Dropout adjuster screws

On Dec 27, 3:05*am, wrote:
someone in the UK wrote:
Billions of bicycles around the world use horizontal slot frame
ends, it's the normal way to adjust for chain 'tension'. *No chain
tension ever broke the frame ends. *Even cheap mass produced bikes
in what used to be called the third world do not break frame ends
from chain tension.

You are speaking for your experience.

It is the experience of billions of people.

*I've broken dozens of
Campagnolo axles and had the right rear Campagnolo dropout replaced
twice before I had the last failure replaced by a vertical dropout.

You are an awkward cuss, who despite the repeated evidence that you
personally are unable to live with a racing bicycle and specifically
its components, continue to do so and make unecessary complaint
because you know best.

That one has lasted nearly 30 years of similar riding and I don't need
to pound with my fist on the tire to make the wheel drop out when I
open the QR.

Neither do I and I've never had an axle stick.

I don't recall which ones may or may not have had steel inserts,
but I'm pretty sure that at least some of them didn't.

That's not the feature of interest, but rather which way the slot
runs.

Vertical slotted frame ends reduce tyre choices in race style frames
for you average user.

On Dec 27, 2:43*pm, wrote:
James Steward wrote:
This has nothing to do with QR's. *It is purely a function of fore and
aft support of the axle jam nut on the right side of the bicycle.
That is where the axles and dropouts break off from lack of support
for axle flex caused by chain tension.
Neither the QR's on my Cannondale (unlabeled ones, presumably the
ones that came with the bike, with "Gipiemme" wheels - which have
been replaced BTW) nor the few Shimano ones that I have from
105-level hubs would keep the rear in place on my Trek. *However,
some old school Dura-Ace QR's solved the problem nicely.
"nicely" := "temporarily". *Don't bet on it. *Horizontally slotted
dropouts do not support fore and aft flex of the axle and lead to axle
and dropout failures. *That's why they are no longer in use on current
bicycles.
It's true -- though not necessarily obvious -- chain forces are quite
high.
Many assume rider's weight to be most significant but when you push
down on the pedal, force is (roughly) doubled via crank to chain.
Took me a while to realize why Jobst is right about this...
Not that I wish to contradict what Jobst asserts is the reason for
axle and dropout failures, but have you considered the loading
applied to the rear axle and dropout assembly as a result of riding over
a substantial bump? *What is the peak loading from such an event?
Is it enough to start a crack that propagates over time?
The tradish Campy ones seemed to be a little under engineered to me,
compared with a modern vertical dropout or a track or BMX bike
horizontal dropout.
It would be interesting to see some closeup pictures of cracked/broken
dropouts, to see where they're broken and where the crack started and
the direction it propagated.
Could the indentations from the axle nuts start a crack?
Still says to me the whole mechanical structure was under engineered.
The modern vertical style has much less room for bending, AFAICT.
Older Horizontal:

*http://farm4.static.flickr.com/3162/...5a2567.jpg?v=0

The ones I had broke through the threaded hole for the axle
positioning screw and broke in the direction of axle flex from chain
pull.

If the chain pull was the cause, wouldn't the crack develop at right
angles to the direction of pull?

Modern Vertical:

*http://www.flickr.com/photos/55102679@N05/5112298985/

That doesn't look like the ones Campagnolo offers these days.

It may not. Does it matter the manufacturer?

I think you need to look at failed axles and note that they are bent
in the direction that they break dropouts... forward with chain pull.

That doesn't add up. The hole for the adjuster is horizontal, and the
crack through it is likewise. The bending induced by chain pull, I
would have thought, should not occur so as to cause failure in that
way. I would expect a failure with a vertical crack in the top part
of the horizontal slot.

Besides. I've ridden many miles over bumpy dirt roads with my vertical
dropouts without failures. *Last Chance Road is the bumpiest washboard
road I know in the Santa Cruz Mountains. *Much of it must be ridden
standing, it is so rough.

Also my axle and dropout failures ocurred on climbs of paved roads.

I don't recall breaking any more axles once I swapped to using a
cassette instead of a screw on cluster, where in the cassette the
bearing is moved much further out from the hub centre, closer to the
axle end, regardless of the dropout being horizontal or not.

Regards,
James.

