Tire recommendations
02-12-18 | 08:36 AM
#26
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They are a fine tire for a gravel / hard pack dirt trail. Enough that I'll keep them and swap them out when I do a long ride on such a surface.
There's a constant 'whhhiiiiizzzzzz' sound from them on the street. And the knobbie tread pattern feels a little slower than it could be.
They aren't awful for pavement. In fact, they are okay. They just could be better.
If the center line of the tread pattern worn down to flat they'd be a much nicer street tire. But I'd rather save the center line tread pattern for when I hit more gravely trails and put something more naturally slick on for commuting.
These $10 specials from Michellin are perfect for me to test out how much I like something with less tread, without having to risk a lot. So I really couldn't be happier with these as for $20 fro the pair I'll at least learn something.
Last edited by Skipjacks; 02-12-18 at 08:51 AM.
02-12-18 | 09:08 AM
#27
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From: Northern Shenandoah Valley
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I have a pair of Schwalbe Little Big Bens that have the same type of "whirr" on smooth pavement (40mm nominal...38mm actual). The center tread pattern is broken enough that it creates that sound. And I'll admit that it's an annoying noise, and the Schwalbes are hanging up on a hook in my shop right now because of it. I have smooth tread Kenda Kwick Tendril tires on that bike and they are whisper silent (but smaller...37mm nominal...33mm actual).
02-12-18 | 09:23 AM
#28
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From: Elmira, NY
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I have stock tires from Giant. I like them OK in dry conditions but wet performance is a problem. I'm looking forward to my next set once I wear these out and can't replace the ones I got and again, they slip too much in wet conditions. So just putting a feeler out to get some ideas for my next set
02-12-18 | 09:24 AM
#29
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02-12-18 | 10:01 AM
#30
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That's not a thing. It's an urban legend.
Proof?
Pick up a bike wheel separated from a bike. (Or any wheel. Or fidget spinner. Anything that spins fast.)
Hold it still.
Now spin it really fast while still holding it. You'll see it didn't get any heavier.
Want a better test? Pick up a high RPM electric motor with a fairy heavy fly wheel. Something that spins REALLY fast. Hold it still, then turn it on. I guarantee you the spinning motor is no heavier.
Why? Because mass is a constant. Things don't get more massive, and thus don't get heavier, due to rotation or speed (at relativistic speeds. If you approach the speed of light, things change a little...but I ride a hybrid so I don't get going quite that fast)
EDIT: Fudge...I went to edit and error and deleted 80% of the post that cite all kinds of examples I don't feel like retyping.
Short version....
Rotational weight is technically a thing. But it's impact on the overall system of the bike is so ridiculously minuscule it's not even worth thinking about. And it ONLY applies to acceleration. (A heavier wheel it harder to get spinning) Once the wheel is spinning, its actually EASIER to KEEP it spinning if it's heavier at the outside of the circle. It's why fidget spinners have weights on the ends of the plastic arms. Take the weights out of a fidget spinner and it stops spinning much sooner.
Why? Because an object in motion stays in motion until acted upon by an opposing force. And the spinning circle that's heavier at its outer edge requires more opposing force to slow it down.
Proof?
Pick up a bike wheel separated from a bike. (Or any wheel. Or fidget spinner. Anything that spins fast.)
Hold it still.
Now spin it really fast while still holding it. You'll see it didn't get any heavier.
Want a better test? Pick up a high RPM electric motor with a fairy heavy fly wheel. Something that spins REALLY fast. Hold it still, then turn it on. I guarantee you the spinning motor is no heavier.
Why? Because mass is a constant. Things don't get more massive, and thus don't get heavier, due to rotation or speed (at relativistic speeds. If you approach the speed of light, things change a little...but I ride a hybrid so I don't get going quite that fast)
EDIT: Fudge...I went to edit and error and deleted 80% of the post that cite all kinds of examples I don't feel like retyping.
Short version....
Rotational weight is technically a thing. But it's impact on the overall system of the bike is so ridiculously minuscule it's not even worth thinking about. And it ONLY applies to acceleration. (A heavier wheel it harder to get spinning) Once the wheel is spinning, its actually EASIER to KEEP it spinning if it's heavier at the outside of the circle. It's why fidget spinners have weights on the ends of the plastic arms. Take the weights out of a fidget spinner and it stops spinning much sooner.
Why? Because an object in motion stays in motion until acted upon by an opposing force. And the spinning circle that's heavier at its outer edge requires more opposing force to slow it down.
Last edited by Skipjacks; 02-12-18 at 10:30 AM.
