buying a bike (newbie)

Clive George

Martin Wilson wrote:
> On Sun, 9 Jan 2005 18:57:54 -0000, "Clive George"
> <clive@xxxx-x.fsnet.co.uk> wrote:
>
>> "Martin Wilson" <martin.w6@ukonline.co.uk> wrote in message
>> news7r2u095gt75ifuv2v44ac8ccd4t3vb6jn@4ax.com...
>>
>>> However this may be related more to 7005 aluminium
>>> rather than aluminium frames in general. All the very cheap
>>> aluminium bikes seem to have 7005 aluminium only which is prone to
>>> cracking.
>>
>> Some quite nice frames are built from 7005 - eg the fort, tifosi and
>> kinesis training/audax frames. Double butted though.
>>
> I don't know those frames but tifosi sounds italian and probably has
> columbus 7005 rather than low cost generic type taiwanese 7005
> aluminium which is used on a lot of the american/british rebranded
> frames on their sub £500 bikes. If they do use the low end taiwanese
> material as you say they probably build in extra safe guards like
> double butting if they're top quality frames.

The tifosi name is amusing - it was chosen to sound italian by Messrs
Chicken & Sons. They later imply they're made in Belgium - but they use the
word 'prepared'. Which probably means the frames are actually built in
eastern Europe or the far east, but they're too ashamed to admit so.

Fort come from Czechoslovakia. Their 7005 track bikes use Sanko tubing -
that's all I've been able to find.

Kinesis seem to be tube makers - http://www.kinesis.com.tw - and make in
Taiwan and China. However I couldn't easily find a link between them and the
frames I see over here.

Interesting take on double butting - I think you'll find the frames using
this are thinner in the middle than those without.

cheers,
clive

Alan Braggins

In article <1105310295.5972.0@echo.uk.clara.net>, Jon Senior wrote:
>
>> However how
>> much serious engineering goes into a £300 bike lets say.
>
>More than in a £100 bike and even more than in a £50 bike. :-)

That doesn't _have_ to be true. If you can sell five times as many 100 quid
bikes as 300 quid bikes, you could invest four times as much in the
production engineering of the 100 quid bikes and still make more money.

Alan Braggins

In article <rnj3u05l424v80us7pkl1n57390sg4qfp8@4ax.com>, Martin Wilson wrote:
>On Sun, 09 Jan 2005 22:49:27 +0000, Jon Senior
>>
>>The things I listed are not generally "home fixable". You might be able
>>to bend out a derallieur hanger, but a misaligned wheel is not fixable
>
>Misaligned wheel needing a tig welder?!?! Surely there not that bad,
>I've never seen a wheel that was wrongly manufactured fundamentally.

But if the frame is wrong, the wheel alignment will be out when the
wheel itself is right. I suspect this is what Jon means - imagine a
fork with legs of slightly different lengths - put a wheel in, and
it will hit the forks, or at least be skew. Similarly at the back, though
the dropout might let you correct in one direction.

But you don't fix it with a TIG welder, you fix it by taking it back to
the shop, saying "this is unfit for the purpose for which it was sold",
and getting a replacement, or a refund to spend somewhere else.

Mark Tranchant

Alan Braggins wrote:
> In article <1105310295.5972.0@echo.uk.clara.net>, Jon Senior wrote:
>
>>>However how
>>>much serious engineering goes into a £300 bike lets say.
>>
>>More than in a £100 bike and even more than in a £50 bike. :-)
>
> That doesn't _have_ to be true. If you can sell five times as many 100 quid
> bikes as 300 quid bikes, you could invest four times as much in the
> production engineering of the 100 quid bikes and still make more money.

Doesn't your argument completely overlook the cost of the materials and
components?

