max load rating for road bikes?



[email protected] wrote:
> On Feb 20, 9:00 pm, jim beam <[email protected]> wrote:
>> [email protected] wrote:
>>> Here are the only pictures I'm aware of ever taken of any of my bikes
>>> (it's the orange hardtail):
>>> from the back:http://www.mtbadventureseries.org/mtbadventure/EventPics/IMG_3386.JPG
>>> orhttp://tinyurl.com/2pgtwj
>>> from the front:http://www.mtbadventureseries.org/mtbadventure/EventPics/IMG_3255.JPG
>>> orhttp://tinyurl.com/3xxufb

>> dude, keep a /real/ close eye on those cranks for fatigue. inspect them
>> /every/ ride.

>
> Why is that? I appreciate any heads up you may be able to offer me.
> Were you actually able to identify the model from those pictures, or
> are you biased against the brand in general? Perhaps you were just
> commenting on the obvious wear? The rest of the bike, save for the
> new fork, shows the same amount of wear. It's been holding up great
> so far. I do inspect it occasionally, but nowhere near every ride.


it's a matter of design. with those dimensions, is going to experience
more elastic strain than a "beefier" or better yet, hollow section
profile crank. elastic strain begets fatigue. especially when there
are fatigue initiators such as the inevitable nicks and scratches that
cranks pick up in the field.


>
> If you wanted to see pictures of things I ride that look like they'll
> fail on the next ride I could provide a few examples, assuming I
> bother to dig out a camera and take some pictures. Somehow they tend
> to keep going. I heard all last season that my rear rim was going to
> blow off the tire, the rim being seriously pinched/dented from a rock
> it was bounced off during a crash. It's still going strong, much to
> everyone's surprise.
>
 
On Feb 21, 4:10 pm, jim beam <[email protected]> wrote:
> [email protected] wrote:
> > Why is that? I appreciate any heads up you may be able to offer me.
> > Were you actually able to identify the model from those pictures, or
> > are you biased against the brand in general? Perhaps you were just
> > commenting on the obvious wear? The rest of the bike, save for the
> > new fork, shows the same amount of wear. It's been holding up great
> > so far. I do inspect it occasionally, but nowhere near every ride.

>
> it's a matter of design. with those dimensions, is going to experience
> more elastic strain than a "beefier" or better yet, hollow section
> profile crank. elastic strain begets fatigue. especially when there
> are fatigue initiators such as the inevitable nicks and scratches that
> cranks pick up in the field.


Interesting theory. They're cook brothers cranks, and have been in
service without issue for over 10 years. Hard service, as you can
tell by looking. I'll give them a thorough inspection next time I'm
at the bike, likely tomorrow and report back. I will be surprised if
there's any issue though, they've been rather bulletproof so far.
 
On 21 Feb 2008 19:28:25 GMT, [email protected] wrote:

># It appears that the better spokes now available would have made the
># discovery of many of the concepts of this book more difficult for
># lack of failure data. I am grateful in retrospect for the poor
># durability of earlier spokes. They operated so near their limits
># that durability was significantly altered by the techniques that I
># have outlined.
>
>> --Jobst Brandt, "The Bicycle Wheel," 3rd Edition, 1993, p.124

>
>The quote is from text I wrote about 30 years ago, (not 1993)


Dear Jobst,

You seem to be confused.

This is 2008.

The quote is from page 124 of the 1993 3rd edition of "The Bicycle
Wheel," which is 15 years ago, not 30 years ago.

It was added as the third paragraph of the previously two-paragraph
"Spoke Strength" section, right before the stress-strain test graphs.

The two-paragraph "Spoke Strength" section appears on page 131 of my
1981/1983 first edition, after which the early stress-strain graphs
appear for Union, Robegel, and DT spokes, with both stainless steel
and non-stainless steel (carbon) versions.