02-12-18 | 10:07 AM
#31
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From: Montreal, Canada/ Brasilia, Brazil (currently)
Bikes: Giant FCR 3 with lots of mods, Brazilian made Caloi 100.
That's not a thing. It's an urban legend that has no basis in physics.
Proof?
Pick up a bike wheel separated from a bike. (Or any wheel. Or fidget spinner. Anything that spins fast.)
Hold it still.
Now spin it really fast while still holding it. You'll see it didn't get any heavier.
Want a better test? Pick up a high RPM electric motor with a fairy heavy fly wheel. Something that spins REALLY fast. Hold it still, then turn it on. I guarantee you the spinning motor is no heavier.
Why? Because mass is a constant. Things don't get more massive, and thus don't get heavier, due to rotation or speed (at relativistic speeds. If you approach the speed of light, things change a little...but I ride a hybrid so I don't get going quite that fast)
Yes, due to centripetal force the relative weight of the tire IN RELATION TO THE WHEEL ITSELF is greater during rotation. Meaning if you put a little man on a little scale on the inside if your wheel, the scale would show he weighs more when the wheel rotates, BUT ONLY IN RELATION TO THE WHEEL ITSELF. The overall mass of the wheel and the little man didn't increase in relation to the ground, which is all you care about as the bike rider.
Some people will say that means that as the weight of the wheel pushes back and down it increases the weight for the bike. But that same wheel at all times is also pushing up and forward, canceling out the centripetal inertia that pushes down and backwards. Earth's gravity pulls on the entire system at a whole, reducing the 'up' push of the wheel by 1G, and increasing the push 'down' by exactly 1G, meaning the entire system is pulled down by 1G, the same amount Earth pulls EVERYTHING ON IT down.
Is a heavier wheel harder to get moving? Of course it is. The more massive an object, the more force is required to move it. Once it's moving though the heavier wheel is easier to keep moving because it requires more force by all the things that slow you down (air resistance, drag, friction of the road, etc) to stop the more massive object from moving. Real life example: imagine a bike coasting unpowered at 10 mph toward a brick wall. The bike will stop very quick hen it hits the wall. Now imagine a freight train costing upowered at 10mph at the same wall. The brick wall won't even noticeably slow the train down. Both the bike and the train are only moving forward due to their own momentum. But 1 stops instantly. The other barely slows down when hitting the same object.
Heavier things are harder to get moving forward. And they are harder to slow down. But at a constant speed, a heavy object is almost as easy to keep moving at a constant speed than a light object is. Again, the only things that makes the heavy object harder to keep moving forward is the increases friction the extra weight causes by letting Earth pull it down 'harder'. If you take friction out of the equation, a heavy object and a light object will continue to move at the same speed. Think of an astronaut doing a space walk outside the space station. The astronaut is several thousand times less massive that the space station. Both are moving at about 4.71 miles per second as they orbit Earth. If you take the less massive astronaut and put him outside the space station, he'll still move at about 4.71 miles per second just like the space station and both will stay in relative position with each other, neither one falling behind the other because both have the same initial velocity and no friction (to speak of) acting against them.
Back to biking, the extra pound that the Protek tires add to the bike overall will create slightly more friction between the tires and the pavement thus acting harder to slow the system down. But the extra mass of the tires also works in my favor to keep the momentum moving forward to it requires more friction to slow it down. Overall I'd guess the extra friction is higher than the added momentum and it's a net loss for a heavier tire making the Protek's technically slower. (And that's not accounting for the slicker tread pattern reducing the fraction over the rougher pattern of the tires I have now) But I doubt in real word practice that I'd be able to notice the difference caused by that extra pound.
In reality it doesn't matter if that extra pound is in the tires or in a 1lb weight I glued to the top tube.
Proof?
Pick up a bike wheel separated from a bike. (Or any wheel. Or fidget spinner. Anything that spins fast.)
Hold it still.
Now spin it really fast while still holding it. You'll see it didn't get any heavier.
Want a better test? Pick up a high RPM electric motor with a fairy heavy fly wheel. Something that spins REALLY fast. Hold it still, then turn it on. I guarantee you the spinning motor is no heavier.
Why? Because mass is a constant. Things don't get more massive, and thus don't get heavier, due to rotation or speed (at relativistic speeds. If you approach the speed of light, things change a little...but I ride a hybrid so I don't get going quite that fast)
Yes, due to centripetal force the relative weight of the tire IN RELATION TO THE WHEEL ITSELF is greater during rotation. Meaning if you put a little man on a little scale on the inside if your wheel, the scale would show he weighs more when the wheel rotates, BUT ONLY IN RELATION TO THE WHEEL ITSELF. The overall mass of the wheel and the little man didn't increase in relation to the ground, which is all you care about as the bike rider.
