buying a bike (newbie)

Simon Brooke

in message <34a7itF493hskU1@individual.net>, Tony Raven
('junk@raven-family.com') wrote:

> Simon Brooke wrote:
>>
>>>There are also people here that seem to think
>>>lighter construction also means stronger construction which again is
>>>not something that makes sense a lot of the time.
>>

No I didn't. I wrote completely the opposite. Attributions, please.

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

...but have you *seen* the size of the world wide spider?

Simon Brooke

in message <6orvt0lbu0vug6juog2vd2qgn0uf0cindp@4ax.com>, Martin Wilson
('martin.w6@ukonline.co.uk') wrote:

> On Sat, 08 Jan 2005 13:20:09 +0000, Simon Brooke
> <simon@jasmine.org.uk> wrote:
>
>>in message <et4ut0h1ntclsvts99hrs25tu9ns0ljqis@4ax.com>, Martin Wilson
>>('martin.w6@ukonline.co.uk') wrote:
>>
>>> On 04 Jan 2005 11:35:50 GMT, wafflycathcs@aol.compomcom
>>> (dirtylitterboxofferingstospammers) wrote:
>>>
>>>>The problem with too many cheap bikes is that they are indeed total
>>>>crap,
>>>
>>> What is your viewpoint though, are you saying most cheap bikes are
>>> bad or all cheap bikes?
>>
>>RTFA. 'Too many' does not mean either 'most' or 'all'.
>
> Thats the question though isn't it? What is meant by 'too many' as it
> could mean 'most' or 'all'. You could say just one was 'too many'.

Well, in my opinion, something above 90% of sub-£100 bikes are not value
for money. By which I mean, they're not even half as useful or
serviceable as something you can get from EBC or Claud Butler for £200.

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

'there are no solutions, only precipitates'

JLB

Jon Senior wrote:
> Martin Wilson wrote:
>
>> I'm certainly not saying heavy=strong but as a general rule its
>> obviously better than light=strong. Its just one of those things where
>> the variables are enormous. However I do think that when a bike is
>> trying to be as light as possible for performance reasons with
>> aluminium replacing steel, tube thickness thinning down and triple
>> butting in the frame on fairly standard size tubeing , spoke numbers
>> cut down etc you are not going to have a stronger bike a lot of the
>> time.
>
>
> But very few of these occur on cheaper bikes. I did discover the other
> day that Columbus now make a steel tubeset which has 0.38mm walls at
> it's thinnest point. You won't be seeing that on anything other than a
> custom high-end racer though.
>
> It's amazing how much weight you can shave off a bike before you have
> any major impact on strength (In normal use). I suspect that it is
> easier to do this by switching to Aluminium than by thinning steel though.
>
> In the bike world, light quite often does equal strong, simply because
> at the high end of componentry design considerations are better.
>
> Actually, with regard to components I've heard it said that the top and
> bottom are better than the middle. In the mid-range, weight is being
> removed but the materials and basic design remain the same as at the
> bottom which makes them weaker.

It seems to me that some of the discussion in this whole thread is a
little confused because it is being conducted as though the only
parameters of concern in selecting a bike frame material are strength
and weight (presumably density in this context). It would be more
realistic to include also, at the least, stiffness and toughness, both
of which are quite distinct from strength and density and are also
important in how they effect a bike frame.


--
Joe * If I cannot be free I'll be cheap

Jon Senior

JLB wrote:
> It seems to me that some of the discussion in this whole thread is a
> little confused because it is being conducted as though the only
> parameters of concern in selecting a bike frame material are strength
> and weight (presumably density in this context). It would be more
> realistic to include also, at the least, stiffness and toughness, both
> of which are quite distinct from strength and density and are also
> important in how they effect a bike frame.

Strength (and to a lesser extent) toughness was the original topic
(Well. The one I got involved in). Stiffness is far more a part of the
frame design than the material choice.

Jon

JLB

Jon Senior wrote:
> JLB wrote:
>
>> It seems to me that some of the discussion in this whole thread is a
>> little confused because it is being conducted as though the only
>> parameters of concern in selecting a bike frame material are strength
>> and weight (presumably density in this context). It would be more
>> realistic to include also, at the least, stiffness and toughness, both
>> of which are quite distinct from strength and density and are also
>> important in how they effect a bike frame.
>
>
> Strength (and to a lesser extent) toughness was the original topic
> (Well. The one I got involved in). Stiffness is far more a part of the
> frame design than the material choice.

