16 tubes/tires/pressures
08-20-18, 09:24 AM
#1
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16 tubes/tires/pressures
We have a Dahon Presto. Tires are Kenda 16x1.5, labeled 100psi. Rims are Allez Aero 6061 aluminum. Tubes are Kenda 1.5. Rim tape is Velox 10mm. I have had two blowouts at the nipples when running 100psi. There are stretch marks on the blown tubes at many of the nipples. Rim tape is still in place. No spoke heads are through the tape. The Kenda tube seems to be quite thin and just cant handle the pressure. A couple of questions:
Better or wider rim tape?
A different brand of tube? (I can use Presta with adapters or Schrader.)
Just run lower pressure (which is what I have been doing)?
I would appreciate your suggestions. Thanks,
Fred
Better or wider rim tape?
A different brand of tube? (I can use Presta with adapters or Schrader.)
Just run lower pressure (which is what I have been doing)?
I would appreciate your suggestions. Thanks,
Fred
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2,500 (yes 2,500) bikes given EACH YEAR to the needy 2011- 2018. All volunteer.
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08-20-18, 10:17 AM
#2
Banned
Allez is just French for Go.(faster)
does not tell me anything about rim cross section details, who made it and etc.
aftermarket wheels bought or just what came on the bike?
Such a wide tire, 1.5" , considering you blew it off the rim .. 2X.
go more modest on the operating PSI.. bottom of the range, rather than the top..
and after mounting the tire, check no portion of the tube is not between the tire beads ..
any sticking under the bead has been shown to push the tire off, when inflated..
On my single wall rim, I was getting punctures, although the rim tape covered the spoke heads.
I created a short rubber rim strip, from a longer, put it under the one already there (fused loop plastic)
and that issue stopped..
....
does not tell me anything about rim cross section details, who made it and etc.
aftermarket wheels bought or just what came on the bike?
Such a wide tire, 1.5" , considering you blew it off the rim .. 2X.
go more modest on the operating PSI.. bottom of the range, rather than the top..
and after mounting the tire, check no portion of the tube is not between the tire beads ..
any sticking under the bead has been shown to push the tire off, when inflated..
On my single wall rim, I was getting punctures, although the rim tape covered the spoke heads.
I created a short rubber rim strip, from a longer, put it under the one already there (fused loop plastic)
and that issue stopped..
....
08-27-18, 06:50 AM
#3
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OK now
Thanks for your comments.
The Allez rim is a single wall rim that came with the bike. The tire was Kenda 100psi. Tube was Kenda 1.50-1.75. The tire did not blow off the rim. The Velox rim tape was in place with no spoke holes. The hole was at the nipple on the inside of the tube both times. I cut the Kenda tube and it looked very thin on the nipple side.
Solution was to switch the tubes to Sunlite UTILI-T 1.50-1.95 and put a rubber rim strip on top of the Velox tape. The Sunlite tubes look much thicker than the Kenda. I lowered the pressure to 80psi and everything seems fine.
The Allez rim is a single wall rim that came with the bike. The tire was Kenda 100psi. Tube was Kenda 1.50-1.75. The tire did not blow off the rim. The Velox rim tape was in place with no spoke holes. The hole was at the nipple on the inside of the tube both times. I cut the Kenda tube and it looked very thin on the nipple side.
Solution was to switch the tubes to Sunlite UTILI-T 1.50-1.95 and put a rubber rim strip on top of the Velox tape. The Sunlite tubes look much thicker than the Kenda. I lowered the pressure to 80psi and everything seems fine.
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08-27-18, 08:32 PM
#4
Senior Member
FWIW, engine + bike ~ 85kg. On 16x1.50" tires, I run 45/65psi.
08-28-18, 01:03 AM
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I'm inclined to think that's too low. I have 16" Kenda tyres in my Neo, and run them at 85psi. I'm a great believer in following manufacturer's specs after a couple of incidents with under-inflated tyres.
08-28-18, 02:27 AM
#6
Senior Member
well, the world is full of people who believe crazy or highly improbable things. Doesn't mean it's true. The manufacturer cannot possibly know the weights of bikes and riders so they spec out the max and min pressure. Pressure is a function of load. It is not an absolute irrespective of load. How much do you and the bike weigh? It is possible that both you and I are correct. If you and your rig weigh more than I and my rig do, you will need higher pressure, yes.
08-28-18, 03:37 AM
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There are other factors that come into play, Abu, as you well know. Also, manufacturers do indeed specify a maximum and a minimum, so therefore it makes sens not to go beyond them. Kenda don't appear to give a minimum, only a maximum, but your 45psi figure in particular seems too low. I know you like doing things your own particular way, but I'd still say that, for the vast majority of us, manufacturer's recommendations are the safe option.
08-28-18, 03:47 AM
#8
Senior Member
There are other factors that come into play, Abu, as you well know. Also, manufacturers do indeed specify a maximum and a minimum, so therefore it makes sens not to go beyond them. Kenda don't appear to give a minimum, only a maximum, but your 45psi figure in particular seems too low. I know you like doing things your own particular way, but I'd still say that, for the vast majority of us, manufacturer's recommendations are the safe option.
Two internet tire pressure calculators. They both agree generally with my range of pressures for a 37mm-wide tire.
https://oniony.com/cycling/calc/pressure/
https://www.dorkypantsr.us/bike-tire-pressure-calculator.html
The actual tire in question. 16x1.50". Min/Max pressure on the sidewall 40/65psi. No one here---or at least me--is doing anything dangerous or outside product tolerances, as it was previously put forth as explanations for my tire pressure.
