Front brake caliper on the back of a fork

On Mar 30, 9:38*am, Frank Krygowski wrote:
On Mar 30, 12:12*pm, Tom Ace wrote:

I've put the rear brake on the front side of the bridge
on all the frames I've had that permitted it, e.g.
* *http://minortriad.com/prime/brake.jpg

What do you see as the advantage?

I like how it looks.

Tom Ace

On Mar 30, 6:00*pm, Tom Ace wrote:
On Mar 30, 9:38*am, Frank Krygowski wrote:

On Mar 30, 12:12*pm, Tom Ace wrote:

I've put the rear brake on the front side of the bridge
on all the frames I've had that permitted it, e.g.
* *http://minortriad.com/prime/brake.jpg

What do you see as the advantage?

I like how it looks.

Tom Ace

Did you weight that up against the disadvantages?

On Mar 30, 10:14*am, thirty-six wrote:
On Mar 30, 6:00*pm, Tom Ace wrote:

On Mar 30, 9:38*am, Frank Krygowski wrote:

On Mar 30, 12:12*pm, Tom Ace wrote:

I've put the rear brake on the front side of the bridge
on all the frames I've had that permitted it, e.g.
* *http://minortriad.com/prime/brake.jpg

What do you see as the advantage?

I like how it looks.

Tom Ace

Did you weight that up against the disadvantages?

Yup.

Tom Ace

On Sat, 31 Mar 2012 02:37:32 +0100, Phil W Lee
wrote:

Frank Krygowski considered Fri, 30 Mar
2012 11:08:51 -0400 the perfect time to write:

User Bp wrote:
I'm interested in moving the front brake caliper from the front of the
fork to the back. It's an old-fashioned Shimano 600 setup, far from
high tech but adequate for my riding. The motive is a little convoluted:
A roller dynamo is hanging on the caliper mount bolt, at the back.
A fender would be highly desirable, but is obstructed by the dynamo
(but not by a brake). If it were possible to "turn things around" so
the caliper was in back and the dynamo was in front a fender would fit.

It's clear the caliper reach would be longer and the angle to the
wheel different. Does anybody know if this can (or can't) be done
successfully?

Thanks for reading,

bob prohaska

Changing the subject: Depending on which computer I'm using and where
I happen to be at the time (home or away) I sometimes post using
Google Groups, sometimes using news.eternal-september.org via
Thunderbird. It seems to make little difference, except eternal-
september's interface is much better.

For whatever reason, my previous response and many other responses to
this thread do not appear via eternal-september. They do appear on
Google Groups.

I posted the above via Google Groups yesterday. I'm posting it via
eternal-september today. The problem persists today, and it's not just
me. Google shows about 22 posts in this thread. Eternal-september
shows about a dozen.

What the heck?

I see a similar pattern, and I'm aggregating several nntp sources, so
it would appear that the problem is with gurgle gropes, not ES.


I have been using albasani which appeared to be dropping posts so
changed to eternal-september.... which seems to be doing the same
thing.
--
Cheers,

John B.

On Sat, 31 Mar 2012 02:34:34 +0100, Phil W Lee
wrote:

John B. considered Fri, 30 Mar 2012 18:37:57
+0700 the perfect time to write:

On Fri, 30 Mar 2012 05:32:03 +0100, Phil W Lee
wrote:

John B. considered Fri, 30 Mar 2012 08:05:30
+0700 the perfect time to write:

On Thu, 29 Mar 2012 22:45:56 +0100, Phil W Lee
wrote:

User Bp considered Thu, 29 Mar 2012 04:28:42 +0000
(UTC) the perfect time to write:

I'm interested in moving the front brake caliper from the front of the
fork to the back. It's an old-fashioned Shimano 600 setup, far from
high tech but adequate for my riding. The motive is a little convoluted:
A roller dynamo is hanging on the caliper mount bolt, at the back.
A fender would be highly desirable, but is obstructed by the dynamo
(but not by a brake). If it were possible to "turn things around" so
the caliper was in back and the dynamo was in front a fender would fit.