--
Mark.
http://tranchant.plus.com/

Alan Braggins

Mark Tranchant wrote:
>Alan Braggins wrote:
>> In article <1105310295.5972.0@echo.uk.clara.net>, Jon Senior wrote:
>>
>>>>However how
>>>>much serious engineering goes into a £300 bike lets say.
>>>
>>>More than in a £100 bike and even more than in a £50 bike. :-)
>>
>> That doesn't _have_ to be true. If you can sell five times as many 100 quid
>> bikes as 300 quid bikes, you could invest four times as much in the
>> production engineering of the 100 quid bikes and still make more money.
>
>Doesn't your argument completely overlook the cost of the materials and
>components?

It doesn't bother with them for the sake of brevity, but they don't have
to invalidate it. For the simplest demonstration of this, consider the case
where you use exactly the same materials and components, but can assemble them
for a fraction of the cost if you invest more in the production engineering,
so sell more of the same bike for a lower unit price and more profit.
Or where the cost of components is reduced because you can now make them
yourself for less than the cost of buying them in.

That doesn't mean that's a typical or even likely case - "that doesn't
_have_ to be true" is very different from "that isn't often true". It
isn't the same as "that isn't always true", it could be not true only in
a hypothetical case that never actually happens.

Martin Wilson

>> I don't know those frames but tifosi sounds italian and probably has
>> columbus 7005 rather than low cost generic type taiwanese 7005
>> aluminium which is used on a lot of the american/british rebranded
>> frames on their sub £500 bikes. If they do use the low end taiwanese
>> material as you say they probably build in extra safe guards like
>> double butting if they're top quality frames.
>
>The tifosi name is amusing - it was chosen to sound italian by Messrs
>Chicken & Sons. They later imply they're made in Belgium - but they use the
>word 'prepared'. Which probably means the frames are actually built in
>eastern Europe or the far east, but they're too ashamed to admit so.
>
>Fort come from Czechoslovakia. Their 7005 track bikes use Sanko tubing -
>that's all I've been able to find.
>
>Kinesis seem to be tube makers - http://www.kinesis.com.tw - and make in
>Taiwan and China. However I couldn't easily find a link between them and the
>frames I see over here.
>
>Interesting take on double butting - I think you'll find the frames using
>this are thinner in the middle than those without.
>
>cheers,
>clive
>

My understanding of double butting or even triple butting is it
creates thicker sections for where strength is needed especially near
the welds. How strong that frame will be is dependant on the overall
thickness of the tubeing used. So a double butted or triple butted
frame could be optimised for lightness or strength depending on what
the overall thickness of the tubeing is. Again I don't know these
particular frames. However if they are using cheap 7005
taiwanese/chinese aluminium and the same welding techniques normally
used where the aluminium is strengthened/heat treated by the weld but
other non welded parts are unheat treated then they won't be as strong
as 6061 generally and will be more prone to cracking and less safe as
a very general/vague rule compared to steel other aluminium frames.

Its a difficult thing to nail down though as there's always going to
be frames which compensate by superior design or thicker sections and
obviously performance racing bikes are more about light riders and
relatively smooth surfaces than other bikes.

Anyway the point is bicycle manufacturers/importers offer relatively
short guarantees on 7005 frames. Frames that crack tend to be 7005
frames more than anything else. A 7005 frame is an indication of a
less sophisticated factory as 6061 based frames need huge ovens to
heat treat them for many hours.7005 frames are more brittle than 6061
and will more likely crack rather than bend. That doesn't mean 7005
frames are unsafe or rubbish its just a bit more reassuring to have
6061, it might cope a bit better in accidents and last longer into the
future.

Martin Wilson

>I imagine that the cost of making frames correlates quite directly to their
>quality, both in the cost of the raw materials, as you seem to have
>conceded, and in the cost of their assembly.
>

Your saying the american firms are paying more for their frames. I'm
not sure this is true as american brand costs are far, far higher due
to many things. Obviously they are paying more for more sophisticated
frames but at the bottom end I'm not so sure.

