Myths about tires (part 1)

[Hillhater]

Pure NITROGEN is used in race car tyres for one primary purpose......less pressure variation with temperature changes .!
This is due to the elimination of WATER VAPOUR in the Nitrogen as a result of its production process.
Water vapour in normal compressed air can result in significant pressure changes, ....unwanted in race cars and Moto’s etc
Other suggestions regarding leakage rate, oxidation, etc, may /may not be real , but are irrelevent and not considered in practice.
I assume most folk know that air is 80% Nitrogen anyway.....and much more practical for normal everyday use on cars and cycles.

 

[speedmd]

Agree, Dryness is key. Here's a chart depicting why N2 vs undried air is more important in race circles.

 

[Chalo]

Agree, Dryness is key. Here's a chart depicting why N2 vs undried air is more important in race circles.

I'd be very surprised if anybody here gets their e-bike tires up into the temperature range where those curves diverge significantly. Maybe Dogman Dan in the New Mexico desert summer, but surely he wouldn't be pumping in moist air to begin with.

 

[99t4]

Looks like we are coming to the conclusion that nitrogen is not that beneficial for our bicycle tires (tubes?).

Thanks for the tip about Schwalbe innertubes. I have been getting good results from the Specialized tubes recently but will try the Schwalbe next.

When do we get to part 2?

 

[ebike4healthandfitness]

The extra tire weight is much worse than rider or bike weight for braking and performance efficiency. That is because the rotating mass has a strong momentum, making a high resistance to change speed and orientation. A 12 lbs motorcycle tire does require a lot of energy to accelerate and brake, and it has a strong resistance to change trajectory when the tire is an important percentage of the total weight especially.

I've never heard of rotational inertia being considered a strong force in braking or acceleration of a bicycle.

How do you know this extra braking distance isn't the result of increased total weight and decreased rolling resistance?

 

[E-HP]

The extra tire weight is much worse than rider or bike weight for braking and performance efficiency. That is because the rotating mass has a strong momentum, making a high resistance to change speed and orientation. A 12 lbs motorcycle tire does require a lot of energy to accelerate and brake, and it has a strong resistance to change trajectory when the tire is an important percentage of the total weight especially.

I've never heard of rotational inertia being considered a strong force in braking or acceleration of a bicycle.

Have you ever taken a science class?

 

[Chalo]

I've never heard of rotational inertia being considered a strong force in braking or acceleration of a bicycle.

Mass at the perimeter of a wheel takes twice as much energy to accelerate to a given road speed as the same amount of non-rotating mass elsewhere on the bike. So a 9 pound moto tire takes about as much energy to accelerate as an 18 pound battery pack (actually a little less because all the tire's mass isn't at the outer perimeter).

 

[ebike4healthandfitness]

I've never heard of rotational inertia being considered a strong force in braking or acceleration of a bicycle.

Mass at the perimeter of a wheel takes twice as much energy to accelerate to a given road speed as the same amount of non-rotating mass elsewhere on the bike. So a 9 pound moto tire takes about as much energy to accelerate as an 18 pound battery pack (actually a little less because all the tire's mass isn't at the outer perimeter).

That is not a strong force and would hardly make any difference in the amount of extra brakes needed.

 

[Chalo]

I've never heard of rotational inertia being considered a strong force in braking or acceleration of a bicycle.

Mass at the perimeter of a wheel takes twice as much energy to accelerate to a given road speed as the same amount of non-rotating mass elsewhere on the bike. So a 9 pound moto tire takes about as much energy to accelerate as an 18 pound battery pack (actually a little less because all the tire's mass isn't at the outer perimeter).

That is not a strong force and would hardly make any difference in the amount of extra brakes needed.

That's your subjective judgment, but the objective fact is two such tires would add about 13% to the total inertia of a 275 pound bike and rider system. Nobody wants to give up 13% of their acceleration or braking performance for no reason.

 

[DogDipstick]

I'd be very surprised if anybody here gets their e-bike tires up into the temperature range where those curves diverge significantly. Maybe Dogman Dan in the New Mexico desert summer, but surely he wouldn't be pumping in moist air to begin with.

Lol betcha I can. I got pics of the tires well over 120*... 130ish* even not that hot of a day. 140* should be no prob, on the rear at least. Up hilll. Pavement. Thermal images... . But yeah kWs.


In this pic the rear tire is nearing 120*. I think its like.. right at 2x the weight of a 26" bicycle rim.





This is a cool thread. Imma keep reading.

