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Old 09-06-07, 12:25 AM   #1
elai
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Being Fast (as a city car)

I know if I get a decent road bicycle I can go a consistent 50km/h (30mph) without too much effort. (Something that would remove a major advantage of a car for me). My worry is how safe is going that fast. Does anyone else go that speed here consistently? Can you properly brake and maneuver in that speed bracket? Do you have way more close calls then you did before when you bicycled at more typical speeds of 20/30kmh? Does bicycling in that speed bracket push up the fatality/injury rate to that of a motorcycle?
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Old 09-06-07, 02:34 AM   #2
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On Monday I went to see a bike race in SF. Afterwards I went against the wind as hard as I could for about 2 miles... a single-speed mind you. Turned around and had a sweet tail wind. Then a car, then a curb, now a new wheel set. Just be careful.

I've rear ended cars in the city because I have slicks on my bike. Stopping isn't exactly the high point for the thing, and drivers are ******** (Neither driver noticed... I think). Again, be careful.
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Old 09-06-07, 03:53 AM   #3
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30MPH without too much effort?? You're only talking about the downhill part, right? Normal sustained speed for me is definitely less than 20MPH.

Anything 30MPH plus I usually worry a lot about being able to brake effectively. Even if you think you can read the traffic remember that dogs, cats, skateboards, etc can come at you from any direction without warning.
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Old 09-06-07, 03:59 AM   #4
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I know if I get a decent road bicycle I can go a consistent 50km/h (30mph) without too much effort.
Well I for one am impressed. What are you riding now? How fast?

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My worry is how safe is going that fast. Does anyone else go that speed here consistently? Can you properly brake and maneuver in that speed bracket? Do you have way more close calls then you did before when you bicycled at more typical speeds of 20/30kmh? Does bicycling in that speed bracket push up the fatality/injury rate to that of a motorcycle?
It's as safe as you want to make it. If you can ride 'consistently' at 50km/h and the conditions are appropriate for it, there's no reason it can't be as safe as riding at 20 or 30.

My normal speed on the flat isn't quite as fast as that, (although I have gone that fast and faster on decents), so I'd be interested in hearing about your high speed experiences once you do get your bike.
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Old 09-06-07, 06:27 AM   #5
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If you can ride consistently at 50kph with little effort then you won't have to worry about traffic since you'll always be followed by the team car on a closed route. ...maybe you should be riding a Denali
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Old 09-06-07, 07:42 AM   #6
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You say you can ride 30 mph without "too much effort". I have a very hard time believing that. Eddy Merckx was the first cyclist to average 30 mph for an hour and that was a really big deal at the time. It was regarded as verging on the superhuman.

As for manuevering, bicycles manuever better than cars at those speeds. On mountain descents, cars can not keep up with skilled cyclists. As for braking, a bicycle is slower at braking than a car. The coefficient of friction is the same since both cars and bikes use tires made pretty much of the same stuff. However, bicycles tend to flip when they brake too hard and cars do not. Even that is not a major consideration. The major problem is the fact that motorists tend to pull out in front of cyclists, or turn in front of them. Motorists sometimes do not see the cyclists, other times they clearly see the cyclist and turn anyway. In this case, they either misjudge the speed of the cyclist or they figure that the cyclists will yield to them.
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Old 09-06-07, 07:54 AM   #7
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Messengers aren't generally going THAT fast but the trick to fast riding is developing the ability to see and think ahead. Just because the bike can move well at speed doesn't make it less dangerous. It's all up to the rider, but I would recommend ramping up your speed in traffic until you are comfy going flat out.

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Old 09-06-07, 08:42 AM   #8
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At 30mph in traffic (slight downgrade) I have had a few upsetting left-cross incidents, where oncoming drivers turned left in front of me. Not actual crashes, but situations requiring emergency braking. These seem to be less of a worry at slower speeds.

I've also had to do some emergency braking for drivers pulling out from side streets when I was traveling over 20 mph. At slower speeds I still have to brake for these sorts of things, but it isn't quite as unsettling.

