Thread: Better Braking?
View Single Post
  #273  
Old February 16th 20, 08:55 AM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 824
Default Better Braking?

On Sunday, February 16, 2020 at 12:57:47 AM UTC+1, jbeattie wrote:
On Saturday, February 15, 2020 at 2:30:14 PM UTC-8, Frank Krygowski wrote:
On Saturday, February 15, 2020 at 2:49:36 PM UTC-5, wrote:
On Saturday, February 15, 2020 at 8:00:21 PM UTC+1, Frank Krygowski wrote:
On 2/15/2020 3:16 AM, wrote:
On Saturday, February 15, 2020 at 5:30:59 AM UTC+1, Frank Krygowski wrote:
On Friday, February 14, 2020 at 7:40:02 PM UTC-5, Tom Kunich wrote:
On Friday, February 14, 2020 at 11:23:24 AM UTC-8, Sir Ridesalot wrote:
On Friday, 14 February 2020 12:00:11 UTC-5, Frank Krygowski wrote:
On 2/13/2020 5:47 PM, Tom Kunich wrote:
On Thursday, February 13, 2020 at 2:36:58 PM UTC-8, John B. Slocomb wrote:

Own Data? You mean like your assertions that a cheap Chinese
flashlight is a perfect bicycle head light? ...

I have taken Steven's word at the effectiveness of "cheap Chinese flashlights as bicycle lights" and he was completely correct. Sorry if you seem to think that you know anything about anything but you have shown yourself to be a great deal heavier on opinion than knowledge of anything..

You say Mr. Scharf was completely correct when he touted cheap Chinese
flashlights as bike headlights. That was when he said dyno powered
headlights were terrible and foolish.

Problem is, Mr. Scharf is now using dyno powered headlights on his
bikes, and no longer seems to say cheap Chinese flashlights are perfect.

My first question is, was he completely correct back then? Or is he
completely correct now?

My second question regards specific details. My dyno powered LED
headlights illuminate the entire width of the lane, and simultaneously
illuminate stop signs up to a quarter mile away from me, all without
blinding oncoming riders.

The Chinese flashlight I tried could not do that, no matter how I
adjusted the tilt and the focus. It was a truly crappy headlight. What,
specifically, does yours do? What's its brand and model?



--
- Frank Krygowski

Some people use flashlights that have a narrow beam but good range. Those lights might be okay as a be seen light but they don't light up much of the road. Others use flashlights with adjustable focus that spread the beams to light of more of the road. the trouble is that when they do that they lose the range they need if riding in totally dark conditions with no city lights.

I really like my CygoLite Rover II light as it does light up the two lanes of the country roads around here and it does so no matter what speed I'm riding at. Also, I can move the battery and light unit from bike to bike easily. I do wish it had a bit more range. For that reason I was considering getting the Centauri or Trident. Dynamo lights simply don't meet my needs.

Cheers

I think that there was a GCN video of a rim driven dynamo light and it was pretty funny because it was just like I remembered it as a kid. As you pushed the pedal down you would get a light and as you were changing over to the opposite the bike would stop from the massive resistance of a 30 watt dynamo. If Frank really uses those things he must ride a bike with a triple and a 26 to 42 gear ratio.

Tom, you have a problem confusing fantasy with reality.

Let me describe a spontaneous, unplanned dynamo test I did once. I've
described it before, but you probably wouldn't remember.

I was on a solo bike tour, heading to Bloomington IN where my kid was
soon to finish college. ("Dad, you've been talking about riding your
bike here. This is your last chance.")

I was on a nice, empty, flat four lane highway heading due west, and
feeling good because I was cranking along nicely at 20 mph despite my
full camping load.

Then I hit a bump in the pavement. After that, I heard some new noise
from my bike, and to my dismay my speed dropped about a mile per hour.

I remember checking for dragging brakes by squeezing the levers and
looking at the brake arms. Nothing. I didn't stop, but I worried
about what damage I had done that was slowing my bike. Then I realized
the bump had caused my generator to click on. I clicked it off and my
speed returned.

So at the power output needed for 20 mph, putting on the generator
slowed me to maybe 19 mph. This was with a bottom bracket generator,
but I haven't seen any real difference with a bottle dyno as I set
them up. And note, this matches Chris Juden's numbers that John
alluded to. Let me know if you need a link.

As always: Sorry for introducing real numbers into a discussion.

- Frank Krygowski

Hmm, you saying that your speed dropped from 20-19 mph in uncontrolled conditions are real numbers?

Those were the numbers I experienced. A dead flat four lane road with no
traffic is a fairly simple test situation. And again, it was at least
roughly corroborated by tests I've done and others have done.

Do you have different numbers?


--
- Frank Krygowski

It is crappy research Frank, you should know that. Maybe a tad better than saying 'these brakes are better' after using them for a longer time. Your real speed could went from 19.6 mph to 18.6 mph or from 19.6 mph to 19..4 mph. Who knows. When I was in the market for a dyno hub I wanted the one with the highest efficiency and my choice was based on measurements in a laboratory with real instruments. It is not difficult in these conditions to measure accurately. After my choice I'm not the least interested in numbers anymore and just use the damn thing and not trying to convince/impress others with numbers that don't say anything. When I switch the light on and of a don't notice anything in feel and speed but I have to reach down to switch it on or off which changes the situation so this doesn't anything either, but I know that I go from 6-7 Watt to 0.5-1 Watt turning in on and off.
BTW my good friend who is a skilled and enthusiast brick layer agrees with me.


You're losing track of the conversation, Lou. My post was to counter
Tom Kunich's claim that the dynamo slowed the bike almost to a stop.
His is an exaggerated variation on a frequent complaint - that dynos
make no sense because they slow a rider down.

I related what some researchers call "a natural experiment" - that is,
a change made inadvertently, or for reasons not connected to the
present question. Natural experiments can still yield reasonably good
data. Yes, in this case it wasn't as precise as laboratory data -
but then, if I gave laboratory data, Tom or other more obnoxious
people would say "That can't be trusted."

Mine was a real world experience. Conditions were constant except for
the sudden engagement of the dyno. The main weakness is that I know
the before and after speeds only approximately. But I know that there
was very little reduction in speed, which was all I cared about.

That is what you confirmed from your own experience. Yet you argue
with me! How odd.


Not odd at all. I don't doubt the drag scrubbed off some speed, but even your story suggests confounding factors like tracking down a noise, looking around for dragging brakes, etc. It's hard to do all those things while maintaining speed.

-- Jay Beattie.


The big problem with this 'test' is maintaining the same power. The natural tendency is to increase power when the resistance increases. Everyone who has ridden with a power meter know that the power varies significant even when trying to keep it constant. Plus minus 10 Watt is about the accuracy when you try to keep it constant if the restistance varies. Like I said the speed difference is crappy data.

Lou, going for another ride in the wet.
Ads
 

Home - Home - Home - Home - Home