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The track of a bicycle back tire [pdf]

tlakoba.w3.uvm.edu

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Re: The track of a bicycle back tire [pdf]

#61

Post by anthomtb »

matsemann wrote: post #35
fluoridation wrote: post #24

Earlier quoted context omitted.

How does that work? I don't see any way that just turning the bars would imprint forward momentum.

By "pumping" it's quite easy: https://www.youtube.com/watch?v=5tVlAlZ9wfM You can to some extent do it without that much motion as well. Basically, you're "falling" to one side and getting momentum, and then you "save" the fall by twisting back getting the bike under you, and that instead puts the momentum forward.

I would like to add that you are not just "turning the handlebars" - you need to apply a lot of force to get the forward action to take place.

Pumping is fun skill, easy to get the hang of with a little dedicated practice, and a prerequisite for BMX racing or any advanced MTB riding. Its also extremely inefficient for forward motion. You don't see any TDF guys using pump motion unless they're saving a crash.

Re: The track of a bicycle back tire [pdf]

#62

Post by Moru »

fluoridation wrote: post #24
Moru wrote: post #18

Earlier quoted context omitted.

It depends on how you use the bike. When I was a kid I used to turn the front wheel left/right to go forward instead of using the pedals. This ofcourse wore out the front tire realy fast :-)

How does that work? I don't see any way that just turning the bars would imprint forward momentum.

It was 40 years ago, what I remember it works but not very good. As they say lower down, you need more movement to actually get any sort of speed forward. It was just something I liked doing while waiting for someone to show up.

Re: The track of a bicycle back tire [pdf]

#63

Post by doubled112 »

newsclues wrote: post #54
doubled112 wrote: post #29

Earlier quoted context omitted.

I don't even have a rear brake. Weight is transferred to the front on heavy braking, and if you have proper technique, you will not go over the bars. The front tire does all of the actual stopping.

If you don't have a rear brake, perhaps listen to people who have front and rear brakes, and thousands of kilometres of riding. I have literally seen people flip over their handle bars by solely using their front brake going downhill.

I have done thousands of KMs of riding.

Re: The track of a bicycle back tire [pdf]

#64

Post by JohnFen »

snozolli wrote: post #41
doubled112 wrote: post #29

Earlier quoted context omitted.

I don't even have a rear brake. Weight is transferred to the front on heavy braking, and if you have proper technique, you will not go over the bars. The front tire does all of the actual stopping.

The rear brake is very important for initial braking, in order to transfer weight to the front, which allows harder braking without locking up the front tire. When you initially hit the brakes, your braking potential is split around 50:50. At absolute maximum potential braking force, your rear tire is near lifting, so it's around 100:0. That said, if you only have one brake, it's better to have it on the front than t…

Interesting. I have to replace the shoes on my rear brakes about 10 times more often than my front brakes.

But then, if I'm not going very fast, I only use my rear brake. That might explain it.

Re: The track of a bicycle back tire [pdf]

#65

Post by matsemann »

toast0 wrote: post #49
kiliantics wrote: post #42

Earlier quoted context omitted.

There's really no question. Cost of bike maintenance vs car maintenance. Societal cost of road wear due to a huge car vs a tiny bike. Burden on healthcare system, regulation and enforcement for dangerous driving habits. We all pay so much for cars, even when not driving one, when usually a bicycle is perfectly sufficient.

maintenance and road wear are clear winners for bikes being cheaper. Healthcare burden, I'm not so sure. Even with the massive difference in usage, street car tracks in Seattle cause a lot more healthcare burden to bikers (and pedestrians) than car drivers. There's certainly a benefit from exercise, but bicycling also has more exposure to injury during use, and not all of them are superficial injuries. Add in things…

Thousands are dying directly from car usage ("accidents"). A lot more indirectly from being sedentary, and lots of shortened life spans due to the pollution.

So it's not even comparable. It's probably multiple orders of magnitude better on a societal level to be biking. Even better if we got rid of the cars causing the cyclists to be killed.

Re: The track of a bicycle back tire [pdf]

#66

Post by OffensiveIdiom »

navane wrote: post #4
Someone wrote: post #2

FTA: Can we verify the folklore that on a long bike trip the back-tire wear is less than that of the front tire? I’ve never heard that folklore. I thought ‘everybody’ knew back-tires wear out a lot faster because the load on them is higher and because they’re the one being powered. https://www.sheldonbrown.com/tire-rotation.html : “It is common for a front tire to outlast a rear tire by as much as three to one. Rear…

From my experience, front tires only wear of age, not use. Backtires experience (frictional) shear forces, pushing along the earth. This erodes the surface.

This has been my experience as well. The back tire gets worn down and the front tire lasts until the rubber starts cracking from age.

Re: The track of a bicycle back tire [pdf]

#67

Post by toast0 »

matsemann wrote: post #65
toast0 wrote: post #49

Earlier quoted context omitted.

maintenance and road wear are clear winners for bikes being cheaper. Healthcare burden, I'm not so sure. Even with the massive difference in usage, street car tracks in Seattle cause a lot more healthcare burden to bikers (and pedestrians) than car drivers. There's certainly a benefit from exercise, but bicycling also has more exposure to injury during use, and not all of them are superficial injuries. Add in things…

Thousands are dying directly from car usage ("accidents"). A lot more indirectly from being sedentary, and lots of shortened life spans due to the pollution. So it's not even comparable. It's probably multiple orders of magnitude better on a societal level to be biking. Even better if we got rid of the cars causing the cyclists to be killed.

There were apparently 454 non-traffic bicycle deaths in 2020[1], compared to 38,824 traffic deaths reported by NHTSA in 2020 [2]. I don't feel like bicycles are doing 1% of the trips in the US, even though they're more than 1% of the deaths. I feel like non-traffic death eliminates car vs bike deaths, but captures the basic idea that bicycles are more immediately risky.

All sorts of terrain issues that are minor for a car are dangerous for a bicycle, especially at higher speeds. Where I live, it's very hilly, so it's hard to go anywhere on a bike without hitting speeds of at least 25 mph at some point on the journey. Mechanical issues, unexpected objects in the road, or errors in piloting at that speed will result in an injury for sure.

[1] https://injuryfacts.nsc.org/home-and-community/safety-topics...

[2] https://www.nhtsa.gov/press-releases/2020-traffic-crash-data...

Re: The track of a bicycle back tire [pdf]

#68

Post by newsclues »

doubled112 wrote: post #63
newsclues wrote: post #54

Earlier quoted context omitted.

If you don't have a rear brake, perhaps listen to people who have front and rear brakes, and thousands of kilometres of riding. I have literally seen people flip over their handle bars by solely using their front brake going downhill.

I have done thousands of KMs of riding.

Cool, I've done thousands in a month. Do thousands every year.

But if your bike doesn't have two brakes as you have stated, it doesn't matter how many KMs you ride, because you are not getting that experience to inform you.

Re: The track of a bicycle back tire [pdf]

#70

Post by jackvalentine »

JohnFen wrote: post #64
snozolli wrote: post #41

Earlier quoted context omitted.

The rear brake is very important for initial braking, in order to transfer weight to the front, which allows harder braking without locking up the front tire. When you initially hit the brakes, your braking potential is split around 50:50. At absolute maximum potential braking force, your rear tire is near lifting, so it's around 100:0. That said, if you only have one brake, it's better to have it on the front than t…

Interesting. I have to replace the shoes on my rear brakes about 10 times more often than my front brakes. But then, if I'm not going very fast, I only use my rear brake. That might explain it.

Do you ‘ride the brake’ to control your speed a lot?
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