Mildenhall today.

[Alan Braggins]

In article <[email protected]>, Peter Clinch wrote:
>
>> There are practical advantages to having the monoblade, we've mentioned many
>> already. But I want to know the penalties in terms of cost and weight as well.
>
>If they were heavier Cannondale wouldn't be using them, though that is
>with the caveat of excellent engineering. Which does cost money, but
>then again so does Titanium and carbon fibre and it isn't like people
>are complaining about those...

Well I'm not going to waste time complaining about their cost, but it is a
good reason why they aren't more widely used. And for some applications,
unusual precision engineering and exotic materials are both related to
"can't easily and quickly be fixed almost anywhere". With a conventional
steel frame, there's a good chance someone local will be able to provide
something usable if a bike is at all repairable.

 

[Simon Brooke]

in message <[email protected]>, Mark South
('[email protected]') wrote:

> All good points.  But as I said below, you are using heavier members,
> only fewer of them.  Do you win or not?

You win. Basic physics. The strength of tube increases with the square
of the diameter, the weight only a bit more than linearly. So for a
given weight one larger diameter tube will always be stronger than two
smaller diameter tubes.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; If Python is executable pseudocode,
;; then Perl is executable line noise
-- seen on Slashdot.

 

[Simon Brooke]

in message <[email protected]>, Alan Braggins
('[email protected]') wrote:

> In article <[email protected]>, Peter Clinch wrote:
>>
>>> There are practical advantages to having the monoblade, we've
>>> mentioned many
>>> already. But I want to know the penalties in terms of cost and
>>> weight as well.
>>
>>If they were heavier Cannondale wouldn't be using them, though that is
>>with the caveat of excellent engineering. Which does cost money, but
>>then again so does Titanium and carbon fibre and it isn't like people
>>are complaining about those...
>
> Well I'm not going to waste time complaining about their cost, but it
> is a good reason why they aren't more widely used. And for some
> applications, unusual precision engineering and exotic materials are
> both related to "can't easily and quickly be fixed almost anywhere".
> With a conventional steel frame, there's a good chance someone local
> will be able to provide something usable if a bike is at all
> repairable.

That's sort of fair enough. Cannondale Leftys as replacement items cost
from about £500 and go rapidly upwards. The USE SUB (which I believe is
probably the best front suspension unit for cross country bikes out
there) costs about £800. The Challenge Katana Monoblade costs £250 as
an upgrade. And as you rightly point out there is no standard for
monoblade stub axles and hubs.

As these things become more common and more standardised, costs will
fall.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; this is not a .sig

 

[Jon Senior]

In article <[email protected]>, [email protected]
says...
> Not only 'bents, as the 8 Freight demonstrates.

But not uprights. I'm not sure why this hasn't been done (Other than the
London bike). I strongly suspect that at speed you'd start to notice the
cornering issues and in a competition that might become an problem.

> Or. more visibly, the front forks of top-end Cannondale MTBs, which are
> /not/ known for being ghastly overweight things. In fact the whole
> /point/ of the 'Dale Lefty is to reduce the weight at a given level of
> strength.

Burrow's given reason was also that it is easier to engineer a single
stantion that a double since the single only needs be aligned with
itself, thus reducing stiction.

Jon

 

[Mark South]

"Dave Larrington" <[email protected]> wrote in message
news:[email protected]...
> Mark South wrote:
>
> > I may be naive but lining up the wheels seems to be pretty much
> > essential to the operation of the bicycle.
>
> Up to a point, Lord Copper. I have spent the equivalent of a Several of
> days following numerous Burrows RatRacers around the race tracks both of the
> Sceptred Isle and Abroad, where the Foreigners come from, and there seems to
> be little wrong with the way they handle. They've won the unfaired class in
> every BHPC race this season and seven out of eleven last year.

How much out of line are the wheels? Or equivalently, how wide is the track?
--
Mark South: World Citizen, Net Denizen

 

[Jon Senior]

In article <[email protected]>, [email protected]lid
says...
> I may be naive but lining up the wheels seems to be pretty much essential to the
> operation of the bicycle.

