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From: Catrike Ryder <Soloman@old.bikers.org>
Newsgroups: rec.bicycles.tech
Subject: Re: Extensive article on Rivendell and Grant Petersen
Date: Thu, 26 Sep 2024 05:03:02 -0400
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On Thu, 26 Sep 2024 10:29:14 +0200, Rolf Mantel
<news@hartig-mantel.de> wrote:

>Am 25.09.2024 um 16:15 schrieb Catrike Ryder:
>> On Wed, 25 Sep 2024 15:24:29 +0200, Rolf Mantel
>> <news@hartig-mantel.de> wrote:
>> 
>>> Am 25.09.2024 um 14:46 schrieb Catrike Ryder:
>>>> On Wed, 25 Sep 2024 10:57:52 GMT, Roger Merriman <roger@sarlet.com>
>>>> wrote:
>>>>
>>>>> Catrike Ryder <Soloman@old.bikers.org> wrote:
>>>
>>>>>> 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.
>>>>>
>>>>> That’s really hard to see how, you’ve mentioned that the trike pitches
>>>>> which suggests that its weight is quite forward.
>>>>
>>>> Indeed it does pitch forward. It's easy to lift the rear tire off the
>>>> road, however, the center of gravity of me on the Catrike compared to
>>>> someone on a two wheeler is much lower. LIfting the rear wheel of the
>>>> ground still requires a lot of braking force.
>>>
>>> Pitching forward is a clear indicator that for your Cattrike (like for
>>> most upright bike but unlike some recumben bicycles) , the limiting
>>> factor for braking performance is the geometry rather than tires or brakes.
>> 
>> Any bike will lift the rear wheel given enough braking power at the
>> front wheel.
>
>This assumption gave me a fractured wrist when I was 18:
>Motorbikes will lock the front wheel before lifting the rear wheel.
>
>Motorbikes and some recumbent bikes (where the line from the front wheel 
>patch to the dynamic center of gravity is shallower than 45 degrees) 
>will lock the front whell instead of lifting the rear wheel, enabling a 
>deceleration of around 1 g (but the biker will not normally be able to 
>handle that unless he's supported by anti-lock brakes).
>Your description of pitching the Cattrike points to a deceleration of 
>just under 1 g.
>
>*Normal bicycles* on *dry tarmac* roads will lift the rear wheel, 
>therefore for them the tire details are irrelevant for braking performance.
>When braking on ice or wet grass, the tire details will be very 
>important for braking performance.
>
>Rolf

I don't know exactly where my center of gravity is on the Catrike, so
I can't define what angle it is to the front tire patch, but I think
it may be more than 45 degrees. The front wheels on the Catrike are
not so very far ahead of my body mass. Only my lower legs are out in
front of them.

As for truly locking the brakes (skidding the front tires) , I don't
think that's even possible with two 40mm front tires on dry asphalt,
but I have backed off the calipers to where a full pull at higher
speeds won't slam the chainrings into the ground, nor pitch me out on
my face. 

--
C'est bon
Soloman