.)
This calculator makes it easy: Bicycle tire pressure calculator (I use the "Weight of (Fully-dressed) Rider & Bike" option and select the 45%/55% weight distribution for any road-style bike.)
09-22-17 | 07:06 AM
#31
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I often wonder how much air is lost (w a schrader valve) when removing a standard pump chuck. meaning if I want 100 lbs should I go up to 110 or 105? anyone ever take the time to actually measure AFTER pumping w a gauge? also knowing that with low volume tires, even just checking with a gauge lets a little air out. or is the lost air I hear just coming from the hose?
Last edited by rumrunn6; 09-22-17 at 07:13 AM.
09-22-17 | 09:31 AM
#33
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09-22-17 | 09:44 AM
#34
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I do, every time.
I didn't trust the gauge on my floor pump. Plus it was hard to see and impossible to adjust tire pressure via bleeding.
So I bought one of these for this exact reason. I over inflate with the floor pump by just a few strokes and then use this gauge. Once forced onto the stem, it will stay in place by itself. The bleeder valve works great and allows me to precisely and easily control the pressure, even to partial pounds. This one is for Presta but they are available for Schrader as well and in a wide variety of PSI ranges for specific needs.
$12.00 directly from the manufacturer.
09-22-17 | 12:22 PM
#36
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09-22-17 | 01:20 PM
#37
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09-22-17 | 01:24 PM
#38
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Triple the volume of a 23mm tire, half the starting pressure. You lose pressure MUCH less quickly at low pressures than high.
I'd wager I could fill my 40mm tires up to 60psi, hang the bike up in the garage until spring, take it down and go for a ride without having to top the tires off.
I'd wager I could fill my 40mm tires up to 60psi, hang the bike up in the garage until spring, take it down and go for a ride without having to top the tires off.
09-22-17 | 06:21 PM
#40
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Not magic tubes. Thicker tubes.
I'll take as an exaggeration.
I'll take as a maybe.
The 40x700C tube that came out of my son's Trek Marlen 29er feels like thicker rubber than the 20x700C that came out of one of my road tires. Might not be a good comparison, but I'm willing to generalize.........
Thicker tubes and higher volume make the loss of psi less noticeable on big wide tires as opposed to my narrower 23mm tires.
"Forever"
"3 to 4 months"
The 40x700C tube that came out of my son's Trek Marlen 29er feels like thicker rubber than the 20x700C that came out of one of my road tires. Might not be a good comparison, but I'm willing to generalize.........
Thicker tubes and higher volume make the loss of psi less noticeable on big wide tires as opposed to my narrower 23mm tires.
09-22-17 | 07:22 PM
#41
+1. Since experimenting with the Frank Berto recommendations years ago, I have not been disappointed. No pinch flats, and the ride is much more comfortable than when I simply aired up the tires to the max pressure rating.
This calculator makes it easy: Bicycle tire pressure calculator (I use the "Weight of (Fully-dressed) Rider & Bike" option and select the 45%/55% weight distribution for any road-style bike.)
This calculator makes it easy: Bicycle tire pressure calculator (I use the "Weight of (Fully-dressed) Rider & Bike" option and select the 45%/55% weight distribution for any road-style bike.)
I just tried the calculator, and it was pretty close to the pressures I use on three different tire sizes.
My tires
I'm about 170 pounds. These are actual tire widths. I have wide aluminum rims, so the measured widths are somewhat bigger than the nominal sizes.
26mm:
80 psi front, 95 psi rear.
Just for a little insurance, I'll add 5 psi to each tire if it's a fast group ride on rougher roads, where I might hit a pothole or blast over a RR track. Or if the roads will all be very smooth (yeah, sure...) , I might use this higher pressure.
29mm:
65 psi front, 80 psi rear.
Very nice on rough chipseal roads. Even though it's only 3mm wider diameter, the volume is about 25% larger, so the air pressure can be reduced similarly. ( the cross section area is pi * radius^2. That's 550 sq mm vs 660 sq mm)
39 mm! Smooth tread Compass Barlow Pass tires.
38 psi front, 45 psi rear. This is fast and efficient on paved roads.
For rough gravel roads: 32-34 psi front, 40-43 psi rear.
Last edited by rm -rf; 09-22-17 at 07:33 PM.
09-22-17 | 08:16 PM
#42
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Anyone run the Continental Touring Plus Reflex tire? The max psi states 75 psi iirc, why is that psi maxed at 75? What would likely occur if inflated up to 95? Is that rating for tubeless or both tube and tubeless?
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09-23-17 | 11:09 AM
#44
09-23-17 | 11:55 AM
#45
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I wonder if anybody has done studies (or personal experiments) on recommended inflation and lighter riders. Obviously heavier riders benefit from higher pressure, lighter riders from less.
I know that I overinflate my tires and should probably go a bit lower. That said, I cannot fathom the idea of running 700x23 tires at 60PSI on a normal road ride
I know that I overinflate my tires and should probably go a bit lower. That said, I cannot fathom the idea of running 700x23 tires at 60PSI on a normal road ride
09-23-17 | 10:04 PM
#47
What size tire?
"Hoop stress" increases for the same inflation pressure when the tires are larger. (I suppose it's due to air pressing on more linear inches of tire casing from bead to bead, but the same strength of casing.)
See this FLO Cycling explanation.
Your tires:
95 psi for a 32mm tire is very high. The tire pressure calculator mentioned in previous posts shows:
rider+bike: 290 pounds
distribution: 45% / 55%
32mm tires
Front: 76 psi
Rear: 94 psi
"Hoop stress" increases for the same inflation pressure when the tires are larger. (I suppose it's due to air pressing on more linear inches of tire casing from bead to bead, but the same strength of casing.)
See this FLO Cycling explanation.
Your tires:
95 psi for a 32mm tire is very high. The tire pressure calculator mentioned in previous posts shows:
rider+bike: 290 pounds
distribution: 45% / 55%
32mm tires
Front: 76 psi
Rear: 94 psi
Last edited by rm -rf; 09-23-17 at 10:07 PM.
09-23-17 | 10:17 PM
#48
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What size tire?
"Hoop stress" increases for the same inflation pressure when the tires are larger. (I suppose it's due to air pressing on more linear inches of tire casing from bead to bead, but the same strength of casing.)
See this FLO Cycling explanation.
Your tires:
95 psi for a 32mm tire is very high. The tire pressure calculator mentioned in previous posts shows:
rider+bike: 290 pounds
distribution: 45% / 55%
32mm tires
Front: 76 psi
Rear: 94 psi
"Hoop stress" increases for the same inflation pressure when the tires are larger. (I suppose it's due to air pressing on more linear inches of tire casing from bead to bead, but the same strength of casing.)
See this FLO Cycling explanation.
Your tires:
95 psi for a 32mm tire is very high. The tire pressure calculator mentioned in previous posts shows:
rider+bike: 290 pounds
distribution: 45% / 55%
32mm tires
Front: 76 psi
Rear: 94 psi