A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Mountain Biking
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

"Actually you are the first person to bring up this issue"



 
 
Thread Tools Display Modes
  #391  
Old March 29th 04, 05:52 PM
Peter B
external usenet poster
 
Posts: n/a
Default "Actually you are the first person to bring up this issue"


"Russ" wrote in message
...

The issue of retrospectively recalling all existing forks is much more
problematical and possibly unecessary, that's something that will be
addressed by the manufacturrs in the light of legal cases and costs.


I'd have thought that "lawyer-lips" have set a precedent that gives
manufacturers a loop-hole to use regarding forks already on the market/in
use.

Lawyer lips were created not because of any inherent design flaw but because
there was a risk of user error, ie the user *might* forget to tighten the
QR correctly before riding or might not do it correctly.
So there is no admission of an engineering problem, just an acknowledgement
that someone may not use the device as intended and therefore a
belt-and-braces (belt-and-suspenders for our American friends) approach has
been adopted..

So based on this there is no reason why manufacturers couldn't move the
mounts to the other leg, they wouldn't be admitting to any previous
liability due to poor design but would be seen to be further addressing the
risk of user error.

--
Regards,
Pete




Ads
  #392  
Old March 29th 04, 08:11 PM
external usenet poster
 
Posts: n/a
Default "Actually you are the first person to bring up this issue"

Tom Sherman writes:


I didn't see a picture of this tricycle but short wheelbase recumbent
bicycles, ones where pedal cranks are ahead of the front wheel, do
endo's more easily than a conventional bicycle. Drawing a visual line
from the rider's belly button (rider CG) to the contact patch of the
front wheel shows that the CG is no better positioned than that of a
conventional bicycle and usually worse....


Picture of my trike.


http://www.ihpva.org/incoming/2002/df1a.jpg

This picture could not be retrieved. The URL produces an error.

Mr. Brandt's comments on short wheelbase (SWB) recumbents indicate
outdated and/or incomplete knowledge. The first regular production SWB
recumbent was the Hypercycle. Among other design defects, the Hypercycle
had a very long pedal boom, which meant that the rear wheel would lift
easily when the front brake was applied, and hard braking could well
launch the rider off the front of the bike in a near standing position
and/or put the chainring into the ground.


Better designed (not all, by any means) modern SWB recumbents have a
static weight distribution of approximately 40%/60% front/rear and will
not lift the rear wheel under hard braking. Here is one such common
design that I have ridden extensively (including emergency braking)
without ever lifting the rear wheel.


http://www.ransbikes.com/2004Bikes/Rocket.htm

This is the exact design to which I refer. Drawing a line from the
tire contact patch to the belly button of the rider produces a steeper
inclination than a conventional bicycle. An endo was demonstrated by
a rider who was convinced it would not occur. He left the recumbent
behind as he went over the pedals to run down the parking lot. It was
a relatively benign dismount although the bicycle got a few scrapes.

Don't try this at higher speeds.

Here is a picture of the SWB recumbent I regularly use for longer
rides:


http://www.ihpva.org/incoming/2002/sunset/Sunset001.jpg

With the low seat height and short pedal boom, the angle formed by
the ground, front tire contact patch, and combined bike/rider center
of mass is very small. It would take sudden stoppage of the front
wheel (e.g., wedged in a storm sewer inlet grating) for the rear
wheel to lift off of the ground.


That is certainly a compendium of mechanical oddities, unistrut fork,
front spoke guard, primary and secondary chains with cross-over and
dual tensioners. The tiller style steering is also unusual for using
arm force while pedaling. How do you keep pant legs out of the chain?

In the line with this thread, I cannot see riding this on steep trails
or trails at all for that matter.

