Spoke life with disc brakes

On 22 Nov, 19:49, Jobst Brandt wrote:
Chalo Colina wrote:
A discussion on CrazyGuyOnaBike.com has one camp claiming that disc
brakes shorten spoke life enough to eliminate the seeming advantage in
rim life discs bring.
Any opinions here?
The forces are quite high, but they don't occur very often compared
with the fatigue from just rolling along.
The quite-high forces you mention are distributed among all
tangentially laced spokes in the wheel. *Thus they are not large on
a per spoke basis. *And as Carl Fogel points out, they are on the
same close order of magnitude as the forces applied to the rear
wheel's spokes by pedaling.
The fact that disc front wheels are dished is of far more
significance to wheel durability.

The amount of conjecture I in this thread implies that the writers
missed these analyses in "the Bicycle Wheel" where the matter is
measured, computed and shown in detailed annotated graphs.


That work is irrelevant to real bicycle wheels which have to steer and
brake at the same time. The forces are easily great enough to
collapse an improperly built wheel when you use a hub brake system on
normal rims and spokes. In a lot of cases, this is why non-
interlaced spokes are used on hub brakes, but get the interlace
correct and you dont negate the benefit by not having it.

On Sun, 22 Nov 2009 09:34:02 -0800 (PST), Chalo wrote:

Zog The Undeniable wrote:

Brian Huntley wrote:

A discussion on CrazyGuyOnaBike.com has one camp claiming that disc
brakes shorten spoke life enough to eliminate the seeming advantage in
rim life discs bring.

Any opinions here?

The forces are quite high, but they don't occur very often compared with
the fatigue from just rolling along.

The quite-high forces you mention are distributed among all
tangentially laced spokes in the wheel. Thus they are not large on a
per spoke basis. And as Carl Fogel points out, they are on the same
close order of magnitude as the forces applied to the rear wheel's
spokes by pedaling.

They are traction and tipover limited, but still far greater than anything you
can create by pedaling.

The fact that disc front wheels are dished is of far more significance
to wheel durability.

That is a bigger deal.

On Nov 22, 2:28*pm, Tosspot wrote:
Tom Sherman °_° wrote:
Chalo Colina wrote:
[...]
Your point is concise and accurate in any case, but just to be fair:
Disc front wheels are dished.[...]

Not on a tadpole trike.
http://www.flickr.com/photos/19704682@N08/1939614761/sizes/o/in/set-7....

http://www.flickr.com/photos/19704682@N08/1939615951/sizes/o/in/set-7....

Is it just me (truth be known I've had a few beers), but isn't the spoke to the
right of the label on the rim *horribly bent?

Looks like fairly normal curve for interlaced spokes, on 36 3x
(& what are those? 406?) 406 rims. You should see what
happens when you interlace 36 spoke 1x, or 28 spoke 3x on
high-flange hubs for that matter.

On 24 Nov, 21:23, Norman wrote:
On Nov 22, 2:28*pm, Tosspot wrote:

Tom Sherman °_° wrote:
Chalo Colina wrote:
[...]
Your point is concise and accurate in any case, but just to be fair:
Disc front wheels are dished.[...]

Not on a tadpole trike.
http://www.flickr.com/photos/19704682@N08/1939614761/sizes/o/in/set-7...

http://www.flickr.com/photos/19704682@N08/1939615951/sizes/o/in/set-7...

Is it just me (truth be known I've had a few beers), but isn't the spoke to the
right of the label on the rim *horribly bent?

Looks like fairly normal curve for interlaced spokes, on 36 3x
(& what are those? *406?) 406 rims. *You should see what
happens when you interlace 36 spoke 1x, or 28 spoke 3x on
high-flange hubs for that matter.


It might be normal, but it's not right. That is what makes for
torsional (about forward direction axis) defficiency in a 27" wheel.

Tosspot wrote:

Chalo wrote:

The fact that disc front wheels are dished is of far more significance
to wheel durability.

I wondered about that, then I thought, what the hell, the rear one is dished.
Do you think it makes ant practical difference?

Sure, why not? A dished front wheel won't outlast a dished rear wheel
by 3X or more as is typical with symmetrical fronts. It may or may
not be consequential, but it is a difference.

Chalo

On Nov 22, 11:42*am, thirty-six wrote:
On 22 Nov, 19:26, Tosspot wrote:

I wondered about that, then I thought, what the hell, the rear one is dished.
Do you think it makes ant practical difference?

Olive oil, basil, bit of cheese, it'll be fine with a fork.

At a bike shop I once worked at a women came in with a drive train
that was absolutely ruined. It looked like she had poured epoxy all
over her chain and then rolled it in mud and leaves. When I enquired
as to what had happened, she explained that the chain had been giving
her problems and a friend of hers told her to oil it. It turned out
that she had used olive oil. I got yelled at by the boss for telling
her with a straight face that you must only use extra-virgin on
bicycle chains.

-Rando

On 25 Nov, 21:45, pdxrandonneur wrote:
On Nov 22, 11:42*am, thirty-six wrote:

On 22 Nov, 19:26, Tosspot wrote:

I wondered about that, then I thought, what the hell, the rear one is dished.
Do you think it makes ant practical difference?

Olive oil, basil, bit of cheese, it'll be fine with a fork.

At a bike shop I once worked at a women came in with a drive train
that was absolutely ruined. It looked like she had poured epoxy all
over her chain and then rolled it in mud and leaves. When I enquired
as to what had happened, she explained that the chain had been giving
her problems and a friend of hers told her to oil it. It turned out
that she had used olive oil. I got yelled at by the boss for telling
her with a straight face that you must only use extra-virgin on
bicycle chains.

