Science & bikes

[Frank Krygowski]

What people don't know about bikes. And a nicely presented video:

http://www.npr.org/sections/13.7/2015/07/06/420513593/what-you-really-know-about-bicycles


--
- Frank Krygowski

[Andy K]

In one study, for example, 40 percent of participants (many of them psychology undergraduates who rarely cycled) made at least one of these errors: failing to recognize the correct bicycle frame from a set of four options; failing to recognize the correct pedal location from a set of four options; or failing to recognize the correct chain location from a set of four options.

Real bright study with folks that rarely bike. :-)

Andy

[John B.]

Years ago I was running a course to train mechanics for a steel mill
in West Java and we got a new guy came in - been in the Peace Corps
and had some additional training material. Anyway, he proceeded to
give all the students a test, from his peace corps days, to determine
their mechanical knowledge.... and they all failed it :-)

He came in with the results and was telling me how these guys would
never become mechanics, etc., etc. I finally asked him to let me see
the test. The first look showed such brain teasers as drawings of
three buildings one with a flat roof, one with a moderate peak and one
with a very steep pitch. the question was, "Which roof will have the
highest snow load"... to a peasant lad from West Java?

We later redesigned the test and discovered that our lads were just as
bright in areas that were familiar to them than any other bunch of
young fellows.

Tests have to test areas that the student is familiar with :-)
--
cheers,

John B.

[avag...@gmail.com]

SUPER

[Ralph Barone]

Frank Krygowski <frkr...@sbcglobal.net> wrote:
> What people don't know about bikes. And a nicely presented video:
>
> http://www.npr.org/sections/13.7/2015/07/06/420513593/what-you-really-know-about-bicycles
>

Thanks Frank. So according to that video, I should move my front panniers
forwards to increase stability. For some reason, that seemed
counter-intuitive to me.

[James]

Too far forward and the front wheel may flop to the side too readily.
My MTB does this. The steering angle is less steep than a road bike, so
there's more mass to pull the front wheel to the side.

Perhaps better to aim for the CG to be close to the steering axis?

--
JS

[Andre Jute]

Seems to me that even in the most ideal setup you'd still be left with a lever arm of the same length as the trail.

Here's the logic. Unless you can get the lowrider panniers right on the ground, there will be an unavoidable lever arm of some length, to be empirically discovered for each bike/pannier setup. Perhaps if the weight of the panniers were centred over the contact patch and really very low down, the lever arm (the horizontal distance between the vertical weight centre of the pannier and steering axis) will be as small as possible, and likely smaller than in your case above. Practical fitting realities aside, eh?

Whether the minimum weighting is desirable is an entirely different matter. Though I very rarely have enough luggage to use lowriders, since I got the Big Apples with their ferocious grip and just about doubled my downhill speed (as compared to on narrow high pressure tyres`), I like slightly weighty steering to slow down the response and give me a bit of understeer, on precisely the same principle as a good designer loads up the steering on a big car or a big motorbike the faster it goes, that reaction and recovery from excessive input (not necessarily voluntary, as in hitting a pothole or bump in the road) might be difficult at speed. If that were the controlling parameter, however, I think I'd move the centre of the lowrider mass backwards rather than forwards of the contact patch. Forward would give you oversteer, exactly what you don't want (unless you ride dead slow on dead smooth roads with zero camber, which of course you can in the Wonderland of Ohio...).

Andre Jute

[Frank Krygowski]

I agree with James, front pannier weight too far forward will induce
some tendency to wheel flop. Whether this matters to you may depend on
riding conditions and style.

My Cannondale touring bike does very nicely with its front panniers. I
use them on low rider racks that came with the bike. They do increase
stability, in the sense that the steering sort of slows down, making it
nicely relaxed for touring. (Not that the steering is the least bit
twitchy when the bike is empty.) I think it's just a matter of more
rotational inertia about the steering axis.

I haven't experimented with front-to-rear placement of front panniers on
those racks. I've never felt the need to change anything there. (Well,
except some minor complexity fitting both the racks and fenders.)


--
- Frank Krygowski

[AMuzi]

Well known for a good long while. Dense and heavy (tools,
food) in the front panniers, bulky (clothing etc) in the rear.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

[Frank Krygowski]

On 7/10/2015 2:48 PM, AMuzi wrote:
> On 7/9/2015 8:15 PM, Ralph Barone wrote:
>> Frank Krygowski <frkr...@sbcglobal.net> wrote:
>>> What people don't know about bikes. And a nicely presented video:
>>>
>>> http://www.npr.org/sections/13.7/2015/07/06/420513593/what-you-really-know-about-bicycles
>>>
>>>
>>
>>
>> Thanks Frank. So according to that video, I should move my front panniers
>> forwards to increase stability. For some reason, that seemed
>> counter-intuitive to me.
>>
>
> Well known for a good long while. Dense and heavy (tools, food) in the
> front panniers, bulky (clothing etc) in the rear.

I think Ralph was referring to the position of the front panniers with
respect to the steering axis, i.e. whether further forward would be better.


--
- Frank Krygowski