Last edited by Abu Mahendra; 08-28-18 at 06:23 AM.
08-28-18, 05:01 AM
#9
Stardust
I have 16" 1.3 kenda ksmart tyres and i run then at 60psi. No puntures for 2 years.In this tyre, the recomended pressure is 60psi to 85psi.
i also have 16"1/3 schwalbe kojak tyres that runs at 75psi for 3 years 1 puncture. In this tyre recomended pressure is 85 to 110psi.
mylself have 70kg and my wife 58.
i also have 16"1/3 schwalbe kojak tyres that runs at 75psi for 3 years 1 puncture. In this tyre recomended pressure is 85 to 110psi.
mylself have 70kg and my wife 58.
Last edited by BromptonINrio; 08-28-18 at 05:24 AM.
08-28-18, 07:12 AM
#10
Schwinnasaur
well, the world is full of people who believe crazy or highly improbable things. Doesn't mean it's true. The manufacturer cannot possibly know the weights of bikes and riders so they spec out the max and min pressure. Pressure is a function of load. It is not an absolute irrespective of load. How much do you and the bike weigh? It is possible that both you and I are correct. If you and your rig weigh more than I and my rig do, you will need higher pressure, yes.
The pressure in the tire is not a function of load. The pressure in the tire is a function of how much air is in the tire. The more air (you put) in the tire, the higher the pressure. Since the amount of air does not change when you mount the bike, the pressure does not change. The tire deforms or "drops" slightly where it contacts the road until the area of contact patch on the road multiplied by the tire pressure is equal to the bike weight and rider.
The formulas you quote are based on a 15% drop for 700c tires only. You would know this if you went back to the source of the formula, Berto, who got it from the tire manufacturers. I would expect its accuracy to change as tire size changes.
My experience with pressure in tires is that it does not affect my speed that much on my rides but I am in the city where speed is more of a function of traffic. The pressure does effect comfort.
The part about the world being full of people who believe in crazy things is unfortunately true. I take this tone Abu because it is how you respond to others in these threads.
08-28-18, 07:30 AM
#11
Senior Member
This is mostly wrong. I guess I will be flamed for pointing this out.
The pressure in the tire is not a function of load. The pressure in the tire is a function of how much air is in the tire. The more air (you put) in the tire, the higher the pressure. Since the amount of air does not change when you mount the bike, the pressure does not change. The tire deforms or "drops" slightly where it contacts the road until the area of contact patch on the road multiplied by the tire pressure is equal to the bike weight and rider.
The formulas you quote are based on a 15% drop for 700c tires only. You would know this if you went back to the source of the formula, Berto, who got it from the tire manufacturers. I would expect its accuracy to change as tire size changes.
My experience with pressure in tires is that it does not affect my speed that much on my rides but I am in the city where speed is more of a function of traffic. The pressure does effect comfort.
The part about the world being full of people who believe in crazy things is unfortunately true. I take this tone Abu because it is how you respond to others in these threads.
The pressure in the tire is not a function of load. The pressure in the tire is a function of how much air is in the tire. The more air (you put) in the tire, the higher the pressure. Since the amount of air does not change when you mount the bike, the pressure does not change. The tire deforms or "drops" slightly where it contacts the road until the area of contact patch on the road multiplied by the tire pressure is equal to the bike weight and rider.
The formulas you quote are based on a 15% drop for 700c tires only. You would know this if you went back to the source of the formula, Berto, who got it from the tire manufacturers. I would expect its accuracy to change as tire size changes.
My experience with pressure in tires is that it does not affect my speed that much on my rides but I am in the city where speed is more of a function of traffic. The pressure does effect comfort.
The part about the world being full of people who believe in crazy things is unfortunately true. I take this tone Abu because it is how you respond to others in these threads.
Last edited by Abu Mahendra; 08-28-18 at 10:58 PM.
08-29-18, 02:44 AM
#12
Senior Member
Another example...
I just got a pair of Kenda KWest (45-305) 16x1.75...
What's the min/max pressure on the sidewall? 40/65psi
Now, i suspect these tires have a relatively low weight capacity because they are not rated for higher pressures. If you weigh so much that 65psi is not sufficient pressure, these tires are not for you. I, at 75kg, am at the upper threshold of those tires.
What's the min/max pressure on the sidewall? 40/65psi
Now, i suspect these tires have a relatively low weight capacity because they are not rated for higher pressures. If you weigh so much that 65psi is not sufficient pressure, these tires are not for you. I, at 75kg, am at the upper threshold of those tires.
Last edited by Abu Mahendra; 08-30-18 at 12:27 AM.
08-29-18, 08:14 AM
#13
Schwinnasaur
you are being pedantic. You knew what i meant. Of course, it is the fluid inside the tube that causes the pressure, the molecules bouncing around and pressing outwards in all directions. "The more air (you put) in the tire, the higher the pressure". Really? You don't say...The point, my point was that we cannot talk about the 'correct' pressure without referring to the load weight. I meant pressure is a function of load weight, however much we quibble about sag levels anc egardless of tire volume, in the sense depicted in graphs like the one below in which weight is the independent variable, the input, and pressure is the dependent variable, or the output.
08-29-18, 11:10 AM
#14
Banned
349-32 is the 16" wheel-tire choice if you want to run @ 100 psi ..
rim a good hook clincher ..
rim a good hook clincher ..
08-29-18, 04:28 PM
#15
Senior Member