In comparing materials, it is possible to quantify the difference in
stiffness for identical geometry of components, and so isolate the
material property from the effect of component design. But I agree the
geometry is very important in the final overall result. The stiffness of
a load bearing beam increases as the cube of its thickness in the
direction of the load, and for the same cross-section area a wide
diamter tube is much stiffer than a smaller one. However, thin wall
tubes are much more easily dented (external impacts) or buckled by local
stresses (typically at junctions) and that severely weakens them.
Engineering is mostly about intelligent compromises between conflicting
requirements.


--
Joe * If I cannot be free I'll be cheap

Simon Brooke

in message <cronpk$6hn$1$8302bc10@news.demon.co.uk>, JLB
('JLB@bigbad.demon.co.uk') wrote:

> Simon Brooke wrote:
>> in message <sdvtt0dtgsal3cm2ldnkd1m1gt7ar0qd08@4ax.com>, Martin
>> Wilson ('martin.w6@ukonline.co.uk') wrote:
>>
>>>There are also people here that seem to think
>>>lighter construction also means stronger construction which again is
>>>not something that makes sense a lot of the time.
>>
>> No? I suspect you'd be surprised, then. In my experience lighter
>> components generally are (usually considerably) stronger. Forged
>> aluminium cranks, for example, are several times stronger than cast
>> steel ones, and I strongly suspect that carbon ones are stronger
>> still.
>>
>> Of course, they also cost a lot more.
>
> That's confusing correlation with (implied) causation. The reason cast
> components often fail before forged ones has nothing to do with
> weight, and the cost of forging compared to casting is reflected in
> the price.

Yup, but that is the point. No-one makes expensive heavy parts for
bikes, because people who are prepared to pay premium prices for
lighter parts. So quality parts are generally made using lighter
technologies, and the higher the price premium, the more this is the
case. Yes, you could make a forged steel crank, and yes, it would be
stronger than a forged aluminium crank of the same dimensions. But
no-one would buy it, so no-one does make one.

The causation is that people with the money to pay premiums are looking
for strength and lightness, and the market provides them with that.

--
simon@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/
,/| _.--''^``-...___.._.,;
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`;;' ; ; ;
._..--'' ._,,, _..' .;.'
(,_....----''' (,..--''

Martin Wilson

On Sun, 09 Jan 2005 10:35:44 +0000, Jon Senior
<jon_AT_restlesslemon_DOT_co_DOT_uk> wrote:

>Martin Wilson wrote:
>> I'm certainly not saying heavy=strong but as a general rule its
>> obviously better than light=strong. Its just one of those things where
>> the variables are enormous. However I do think that when a bike is
>> trying to be as light as possible for performance reasons with
>> aluminium replacing steel, tube thickness thinning down and triple
>> butting in the frame on fairly standard size tubeing , spoke numbers
>> cut down etc you are not going to have a stronger bike a lot of the
>> time.
>
>But very few of these occur on cheaper bikes. I did discover the other
>day that Columbus now make a steel tubeset which has 0.38mm walls at
>it's thinnest point. You won't be seeing that on anything other than a
>custom high-end racer though.
>

Well very cheap bikes make no attempt to be light weight. Perhaps from
about £120-400 you get some pretty light weight bikes using 7005
aluminium and some are double or triple butted. Also a few steel
components are replaced with aluminium or aluminium/steel versions.
The wheels might lose a few spokes compared to cheaper bikes to save a
little bit of weight and improve performance.


>It's amazing how much weight you can shave off a bike before you have
>any major impact on strength (In normal use). I suspect that it is
>easier to do this by switching to Aluminium than by thinning steel though.
>

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.

>In the bike world, light quite often does equal strong, simply because
>at the high end of componentry design considerations are better.
>

Theres no doubt this is true a lot of the time but not all the time.
However its important to make a point about what price we are thinking
of. I'm thinking of a cheap sub £100 bike (non suspension) compared to
a £400 bike. Very few people looking to buy a first new bike are going
to go above £400 I bet. Obviously if you start talking about £800+
your getting some serious engineering a lot of the time. However how
much serious engineering goes into a £300 bike lets say.




>Actually, with regard to components I've heard it said that the top and
>bottom are better than the middle. In the mid-range, weight is being
>removed but the materials and basic design remain the same as at the
>bottom which makes them weaker.
>
>Jon

I would say that makes a lot of sense. I can't even use my two middle
quality bikes properly due to weight restrictions. Yet I've used my
super cheap bike without any real problems even at 26 stone although
only for a short period at that weight.

