Spoke life with disc brakes
Brian Huntley
brakes shorten spoke life enough to eliminate the seeming advantage in
rim life discs bring.
Any opinions here?
landotter
Well--if that claim was made with no good evidence, then it's bunk.
The rim life argument is pretty silly. You can get a really decent rim
for the price of the average rotor or even run ceramics. Run whichever
brakes you happen to like, but if you run disks...bring spare pads on
tour. ;-)
thirty-six
If you must insist on using a go slower device, use rim brakes unless
using Westwood rims or are setting up a downhill eventing bike.
carl...@comcast.net
Dear Brian,
Most braking occurs on symmetrical front wheels.
Disk brakes transmit braking torque through some of the spokes.
***
Rear wheels are usually weaker than front wheels, being dished.
Rear wheels transmit torque from the pedals through some the spokes.
***
The spokes on well-built rear wheels last an awfully long time.
Cheers,
Carl Fogel
Chalo
>
> 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?
>
> Dear Brian,
>
> Most braking occurs on symmetrical front wheels.
>
> Disk brakes transmit braking torque through some of the spokes.
>
> ***
>
> Rear wheels are usually weaker than front wheels, being dished.
>
> Rear wheels transmit torque from the pedals through some the spokes.
>
> ***
>
> The spokes on well-built rear wheels last an awfully long time.
Your point is concise and accurate in any case, but just to be fair:
Disc front wheels are dished.
Chalo
Qui si parla Campagnolo
I don't see how spoke life is diminished. On a well built wheel,
whether it be disc or non disc as long as the rim doesn't get wacked
and change the tension, making for broken spokes, the weak link is
still the rim, not the spokes or the hub.
Zog The Undeniable
The forces are quite high, but they don't occur very often compared with
the fatigue from just rolling along.
thirty-six
Spoke fatigue is not from 'just rolling along'. Fatigue failure of a
spoke near to the hub flange is caused by repeated bending. This is
activated by 'just rolling along' but the cause is an improper build.
Elimination of the spoke bows during wheel construction eliminates
spoke failure no matter how much 'just rolling along' you do.
Chalo
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.
Chalo
thirty-six
up with spaghetti
carl...@comcast.net
Dear Chalo,
You're right--oops!
Cheers,
Carl Fogel
Tom Sherman °_°
> [...]
> Your point is concise and accurate in any case, but just to be fair:
Not on a tadpole trike.
<http://www.flickr.com/photos/19704682@N08/1939614761/sizes/o/in/set-72157619269233805/>
<http://www.flickr.com/photos/19704682@N08/1939615951/sizes/o/in/set-72157619269233805/>
--
Tom Sherman - 42.435731,-83.985007
I am a vehicular cyclist.
Tosspot
I wondered about that, then I thought, what the hell, the rear one is dished.
Do you think it makes ant practical difference?
Tosspot
> 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-72157619269233805/>
>
> <http://www.flickr.com/photos/19704682@N08/1939615951/sizes/o/in/set-72157619269233805/>
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?
Lou Holtman
In this part of the world spoke breakage has become very rare even with
dished 10 speed wheels and diskbrakes. It has become almost a non issue.
Last spoke I broke was some 20 years ago.
Lou
thirty-six
>
> > <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?
Italian influence.
thirty-six
> 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.
thirty-six
So why mention it? Durability of a wheel is more than spoke
breakage. Tracking accuracy and and biuckling come to mind.
Jobst Brandt
>>> Any opinions here?
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.
Jobst Brandt
Jobst Brandt
>>> Any opinions here?
The amount of conjecture in this thread implies that the writers
Tosspot
No, I recall distinctly, it was a German influence.
thirty-six
spaghetti spokes
thirty-six
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.
RonSonic
>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.
Norman
> 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@N08/1939615951/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.
thirty-six
It might be normal, but it's not right. That is what makes for
torsional (about forward direction axis) defficiency in a 27" wheel.
Chalo
>
> 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
pdxrandonneur
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
thirty-six
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.
Chalo
>
> 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
thirty-six
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.
Marcus Coles
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
thirty-six
>
> 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.
Will do. I'll do it neat although as I've said before, other oils are
used in the mix to improve the ratio of antioxidants, just dont know
what they are, although it has been said that 3in1 contained fish
oil. I think this has to be tested as the experience with hot engines
and atomisers is not the same as cold chain lubrication. It is of
course possible that the intention was to gum up the chain after a
period of time so that the magic lubricant needed re-application. I
will experiment. Probably spot 2.5ml on a ceramic saucer, one indoors
and one outdoors for one week, if there are no other suggestions
relating to this.
Norman
> 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.