* * * * * * * * * * * * * -Rando

Castor oil, or possibly almond, although probably too thin to last any
appreciable time. Lard should also be good. I do know of a bike
shop from some years back who serviced racing bikes that definitely
had a recipe for their bearing and chain oil which did include
vegetable oils although the specifics escaped my attention, I think
there may have been a little olive oil in there. So it looks like the
olive oil was the thickening part of the mix, although I would have
thought a drop of linseed would do the trick.

In fact, come to think of it, castor and linseed could be the ideal
chain lubricant if I could be bothered to work out a mix. I think
I'll stick to grease soaking for the winter.

thirty-six wrote:

Castor oil, or possibly almond, although probably too thin to last any
appreciable time. * Lard should also be good. *I do know of a bike
shop from some years back who serviced racing bikes that definitely
had a recipe for their bearing and chain oil which did include
vegetable oils although the specifics escaped my attention, I think
there may have been a little olive oil in there. *So it looks like the
olive oil was the thickening part of the mix, although I would have
thought a drop of linseed would do the trick.

In fact, come to think of it, castor and linseed could be the ideal
chain lubricant if I could be bothered to work out a mix. *I think
I'll stick to grease soaking for the winter.

Trevor's home planet must not have oxygen in its atmosphere, because
otherwise he'd know that using vegetable oils as lubricants leads
first to rancidity and then to polymerization and a resultant
intractable gummy, smelly mess.

Chalo

On 25 Nov, 23:18, Chalo wrote:
thirty-six wrote:

Castor oil, or possibly almond, although probably too thin to last any
appreciable time. * Lard should also be good. *I do know of a bike
shop from some years back who serviced racing bikes that definitely
had a recipe for their bearing and chain oil which did include
vegetable oils although the specifics escaped my attention, I think
there may have been a little olive oil in there. *So it looks like the
olive oil was the thickening part of the mix, although I would have
thought a drop of linseed would do the trick.

In fact, come to think of it, castor and linseed could be the ideal
chain lubricant if I could be bothered to work out a mix. *I think
I'll stick to grease soaking for the winter.

Trevor's home planet must not have oxygen in its atmosphere, because
otherwise he'd know that using vegetable oils as lubricants leads
first to rancidity and then to polymerization and a resultant
intractable gummy, smelly mess.


That would depend on precise operating conditions. Castor oil is a
particularly good lubricant and is not as higly susceptible to
oxidation as you suggest. The mixes used were not only used on track
bikes but on regular everyday road machines as well. I dont KNOW what
the mix was but was certainly vegetable based, the difference is smell
between a regular mineral lubricating oil and the oil used in the bike
shop was clear to me despite beiong rather young. The slight 'sweet'
smell of castor seems to trigger memories of this one shop. His
prices were higher, but even at six I knew the proprieter here was
"better" even if I could ignore all the shiny shiny wheels. I dont
know how you can encourage children with black wheels, they want
chrome and bright tyres. I still do. Mind you I have developed a
penchant for enamelled Westwoods with gold lining. If i can find some
20swg Westwoods This will be the basis around I'll build my sand
rider.

thirty-six wrote:
On 25 Nov, 23:18, Chalo wrote:
thirty-six wrote:

Castor oil, or possibly almond, although probably too thin to last any
appreciable time. Lard should also be good. I do know of a bike
shop from some years back who serviced racing bikes that definitely
had a recipe for their bearing and chain oil which did include
vegetable oils although the specifics escaped my attention, I think
there may have been a little olive oil in there. So it looks like the
olive oil was the thickening part of the mix, although I would have
thought a drop of linseed would do the trick.
In fact, come to think of it, castor and linseed could be the ideal
chain lubricant if I could be bothered to work out a mix. I think
I'll stick to grease soaking for the winter.
Trevor's home planet must not have oxygen in its atmosphere, because
otherwise he'd know that using vegetable oils as lubricants leads
first to rancidity and then to polymerization and a resultant
intractable gummy, smelly mess.


That would depend on precise operating conditions. Castor oil is a
particularly good lubricant and is not as higly susceptible to
oxidation as you suggest. The mixes used were not only used on track
bikes but on regular everyday road machines as well. I dont KNOW what
the mix was but was certainly vegetable based, the difference is smell
between a regular mineral lubricating oil and the oil used in the bike
shop was clear to me despite beiong rather young. The slight 'sweet'
smell of castor seems to trigger memories of this one shop. His
prices were higher, but even at six I knew the proprieter here was
"better" even if I could ignore all the shiny shiny wheels. I dont
know how you can encourage children with black wheels, they want
chrome and bright tyres. I still do. Mind you I have developed a
penchant for enamelled Westwoods with gold lining. If i can find some
20swg Westwoods This will be the basis around I'll build my sand
rider.

Being old enough to be a former user of castor based oils in two strokes
I concur with Chalo. Castrol R was more stable due to additives but
still exhibited this behaviour.

It is a good lubricant, doesn't burn easily, in a two stroke it pretty
just gets atomized and blown out the pipe.

The rule of thumb was drain the tank and carb as soon as you got back to
the shop and tear down the engine and clean it out fairly regularly too.

Failure to do so would result in an evil rubbery gum deposit.

Castor oil like most vegetable oils oxidizes fairly readily.
Don't believe me? Run down to the Chemist's and buy a small bottle, pour
it in a saucer (away from your pets) and come back in a week.

For two stroke engines modern synthetics are a vast improvement in
reduction of hassle, but they lack that smell, that pungent racing two
stroke smell. Smelled like....victory.

Now back to disc brakes and spokes, while remembering drum brakes and
spokes.


Marcus