When I get on it, it never creaks or makes any straining sort of
noises I cycle off and its practically whisper quiet. When I cycle I
tend to cycle in quite an upright manner as I have quite a long reach
so I don't even disperse my weight very well on the bike its far more
on the rear wheel than the front.

Recently I tried my Kona Lanai bike. Which I suppose is a typical £300
RRP type bike. 7005 aluminium, step up quality components over the
cheap bikes generally. The bike is definitely lighter and moving off
for the first time the push off took me further. The balance was
different, the gearing felt the same generally but the fact the gear
cables are running along the top tube and not going down the main
frame tubeing I can see makes a lot of sense. Would make it more
resistant to dirt and crap and also mean you could use your fingers to
grab the wire if it got stuck just to try and loosen it. The brakes
don't feel noticably better but they do look slightly better. The
front suspension drops the front of the bike a little bit especially
if I move more of my weight forward. This bike is easily going to be
faster and probably a better bike but it does creak occasionally and
frankly I don't trust it as much. I don't trust the main frame and I
don't trust the front suspension. I'm sure when I'm a little lighter
this will change.

Martin Wilson

On Sun, 09 Jan 2005 01:43:53 +0000, Jon Senior
<jon_AT_restlesslemon_DOT_co_DOT_uk> wrote:

>Martin Wilson wrote:
>> The point is they offer a generous guarantee on the steel frame, much
>> longer than they have to but stick to the bare legal minimum for
>> aluminium. Whats this reference to 'cast iron' though is that some
>> sort of dig against steel frames again? ;-)
>
>But the guarantee is (probably) a gamble. As you demonstrate, it works
>well as a sales pitch, and the number of times they have to actually
>honour it (even if frames fail) is probably very small.
>

It didn't work as a sales pitch for me as its buried in the manual
where it says frame has 15 or 25 years for steel frames (can't
remember which for my bike) but 1 year for all other frames including
steel suspension frames. The point was though why do they not offer
the same generous guarantee on aluminium frames. Why do they give an
actual incentive to buy the cheaper product. They're basically saying
this cheap bike is guaranteed for 25 years for its frame but this more
profitable expensive bike is only guaranteed 1 year for its frame. The
only possible explanation is low cost steel frames have far less
faults/problems. 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.

>The reference to cast iron was demonstration that it heavy != strong.
>The biggest effect on strength is quality of construction. My first two
>homebuilt frames failed at a joint (Or rather... the same frame failed
>twice!) as a consequence of my less-than-capable welding skills and poor
>frame design. The frame in question had 2mm walls on the (square) tubes.
>

Fair enough but if you can imagine that bike factories are going to be
reasonably competent as its their trade and stuff gets returned if its
not any good then the bike frames are going to be reasonably well
made.

>But there is more to a frame than longevity. A badly aligned derallieur
>hanger will induce poor shifting, no matter the components that are
>fitted. A mistracking rear wheel will rob energy, wear tyres and have
>(Albeit small) an effect on the handling.
>

Well with a cheap bike most of these things have to be sorted by the
end user. They are part diy. About 15% of assembly and 100% of final
checks and adjustment are upto the end user unless you have a fairly
bottom end cycle shop that sells such bikes and does this bit. However
even halfords won't touch the bottom end stuff and expect you to do
this yourself.

>The difference between a chip manufactured by Intel and one manufactured
>by Cyrix used to be the quality control. Both manufacturers worked at
>the limits of the technology, but Intel were more stringent about what
>they allowed out[1]. I would not be surprised if the same were true for
>the frames produced in the far east. A guarantee is all very well, but a
>well-known brand would be on dodgy ground if they marketed poor frames
>as their own.
>
>Jon
>
>[1] Despite this, I've always run AMD! :-)

Well I'm an amd user myself. I don't believe the frames are dodgy
though. While they come out of taiwan which used to be known for low
quality I think nowadays the frames are pretty damn good. I'm not sure
what your thinking here but I doubt if the QC varies from one
reseller's order to the next. It will be the same people using the
same equipment and getting paid the same wages. If a load of Apollo
bikes hits british stores and the frames break on a lot of them then
Halfords won't be paying their bill to the frame builder. If
Specialized or Kona and other brands were obsessed about quality they
would go to the more expensive frame builders in taiwan but they
aren't all using giant many are using the lower end factories like
idealbike. Not that there is anything wrong with idealbike its just
Giant are better. Theres probably no way Kona or specialized could
market a low cost introduction bike at £300 if they went to Giant for
their frames though without fitting fairly low end components. Only
Giant I think can do a £300 bike with a 6061 frame and decent
components because they make the frames themselves and don't have to
buy them off other companies.