Some people will say that means that as the weight of the wheel pushes back and down it increases the weight for the bike. But that same wheel at all times is also pushing up and forward, canceling out the centripetal inertia that pushes down and backwards. Earth's gravity pulls on the entire system at a whole, reducing the 'up' push of the wheel by 1G, and increasing the push 'down' by exactly 1G, meaning the entire system is pulled down by 1G, the same amount Earth pulls EVERYTHING ON IT down.
Is a heavier wheel harder to get moving? Of course it is. The more massive an object, the more force is required to move it. Once it's moving though the heavier wheel is easier to keep moving because it requires more force by all the things that slow you down (air resistance, drag, friction of the road, etc) to stop the more massive object from moving. Real life example: imagine a bike coasting unpowered at 10 mph toward a brick wall. The bike will stop very quick hen it hits the wall. Now imagine a freight train costing upowered at 10mph at the same wall. The brick wall won't even noticeably slow the train down. Both the bike and the train are only moving forward due to their own momentum. But 1 stops instantly. The other barely slows down when hitting the same object.
Heavier things are harder to get moving forward. And they are harder to slow down. But at a constant speed, a heavy object is almost as easy to keep moving at a constant speed than a light object is. Again, the only things that makes the heavy object harder to keep moving forward is the increases friction the extra weight causes by letting Earth pull it down 'harder'. If you take friction out of the equation, a heavy object and a light object will continue to move at the same speed. Think of an astronaut doing a space walk outside the space station. The astronaut is several thousand times less massive that the space station. Both are moving at about 4.71 miles per second as they orbit Earth. If you take the less massive astronaut and put him outside the space station, he'll still move at about 4.71 miles per second just like the space station and both will stay in relative position with each other, neither one falling behind the other because both have the same initial velocity and no friction (to speak of) acting against them.
Back to biking, the extra pound that the Protek tires add to the bike overall will create slightly more friction between the tires and the pavement thus acting harder to slow the system down. But the extra mass of the tires also works in my favor to keep the momentum moving forward to it requires more friction to slow it down. Overall I'd guess the extra friction is higher than the added momentum and it's a net loss for a heavier tire making the Protek's technically slower. (And that's not accounting for the slicker tread pattern reducing the fraction over the rougher pattern of the tires I have now) But I doubt in real word practice that I'd be able to notice the difference caused by that extra pound.
In reality it doesn't matter if that extra pound is in the tires or in a 1lb weight I glued to the top tube.
Edited to say that you already know it. You said it yourself: Is a heavier wheel harder to get moving? Of course it is.
Last edited by andrei_r; 02-12-18 at 10:10 AM.
02-12-18 | 10:29 AM
#32
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Nice physics. Now put a light tire on a bike and go ride. Then put a heavy tire on your bike and go ride. I guarantee it'll feel sluggish. It's all about inertia and acceleration...
Edited to say that you already know it. You said it yourself: Is a heavier wheel harder to get moving? Of course it is.
Edited to say that you already know it. You said it yourself: Is a heavier wheel harder to get moving? Of course it is.
How much do you really accelerate while riding though? Not much.
Yes you speed up and slow down a little as you go. But going from 10mph to 15mph isn't really taxing you. Not nearly as much as going from 0mph to 5mph does. And how often are you stopping completely and restarting? Not much compared to how much you just speed up and slow down over the course of a ride.
So the added 1lb isn't having that much of an impact on you in the normal course of riding. It might impact you when starting off. But that only last a second.
And the 1lb is negligible compared to the 250 lbs of bike, rider, and gear I'm pushing down the road. You're talking a 0.4% increase is the weight of the system.
The worst case scenario that the physics equations show is that adding 1 lb to the tires will have a similar effect on the overall system as adding 2 lbs to anywhere else on the bike. So the impact goes from 0.4% to 0.8% and that's ONLY during acceleration. So increasing your speed from 10mph to 15mph becomes 0.8% harder. And increasing from 10mph to 15 mph isn't really THAT hard.
So the full Newtonian Physics equation is... 0.008 x 'not very hard in the first place' = 'you won't notice the difference'
(that's a legit equation if you consider 'not very hard' and won't notice' to be variable that could have real values assigned to them)
AND! if the heavier tires have a slicker tread pattern that reduces rolling resistance, the heavier tire could negate the increased friction from gravity.
Just because something DOES have a effect doesn't mean you will notice that effect.
