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From: AMuzi <am@yellowjersey.org>
Newsgroups: rec.bicycles.tech
Subject: Re: Extensive article on Rivendell and Grant Petersen
Date: Wed, 25 Sep 2024 08:38:02 -0500
Organization: Yellow Jersey, Ltd.
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On 9/25/2024 4:39 AM, Catrike Ryder wrote:
> On Wed, 25 Sep 2024 09:05:25 GMT, Roger Merriman <roger@sarlet.com>
> wrote:
> 
>> Frank Krygowski <frkrygow@sbcglobal.net> wrote:
>>> On 9/24/2024 3:17 PM, Catrike Ryder wrote:
>>>> On Tue, 24 Sep 2024 14:14:41 -0400, Frank Krygowski
>>>> <frkrygow@sbcglobal.net> wrote:
>>>>
>>>>> You might do well to read some of the archives of this group. There have
>>>>> always been people posting opinions that were factually wrong, and there
>>>>> have always been people pointing out those mistakes. As I've noted
>>>>> earlier, having mistakes pointed out is a necessary part of the process
>>>>> of education.
>>>>
>>>> That's fine of the person being corrected understands that the
>>>> corrector is qualified to do so and is truly interested in making
>>>> things better. In my opinion, you fall far short of both those
>>>> standards.
>>>
>>> Your opinion on that matter is worthless. You don't have anywhere near
>>> the background needed to judge technical proficiency. Professional
>>> Engineering licensing boards of two different states have disagreed with
>>> you, not to mention those conferring my engineering degrees and those
>>> institutions for whom I've worked.
>>>
>>>>> There are many examples of ideas that were posted frequently, and noted
>>>>> as wrong. Most of them seldom pop up any more - and not only, I think,
>>>>> just because there are fewer posts. I think people actually learned things.
>>>>>
>>>>> Examples of mistaken claims? Chains wear by stretching the metal. Old
>>>>> frames get "soft." Increasing spoke tension makes a wheel more rigid.
>>>>> Tying and soldering spokes makes a wheel stronger. Headsets fail by true
>>>>> brinelling due to impact loads. Hanging a bike by the front wheel makes
>>>>> the spokes stretch... and many more.
>>>>>
>>>>> BTW, what was that stopping distance from 20 mph again?  ;-)
>>>>
>>>> 20 MPH would be maybe 9/10 feet if I didn't concern myself with
>>>> slamming the chain rings into the ground or doing a face plant on the
>>>> ground in front of the bike. 30 MPH would be a little further. Two
>>>> front brakes work better than one, especially when the rider's weight
>>>> is already more over the front wheels before he applies the brakes.
>>>
>>> Right, good one. There is no way you can stop your tricycle in 10 feet
>>> from 20 miles per hour. That would require a deceleration of 43 ft/s^2
>>> or 1.34 times the acceleration of gravity. IOW you'd need tires with a
>>> static coefficient of friction at least 1.34, plus absolutely perfect
>>> application of both brakes so that both wheels were at the absolute
>>> limit of traction but not skidding. And you'd have to be in a "nose
>>> wheelie" all the while, with your rear tire up in the air so every bit
>>> of your weight was on the front wheels. It's essentially impossible.
>>>
>>> For 9 feet, your acceleration would have to be nearly 48 ft/s^2, and
>>> besides absolutely perfect braking reflexes, you'd need tires with a
>>> static coefficient of friction at least 1.48.
>>>
>>> And 30 mph would be _much_ farther, not "a little." The velocity term
>>> gets squared in the relevant calculation, much as it does when
>>> calculating kinetic energy.
>>>
>>> I'm sure you don't know what a lot of that means. But what you're
>>> claiming is practically impossible. Feel free to prove me wrong by doing
>>> what you claim and posting video evidence.
>>>
>>>
>> Even if he means without thinking time
> 
> Yes, I know I'm going to stop and my fingers are already on the brake
> levers.
> 
>> 20mph is 6 meters or 20ft for a car,
>> which almost certainly can out brake the trike.
> 
> I doubt that.
> 
>> If a planned braking action on the MTB probably could reduce that a touch
>> as it has huge amounts of grip and braking force, and frame allows one to
>> get behind the rear wheel.
>>
>> Other bikes at best would equal, the old commute bike as it has weight to
>> the rear is surprisingly effective at emergency stops or just using the
>> rear brake hard, but even that will during a emergency start to lock the
>> rear.
>>
>> Neither of the road/gravel bikes would do well at emergency stops as your
>> in the wrong position ie far too forward.
>>
>> Roger Merriman
>>
> 
> A few weeks ago, after posting about braking, I tested the Catrike's
> brakes at 15 MPH. I stopped at about 6 feet, keeping the chain rings
> off the ground.
> 
> --
> C'est bon
> Soloman

I understand your point that a dual front disc tricycle can 
stop in much shorter distance than a common two wheeler. I 
agree with that and it's readily observed.

But without an assistant/observer and some measurement 
devices, it merely _seems_ like two meters. The numbers just 
don't work. I believe you are sincere. but haven't actually 
accurately measured.

-- 
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971