Jobst Brandt

  #393  
Old March 29th 04, 08:20 PM
external usenet poster
 
Posts: n/a
Default "Actually you are the first person to bring up this issue"

James Annan writes:

If you consider forks without offset at the dropout end, as they
are commonly made today, where offset is achieved at the fork
crown, No change other than placing the mounting lugs for the disc
brake caliper on the front side is required. I think the same
caliper would be adequate for most brands with the distance between
caliper and fork leg remaining as it is today. This requires a new
fork strut anyway.


It might even be possible to simply swap the left and right fork
lowers. Sometimes one sees bikes where the forks have been
installed backwards... usually on ebay.


How long will it take to get the disc caliper ahead of the fork leg?


I wouldn't be surprised to see different wheel attachment instead.
There are already various quick(ish) release 20mm systems that seem
little more trouble than a QR with retention lips. That can also be
sold as an upgrade rather than merely a bug-fix. And you get to buy
a new shiny hub too!


Well that won't do as I already mentioned. The reversing load from
braking and bouncing on the road makes anything but a conical "lug
nut" ineffective to reliably prevent loosening.

Let's get the caliper in the right place!

Jobst Brandt

  #394  
Old March 29th 04, 09:37 PM
Chris B.
external usenet poster
 
Posts: n/a
Default "Actually you are the first person to bring up this issue"

On Mon, 29 Mar 2004 12:38:21 +0100, "Just zis Guy, you know?"
wrote:

"Chris Malcolm" wrote in message
...
bomba writes:


Since most bike brakes are capable of skidding the front wheel in most
circs, all that better brakes give you is finer control of braking
force and less grip effort.


And less fade.


Why?
  #395  
Old March 29th 04, 09:53 PM
Benjamin Lewis
external usenet poster
 
Posts: n/a
Default "Actually you are the first person to bring up this issue"

Chris B. wrote:

"Just zis Guy, you know?" wrote:

"Chris Malcolm" wrote:

Since most bike brakes are capable of skidding the front wheel in most
circs, all that better brakes give you is finer control of braking
force and less grip effort.


And less fade.


Why?


Brake fade is bad. If brakes give you less of it, it follows that they are
better, all else being equal.

I assume Chris Malcolm wasn't including dry pavement when he said "most
bike brakes are capable of skidding the front wheel in most circs". On dry
pavement the limiting factor is nearly always geometry rather than traction
or "brake power".

--
Benjamin Lewis

F u cn rd ths u cnt spl wrth a dm!
  #396  
Old March 29th 04, 10:17 PM
Chris B.
external usenet poster
 
Posts: n/a
Default "Actually you are the first person to bring up this issue"

On Mon, 29 Mar 2004 12:53:42 -0800, Benjamin Lewis
wrote:

Chris B. wrote:

"Just zis Guy, you know?" wrote:

"Chris Malcolm" wrote:

Since most bike brakes are capable of skidding the front wheel in most
circs, all that better brakes give you is finer control of braking
force and less grip effort.

And less fade.


Why?


Brake fade is bad. If brakes give you less of it, it follows that they are
better, all else being equal.


I agree but the implication was that disc brakes are more fade
resistant (all of the other points Guy mentioned were positive traits
of disc brakes), although this isn't clear by looking at the quoted
section. No doubt Guy will clarify if he was instead referring to rim
brakes. Again, I often hear that disc brakes are less prone to fade
resistant and I wonder if it is true and why.
  #397  
Old March 29th 04, 10:21 PM
Chris B.
external usenet poster
 
Posts: n/a
Default "Actually you are the first person to bring up this issue"

On Mon, 29 Mar 2004 21:17:54 GMT, Chris B.
wrote:

snip

Sorry, that should read "I often hear that disc brakes are less prone
to fade and I wonder if it is true and why."
  #398  
Old March 29th 04, 11:04 PM
Benjamin Lewis
external usenet poster
 
Posts: n/a
Default "Actually you are the first person to bring up this issue"

Chris B. wrote:

On Mon, 29 Mar 2004 12:53:42 -0800, Benjamin Lewis
wrote:

Chris B. wrote:

"Just zis Guy, you know?" wrote:

"Chris Malcolm" wrote:

Since most bike brakes are capable of skidding the front wheel in
most circs, all that better brakes give you is finer control of
braking force and less grip effort.