If I shoot a BB gun at a freight train, the impact of the BB absolutely positively slows down the freight train. I guarantee it. But the amount it slows the train down is probably not measurable.
If you're racing in the Tour de France that 1lb of weight makes a difference over the course of the race. If you're commuting on your hybrid, it doesn't. Keep in mind that the difference the 1 lb makes in the Tour de France is probably like a minute of lost time over a 21 day race. It might make you lose a race against the best competitors in the world. But it's not making a real difference that you as a rider would notice if you weren't being timed.
Last edited by Skipjacks; 02-12-18 at 10:51 AM.
02-12-18 | 10:51 AM
#33
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Here, this physicist says the same thing using fancy equations. (Edit...oh for pete's sake...red dit without the space is flagged as curse word? Here's the text of his post...)
As a physicist and a bike racer, one of the things that kills me is hearing people talk about 'rotating weight' and giving it much more relevance than it deserves.
I"ll put the TL;DR here:
Yes rotating weight is a real thing, but the effect is so minuscule that it does not matter enough to consider when making any sort of bike related decision. Ever.
In an attempt to keep this short lets go straight to the details: Let's examine a 500g difference on the outer rim of a bike wheel (500g is the diff between a pair of 202's and 404's).
Let's make some assumptions:
The bike+rider+ light wheels weigh 80kg. Bike + rider + heavy wheels will then weigh 80.5 kg. I want to find out how much power it takes to accelerate from 10 m/s to 15 m/s. (22.4mph to 33.6mph) in 10 seconds. Air resistance is tricky so we'll first do it without, just using Power=energy/time (see equations below)
Light wheels: 500 Watts
Heavy wheels: 506.25 Watts
That is a 1.25% difference. Note that the 6W saved by the lighter wheels only matter when you're accelerating, and half of that is from the added total mass. The rotational mass difference means absolutely nothing if you're cruising at speed.
But that's without air resistance.
Factor in air resistance and the argument for rotational mass mattering becomes even weaker. Everyone is different here but I'll make a few more assumptions for simplicity.
Let's say that a rider can cruise at 10 m/s by putting out 250 Watts. If that's true, then it takes 840 W to cruise at 15 m/s. To accelerate from 10 m/s to 15 m/s in ten seconds now takes about1:
Light Wheels = 1340 W
Heavy Wheels= 1346 W
That's a difference of 0.4% To put that in perspective, go up a very steep hill as hard as you can for 10 seconds. Then remove one teaspoon of water from your water bottle. Then do it again. That difference you feel is the same as the difference in 500g of rotating weight during a fast flat acceleration. That's the same difference people claim to be able to notice when they're talking about how one wheelset 'spins up' better than another. Here's a tip: if someone talks about wheels spinning up to try to convince you of something, they are wrong.
None of this even begins to touch on the aerodynamic differences between wheels (which will undoubtedly overshadow the rotating weight difference). It's simply saying that rotating weight is NOT. THAT. IMPORTANT.
Yes if all else is the same than lowering rotating weight will make you faster, but everything comes with a tradeoff or compromise, and if you have to compromise anything else in order to reduce rotating weight, it isn't going to be worth it.
Some equations:
Translational KE = 1/2 m(total)*v2
Rotational KE = 1/2 I*w2
v=w*r
I (of a rim with all of its weight on the edge) = m(rim)*r2
Some substitution gets you: KE(total)= 1/2 V2 *(Mtotal+Mrotational)
1 The actual math here requires and integral which isn't too hard, but also isn't particularly enlightening. The number here is a valid representation of what I'm trying to discuss.
I"ll put the TL;DR here:
Yes rotating weight is a real thing, but the effect is so minuscule that it does not matter enough to consider when making any sort of bike related decision. Ever.
In an attempt to keep this short lets go straight to the details: Let's examine a 500g difference on the outer rim of a bike wheel (500g is the diff between a pair of 202's and 404's).
Let's make some assumptions:
The bike+rider+ light wheels weigh 80kg. Bike + rider + heavy wheels will then weigh 80.5 kg. I want to find out how much power it takes to accelerate from 10 m/s to 15 m/s. (22.4mph to 33.6mph) in 10 seconds. Air resistance is tricky so we'll first do it without, just using Power=energy/time (see equations below)
Light wheels: 500 Watts
Heavy wheels: 506.25 Watts
That is a 1.25% difference. Note that the 6W saved by the lighter wheels only matter when you're accelerating, and half of that is from the added total mass. The rotational mass difference means absolutely nothing if you're cruising at speed.
But that's without air resistance.