>Seeing as neither side is giving figures, or apparently knows where to get
>them, this is a decidedly circular argument. If anyone were to have a cost
>breakdown of manufacturing a bike and a bike frame, then that'd be most
>interesting.
>

I think the american brands would be very reluctant to admit to what
they are paying for bike frames for their lower end models.

>Also note that people who label complete bikes are likely to be pretty
>unimportant to a manufacturer, and any loyalty to their own assembly
>division will likely be dwarfed by the costs of actually making the frames
>better.

Why would a importer that buys complete bikes and probably a lot more
of them be less important than a firm that just buys frames. There is
no evidence that the frames from the same factory would be made
better. The american brands would probably have to go to a different
factory to get better frames and this would effect their balance
sheet. They still seem quite keen to use the bottom end manufacturers
like idealbike.

>
>Like I said before, this discussion only threatens to get interesting if
>someone who can speak authoratively about manufacturing engineering can step
>in and rescue it, and solve the point of dispute.
>
>Preferably followed up by someone who can comprehensively enumerate what
>parts of the bike need to be what quality and what doesn't work as well when
>they're not as good.
>
>Just my 25p worth.
>
>A
>

So effectively its pointless having the debate at all because we will
probably never get access to all the information needed. So what do we
decide to do just leave it as it is and say a)most bike frames from
taiwan are relatively the same quality or b) the american brand bike
frames are made better somehow....

Martin Wilson

>But if the frame is wrong, the wheel alignment will be out when the
>wheel itself is right. I suspect this is what Jon means - imagine a
>fork with legs of slightly different lengths - put a wheel in, and
>it will hit the forks, or at least be skew. Similarly at the back, though
>the dropout might let you correct in one direction.
>
>But you don't fix it with a TIG welder, you fix it by taking it back to
>the shop, saying "this is unfit for the purpose for which it was sold",
>and getting a replacement, or a refund to spend somewhere else.

Don't you think your going a bit far with your criticism of such
bikes. They don't have forks the wrong length, or eliptical wheels,
frames with random tubeing coming out at strange angles or any other
massively wrong problems. Have you ever heard of someone getting such
a bike with the forks made so badly?

Try searching for such problems on google groups because I couldn't
find a reference to such a thing.

The factories that make these bikes do have quality control you know.

Simon Brooke

in message <2jh5u0dhn11od1b5tg7gheqjg3uej9ganc@4ax.com>, Martin Wilson
('martin.w6@ukonline.co.uk') wrote:

>
>>> I don't know those frames but tifosi sounds italian and probably has
>>> columbus 7005 rather than low cost generic type taiwanese 7005
>>> aluminium which is used on a lot of the american/british rebranded
>>> frames on their sub £500 bikes. If they do use the low end taiwanese
>>> material as you say they probably build in extra safe guards like
>>> double butting if they're top quality frames.
>>
>>The tifosi name is amusing - it was chosen to sound italian by Messrs
>>Chicken & Sons. They later imply they're made in Belgium - but they
>>use the word 'prepared'. Which probably means the frames are actually
>>built in eastern Europe or the far east, but they're too ashamed to
>>admit so.
>>
>>Fort come from Czechoslovakia. Their 7005 track bikes use Sanko tubing
>>- that's all I've been able to find.
>>
>>Kinesis seem to be tube makers - http://www.kinesis.com.tw - and make
>>in Taiwan and China. However I couldn't easily find a link between
>>them and the frames I see over here.
>>
>>Interesting take on double butting - I think you'll find the frames
>>using this are thinner in the middle than those without.
>
> My understanding of double butting or even triple butting is it
> creates thicker sections for where strength is needed especially near
> the welds. How strong that frame will be is dependant on the overall
> thickness of the tubeing used. So a double butted or triple butted
> frame could be optimised for lightness or strength depending on what
> the overall thickness of the tubeing is.