I achieved 48mph on a bike with a rear wheel that was slightly off
centre and pointed right. It handled like a dream. You can get away with
a hell of a lot more than you'd think!

Jon

 

[Mark South]

"Simon Brooke" <[email protected]> wrote in message
news:[email protected]...
> in message <[email protected]>, Mark South
> ('[email protected]') wrote:
>
> > All good points. But as I said below, you are using heavier members,
> > only fewer of them. Do you win or not?
>
> You win. Basic physics.

Heh. I've written textbooks on advanced physics

> The strength of tube increases with the square
> of the diameter, the weight only a bit more than linearly.

The bending resistance of the tube scales as the diameter^4 for fixed wall
thickness.

For fixed wall thickness, the weight does scale linearly.

As tubes get bigger they also need thicker walls to resist denting.

> So for a
> given weight one larger diameter tube will always be stronger than two
> smaller diameter tubes.

Against the same loads. The loads are different. It might well be OK, but I'm
not curiosity-sated yet.

> [email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/
> ;; If Python is executable pseudocode,
> ;; then Perl is executable line noise

Except really, Python is barely executable line noise, so where does that leave
Perl?
--
Mark South, Super Genius: World Citizen, Net Denizen

 

[Mark South]

"Simon Brooke" <[email protected]> wrote in message
news[email protected]...
> in message <[email protected]>, Mark South
> ('[email protected]') wrote:
>
> > "Simon Brooke" <[email protected]> wrote in message
> > news:[email protected]...
> >> in message <[email protected]>, Mark South
> >> ('[email protected]') wrote:
> >>
> >> > "Jon Senior" <jon_AT_restlesslemon_DOTco_DOT_uk> wrote in message
> >> > news:[email protected]...
> >> >
> >> >> That said. Despite their odd and slightly dubious appearance,
> >> >> monoblade forks (A misnomer if ever there was one!) don't seem to
> >> >> have been subject to any publicised failures.
> >> >
> >> > There are very few, all heavily overbuilt.
> >>
> >> That is the complete opposite of the truth. The lightest, stiffest
> >> full suspension cross-country bikes on the racing circuit today, the
> >> ones that are pretty much cleaning up in all the World Cup cross
> >> country events this year, have monoblade front ends. Why? Because for
> >> a given stiffness they're much lighter, and for a given lightness
> >> they're much stiffer.
> >
> > Durability arguments drawn from lightweight racing kit that is
> > replaced at frequent intervals are bound to be fallacious.
> >
> > We were talking about monoblades for production bikes,
>
> What, you mean like the monoblade on my consumer production mountain
> bike that I ride every week summer and winter? I repeat: it is very
> substantially stronger than a twin stansion fork of the same weight.

OK. That's evidence not from UL racing machinery.

> It
> is stronger because the strength of a tube increases with the square of
> its diameter, whereas its weight increases by a much lower multiplier
> (pi + c, where c is a constant based on the wall thickness needed to
> avoid buckling).

Constants aren't, variables won't. Your "c" is really a fudge factor.

> Consequently, for any system comprised of tubes, a
> system with one tube will be stronger than a system of the same weight
> in two tubes; or, alternatively, if the two systems are built to the
> same strength, the system with one tube will be stronger.

Yeah, against the same load.

> Yes there are torque issues in a monoblade, but they aren't difficult to
> engineer for. It isn't an accident that all cars - including formula
> one racers - use monoblades.

Dead herring. Car wheels are not attached by monoblades anything like that on a
Lefty. They are cantilevered to the main structure.

> Ye cannae change the laws of physics, Captain.

Nor would I wish to, I earn royalties off them.
--
Mark South, Super Genius: World Citizen, Net Denizen

 

[Mark South]

"Peter Clinch" <[email protected]> wrote in message
news:[email protected]...
> Mark South wrote:
>
> > All good points. But as I said below, you are using heavier members, only
fewer
> > of them. Do you win or not?
>
> Cannondale think they do with the Lefty. Since they don't sell bikes by
> making them heavier or weaker, that sounds like if you throw enough
> engineering at them they have the potential to be better.