It's clear the caliper reach would be longer and the angle to the
wheel different. Does anybody know if this can (or can't) be done
successfully?

Thanks for reading,

bob prohaska

You do realise that this has serious safety implications?
The caliper being on the front means that reaction forces hold the
front axle into the dropout, whereas if you move it to the rear, the
reaction forces will be attempting to eject the front axle from the
dropout.
A sensible safety standard would outlaw rear mounted front brake
calipers.

Wile you are certainly correct in regard to the difference in braking
forces on a front wheel equipped with a disk brake having the brake
pads mounted in front of versus behind the fork, I wonder whether the
question is as black and while with a rim brake?

The only reference I have found is a remark made by John Allen in
reference to front disk brakes:

"Your analysis of the forces imposed on the hub axle by the disk brake
is correct, and the alignment of the dropout slot with the direction
of this force guarantees failure if the quick release does not hold.
With a rim brake, weight transfer to the front wheel pushes the axle
*into* the dropout, and the deceleration force is partly taken up by
the forward angle and rake of the fork.

My bad - this only really applies to disk brakes, as you say.

I was considering the idea of putting both brakes on the back side of
the forks and the seat stays on a bike I am building up, thus you
gained my attention, rather forcefully :-)

Ah yes - for the front, that should be fine.
For the rear, see Mike Causer's post, and consider carefully the
direction of the dropouts.


I hear what you are saying but I'm not sure that moving the calipers
for a 700 C rear wheel brake something like 2 inches from in back of
to in front of the seat stays in going to make a tremendous difference
in the brake force vectors. After all rear brakes used to be fairly
commonly mounted below the chain stays.
--
Cheers,

John B.

On Sun, 01 Apr 2012 00:09:13 +0100, Phil W Lee
wrote:

John B. considered Sat, 31 Mar 2012 18:13:08
+0700 the perfect time to write:

On Sat, 31 Mar 2012 02:37:32 +0100, Phil W Lee
wrote:

Frank Krygowski considered Fri, 30 Mar
2012 11:08:51 -0400 the perfect time to write:

User Bp wrote:
I'm interested in moving the front brake caliper from the front of the
fork to the back. It's an old-fashioned Shimano 600 setup, far from
high tech but adequate for my riding. The motive is a little convoluted:
A roller dynamo is hanging on the caliper mount bolt, at the back.
A fender would be highly desirable, but is obstructed by the dynamo
(but not by a brake). If it were possible to "turn things around" so
the caliper was in back and the dynamo was in front a fender would fit.

It's clear the caliper reach would be longer and the angle to the
wheel different. Does anybody know if this can (or can't) be done
successfully?

Thanks for reading,

bob prohaska

Changing the subject: Depending on which computer I'm using and where
I happen to be at the time (home or away) I sometimes post using
Google Groups, sometimes using news.eternal-september.org via
Thunderbird. It seems to make little difference, except eternal-
september's interface is much better.

For whatever reason, my previous response and many other responses to
this thread do not appear via eternal-september. They do appear on
Google Groups.

I posted the above via Google Groups yesterday. I'm posting it via
eternal-september today. The problem persists today, and it's not just
me. Google shows about 22 posts in this thread. Eternal-september
shows about a dozen.

What the heck?

I see a similar pattern, and I'm aggregating several nntp sources, so
it would appear that the problem is with gurgle gropes, not ES.


I have been using albasani which appeared to be dropping posts so
changed to eternal-september.... which seems to be doing the same
thing.

Would it be too far-fetched to suspect that gurgle gropes may be
broken, or on a well-used spam blocklist?

From about 18:0 yesterday to 06:30 this morning I find 10 posts.
--
Cheers,

John B.

On Mar 29, 12:28*am, User Bp wrote:
I'm interested in moving the front brake caliper from the front of the
fork to the back. It's an old-fashioned Shimano 600 setup, far from
high tech but adequate for my riding. The motive is a little convoluted:
A roller dynamo is hanging on the caliper mount bolt, at the back.
A fender would be highly desirable, but is obstructed by the dynamo
(but not by a brake). If it were possible to "turn things around" so
the caliper was in back and the dynamo was in front a fender would fit.