My Industrial Chemistry book lists it as a non-drying oil,
typical iodine numbers look to be 83-88, based on obviously
non-scientific web-extracted values. My Chemist took one
look at me and won't sell me anything that can be used for
nitration or ricin production.
thirty-six
> My Industrial Chemistry book lists it as a non-drying oil,
> typical iodine numbers look to be 83-88, based on obviously
> non-scientific web-extracted values. My Chemist took one
> look at me and won't sell me anything that can be used for
extracted with water, it is not in the oil.
Patrick Lamb
<pe...@vecchios.com> wrote:
>On Nov 21, 8:41�pm, Brian Huntley <brian_hunt...@hotmail.com> 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?
>
>I don't see how spoke life is diminished. On a well built wheel,
>whether it be disc or non disc as long as the rim doesn't get wacked
>and change the tension, making for broken spokes, the weak link is
>still the rim, not the spokes or the hub.
Just catching up, but perhaps you just identified why disc brakes
shorten spoke life. Disc brakes usually are on mountain bikes, which
are more likely to end up with creatively non-round configurations,
ruining the spokes as well as the rest of the wheel?
Email address works as is.
thirty-six
A good case for tied and soldered spokes. Maybe even Ezekiel rings.
Qui si parla Campagnolo
That's true. MTB wheels get wacked more often than road wheels. Why
some wheels that come on MTB's outtaboxes are so poorly designed and
made mystifies me. The ones on Specialized MTBs come to mind. Not
enough thin spokes on a light rim, made poorly to boot.
thirty-six
That one was sticky, unlike the oil atmospheric test. The external
test was abondoned due to much contamination because of wind and heavy
rain. The internal test showed no gumming of the oil.
thirty-six
24 is the minimum for rough conditions and allows no room for
redundancy of spokes. 36 spokes permits the loss of two spokes per
quadrant and is a good amount of overkill. 15swg is more than enough
over a 12" span and lighter gauges can not improve wheel stability.
Jobst Brandt
>>>> A discussion on CrazyGuyOnaBike.com has one camp claiming that
>>>> disc brakes shorten spoke life enough to eliminate the seeming
>>>> advantage in rim life disks bring.
>>>> Any opinions here?
>>> I don't see how spoke life is diminished. On a well built wheel,
>>> whether it be disc or non disc as long as the rim doesn't get
>>> whacked and change the tension, making for broken spokes, the weak
>>> link is still the rim, not the spokes or the hub.
>> Just catching up, but perhaps you just identified why disc brakes
>> shorten spoke life. Disc brakes usually are on mountain bikes,
>> which are more likely to end up with creatively non-round
>> configurations, ruining the spokes as well as the rest of the
>> wheel?
> That's true. MTB wheels get whacked more often than road wheels.
> Why some wheels that come on MTB's out of boxes that are so poorly
> designed and made it mystifies me such as the ones on Specialized
> MTB's with thin spokes with light and poorly made rims, to boot.
I don't believe that has much to do with spoke life with disks. It is
more likely spoke holes in the hub are poorly bored in flanges of the
wrong width. You didn't say where they break and what thickness of
spoke, but I think it is at the elbow... something that has little to
do with packaging or wheel alignment.
As you know, spokes are only unloaded under riding loads and with a
poor spoke line and no stress relief, I would expect failures,
especially with lesser quality spokes and oversized flange holes.
Let's look for causes where they are. This sounds like the claim that
cranks break from riding too large a gear, when they break crosswise,
rather than in line with torque loads.
Jobst Brandt
AMuzi
We have not seen any rash of MTB broken spokes and there's
no reason to believe they should be any more frequent than
on a normal bicycle.
"...rim doesn't get whacked and change the tension, making
for broken spokes,..."
Such a rim will have looser spokes and at least around my
area a 26" wheel bike gets a small fraction of the mileage
road bikes accrue in a year.
Regarding hubs, Shimano is the dominant supplier for 26"
wheel hubs, hubs being an area in which they excel, and no
flange issues are observed.
When you get down to XMart BSOs, 26" MTB wheels and the 700C
suck equally and exhibit all kinds of troubles. But that's
another discussion.
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
thirty-six
> Peter Chisholm wrote:
> > That's true. MTB wheels get whacked more often than road wheels.
> > Why some wheels that come on MTB's out of boxes that are so poorly
> > designed and made it mystifies me such as the ones on Specialized
> > MTB's with thin spokes with light and poorly made rims, to boot.
>
> I don't believe that has much to do with spoke life with disks. It is
> more likely spoke holes in the hub are poorly bored in flanges of the
> wrong width. You didn't say where they break and what thickness of
> spoke, but I think it is at the elbow... something that has little to
> do with packaging or wheel alignment.
>
> As you know, spokes are only unloaded under riding loads and with a
> poor spoke line and no stress relief, I would expect failures,
> especially with lesser quality spokes and oversized flange holes.
Doesn't happen. Build technique covers it.
>
> Let's look for causes where they are.
Spoke bowing for the umpteenth time. The change in tension of a
bowing spoke causes bending loads at the spoke elbow.