You sell bikes by marketing. No other conclusion can be drawn.

> > I may be naive but lining up the wheels seems to be pretty much essential to
the
> > operation of the bicycle.
>
> You're naive then, and I say that safe in the knowledge that my freight
> bike has wheels that don't line up.

So which direction does it prefer to turn?

> > It's MB's chosen role to test and to question, and that's good.
>
> And after he did, Giant produced their folder using monoblades. Giant
> aren't in the job of field testing dodgy technology on production
> machines ridden by thousands.

How many have they actually sold? They put the Halfway in every bike shop in
the world and I've never seen one on the road. Or heard of anyone owning one.

> > There are practical advantages to having the monoblade, we've mentioned many
> > already. But I want to know the penalties in terms of cost and weight as
well.
>
> If they were heavier Cannondale wouldn't be using them, though that is
> with the caveat of excellent engineering. Which does cost money, but
> then again so does Titanium and carbon fibre and it isn't like people
> are complaining about those...

Cannondale, like other US manufacturers, replace a lot of stuff under warranty.
We've done that to death in the materials thread.
--
Mark South, Super Genius: World Citizen, Net Denizen

 

[Mark South]

"Peter Clinch" <[email protected]> wrote in message
news:[email protected]...
> Mark South wrote:
>
> > Durability arguments drawn from lightweight racing kit that is replaced at
> > frequent intervals are bound to be fallacious.
>
> But I think you'll find far more Lefty equipped Cannondales in
> recreational hands than in professional ones, and no reason to suppose
> these are frequently replaced.

Well, I could ask Cannondale but they won't tell. You can google for how many
threads there have been in RBT about broken Cannondales. Like other US
manufacturers, they don't mind the odd product breaking and replacing it under
warranty.

> > We were talking about monoblades for production bikes, and Jon mentioned
> > commuter cycles.
>
> Cannondale Lefty forks are on production bikes though. If you want a
> commuter bike then the Giant Halfway is a production cycle by one of the
> biggest (if not /the/ biggest) manufacturers on the planet and has a
> monoblade fork.

See other reply.

> > There's insufficient evidence to support a case either way.
>
> Perhaps because you're busy failing to notice it?

Pete, I find your tone mildly insulting. You are normally far more concerned in
a discussion with playing the ball.

> The bike market is
> often quite conservative, and a lot of the reason why people don't use
> monoblade forks is probably people would suck air through their teeth
> and say "that can't be any good!".

In an early post in this thread, I added to an enumeration of some advantages of
monoblades, and stub axles in particular, and said that I'd sign up for them.

There's no reason that it's a bad thing to ask for actual EVIDENCE of how these
things perform in different roles.
--
Mark South, Super Genius: World Citizen, Net Denizen

 

[James Annan]

Mark South wrote:

> "Simon Brooke" <[email protected]> wrote in message
> news:[email protected]...
>
>>in message <[email protected]>, Mark South
>>('[email protected]') wrote:
>>
>>
>>>All good points. But as I said below, you are using heavier members,
>>>only fewer of them. Do you win or not?
>>
>>You win. Basic physics.
>
>
> Heh. I've written textbooks on advanced physics
>
>
>>The strength of tube increases with the square
>>of the diameter, the weight only a bit more than linearly.
>
>
> The bending resistance of the tube scales as the diameter^4 for fixed wall
> thickness.

I could be wrong, but I suspect that most authors of advanced physics
textbooks would disagree with you (diameter^3 is what you want).


> As tubes get bigger they also need thicker walls to resist denting.
>

But only if they are close to the threshold at which this becomes an
issue, which some are, but not all.


James
--
If I have seen further than others, it is
by treading on the toes of giants.
http://www.ne.jp/asahi/julesandjames/home/

 

[Dave Larrington]

Mark South wrote:

> How much out of line are the wheels? Or equivalently, how wide is
> the track?

Lessee, the front wheel is in line with the frame tube and the back offset
to the left thereof when viewed from behind, so half the tube thickness plus
half the hub width. At a guess about 60 mm.