And less fade.

Why?


Brake fade is bad. If brakes give you less of it, it follows that they
are better, all else being equal.


I agree but the implication was that disc brakes are more fade
resistant (all of the other points Guy mentioned were positive traits
of disc brakes), although this isn't clear by looking at the quoted
section. No doubt Guy will clarify if he was instead referring to rim
brakes. Again, I often hear that disc brakes are less prone to fade
resistant and I wonder if it is true and why.


I see -- your question was a little unspecific. It would surprise me to
find that disc brakes were less prone to fade, since they appear to have
much less surface area available for heat dissipation, but there may be
other factors I'm overlooking. They certainly must reduce the chances of
tire blow-off due to heating of rims, but this is a different question.

--
Benjamin Lewis

F u cn rd ths u cnt spl wrth a dm!
  #399  
Old March 29th 04, 11:23 PM
Tim McNamara
external usenet poster
 
Posts: n/a
Default "Actually you are the first person to bring up this issue"

writes:

Tim McNamara writes:

Name calling doesn't change the facts, BTW. Neither does your
anger nor your emotional reasoning. Everybody that has disk
brakes may just have been hoodwinked by the companies that made
them- those are the people you should be challenging.


Should not the criticism be leveled at the fork manufacturers and
not the brake manufacturers?


IMHO both, since they are equal parts of the system. The brake is
designed by its maker to be mounted behind the fork leg, and the
fork is designed to put it there by its maker. Both are equal
contributors to the problem.


I don't know but do suspect that changing the dropout design might
be the easier solution, and I don't know but do suspect that
changing the location of the brake would be the better solution.


If you consider forks witqhout offset at the dropout end, as they are
commonly made today, where offset is achieved at the fork crown, No
change other than placing the mounting lugs for the disc brake caliper
on the front side is required. I think the same caliper would be
adequate for most brands with the distance between caliper and fork
leg remaining as it is today. This requires a new fork strut anyway.

Changing the dropout is not a reasonable option because the dropout
would need to face upward, which would release the wheel on normal
wheel loads, while reversing loads of rider and brake force, being
opposite, could still cause QR loosening. The dropout should be
loaded in the same direction at all times as it is with rim brakes.


I was thinking of facing the open end of the dropouts forward, so
that the normal load would be directed into the end of the fork leg,
and the lower "jaw" of the dropout would constrain the braking
force. This wouldn't be suitable?
  #400  
Old March 29th 04, 11:26 PM
Tim McNamara
external usenet poster
 
Posts: n/a
Default "Actually you are the first person to bring up this issue"

"Doug Taylor" writes:

"Tim McNamara" wrote in message
...

Not much of a clue, that, since the thread is also cross-posted to
rec.bicycles.tech which has an international audience as a matter
of course (although seems largely American) and alt.mountain-bike
which has an audience of who-knows-what.


People who know and ride the bikes that are being discussed. Unlike
you.


Well, now, that was certainly a charming response. It's unclear on
what grounds you think this to be the case, nor why you felt the need
for spurious invective. Ah, well, like many mysteries it will no
doubt remain unexplained.
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Seeing the TDF in person (also posted to r.b.r) Mike Jacoubowsky General 0 July 4th 04 05:43 AM
funny things to do on a bike jake jamison General 518 June 11th 04 03:22 AM
Schwinn Rocket 88 "chain suck" issue Fletcher Mountain Biking 9 December 24th 03 05:13 PM
350 Watt Electric Scooter will bring a big smile this holiday Joe General 2 November 21st 03 08:16 AM
Warranty issue D T W .../\\... Mountain Biking 8 July 19th 03 10:53 PM


All times are GMT +1. The time now is 10:25 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.