I've never heard of rotational inertia being considered a strong force in braking or acceleration of a bicycle.

Oh heck yeah they do. Motorcycle design has known this since the first racing rotors and mag wheels.

 

[ebike4healthandfitness]

I've never heard of rotational inertia being considered a strong force in braking or acceleration of a bicycle.

Mass at the perimeter of a wheel takes twice as much energy to accelerate to a given road speed as the same amount of non-rotating mass elsewhere on the bike. So a 9 pound moto tire takes about as much energy to accelerate as an 18 pound battery pack (actually a little less because all the tire's mass isn't at the outer perimeter).

That is not a strong force and would hardly make any difference in the amount of extra brakes needed.

That's your subjective judgment, but the objective fact is two such tires would add about 13% to the total inertia of a 275 pound bike and rider system. Nobody wants to give up 13% of their acceleration or braking performance for no reason.

It only works out to be 6.1% more inertia than 18 pounds added to the frame.

That is not very much at all for such an extreme example being applied to both tires.

And this percent shrinks even more as combined rider-bike weight increases.

But you know what really increases the need for bigger brakes? Speed. MadRhino is claiming 60 to 70 mph for builds. Just going 60 mph is going to be 4 times the total kinetic energy of a 30 mph moped. That is 300% more kinetic kinetic energy. 70 mph would be 5.4 times the kinetic energy of 30 mph...
or 440% more kinetic energy.

 

[E-HP]

It only works out to be 6.1% more inertia than 18 pounds added to the frame.

That is not very much at for such an extreme example being applied to both tires.

And this percent shrinks even more as combined rider-bike weight increases.

But you know what really increases the need for bigger brakes? Speed. Mad Rhino is claiming 60 to 70 mph for builds. Just going 60 mph is going to be 4 times the total kinetic energy of a 30 mph moped. That is 300% more kinetic kinetic energy. 70 mph would be 5.4 times the kinetic energy of 30 mph...
or 440% more kinetic energy.

You could try a very simple experiment like they do in science class to convince yourself.

Even though ebikes are usually faster than this, use this lower speed scenario for safety purposes:

Get a very light weight bicycle wheel and rim and mount it on your bike. Spin the wheel up to roughly 20 mph or 250rpm for a 26" wheel. Quickly push your hand in between the spokes to stop the wheel.

Now, mount a 2.5 lb tire and tube on the rim. Repeat the steps above. Report back when they remove the cast.

 

[Chalo]

That's your subjective judgment, but the objective fact is two such tires would add about 13% to the total inertia of a 275 pound bike and rider system. Nobody wants to give up 13% of their acceleration or braking performance for no reason.

It only works out to be 6.1% more inertia than 18 pounds added to the frame.

Sure, but it's inertia that mostly doesn't need to be there. It's 13% more than if it weren't there.

Also remember a 9 pound moto tire mounts on a 5 to 10 pound rim. If you use bicycle parts, it's a 1/2 to 2-1/2 pound tire on a 2/3 to 2 pound rim. The difference is bigger than the example I used, which only accounted for the tire.

 

[ebike4healthandfitness]

That's your subjective judgment, but the objective fact is two such tires would add about 13% to the total inertia of a 275 pound bike and rider system. Nobody wants to give up 13% of their acceleration or braking performance for no reason.

It only works out to be 6.1% more inertia than 18 pounds added to the frame.

Sure, but it's inertia that mostly doesn't need to be there. It's 13% more than if it weren't there.

Also remember a 9 pound moto tire mounts on a 5 to 10 pound rim. If you use bicycle parts, it's a 1/2 to 2-1/2 pound tire on a 2/3 to 2 pound rim. The difference is bigger than the example I used, which only accounted for the tire.

You are putting me to sleep now.

 

[MadRhino]

That is not a strong force and would hardly make any difference in the amount of extra brakes needed.

It does make a big difference in the energy required to accelerate, stop, and change orientation.

The heavier it is, the larger it is, and the faster it does spin; the stronger the force it will deploy to resist a change. If you’d be in my shop saying inertia is not a strong force, I would only need to hand you a spinning wheel to close the discussion. It is the fundamental nature of every object in this world to find rotational stability, and to resist desperately to give up the stability that it had attained. Inertia is strong enough to shape the universe.

Please note that, if you believe that the earth is flat, none of this does apply to you.

[youtube]iaauRiRX4do[/youtube]

 

[ZeroEm]

Don't forget they use large spinning disc's to store energy, lots of energy!

 

[Chalo]

You are putting me to sleep now.