Methinks the main problem with bikes not designed as multi-track vehicles is
that in addition to the wheels being out of line fore and aft, the rear one
is very likely not parallel with the longitudinal axis of the bike. For a
prime illustration of this, The Reader is invited to examine an old Linear
recumbent. Should The Reader then contrive to drop the thing off a high
bridge, s/he will be doing the world a great service...

--

Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/
===========================================================
Editor - British Human Power Club Newsletter
http://www.bhpc.org.uk/
===========================================================

 

[Peter Clinch]

Mark South wrote:

> You sell bikes by marketing. No other conclusion can be drawn.

But you don't win world cup MTB races by marketing. Winning them is
useful marketing in itself, which helps sell lots of units to people who
don't replace them once a year, and those are the people that prove
they're strong in general use.

> So which direction does it prefer to turn?

Roos claims she finds it skitters a little to one side when empty and
negotiating offroad, I've never noticed any obvious one-sidedness in the
handling myself.

> How many have they actually sold? They put the Halfway in every bike shop in
> the world and I've never seen one on the road. Or heard of anyone owning one.

I don't have figures, but they've kept them on for 3 years so far which
is hardly the mark of a commercial disaster, and I have heard of people
owning them, as it happens. FWIW I've /seen/ very few Dahons, but I
know for a fact they're the world's best selling folding bikes.

The above just smacks of you saying you can't see it so it can't be there!

> Cannondale, like other US manufacturers, replace a lot of stuff under warranty.

Yet retain a vibrant business in acclaimed bicycle manufacture (and it
was the motor division that caused their financial problems, not the bikes).

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/

 

[Peter Clinch]

Jon Senior wrote:

> But not uprights.

The 8 Freight is an upright.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/

 

[Peter Clinch]

Mark South wrote:

> Well, I could ask Cannondale but they won't tell. You can google for how many
> threads there have been in RBT about broken Cannondales. Like other US
> manufacturers, they don't mind the odd product breaking and replacing it under
> warranty.

But "the odd" standard fork break anyway. OTOH, if the mono design was
intrinsically poor you'd have a major reliability problem and would
drive yourself out of business replacing them for nothing. And you
wouldn't do very well in competitions either.

> Pete, I find your tone mildly insulting. You are normally far more concerned in
> a discussion with playing the ball.

But there's plenty of evidence that they work okay, and it appears to me
that you're just writing it off apropos of being in a bad mood. "I
haven't seen any Halfways and don't know anyone with one!" being taken
as reasonable evidence that they're a commercial disaster and have
questionable design and construction is, I'd say, more than mildly
insulting to both manufacturer and designer.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/

 

[Roos Eisma]

James Annan <[email protected]> writes:

>Mark South wrote:

>> Heh. I've written textbooks on advanced physics
>> The bending resistance of the tube scales as the diameter^4 for fixed wall
>> thickness.

>I could be wrong, but I suspect that most authors of advanced physics
>textbooks would disagree with you (diameter^3 is what you want).

Looks like we're reaching the "my physics book is bigger than yours"
level...

(and most advanced physics books I've looked in didn't seem to cover any
sort of practical topics anymore - I did keep my copy of Quantum Field
Theory for posing value but never worked out what it was about)

Roos

 

[Mark South]

"Peter Clinch" <[email protected]> wrote in message
news:[email protected]...
> Mark South wrote:
>
> > You sell bikes by marketing. No other conclusion can be drawn.
>
> But you don't win world cup MTB races by marketing. Winning them is
> useful marketing in itself, which helps sell lots of units to people who
> don't replace them once a year, and those are the people that prove
> they're strong in general use.

OK, so they work perfectly and are cost effective. Why don't all bikes have
them?

> > So which direction does it prefer to turn?
>
> Roos claims she finds it skitters a little to one side when empty and
> negotiating offroad, I've never noticed any obvious one-sidedness in the
> handling myself.

I'm not familiar with the vehicle in question and can't visualise why someone
would build it with the wheels out of line.