The strength of a tube is essentially about the outside diameter; wall
thickness only has to be enough to resist buckling, and any additional
thickness adds no real strength to the structure. The strongest frames
are often among those with the thinnest walled tube - not, admittedly,
_because_ the walls are thin, but because thin walled tube requires
much more careful workmanship so quality control has to be better. It's
also, obviously, lighter.

--
simon@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/

<p>Schroedinger's cat is <blink><strong>NOT</strong></blink> dead.</p>

Martin Wilson

On Sun, 09 Jan 2005 22:44:23 +0000, Jon Senior
<jon_AT_restlesslemon_DOT_co_DOT_uk> wrote:

>Martin Wilson wrote:
>> Theres no doubt that using better grade raw materials and extra
>> manufacturing processes and quality control checks can make a stronger
>> and lighter product but how much of this type of quality will appear
>> on a sub £400 bike? If you look at Giant bikes you often find the
>> american brands are a good £50-100 more for the same component spec
>> near the bottom end and you get a lower grade 7005 frame on the
>> american brand bike instead of 6061.
>
>As much as anything, that price difference probably reflects the costs
>of shipping to the UK since (nominally) the bike will be assembled in
>the states.
>

Fair enough but its an indication of poor value of american brands. If
Giant can do a bike at £300 that would cost £400 by an american brand
the american product is 33% overpriced with no benefit for spending
the extra £100 except a brand that you might prefer.

>> However how
>> much serious engineering goes into a £300 bike lets say.
>
>More than in a £100 bike and even more than in a £50 bike. :-)
>

yeah but how much more. Maybe if american brands rebranded a £100 bike
it would be lets say £150.

>While some people (You are clearly one) are quite happy with their cheap
>bike, I can't shake the feeling that they will give the wrong image of
>cycling. A badly made, badly set up bike wont encourage the owner to
>ride, and the fact that a bike can be bought for £60 with full
>"suspension" promotes the idea that anything over £200 is extravagant
>and only for the truly dedicated.
>

However I don't believe my bike is badly made and I feel the evidence
shows that it isn't badly made. Maybe if it was dual suspension or
from a different manufacturer it would be. Its a good knockabout bike
that I enjoy riding and is relatively theft resistant by its sheer low
value.It hasn't taught me that cycling should be avoided its taught me
the complete opposite. I don't believe its as good as a Cannondale or
as desirable but it is fun. To be honest I have a certain fondness
towards the bike. Its something I've put a lot of trust into and it
hasn't failed me. Well I did have one puncture.

Clive George

"Martin Wilson" <martin.w6@ukonline.co.uk> wrote in message
news:bcm5u0pso5um1rki8l045923lsave12s4t@4ax.com...

> However I don't believe my bike is badly made and I feel the evidence
> shows that it isn't badly made. Maybe if it was dual suspension or
> from a different manufacturer it would be. Its a good knockabout bike
> that I enjoy riding and is relatively theft resistant by its sheer low
> value.It hasn't taught me that cycling should be avoided its taught me
> the complete opposite. I don't believe its as good as a Cannondale or
> as desirable but it is fun. To be honest I have a certain fondness
> towards the bike. Its something I've put a lot of trust into and it
> hasn't failed me. Well I did have one puncture.

How far have you ridden it now? (and in how long?)

cheers,
clive

Jon Senior

Martin Wilson wrote:
> Don't you think your going a bit far with your criticism of such
> bikes. They don't have forks the wrong length, or eliptical wheels,
> frames with random tubeing coming out at strange angles or any other
> massively wrong problems. Have you ever heard of someone getting such
> a bike with the forks made so badly?

Yes. Most frames that you buy have less-than-perfect alignment. Working
in the Bike Station where I see many bikes of various vintages and
qualities it is one of the first things we check. Sometimes it's a case
of cold-setting the rear so that it's straight. Sometimes it can be
safely ignored for having little effect on performance. Sometimes it's
time to jump up and down on the frame and use it for scrap!