Factor in air resistance and the argument for rotational mass mattering becomes even weaker. Everyone is different here but I'll make a few more assumptions for simplicity.
Let's say that a rider can cruise at 10 m/s by putting out 250 Watts. If that's true, then it takes 840 W to cruise at 15 m/s. To accelerate from 10 m/s to 15 m/s in ten seconds now takes about1:
Light Wheels = 1340 W
Heavy Wheels= 1346 W
That's a difference of 0.4% To put that in perspective, go up a very steep hill as hard as you can for 10 seconds. Then remove one teaspoon of water from your water bottle. Then do it again. That difference you feel is the same as the difference in 500g of rotating weight during a fast flat acceleration. That's the same difference people claim to be able to notice when they're talking about how one wheelset 'spins up' better than another. Here's a tip: if someone talks about wheels spinning up to try to convince you of something, they are wrong.
None of this even begins to touch on the aerodynamic differences between wheels (which will undoubtedly overshadow the rotating weight difference). It's simply saying that rotating weight is NOT. THAT. IMPORTANT.
Yes if all else is the same than lowering rotating weight will make you faster, but everything comes with a tradeoff or compromise, and if you have to compromise anything else in order to reduce rotating weight, it isn't going to be worth it.
Some equations:
Translational KE = 1/2 m(total)*v2
Rotational KE = 1/2 I*w2
v=w*r
I (of a rim with all of its weight on the edge) = m(rim)*r2
Some substitution gets you: KE(total)= 1/2 V2 *(Mtotal+Mrotational)
1 The actual math here requires and integral which isn't too hard, but also isn't particularly enlightening. The number here is a valid representation of what I'm trying to discuss.
02-12-18 | 11:07 AM
#34
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02-12-18 | 11:07 AM
#35
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I wish he did the same calculation for a sequence of accelerations from 0 to 15mph like one would experience in stop and go traffic while commuting.
I'm too lazy to do the math but I'm sure the proportion would be bigger than 6/500.
I once had some heavy ass tires and I'm not going back. I know what it feels like to me. I can definitely feel the difference and I enjoy my ride way more with lighter tires.
Last edited by andrei_r; 02-12-18 at 11:11 AM.
02-12-18 | 11:22 AM
#37
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Last edited by andrei_r; 02-12-18 at 11:33 AM.
02-12-18 | 11:31 AM
#38
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As far as YOUR heavy tires that YOU didn't like that one time...that's anecdotal evidence. I believe you that you didn't like them.
But there's so many variables left out there. What was the weight difference? What was the tread pattern difference? What were the riding conditions? How soft or hard was the rubber in each tire? Was it hot or cold? The list goes on....and those are all going to influence the results. And even if everything else was equal in a pure scientific study, it's 1 test based on the impressions of 1 rider subjectively measuring 2 tires. T
02-12-18 | 12:03 PM
#40
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02-12-18 | 12:13 PM
#41
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I think tire weight and "ride quality" are more indirectly linked than directly linked (on a bicycle).
Tire weight and ride quality is much more relevant in an automobile, where a spring and damper have to act against tire mass that moves upward from a bump (if the spring and damper were not there, the tire would keep traveling upward until gravity eventually pulled it back down). From that respect, wheel and tire weight in an automotive situation matters in a way that is not relevant to bicyclists.
That being said, tire materials and construction have a lot to do with ride quality on a bicycle, and it's here where I think weight is only indirectly correlated. A heavier tire is so due to a number of factors, but a leading factor is the presence (or the lack) of a puncture barrier. These are likely getting better all the time, but I think it's generally true that there's a degradation in ride quality. A puncture barrier usually reduces flex and "suppleness" in a tire, and makes it less compliant. Another leading factor in weight is the rubber and casing material. Thick casings (typically with a lower threads-per-inch count) are also generally less supple than thinner casings that may have a higher threads-per-inch count.
Combine an inexpensive tire (with a low TPI) that also has a puncture barrier (like a Bell tire with Kevlar), and you have the recipe for a really "dull" feeling tire. It doesn't feel dull because it weighs more; it weighs more because it has attributes that make it feel dull.
Another factor that influences speed and acceleration that is only indirectly related to weight is the rubber compound. One with a high rolling resistance is generally more likely to be found on inexpensive tires (that also typically weigh more, due to the use of non-exotic materials). More expensive tires, that often use more sophisticated design, material, and construction, that also may tend to weigh less, may also have a more advanced rubber formulation that doesn't consume as much of the rider's power to just push it down the road.