> > How many have they actually sold? They put the Halfway in every bike shop
in
> > the world and I've never seen one on the road. Or heard of anyone owning
one.
>
> I don't have figures, but they've kept them on for 3 years so far which
> is hardly the mark of a commercial disaster, and I have heard of people
> owning them, as it happens. FWIW I've /seen/ very few Dahons, but I
> know for a fact they're the world's best selling folding bikes.

Well, Dahon say so, but they must sell them into different markets.

Of course, you say that they're **** compared to a Brompton, so purely selling
large numbers doesn't tell the whole story, right?

> The above just smacks of you saying you can't see it so it can't be there!

No, it doesn't "smack" of anything. It's me saying that since you are beating
on me for not agreeing with you, some evidence would be fun to see. Visible,
under-the-nose evidence is easy to belive and nice to have. Since I don't see
them and don't know anyone who has one, I'd love to hear from peope who do see
them and do know people who have them.

So do tell.

> > Cannondale, like other US manufacturers, replace a lot of stuff under
warranty.
>
> Yet retain a vibrant business in acclaimed bicycle manufacture (and it
> was the motor division that caused their financial problems, not the bikes).

You're obviously a big fan of Cannondale. I'm not so convinced that what they
say is gospel or that what they make is perfect.
--
Mark South, Super Genius: World Citizen, Net Denizen

 

[Ambrose Nankivell]

"Mark South" <[email protected]> writes:

> "Peter Clinch" <[email protected]> wrote in message
> news:[email protected]...
> > Mark South wrote:
> >
> > > You sell bikes by marketing. No other conclusion can be drawn.
> >
> > But you don't win world cup MTB races by marketing. Winning them
> > is useful marketing in itself, which helps sell lots of units to
> > people who don't replace them once a year, and those are the
> > people that prove they're strong in general use.
>
> OK, so they work perfectly and are cost effective. Why don't all
> bikes have them?
>
They're harder to sell, the improvements aren't all that great, the
design cost is significantly higher, the hub designs don't have the
necessary economies of scale, they don't look as nice.

Lots of reasons. None of them particularly technical.

A

 

[Mark South]

"James Annan" <[email protected]> wrote in message
news:[email protected]...
> Mark South wrote:
> > "Simon Brooke" <[email protected]> wrote in message
> > news:[email protected]...
> >
> >>in message <[email protected]>, Mark South
> >>('[email protected]') wrote:
> >>
> >>>All good points. But as I said below, you are using heavier members,
> >>>only fewer of them. Do you win or not?
> >>
> >>You win. Basic physics.
> >
> > Heh. I've written textbooks on advanced physics
> >
> >>The strength of tube increases with the square
> >>of the diameter, the weight only a bit more than linearly.
> >
> > The bending resistance of the tube scales as the diameter^4 for fixed wall
> > thickness.
>
> I could be wrong, but I suspect that most authors of advanced physics
> textbooks would disagree with you (diameter^3 is what you want).

<G> The readers now have three possibilities for the index: 2, 3 or 4. The BBC
would conduct a readers' poll to determine which scaling law is most popular at
this point.

> > As tubes get bigger they also need thicker walls to resist denting.
> >
> But only if they are close to the threshold at which this becomes an
> issue, which some are, but not all.

It certainly is for fat-tubed Al frames. However, they already have thicker
walls because that's a component of fatigue reduction. (And that's why very few
coke-can tubed frames are left from the early 90's.)
--
Mark South, Super Genius: World Citizen, Net Denizen

 

[Mark South]

"Jon Senior" <jon@restlesslemon_DOT_co_DOT_uk.remove> wrote in message
news:[email protected]...
> In article <[email protected]>, [email protected]lid
> says...
> > I may be naive but lining up the wheels seems to be pretty much essential to
the
> > operation of the bicycle.
>
> I achieved 48mph on a bike with a rear wheel that was slightly off
> centre and pointed right. It handled like a dream. You can get away with
> a hell of a lot more than you'd think!

Yeah, and I've ridden bikes that had no brakes and headsets held together with
duct tape. But I gave it up once I stopped being a teenager and started
requiring longer healing times.
--
Mark South, Super Genius: World Citizen, Net Denizen