An obviously revised two-paragraph "Spoke Strength" section appears on
page 132 of my 1988 second edition, addressing entirely new tests of
stainless steel (carbon spokes had fallen by the wayside) from DT and
WheelSmith.

Those new stress-strain tests for new spokes for the second edition in
1988, 20 years ago, produced strikingly different stress-strain
results:

"In contrast to tests performed for the first edition of this book,
these spokes stretched more than six millimeters without breaking, at
which point the test was stopped."

--p. 132, 2nd edition

The passage that I keep quoting does not appear in the first or second
editions. It appeared in 1993 in the third edition as an entirely new
third paragraph in what was previously a two-paragraph "Spoke
Strength" section.

Anyone reading the three editions would take it that you were adding
new material in 1993 to address the obvious and widely noted change in
spoke failures in the ten years since the first edition in 1981/1983.

Riders used to carry spare spokes on century rides, but that habit
pretty much vanished by the time that the quote appeared in the 1993
edition.

Since 2004, you've posted numerous replies in RBT threads where I've
included that quote with the same page number, date, and edition:

http://groups.google.com/group/rec.bicycles.tech/search?q=carl+jobst+p.124&start=0&scoring=d&

Has some new explanation suddenly occurred to you after you've been
replying to that quote since 2004?

Your claim simply doesn't make sense to anyone who looks at the text
of the three editions.

Since most people haven't got all three editions, here are the three
complete versions of the text of the "Spoke Strength' section, showing
where the passage in question first appears:

1st edition, 1981/1983, with old Union, DT, and Robegel spoke tests,
some stainless, some carbon:
http://i27.tinypic.com/5mi7ph.jpg

2nd edition, 1988, with completely new DT and Wheelsmith spoke tests,
all stainless steel:
http://i28.tinypic.com/f2ty8j.jpg

3rd edition, 1993, adds the quoted passage as a third paragraph:
http://i25.tinypic.com/ixaxdk.jpg

Cheers,

Carl Fogel
 
Michael Press wrote:
> In article <[email protected]>,
> Tom Sherman <[email protected]> wrote:
>
>> "jim beam" WHO? wrote:
>>> Tom Sherman wrote:
>>>> "jim beam" wrote:
>>>>> [email protected] wrote:
>>>>>> [...]
>>>>>> Here are the only pictures I'm aware of ever taken of any of my bikes
>>>>>> (it's the orange hardtail):
>>>>>> from the back:
>>>>>> http://www.mtbadventureseries.org/mtbadventure/EventPics/IMG_3386.JPG
>>>>>> or http://tinyurl.com/2pgtwj
>>>>>> from the front:
>>>>>> http://www.mtbadventureseries.org/mtbadventure/EventPics/IMG_3255.JPG
>>>>>> or http://tinyurl.com/3xxufb
>>>>> dude, keep a /real/ close eye on those cranks for fatigue. inspect
>>>>> them /every/ ride.
>>>>>
>>>> What brand and model are the cranks, and are they known for having a
>>>> fatigue cracking problem?
>>>>
>>> bored tom? can't be bothered to do any of your own homework this evening?

>> So I should spend hours doing web searches for pictures of cranks to
>> identify the model on the bicycle in question, when "jim beam" could
>> provide us the answer?

>
> This is the bait and switch. jb is in sales.
>

Yes, BS works a lot better in sales than in engineering.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful
 
