Smooth Riding: Upgrading My Bicycle with Slick Tires

[BicycleTree]

I just put slick tires on My Bicycle, my beloved Fuji. It used to have nubby tires. Now the ride is so smooth...

They say that there is not a significant decrease in traction on smooth tires, because the rubber-coated nylon tires actually take on the shape of the pavement pebbles as they roll.

Recommended pressure 90 pounds per square inch! Though they're probably at 70 or so right now.

I want it to stop raining

 

[Danger]

I just put slick tires on My Bicycle, my beloved Fuji. It used to have nubby tires. Now the ride is so smooth...

They say that there is not a significant decrease in traction on smooth tires, because the rubber-coated nylon tires actually take on the shape of the pavement pebbles as they roll.

Take it from an old street racer (and Hypatia can back me on this because she was there)... knobby tires are for traction on rough terrain. (My current vehicle is a 4-wheel drive El Camino with 33 inch Trailblazers, and I can go places that a bulldozer can't.) Slicks, particularly very soft, no-discernable-sidewall slicks, are for maximum traction on dry pavement. For wet, but warm, areas you need something with water-displacement tread design (it essentially squishes the water out the sides so you don't hydroplane). Winter is tougher, between snow or ice traction, but you need a softer compound. Regardless of the tread design, you get more traction with less inflation; but also more torture and shorter life for the tire.

 

[BicycleTree]

So where were you and Hypatia?

Bicycles can't hydroplane because the tires are too skinny and round and the pressure is too high. That's cool about slicks actually having more traction on dry pavement--I didn't know that. They have less rolling resistance.

So "no sidewall" means better traction for cars? I've wondered why some cars have tires like that.

 

[Danger]

So where were you and Hypatia?

Detroit, late '60s-early '70s. She's still there. I was on our side of the border, and left in '78. (If I'd known about her, I wouldn't have left.)

That's cool about slicks actually having more traction on dry pavement--I didn't know that. They have less rolling resistance.

Wrong... they have more. But what they suffer in rolling resistance, they way more than make up for in traction.

So "no sidewall" means better traction for cars? I've wondered why some cars have tires like that.

You're mistaking low-profile tires, like the ones that come stock on a rice-rocket, for racing slicks. A short sidewall like you're thinking of gives better rigidity on curves, and hence less sway, and look a lot better on a car that's the size of model kits that I bought as a kid. Racing slicks are specifically designed to act as not only the car/pavement interface, but also a transmission. They're very soft and very wide (generally 15-20 inches across). The compound is gummier than standard to start with, but they also do a 'burn-out' on a section of track with bleach poured on it. That's when they just smoke the **** out of the tires a couple of times before staging. The reason for doing that is to heat, and therefore soften, the rubber. Soft rubber grabs the pavement better. The special feature of the tires is in the sidewall/tread integration. They start out very short and fat for maximum surface contact (traction) and gearing (small diameter). As the car accelerates, centrifugal force narrows the tire and expands its diameter. Hence less surface contact (rolling resistance) and gearing (large diameter). It's all far more technical than that, and beyond my knowledge, but I'm sure that someone else around here can give you better information.

 

[hypatia]

I love new tires! I even love the smell of them..I know that can sound kind of sick..but I was raised in the Motor city And still sneak in with the street racers at times.
I ride a cannondale bike. Its kind of hybrid/crossover. Ihave road tires on it now{ribbed for my pleasure}, and keep the knobies for ruff land. I don't think I'd ride with pure slicks here..too much road oils and in the summer with our 90% humidity..its like riding on ice.

 

[Danger]

I love new tires! I even love the smell of them..I know that can sound kind of sick..but I was raised in the Motor city And still sneak in with the street racers at times.
in the summer with our 90% humidity..its like riding on ice.

Hi gorgeous; I figured you wouldn't mind me dragging you into this. Kind of sick...? Are you daft, woman? Burning rubber and nitro fumes should be made into an air freshener (or at least an after-shave). And anybody who's ever felt a blown/injected nitro-burning 484 cube elephant rattle their ribcage at 50 feet will buy it by the truckload.
So you've got the humidity down to 90% now, huh? That's 9% better than when I left.
Hey, just out of curiosity... who's on top now? When I left, Steve Lisk's 430 cube hemi T/A Challenger with the Lenco had just displaced Joe Ruggarilo's 505" Mustang II. But Joe had a 600" aluminum Can Am to put into the 'Stang. Is either one of them still in the scene, or has something ever wilder turned up? (Jeez, it's pitiful how much I miss that crap.)

 

[hypatia]

Theirs a whole crop of new young racers, with there souped up hot wheels.{Fast and Furrious} I like cars with some meat on them still. My son and I have a 69 Chevelle with a 350, Its been a joint project for 3 yrs now. Last summer we were pulling high 6's in the 1/4.

 

[BicycleTree]

Wrong... they have more. But what they suffer in rolling resistance, they way more than make up for in traction.

Well, on cars. On bikes, slicks aren't sticky, they are made to be inflated to very high pressure, and heat energy isn't wasted compressing and pushing around any tread nubs. As a result they have a big advantage in rolling resistance (you think they'd use slicks in the Tour de France if they were inefficient?). If you feel them when inflated, they feel like solid rubber. The reduced resistance is noticeable.