On Dec 26, 9:43*pm, wrote:
James Steward wrote:
This has nothing to do with QR's. *It is purely a function of fore and
aft support of the axle jam nut on the right side of the bicycle.
That is where the axles and dropouts break off from lack of support
for axle flex caused by chain tension.
Neither the QR's on my Cannondale (unlabeled ones, presumably the
ones that came with the bike, with "Gipiemme" wheels - which have
been replaced BTW) nor the few Shimano ones that I have from
105-level hubs would keep the rear in place on my Trek. *However,
some old school Dura-Ace QR's solved the problem nicely.
"nicely" := "temporarily". *Don't bet on it. *Horizontally slotted
dropouts do not support fore and aft flex of the axle and lead to axle
and dropout failures. *That's why they are no longer in use on current
bicycles.
It's true -- though not necessarily obvious -- chain forces are quite
high.
Many assume rider's weight to be most significant but when you push
down on the pedal, force is (roughly) doubled via crank to chain.
Took me a while to realize why Jobst is right about this...
Not that I wish to contradict what Jobst asserts is the reason for
axle and dropout failures, but have you considered the loading
applied to the rear axle and dropout assembly as a result of riding over
a substantial bump? *What is the peak loading from such an event?
Is it enough to start a crack that propagates over time?
The tradish Campy ones seemed to be a little under engineered to me,
compared with a modern vertical dropout or a track or BMX bike
horizontal dropout.
It would be interesting to see some closeup pictures of cracked/broken
dropouts, to see where they're broken and where the crack started and
the direction it propagated.
Could the indentations from the axle nuts start a crack?
Still says to me the whole mechanical structure was under engineered.
The modern vertical style has much less room for bending, AFAICT.
Older Horizontal:

*http://farm4.static.flickr.com/3162/...5a2567.jpg?v=0

The ones I had broke through the threaded hole for the axle
positioning screw and broke in the direction of axle flex from chain
pull.

Modern Vertical:

*http://www.flickr.com/photos/55102679@N05/5112298985/

That doesn't look like the ones Campagnolo offers these days.

I think you need to look at failed axles and note that they are bent
in the direction that they break dropouts... forward with chain pull.
Besides. I've ridden many miles over bumpy dirt roads with my vertical
dropouts without failures. *Last Chance Road is the bumpiest washboard
road I know in the Santa Cruz Mountains. *Much of it must be ridden
standing, it is so rough.

Also my axle and dropout failures ocurred on climbs of paved roads.

The people who broke horizontal DO's in my old cohort were the "curb
hoppers".
I preferred to embarrass myself by unclipping one foot and stepping
over, rather than by a mis-timed lift or drop.
Being of a relatively heavy build and a good 25 lbs. and more heavier
than at least one of these "climbers" who broke rear DO's, while we
all rode the same bumpy dirt and gravel roads on our Sunday
explorations of such surfaces, and never breaking a DO even while
mounted on the same make/model/approx. year of frame in at least a
couple of instances, I'd guess the extremely bumpy roads killed your
DO's and axles (I did break one freewheel-style Campy axle in that
era), which coincidentally gave up the ghost on smoother paved
surfaces.

Perhaps you had certain routes with an aspect of routine in them? IOW,
where the punishment pushed the parts to near breaking, and one of
your high-gear climbs finished them off?

I don't exactly remember or have photos of these old broken horizontal
DO's, so I don't know if the break pattern matches your examples. I do
seem to remember one of these "hopper" guys also breaking a DO on his
early Ti Merlin; unknown if these DO's were still horizontal design,
or had migrated to vertical. Also, I seem to remember rear DO breakage
not being unknown on these early Ti frames-- Merlin notable, at least
partly because they were "leaders", and perhaps partly because they
were emphasizing "light"-- which might be supported by very "block-y"
DO's being the norm on many later Ti production frames such as my
Litespeed.

BTW, I have an early Merckx Ti bike, a retired Eurp pro example, that
has short horizontal DO's that is doing just fine and doesn't need the
wheels hammered on to change flats even after being subjected to
hauling my considerable contemporary bulk up hills in low gears. But
then, I still don't jump curbs g or for that matter seek out nasty
washboard roads to ride on these days.

I have seen "stuck" rear wheels but they are not at all normal IME.

BTW II, I'm not saying I prefer freewheels and horizontal DO's g.
--D-y