I tend to stay away from heavier tires because I prefer the ride quality that usually comes with lighter tires. I would agree with the notion that mass itself is not terribly relevant, and certainly not to me. I don't ride even close to The Limit to where an additional 1% one way or the other makes any difference. Most of my riding is toodling along with the kids on our way to the park, or down a trail along the Shenandoah or the Potomac.
Tire weight and ride quality is much more relevant in an automobile, where a spring and damper have to act against tire mass that moves upward from a bump (if the spring and damper were not there, the tire would keep traveling upward until gravity eventually pulled it back down). From that respect, wheel and tire weight in an automotive situation matters in a way that is not relevant to bicyclists.
That being said, tire materials and construction have a lot to do with ride quality on a bicycle, and it's here where I think weight is only indirectly correlated. A heavier tire is so due to a number of factors, but a leading factor is the presence (or the lack) of a puncture barrier. These are likely getting better all the time, but I think it's generally true that there's a degradation in ride quality. A puncture barrier usually reduces flex and "suppleness" in a tire, and makes it less compliant. Another leading factor in weight is the rubber and casing material. Thick casings (typically with a lower threads-per-inch count) are also generally less supple than thinner casings that may have a higher threads-per-inch count.
Combine an inexpensive tire (with a low TPI) that also has a puncture barrier (like a Bell tire with Kevlar), and you have the recipe for a really "dull" feeling tire. It doesn't feel dull because it weighs more; it weighs more because it has attributes that make it feel dull.
Another factor that influences speed and acceleration that is only indirectly related to weight is the rubber compound. One with a high rolling resistance is generally more likely to be found on inexpensive tires (that also typically weigh more, due to the use of non-exotic materials). More expensive tires, that often use more sophisticated design, material, and construction, that also may tend to weigh less, may also have a more advanced rubber formulation that doesn't consume as much of the rider's power to just push it down the road.
I tend to stay away from heavier tires because I prefer the ride quality that usually comes with lighter tires. I would agree with the notion that mass itself is not terribly relevant, and certainly not to me. I don't ride even close to The Limit to where an additional 1% one way or the other makes any difference. Most of my riding is toodling along with the kids on our way to the park, or down a trail along the Shenandoah or the Potomac.
02-12-18 | 12:14 PM
#42
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So first, that was very interesting. I agree. I don't often read an entire article online, but that was cool. It really shows how competitive professional cycling is and how the difference between a winner and a 10th place rider isn't very much at that level.
I also get your point about the wattage in real world vs the hypothetical mathematical world. But....the equations in the hypothetical mathematical world are still valid. And they equal "not much difference in energy needed for an extra pound"
Keep in mind that your article is talking about the wattage output for sustained riding. The mathematical hypotheticals were for wattage output during acceleration, which is much higher.
And taking the information in the article back to the equations....the article shows that a 5W output makes the difference between winning and losing a race by seconds.
For me, commuting to work for a couple miles as a fairly leisurely pace, usually before I've finished my coffee.....that 5W of extra output I'd need to take the same route with an extra pound is negligible. I won't notice it. And if I have the same energy output and reduce the pound of weight, it might get me to work 5 seconds faster.
That extra pound, rotational or otherwise, just isn't a real world problem for your average non competitive rider.
Racing is a different story. Every second matters.
I also get your point about the wattage in real world vs the hypothetical mathematical world. But....the equations in the hypothetical mathematical world are still valid. And they equal "not much difference in energy needed for an extra pound"
Keep in mind that your article is talking about the wattage output for sustained riding. The mathematical hypotheticals were for wattage output during acceleration, which is much higher.
And taking the information in the article back to the equations....the article shows that a 5W output makes the difference between winning and losing a race by seconds.
For me, commuting to work for a couple miles as a fairly leisurely pace, usually before I've finished my coffee.....that 5W of extra output I'd need to take the same route with an extra pound is negligible. I won't notice it. And if I have the same energy output and reduce the pound of weight, it might get me to work 5 seconds faster.
That extra pound, rotational or otherwise, just isn't a real world problem for your average non competitive rider.
Racing is a different story. Every second matters.
02-12-18 | 12:21 PM
#43
Senior Member
Joined: Aug 2017
Posts: 2,114
Likes: 239
From: Mid Atlantic / USA
Bikes: 2017 Specialized Crosstrail / 2013 Trek Crossrip Elite
I think tire weight and "ride quality" are more indirectly linked than directly linked (on a bicycle).
Tire weight and ride quality is much more relevant in an automobile, where a spring and damper have to act against tire mass that moves upward from a bump (if the spring and damper were not there, the tire would keep traveling upward until gravity eventually pulled it back down). From that respect, wheel and tire weight in an automotive situation matters in a way that is not relevant to bicyclists.