You're mistaking low-profile tires, like the ones that come stock on a rice-rocket, for racing slicks. A short sidewall like you're thinking of gives better rigidity on curves, and hence less sway, and look a lot better on a car that's the size of model kits that I bought as a kid. Racing slicks are specifically designed to act as not only the car/pavement interface, but also a transmission. They're very soft and very wide (generally 15-20 inches across). The compound is gummier than standard to start with, but they also do a 'burn-out' on a section of track with bleach poured on it. That's when they just smoke the **** out of the tires a couple of times before staging. The reason for doing that is to heat, and therefore soften, the rubber. Soft rubber grabs the pavement better. The special feature of the tires is in the sidewall/tread integration. They start out very short and fat for maximum surface contact (traction) and gearing (small diameter). As the car accelerates, centrifugal force narrows the tire and expands its diameter. Hence less surface contact (rolling resistance) and gearing (large diameter). It's all far more technical than that, and beyond my knowledge, but I'm sure that someone else around here can give you better information.

Weird.

 

[Danger]

My son and I have a 69 Chevelle with a 350, Its been a joint project for 3 yrs now. Last summer we were pulling high 6's in the 1/4.

Holy sheep ****! I used to just love you for your body! We might have to finish this on PM; my keyboard's getting wet.

 

[BicycleTree]

Hypatia, if you like your bike you should get a regular street bike.

Truth be told, only the front wheel on my bike is a slick right now. The back one doesn't have nubs but it does have a pattern--it has a raised longitudinal ridge for a centerline. They're both smooth though and that's what counts in terms of feel, and mostly for resistance. (They're 27 x 1 1/4 inches, not real ultra-skinny racing tires; roads around here aren't good enough for those anyways)

 

[Danger]

(you think they'd use slicks in the Tour de France if they were inefficient?)

Oooppps! My mistake. I thought that you were referring to a real bike, not one that you have to pedal. I haven't a clue about those things.

 

[BicycleTree]

Well, I did say bicycle in the original post. Besides, bicycles _are_ the real bikes (grandfathered in). Motorcycles are... good god... they suck. Dangerous, loud, SLOW in the city! No exercise, expensive... they sound like flatulence going down the street on two wheels.

 

[Danger]

Well, I did say bicycle in the original post.

Yeah... I saw that when I checked back. By the time we got through the first round of tire talk, I'd forgotten.

Motorcycles are... good god... they suck. Dangerous, loud, SLOW in the city! No exercise, expensive... they sound like flatulence going down the street on two wheels.

And to you this is a bad thing...? 'No exercise'... Cripes, man! The only excercise that I burden myself with is breathing, and if I could hire somebody to do that for me without dropping dead I would. I live by the principle of 'what's a gallon of gas to save a few steps?' And as for the flatulence on wheels, just ask Hypatia about the afterburners on my car...

 

[gnome]

Bicycles can't hydroplane because the tires are too skinny and round and the pressure is too high.

You're probably right about that for rolling straight ahead, but I've seen enough guys (including myself) riding slick 110psi 700x20's go down in turns on wet pavement to suspect that they can hydroplane sideways.

Maybe not so much of a problem with your "fat" 1¼ inchers, but I'd still be careful when it rains.

 

[BicycleTree]

Hmm, I'd have thought it would have been more of a problem with wider tires (more room to trap water). Maybe the book I read it from was misinformed.

The really skinny tires would have longer contact patches even though they have higher pressure, so that might contribute.

 

[Danger]

The really skinny tires would have longer contact patches even though they have higher pressure, so that might contribute.

How do you get that? For any given pressure, the wider the tire, the more surface area in contact with the road.

 

[gnome]

I'd have thought it would have been more of a problem with wider tires

You're right (about the wider tires; not about the "longer contact patches"), as long as the tire is moving forwards. But on a fast turn, as soon as it starts slipping sideways ...

Well, just look at it from the side. If it starts moving that way, it makes no difference how fat or skinny the tire is -- they're all pretty much the same in that direction, except for differences due to tire pressure.

 

[BicycleTree]

Well, what I was thinking about the contact patch is that my tire is about 50% wider than yours and your tire is at about 50% more pressure, and the width counts more than the pressure. Say that the contact patch width is the width of the tire (which it isn't, but say it is), and the contact patch is a rectangle (which it isn't, but say it is). For a 100 lb load, your contact patch is .91 square inches, and since your tire is 4/5 in. wide (assuming the 20 means 20 mm... does it?), 4/5 x = .91 and x (the length) = 1.14 (inches). For mine (at 70 PSI), the contact patch is 1.43 square inches, and the width is 1.25 in., so the length is... um... 1.14 inches.

So it seems there is not much of a difference. But that's the way I was thinking.


Maybe it's not hydroplaning at all. Hydroplaning has to trap water under the tire. I just can't imagine that happening on a 110 PSI tire. It may be just ordinary loss of traction on slippery roads. I don't think that's always due to hydroplaning.

 

[gnome]

Well I don't know if its technically hydroplaning or not.

The way I understand it, hydroplaning happens when you get a sort of "wedge" of water trapped in front of the tire, and then the tire rides up on top of the water. It's not likely to happen to a skinny tire moving straight ahead, but if starts to slip sideways at all, it can "squeegee" the water in that direction & then slip up onto that water. In that direction the width of the tire makes no difference because the length of the contact patches are roughly the same.

Hydroplaning or not, it doesn't feel nice.

 

[Moonbear]

Burning rubber and nitro fumes should be made into an air freshener (or at least an after-shave). And anybody who's ever felt a blown/injected nitro-burning 484 cube elephant rattle their ribcage at 50 feet will buy it by the truckload.

I'm thinking it might be more effective as a woman's perfume. A little dab on the neck and watch the guys line up! I don't think it'll work as well as an aftershave, unless of course you're trying to get rid of a few women.

 

[Danger]

I'm thinking it might be more effective as a woman's perfume. A little dab on the neck and watch the guys line up!

't'would definitely work on me!

I don't think it'll work as well as an aftershave, unless of course you're trying to get rid of a few women.

Hey, I know that it'll work on Hypatia. When you grow up with 120 octane in your blood, there's no getting over it.