> Try searching for such problems on google groups because I couldn't
> find a reference to such a thing.
>
> The factories that make these bikes do have quality control you know.

Yes, but the stringency of that quality control is the issue. A
misaligned rear wheel doesn't have to be so bad that it touches the
frame (And that would be unusual), but it's quite common that it is out
of alignment. How much by is a matter for QC.

Jon

Martin Wilson

>The strength of a tube is essentially about the outside diameter; wall
>thickness only has to be enough to resist buckling, and any additional
>thickness adds no real strength to the structure. The strongest frames
>are often among those with the thinnest walled tube - not, admittedly,
>_because_ the walls are thin, but because thin walled tube requires
>much more careful workmanship so quality control has to be better. It's
>also, obviously, lighter.

Come off it, there will be an optimium balance between wall thickness
and diameter but if you had two tubes of the same diameter and two
different thicknesses for the wall, the thicker wall would be stronger
unless theres some other factor involved like heat strengthening or
the grade of metal used. Lets say I have two tubes of aluminium, one
of which is just small enough to tightly fit in the other but both
have the same wall thickness. With just the outer tube in my hand
using all my strength I can just bend it by applying pressure at the
far ends with my hands. Then into another tube with the same
dimensions as before I insert a tight fitting second tube so the wall
thickness is doubled. Your now saying its easier to bend this
tube?!?!?!

I'd like to know how careful workmanship is going to re-arrange those
atoms individually to make a stronger tube. I don't know what
pricepoint your thinking of but my point was about sub £500 bikes and
I very much doubt much in the way of additional workmanship comes into
play. If your spending serious money you can age the frame or heat
treat it but most of the bottom end sub £500 bikes frames are standard
7005 taiwanese/chinese aluminium. They are not 7005 T6 or 7075. They
are just plain basic 7005 and the only heat strengthening they get is
the heat of the welds.

Companies like Giant have moved away from 7005 and I'm sure others
will too over the next few years.

Simon Brooke

in message <rm37u0pjmaicoksauqcqcuk5rtqemd6j4i@4ax.com>, Martin Wilson
('martin.w6@ukonline.co.uk') wrote:

>
>>The strength of a tube is essentially about the outside diameter; wall
>>thickness only has to be enough to resist buckling, and any additional
>>thickness adds no real strength to the structure. The strongest frames
>>are often among those with the thinnest walled tube - not, admittedly,
>>_because_ the walls are thin, but because thin walled tube requires
>>much more careful workmanship so quality control has to be better.
>>It's also, obviously, lighter.
>
> Come off it, there will be an optimium balance between wall thickness
> and diameter but if you had two tubes of the same diameter and two
> different thicknesses for the wall, the thicker wall would be stronger
> unless theres some other factor involved like heat strengthening or
> the grade of metal used. Lets say I have two tubes of aluminium, one
> of which is just small enough to tightly fit in the other but both
> have the same wall thickness. With just the outer tube in my hand
> using all my strength I can just bend it by applying pressure at the
> far ends with my hands. Then into another tube with the same
> dimensions as before I insert a tight fitting second tube so the wall
> thickness is doubled. Your now saying its easier to bend this
> tube?!?!?!

Bike frames are not normally under bending stress[1]; they're under
compressive and tensive stresses. Provided the wall thickness is
sufficient to prevent buckling, doubling the thickness will have
precisely zero effect on the ability to resist compression/tension.

Try it with rolled up paper tubes if you don't believe me.

> I'd like to know how careful workmanship is going to re-arrange those
> atoms individually to make a stronger tube.

Careful workmanship makes stronger joints; the joints are usually the
weak point on a frame.

> I don't know what
> pricepoint your thinking of but my point was about sub £500 bikes and
> I very much doubt much in the way of additional workmanship comes into
> play.

Sub £500 for a complete bike you aren't going to get a very good frame,
although you should get a reasonable one.

[1] except around the bottom bracket area

--
simon@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; When all else fails, read the distractions.