That being said, tire materials and construction have a lot to do with ride quality on a bicycle, and it's here where I think weight is only indirectly correlated. A heavier tire is so due to a number of factors, but a leading factor is the presence (or the lack) of a puncture barrier. These are likely getting better all the time, but I think it's generally true that there's a degradation in ride quality. A puncture barrier usually reduces flex and "suppleness" in a tire, and makes it less compliant. Another leading factor in weight is the rubber and casing material. Thick casings (typically with a lower threads-per-inch count) are also generally less supple than thinner casings that may have a higher threads-per-inch count.
Combine an inexpensive tire (with a low TPI) that also has a puncture barrier (like a Bell tire with Kevlar), and you have the recipe for a really "dull" feeling tire. It doesn't feel dull because it weighs more; it weighs more because it has attributes that make it feel dull.
Another factor that influences speed and acceleration that is only indirectly related to weight is the rubber compound. One with a high rolling resistance is generally more likely to be found on inexpensive tires (that also typically weigh more, due to the use of non-exotic materials). More expensive tires, that often use more sophisticated design, material, and construction, that also may tend to weigh less, may also have a more advanced rubber formulation that doesn't consume as much of the rider's power to just push it down the road.
I tend to stay away from heavier tires because I prefer the ride quality that usually comes with lighter tires. I would agree with the notion that mass itself is not terribly relevant, and certainly not to me. I don't ride even close to The Limit to where an additional 1% one way or the other makes any difference. Most of my riding is toodling along with the kids on our way to the park, or down a trail along the Shenandoah or the Potomac.
Tire weight and ride quality is much more relevant in an automobile, where a spring and damper have to act against tire mass that moves upward from a bump (if the spring and damper were not there, the tire would keep traveling upward until gravity eventually pulled it back down). From that respect, wheel and tire weight in an automotive situation matters in a way that is not relevant to bicyclists.
That being said, tire materials and construction have a lot to do with ride quality on a bicycle, and it's here where I think weight is only indirectly correlated. A heavier tire is so due to a number of factors, but a leading factor is the presence (or the lack) of a puncture barrier. These are likely getting better all the time, but I think it's generally true that there's a degradation in ride quality. A puncture barrier usually reduces flex and "suppleness" in a tire, and makes it less compliant. Another leading factor in weight is the rubber and casing material. Thick casings (typically with a lower threads-per-inch count) are also generally less supple than thinner casings that may have a higher threads-per-inch count.
Combine an inexpensive tire (with a low TPI) that also has a puncture barrier (like a Bell tire with Kevlar), and you have the recipe for a really "dull" feeling tire. It doesn't feel dull because it weighs more; it weighs more because it has attributes that make it feel dull.
Another factor that influences speed and acceleration that is only indirectly related to weight is the rubber compound. One with a high rolling resistance is generally more likely to be found on inexpensive tires (that also typically weigh more, due to the use of non-exotic materials). More expensive tires, that often use more sophisticated design, material, and construction, that also may tend to weigh less, may also have a more advanced rubber formulation that doesn't consume as much of the rider's power to just push it down the road.
I tend to stay away from heavier tires because I prefer the ride quality that usually comes with lighter tires. I would agree with the notion that mass itself is not terribly relevant, and certainly not to me. I don't ride even close to The Limit to where an additional 1% one way or the other makes any difference. Most of my riding is toodling along with the kids on our way to the park, or down a trail along the Shenandoah or the Potomac.
If I got a $100 tire with the same tread as a $10 tire, but the $100 tire was 50% more comfortable to ride (150 comfort units vs 100 comfort units)...I'd hate it.
I'd be much happier on the $10 tire knowing that it's 66% as comfortable (100 comfort units vs 150 comfort units) for 90% less cost. Every bump I felt on the $10 tire would feel like happy dollar signs.
There's a lower limit to that. The $1 tire than had "20 comfort units" and was miserable to ride isn't worth the savings over the $10 tire. But the $10 tie is worth the savings over the $100 tire.
Yes. I made up my own unit of measure can called if comfort units. I'm going to call Continental and see if they want to buy my awesome idea. Patent pending.
02-12-18 | 01:22 PM
#44
Senior Member
Joined: Sep 2017
Posts: 148
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From: Connecticut
Bikes: 2000 Trek 720 Multitrack (plus)
True, the math works out the same. It doesn't matter how much the rider/bike weigh or the initial speed, the extra weight will take exactly the same watts to accelerate whether you start from 0 or 22.4mph. 6 watts may only be 0.4% for a sprinter but it's 3% for a rider who only puts out 200W.