My usual commute speed in urban traffic on a level road segment between red lights is close to 20 mph on my drop-bar road bike. Sometimes with some draft from cars around me I can maintain over 25 for a short while. I keep a sharp eye on intersection traffic at these speeds. Downhill on the road that leads to my office I regularly hit 40mph - but there is a raised center median protecting me from left turn conflicts, and nobody is leaving the office building driveways at that time of day, so it's a pretty safe place to let it all out - especially when my co-workers are following me in their cars and I want to give them a story for the water cooler.
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Old 09-06-07, 08:50 AM   #9
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At 30mph in traffic (slight downgrade) I have had a few upsetting left-cross incidents, where oncoming drivers turned left in front of me. Not actual crashes, but situations requiring emergency braking. These seem to be less of a worry at slower speeds.
People have trouble judging the speeds of bikes. First, there's the perception that you can't be going that fast. Second is that drivers become highly trained to juding speeds of cars based on how far apart the headlights are and things like that. I know personally I can't judge the speed of motorcycles as well as cars. I have no doubt that people have trouble figuring out my speed.
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Old 09-06-07, 09:26 AM   #10
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maybe you should be riding a Denali
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Old 09-06-07, 09:37 AM   #11
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People have trouble judging the speeds of bikes. First, there's the perception that you can't be going that fast. Second is that drivers become highly trained to juding speeds of cars based on how far apart the headlights are and things like that. I know personally I can't judge the speed of motorcycles as well as cars. I have no doubt that people have trouble figuring out my speed.
Pedestrians can't tell either (for those rare times I'm on the DC Mall), so that's why I've put two headlights on the handlebars. I try to space them out (Jeeps are difficult to judge, too, since their headlights are so close together and, at night, look farther away than they really are), but no matter what, two lights are easier to judge than just one.

Honda built a safety demonstrator motorcycle that has a couple interesting lighting features. The most obvious was a third front-facing "headlight" mounted in the rear on a mast high above the rider, about the same place you'd expect to see a flag. Its purpose was to provide another way for others to judge distance. The other thing was with the regular headlights; not only were both lights meant to stay on, but they were mounted in enclosures that gave a slanted appearance. The idea is that people can distinguish diagonal lines more quickly.
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Old 09-06-07, 09:48 AM   #12
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You say you can ride 30 mph without "too much effort". I have a very hard time believing that. Eddy Merckx was the first cyclist to average 30 mph for an hour and that was a really big deal at the time. It was regarded as verging on the superhuman.

As for manuevering, bicycles manuever better than cars at those speeds. On mountain descents, cars can not keep up with skilled cyclists. As for braking, a bicycle is slower at braking than a car. The coefficient of friction is the same since both cars and bikes use tires made pretty much of the same stuff. However, bicycles tend to flip when they brake too hard and cars do not. Even that is not a major consideration. The major problem is the fact that motorists tend to pull out in front of cyclists, or turn in front of them. Motorists sometimes do not see the cyclists, other times they clearly see the cyclist and turn anyway. In this case, they either misjudge the speed of the cyclist or they figure that the cyclists will yield to them.
Sorry the first to pass 30 MPH for the hour was Ole Ritter at 48.653 Kms for an hour, which comes out to 30.23 Miles.

But the OP equated 50 Kms to 30 Miles. If we go with the 50Kms we are talking about a speed that has not yet been attained with a standard bike.

Oh and when Eddy broke Ole's record (substantially) he said it was the most painful thing he ever did. He had set out to break the 10 and 20 KM records along with the hour, which he did. It was pretty sure that without the quick start required to break the 10 and 20 he could lower the hour by a bit more. He decided it was not worth the suffering.

I don't doubt the OP I know he is mistaken.
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Old 09-06-07, 09:52 AM   #13
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30mph...pffft.

Get used to hearing the phrase "On your left".
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Old 09-06-07, 09:55 AM   #14
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50km/h without much effort? that's just a tad slower than my solo sprinting speed, lol. I can sustain 40km/h for 6km and at that speed, I'm always keeping up with the cars since they get stuck in traffic while I can just filter/lane split to the front.