That's what happens when you wander way out of your depth. Better drop this course and register for the remedial one.

 

[DogDipstick]

Also remember a 9 pound moto tire mounts on a 5 to 10 pound rim. If you use bicycle parts, it's a 1/2 to 2-1/2 pound tire on a 2/3 to 2 pound rim. The difference is bigger than the example I used, which only accounted for the tire.

Not all moto rims are that heavy. I dont thing the rim on my 170hp Ninja was nine pounds. Lol. Def not my bike. Who would put a ten pound rim on a bicycle. Moto rim on my bike is like 7.5lbs or something. Rotor to treads. Axle included. Its not much heavier than a bicycle rim mass.

Yeah put it that way, if you had to brake 20 lbs of rim with 9 pounds of tire each.. Lol. 40lbs rotating on a bicycle? Hey my motor wheel is heavy enough with its 17 lb motor.

Moto rims are not that heavy. They are not "14-19 lbs".. Like I said at least mine is not. From the experience I have.

 

[markz]

I have two motorcycle rims I bought used, cut the spokes and threw out the hub, the rim itself is not heavy. I could weigh it, ones 19" anothers 21" had plans to install but I am not having any problems with a front hub setup and no plans to go back to a rear hub anytime soon.

Be easy enough to find the weight online wouldnt it?
Lemme tingle my Goo Google Juice
https://www.denniskirk.com/moose/red-front-spoked-1-60-x-21-rim-0210-0361.p5504469.prd/5504469.sku
Weight 2.00 lbs

https://www.denniskirk.com/irc/front-rear-nr73-90-90p-14-blackwall-tire-t10272.p543894.prd/543894.sku
21" 90/90 tire is 6lbs

 

[Chalo]

I have two motorcycle rims I bought used, cut the spokes and threw out the hub, the rim itself is not heavy. I could weigh it, ones 19" anothers 21" had plans to install but I am not having any problems with a front hub setup and no plans to go back to a rear hub anytime soon.

Be easy enough to find the weight online wouldnt it?
Lemme tingle my Goo Google Juice
https://www.denniskirk.com/moose/red-front-spoked-1-60-x-21-rim-0210-0361.p5504469.prd/5504469.sku
Weight 2.00 lbs

https://www.denniskirk.com/irc/front-rear-nr73-90-90p-14-blackwall-tire-t10272.p543894.prd/543894.sku
21" 90/90 tire is 6lbs

Homeboy is constantly recommending a 3.50-17 tire to substitute for a 24" freestyle tire. That implies a ~10 pound tire on a 5-10 pound rim. If you dispute that, find me a contrary example. A 1.60-21 rim ain't it.

 

[markz]

100/90 or 110/90 is 3.50 is going to be a real heavy mofo!

Motorcycle/Moped components isn't the vast majority of peoples priority, only the select few.

About the closest I can find with my laziness and level of caring tonight. 110/90-18 not 17
https://www.denniskirk.com/shinko/230-tour-master-tire.pfp544683.prdf?fs=544697

Weight 11.80 lbs

Times by two, then add in the tires and tubes..... it all adds up.

To each their own, I think most people aren't going to go into the realm of motorcycle or moped rims and tires, just those who are having problems like countless flats and they've tried it all, or those who require speed. Since I switched things up, doing bicycle stuff went from rear hub to front, my spoke breaking and flats have dramatically reduced. I like front hubs, but I dont ride fast, I ride courteously with everyone else's safety in mind at all times no matter how stupid those other people are using the same pathways as me. Last incident a day ago (didnt ride today) was a dog owner with 30' of leash, all to common. Zig zagging walkers, full path width blockers, and the most fun of all are the startled jumpers, and protective dogs lashing out at the ebike electrical hum.

I can only speak for myself, I have ridden a motorcycle rim and knobby dirtbike tire about the same 3.50 size in 19" and it was a heavy mofo, then add to that a hub motor in the front and it was a real bitch to lift up or pop curbs. I did the same with a rear hub motor setup but moped tire which I liked again in 19" x 2.75, problem with the rear for me was never the weight but the smaller diameter wheel that came close to the V-brake mounts.

 

[ebike4healthandfitness]

100/90 or 110/90 is 3.50 is going to be a real heavy mofo!

Motorcycle/Moped components isn't the vast majority of peoples priority, only the select few.