02-12-18 | 01:56 PM
#45
Senior Member
Joined: Sep 2015
Posts: 720
Likes: 181
From: /dev/null
Bikes: Soma Double Cross Disc (2017), Surly DT (2023)
Assuming the bike is moving straight, the kinetic energy of the rider is 1/2 * rider_mass * velocity^2, and it is solely the energy of the forward movement. This is not the case with the wheel. The kinetic energy of the wheel = kinetic energy of the forward motion + kinetic energy of the rotational motion. For the tire rotational kinetic energy equals the kinetic energy of the forward motion. Adding 1lb of weight to the tire has the same effect on acceleration as adding 2lb of weight to the rider (water bottle, saddle bag, ...). The hubs have a small radius compared to the tire, and their rotational kinetic energy is negligible compared to the kinetic energy of their forward motion. Adding 1lb to the hub equals adding 1lb to the rider. Mathematically this effect can be quantified using the moment of inertia.I think there is another reason why heavy tires feel sluggish: they are thicker, and more energy is lost when constantly deforming them. This results in a higher rolling resistance.
Not sure about the grip when wet, but I like Vittoria Voyager Hypers that people recommended to me here. I also have 42mm Soma Supple Vitesse (very light, similar to Compass, but cheaper), they are excellent. Also Paselas, but I have not tried them yet.
02-12-18 | 02:01 PM
#46
Senior Member
Joined: Feb 2017
Posts: 4,244
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From: Northern Shenandoah Valley
Bikes: More bikes than riders
02-12-18 | 02:13 PM
#47
Senior Member
Joined: Aug 2017
Posts: 2,114
Likes: 239
From: Mid Atlantic / USA
Bikes: 2017 Specialized Crosstrail / 2013 Trek Crossrip Elite
02-12-18 | 02:36 PM
#48
Senior Member
Joined: Feb 2017
Posts: 4,244
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From: Northern Shenandoah Valley
Bikes: More bikes than riders
I'm with you on the index, though. Which is why the Continental Speed Rides hit it just right for me. They ride super plush, are a great size (38mm actual) with a nice round profile, are foldable, and are silly cheap for the performance you get (about 20-25 bucks each). Definitely not good cross-country touring tires, without that puncture layer, but I could definitely feel the difference in comfort between them and the Schwalbe Little Big Bens (which aren't even super durable tires like Marathons). The Contis are just plush. Only 430 grams for the weight weenies, too. 
My dream tire would be Michelin's Country Rock in a 40-622 or something similar. I have a set in 44-559 (26x1.75") and they're just excellent tires. Soft and compliant, with a nice tread pattern, and not too expensive. Only 560 grams or something like it for the 44-559 size, so they'd probably weigh about the same in a 40-622.
My dream tire would be Michelin's Country Rock in a 40-622 or something similar. I have a set in 44-559 (26x1.75") and they're just excellent tires. Soft and compliant, with a nice tread pattern, and not too expensive. Only 560 grams or something like it for the 44-559 size, so they'd probably weigh about the same in a 40-622.
02-19-18 | 02:29 PM
#49
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Joined: Aug 2017
Posts: 2,114
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From: Mid Atlantic / USA
Bikes: 2017 Specialized Crosstrail / 2013 Trek Crossrip Elite
let me know how you like them. I've been very happy with them. the big ones run a little wider than advertised at max pressure & they say that right up front. the 28 (gone) & 32mm models should be true to advertised width
took another look at biketiresdirect, looks like that is a daily special. I paid $20.49 ea last year for the 40mm model
what size did you get?
took another look at biketiresdirect, looks like that is a daily special. I paid $20.49 ea last year for the 40mm model
what size did you get?
I went with 35's. They definitely run about 37mm in real life, just like the website said. They are much more rounded than the Trigger Sports that came with the bike, which had a less severe curve to the tread pattern. Great for traction in muck and ride comfort, bad for speed and efficiency. So they don't fill out the fenders as much, but they fit inside them just fine which is all that matters.
So we'll see how the Michelin's do. I'm not expecting these to turn a Yugo in a Ferrari. But I do expect a noticeable ride difference.
I'll let you know in the morning.
02-19-18 | 02:42 PM
#50
Senior Member
Joined: Jul 2008
Posts: 30,497
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From: 25 miles northwest of Boston
Bikes: Bottecchia Sprint, GT Timberline 29r, Marin Muirwoods 29er, Trek FX Alpha 7.0