and IMO, slicks tyres are better than knobby tyres on bikes. They allow more grip and more stopping power. I can stop quite a bit faster than a car going the same speed (some guy in a car came within 1in of my rear wheel). Proper use of front brakes means a very quick stop.
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Old 09-06-07, 10:39 AM   #15
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I know if I get a decent road bicycle I can go a consistent 50km/h (30mph) without too much effort.
Would you like to be my leadout man?
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Old 09-06-07, 11:55 AM   #16
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Ok, I was wrong in my estimates. Currently if I go flat out on my current crapo biycle (with pseudo road tires that seem not to do much) I can go 40kmh. Uphills and tailwinds obviously slow me down. I currently go about 30kmh with a sustainable effort. A friend of mine with a semi-proper road bicycle when on a slight down incline on a highway said he could go around 60kmh. That might of been your standard guesstimate vs. a bicycle computer measurement. I thought with a nice road bicycle, it would be a worlds improvement over my current piece of crap but from everyone's comments here I guess I'm wrong.
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Old 09-06-07, 12:06 PM   #17
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...or maybe you just have to recalibrate your computer?
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Old 09-06-07, 12:08 PM   #18
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Ok, I was wrong in my estimates. Currently if I go flat out on my current crapo biycle (with pseudo road tires that seem not to do much) I can go 40kmh. Uphills and tailwinds obviously slow me down. I currently go about 30kmh with a sustainable effort. A friend of mine with a semi-proper road bicycle when on a slight down incline on a highway said he could go around 60kmh. That might of been your standard guesstimate vs. a bicycle computer measurement. I thought with a nice road bicycle, it would be a worlds improvement over my current piece of crap but from everyone's comments here I guess I'm wrong.
If you have knobby tires or a particularly upright position, then you will be able to go significantly faster. Just not a sustainable 50kph. I guess your question is how much speed you could gain. That is difficult to answer, other than just giving it a try.
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Old 09-06-07, 12:17 PM   #19
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So why hasn't anyone recommended the only way to sustain 30mph for long periods of time with little effort?

eBike. There's a whole forum here for them.
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Old 09-06-07, 12:20 PM   #20
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So why hasn't anyone recommended the only way to sustain 30mph for long periods of time with little effort?

eBike. There's a whole forum here for them.
hahhahahhahha

That's rich! Thanks but I'll save the assisted cycling for my assisted living days!
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Old 09-06-07, 12:29 PM   #21
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My worry is how safe is going that fast. Does anyone else go that speed here consistently?
The only times I go that fast are on wide, smooth roads, like Steve, I need a gravity assist. I'll hit (and pass) 30 mph on curvy mountain roads, too, and I'm smack in the middle of the lane or sometimes even near the yellow line when I'm going that fast. Tailwinds are even better. I might have hit 30 mph drafting behind trucks, but I'm not watching the speedometer when I do that.

There's a woman with an electric scooter in my area who lets cyclists draft behind her in the bike lane. She moves along at 25 mph and I can hold on to that for maybe a mile or two before I lose her, usually on an uphill.

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Old 09-06-07, 01:58 PM   #22
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So why hasn't anyone recommended the only way to sustain 30mph for long periods of time with little effort?

eBike. There's a whole forum here for them.
Here in Indiana it's illegal to ride a ebike faster that 25 mph. On the other had you can ride a bicycle as fast as you can push (assuming an high enough speed limit on the road.)

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Old 09-06-07, 02:23 PM   #23
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Here in Indiana it's legal to ride a ebike faster that 25 mph. On the other had you can ride a bicycle as fast as you can push (assuming an high enough speed limit on the road.)
Do you mean illegal? That would be bonkers. Turn the motor off and the speed limit goes up?
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Old 09-06-07, 04:53 PM   #24
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I think its more like they never think that you ever could get that fast so they never thought of regulating it.
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Old 09-06-07, 05:17 PM   #25
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Trust me; 30 mph is hard to get to. Wind resistance is a cube law function, meaning that compared to traveling at 15 mph, at 30 mph you are working 8 times harder.

Going fast, however, is a function of space and your ability and comfort level. In tight spots, you'll find the urge to slow down. In wide open areas, you'll be comfortable speeding up. If you ride a lot in tight spots, you'll be more comfortable going faster than someone who doesn't ride in tight spots. And if you have the entire road to yourself (you claim the lane going down a hill), then 40 mph isn't so bad, as long as you are aware of what's going on around you.

Just travel at a speed which doesn't set your brain off as being too fast. On a bicycle, you don't really have to worry that much about speed restrictions, so the basic speed law is what you use basically all the time. As you gain experience on your new road bike, you'll see exactly where you need to slow down, and those instances where you are okay speeding up (if your lungs don't pop first).
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