It's clear the caliper reach would be longer and the angle to the
wheel different. Does anybody know if this can (or can't) be done
successfully?

Thanks for reading,

bob prohaska

One other thing to watch for depending on the age of your brake shoe
holders. Make sure they do not have an open end because if you turn
the caliper around to mount it behind the forkthe open ends of the
brake shoe holders will be facing the front of the bike and the brake
shoes can be ejected under pressure when the brakes are applied. I
haven't seen that type of holder in a long time but they do still
exist on some old bikes.

Cheers

James wrote:


Bob, I would leave it the way it is, and simply cut a slot in the fender
and possibly fashion a bit of PVC or similar to cover the whole shebang.

Or do something like this...

http://www.flickr.com/photos/55102679@N05/5878886758

That is a most interesting setup, not least because it exactly matches
the layout I wanted... But, in your case it's on the rear, and I need
to deal with the fork.

Very neat work, thank you for sharing the picture. What dynamo is shown?

bob prohaska

On Apr 1, 1:25*pm, User Bp wrote:
James wrote:

Bob, I would leave it the way it is, and simply cut a slot in the fender
and possibly fashion a bit of PVC or similar to cover the whole shebang..

Or do something like this...

http://www.flickr.com/photos/55102679@N05/5878886758

That is a most interesting setup, not least because it exactly matches
the layout I wanted... But, in your case it's on the rear, and I need
to deal with the fork.

Very neat work, thank you for sharing the picture. What dynamo is shown?

The dynamo is a Sanyo Dynapower, from the late 80's I think. I
resurrected it and built a headlight from 4 CREE LEDs. It works a
treat with the LEDs, but it had a habit of blowing globes which is why
I'd stopped using it. I tested it recently and found the output is
not self regulated to a low enough level to safely power incandescent
bulbs. It would need some form of protection (zener diodes for
example) for that.

--
JS.

On Apr 1, 7:51*am, James wrote:
On Apr 1, 1:25*pm, User Bp wrote:

James wrote:

Bob, I would leave it the way it is, and simply cut a slot in the fender
and possibly fashion a bit of PVC or similar to cover the whole shebang.

Or do something like this...

http://www.flickr.com/photos/55102679@N05/5878886758

That is a most interesting setup, not least because it exactly matches
the layout I wanted... But, in your case it's on the rear, and I need
to deal with the fork.

Very neat work, thank you for sharing the picture. What dynamo is shown?

The dynamo is a Sanyo Dynapower, from the late 80's I think. *I
resurrected it and built a headlight from 4 CREE LEDs. *It works a
treat with the LEDs, but it had a habit of blowing globes which is why
I'd stopped using it. *I tested it recently and found the output is
not self regulated to a low enough level to safely power incandescent
bulbs. *It would need some form of protection (zener diodes for
example) for that.

I just dug out my old notes from testing some dynamos when I was first
trying to learn about them. That was the first one I tested, by just
putting a standard AC voltmeter across it and taking voltage vs. speed
readings with the bike on a workstand. Anyway, I took voltage values
with a few different loads, and I see I was having some trouble,
because I got inconsistent readings in come cases.

But speaking of blowing bulbs, when I tested it with a Union halogen
headlight plus incandescent taillight, I got an indicated 7.25 VAC at
20 mph. But when I tried it with the headlight alone, it blew the
bulb at 16 mph! So my bench test experience matches James's on-bike
experience. (On my bike, I always used it with an incandescent
taillight, and it was fine. Except it had lower output at low speeds
like 6 to 8 mph than most other dynamos. I remember that annoying me
when I was riding my bike slowly around some campgrounds.)

The other interesting point about that dynamo is that its output (on
an oscilloscope) doesn't look anything like a sine wave. All the
others I tested were basically sinusoidal, perhaps with a bit of a
harmonic. That means my primitive AC meter would probably not have
been giving accurate RMS values. I later borrowed a true-RMS meter
for testing other dynamos, but I never re-tested the Sanyo.

- Frank Krygowski