About the closest I can find with my laziness and level of caring tonight. 110/90-18 not 17
https://www.denniskirk.com/shinko/230-tour-master-tire.pfp544683.prdf?fs=544697

Weight 11.80 lbs

A 110 section tire is 4.4" wide, not 3.5" wide. It even says 4.29" inflated width in the specs part of that listing. Also notice it has a speed rating of 149 mph and a load rating of 551 pounds. So that example is way off for what would be used on a moped.

 

[markz]

Yeah I just went on the first site I saw
https://www.weeksmotorcycle.com/tire-size-conversion-chart.html#gsc.tab=0
first box, front.
plus the tire was 2.50 rim width


So could be a wide range of heavy lbs # for anynumber of variables for the select few that want to rock n roll to the dark side aka motorcycle/moped components.

 

[DogDipstick]

100/90 or 110/90 is 3.50 is go~

A 110 section tire is 4.4" ~

I certainly agree..... my ~70mph rated tire is appropriate for our level of application load. It is about 2 lbs, DOT rated and name brand. 4 ply.

Every argument is viable if you make uyp the numbers to suit the argument. I will go weigh a moped tire in 2.75 rightnow, or take a temperature reading on a tire @ 140* right now, and my moped rim/combo is much lighter than the opinion of others on this thread, even if i ahve empirical experience, with the weight of the rims. I specifically try to make them light.. For sure. Ihave held all the Shinkos, I have held Metzeller in 100/100-19, I have put them on 60mph plus bikes, I know how much they weigh, I even know how much the chrome adds in extra. If the rim is chrome.

I will never use a steel rim on an ebike, but an aluminum 1.4" x 19" rim is very light in my pinion, even though long time posts say it is not.

Interesting thing about a wheel is the tire moves zero (0) (velocity) at its contact patch, but the relative velocity of the tire doubles in one RPM. Then back to zero, every RPM.

 

[litespeed]

For me, moto rims and tires win hands down simply because they work. Shinko 241’s are just amazing on my 125 lbs “17 KW 65+ mph bicycle!” I’m a pretty smart person and know that the rotational inertia is higher which does slow my acceleration/braking but, and I mean a huge “I like big butts” but, ( I actually do not like actual big butts by the way!!!!) the traction, sure footed feeling, longevity, flat resistance and over all feeling out weighs (pun intended! ) the parasitic losses in my opinion. Even when I was running 14kw on a maxed out MaxE running a 3.0 26” Minion down hill (was supposed to be the best at the time but tried a few others with same results!) bicycle tire I could never keep the front end planted in a hard turn with power. On street the knobs were too little, too soft and on trail not enough grip. I had too much power and made the front end too light. Grab too much front brake and the front end would wash………But, even with my 19 x 1.6 rim with a Shinko 241 2.75 the front end comes up with a flick of the right hand but has grip for days on street or trail. Believe it or not but I’m faster through the corners and trails with the heavier tire. Your results may be different but mine are as stated! How many times have I had a flat tire on bicycle tires…..more than I care to admit. Had more than my fair share of walk of shames! Granted now there are thicker tubes, slimey shit to fill them up with, extra tube protectors, blah, blah blah that I have not tried but I feel no need to. I don’t need them with my Shinko tires….nor do I need or carry a patch kit…..never did on my motorcycle either.

While many may be faster my bike will do 0 to 60 mph in 10 seconds. With a 220 mm front disk/MT5e I can do a stoppie (I’m not good at it and it scares the shit out of me when the rear end comes up…..just compressing the 7+ inch front fork will get you clinched up tight enough to turn a piece of coal into a diamond of really good quality! ) and can lock up the rear brake at any speed with a 203 mm/Hayes Stroker Ace with 2 fingers. While I’m sure a lighter set up could do it faster or better, I don’t feel I’m giving up much.

So I’m 6’-4” and 220 fit lbs. I have a dirt bike background my whole life. Even having the best motor bikes available there were always compromises that had to be made and on my ebike this is the one I have made. Since I have a QS 205 V3 hub motor ebike with the motorcycle tires I am able to run at lower PSI which helps mask the weight of it. Compared to bicycle tires I have had to run at higher pressures to keep from pinch flatting is night and day. The chatter from small trail imperfections even with 10” of wheel travel is enough to sterilize the most vibrant man out there. The motorcycle tire is like gliding on a cloud. So is this for everyone? Maybe not but for me there is no other way. If I was just doing this or that, looking for the utmost performance or racing the bike my compromises may be different. For my all purpose, jack of all trades, do it all crazy powerful always ready to go, non tire repair kit carrying black beauty motorcycle rims and tires are the way to a better ride. <mic drop>

Tom