Tom Sherman wrote:
> Michael Press wrote:
>> In article <[email protected]>,
>> Tom Sherman <[email protected]> wrote:
>>
>>> "jim beam" WHO? wrote:
>>>> Tom Sherman wrote:
>>>>> "jim beam" wrote:
>>>>>> [email protected] wrote:
>>>>>>> [...]
>>>>>>> Here are the only pictures I'm aware of ever taken of any of my
>>>>>>> bikes
>>>>>>> (it's the orange hardtail):
>>>>>>> from the back:
>>>>>>> http://www.mtbadventureseries.org/mtbadventure/EventPics/IMG_3386.JPG
>>>>>>>
>>>>>>> or http://tinyurl.com/2pgtwj
>>>>>>> from the front:
>>>>>>> http://www.mtbadventureseries.org/mtbadventure/EventPics/IMG_3255.JPG
>>>>>>>
>>>>>>> or http://tinyurl.com/3xxufb
>>>>>> dude, keep a /real/ close eye on those cranks for fatigue.
>>>>>> inspect them /every/ ride.
>>>>>>
>>>>> What brand and model are the cranks, and are they known for having
>>>>> a fatigue cracking problem?
>>>>>
>>>> bored tom? can't be bothered to do any of your own homework this
>>>> evening?
>>> So I should spend hours doing web searches for pictures of cranks to
>>> identify the model on the bicycle in question, when "jim beam" could
>>> provide us the answer?

>>
>> This is the bait and switch. jb is in sales.
>>

> Yes, BS works a lot better in sales than in engineering.
>


two recreational drug users trying to cry ********, when bullshitting
themselves? only the perceptionally maladjusted [either temporarily or
permanently] could think that smart.
 
In article <[email protected]>,
jim beam <[email protected]> wrote:

> Tom Sherman wrote:
> > Michael Press wrote:
> >> In article <[email protected]>,
> >> Tom Sherman <[email protected]> wrote:
> >>
> >>> "jim beam" WHO? wrote:
> >>>> Tom Sherman wrote:
> >>>>> "jim beam" wrote:
> >>>>>> [email protected] wrote:
> >>>>>>> [...]
> >>>>>>> Here are the only pictures I'm aware of ever taken of any of my
> >>>>>>> bikes
> >>>>>>> (it's the orange hardtail):
> >>>>>>> from the back:
> >>>>>>> http://www.mtbadventureseries.org/mtbadventure/EventPics/IMG_3386.JPG
> >>>>>>>
> >>>>>>> or http://tinyurl.com/2pgtwj
> >>>>>>> from the front:
> >>>>>>> http://www.mtbadventureseries.org/mtbadventure/EventPics/IMG_3255.JPG
> >>>>>>>
> >>>>>>> or http://tinyurl.com/3xxufb
> >>>>>> dude, keep a /real/ close eye on those cranks for fatigue.
> >>>>>> inspect them /every/ ride.
> >>>>>>
> >>>>> What brand and model are the cranks, and are they known for having
> >>>>> a fatigue cracking problem?
> >>>>>
> >>>> bored tom? can't be bothered to do any of your own homework this
> >>>> evening?
> >>> So I should spend hours doing web searches for pictures of cranks to
> >>> identify the model on the bicycle in question, when "jim beam" could
> >>> provide us the answer?
> >>
> >> This is the bait and switch. jb is in sales.
> >>

> > Yes, BS works a lot better in sales than in engineering.
> >

>
> two recreational drug users trying to cry ********, when bullshitting
> themselves? only the perceptionally maladjusted [either temporarily or
> permanently] could think that smart.


The BS Tom wrote does not refer to excrement.

--
Michael Press
 
Woland99 wrote:
> I know that roadie suppose to be skinny but not everybody is.
> Or at least not yet. I am shopping for a road bike (have MTB) now
> and I cannot find any info on what would be reasonable "max load".
> I consider getting cyclocross bike as a step toward road bike but
> perhaps somebody here knows - what would be max rider weight
> that eg. Masi Gran Corsa can carry?
>


I do not know about road bikes--but from being big (225 lbs) and riding
MTB's a lot, what I do know is that the rear drive side spokes tended to
break until I had a custom rear wheel built with good spokes. I rarely
bothered to upgrade the hubs or rims, just the spokes, and the wheels
would be good from then on.

I had road bikes back then also, but I never had the spoke-breakage
problems on them. Likely because I didn't crank on them in the shortest
gear up steep hills much.
~