Clive George

"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.

cheers,
clive

David Martin

Martin Wilson wrote:

> Well very cheap bikes make no attempt to be light weight.

Tell me about it.. I have the frame from a Univeral megadeath rad
oversized 'look like aluminium but made of cheese steel' frame in the
garage and it weighs as much as the frame for Igor[1], and probably more
than my road bike (a svelte 10kg with a B17).

...d

[1] two and a bit cheap steel frames brazed together

Jon Senior

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.

> 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. :-)

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.

> Recently I tried my Kona Lanai bike. Which I suppose is a typical £300
> RRP type bike. 7005 aluminium, step up quality components over the
> cheap bikes generally. The bike is definitely lighter and moving off
> for the first time the push off took me further. The balance was
> different, the gearing felt the same generally but the fact the gear
> cables are running along the top tube and not going down the main
> frame tubeing I can see makes a lot of sense. Would make it more
> resistant to dirt and crap and also mean you could use your fingers to
> grab the wire if it got stuck just to try and loosen it. The brakes
> don't feel noticably better but they do look slightly better. The
> front suspension drops the front of the bike a little bit especially
> if I move more of my weight forward. This bike is easily going to be
> faster and probably a better bike but it does creak occasionally and
> frankly I don't trust it as much. I don't trust the main frame and I
> don't trust the front suspension. I'm sure when I'm a little lighter
> this will change.

Aluminium bikes tend to creak more than steel. This is not usually the
frame making ominous noises (A creak is generally metal failure and
you'd know about it!) but the interaction between the frame and
componentry like cable ferrules. My Giant tends to develop a set of
creaks which (when they get too annoying) go away when I regrease the
contact points on the steering (Stem clamps) and the ferrules for the
gear cables.

Jon

Jon Senior

Martin Wilson wrote:
> Fair enough but if you can imagine that bike factories are going to be
> reasonably competent as its their trade and stuff gets returned if its
> not any good then the bike frames are going to be reasonably well
> made.

You'd hope so... but it's not necessarily the case.

> Well with a cheap bike most of these things have to be sorted by the
> end user. They are part diy. About 15% of assembly and 100% of final
> checks and adjustment are upto the end user unless you have a fairly
> bottom end cycle shop that sells such bikes and does this bit. However
> even halfords won't touch the bottom end stuff and expect you to do
> this yourself.

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
without access to a TIG welder (If you're dealing with aluminium).

As I've explained (sort of) in another post, part of the problem with
badly made cheap bikes, is that they devalue bikes and cycling. They are
categorised as toys. I'd rather see them taken more seriously.

Jon

Martin Wilson

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.
>
>cheers,
>clive

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.

Martin Wilson

On Sun, 09 Jan 2005 22:49:27 +0000, Jon Senior
<jon_AT_restlesslemon_DOT_co_DOT_uk> wrote:

>Martin Wilson wrote:
>> Fair enough but if you can imagine that bike factories are going to be
>> reasonably competent as its their trade and stuff gets returned if its
>> not any good then the bike frames are going to be reasonably well
>> made.
>
>You'd hope so... but it's not necessarily the case.
>

Why would it differ though between making a batch of Trek's compared
to a batch of Raleighs or Apollo's? Who will be more important to that
company, a uk importer like conceptcycles or universal who buy loads
of 85% assembled 100% complete bikes and sell in huge numbers in the
uk due to their low cost or a niche manufacturer who just buy frames
and buy components elsewhere and assembles back in the usa/uk?


>> Well with a cheap bike most of these things have to be sorted by the
>> end user. They are part diy. About 15% of assembly and 100% of final
>> checks and adjustment are upto the end user unless you have a fairly
>> bottom end cycle shop that sells such bikes and does this bit. However
>> even halfords won't touch the bottom end stuff and expect you to do
>> this yourself.
>
>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
>without access to a TIG welder (If you're dealing with aluminium).
>

Misaligned wheel needing a tig welder?!?! Surely there not that bad,
I've never seen a wheel that was wrongly manufactured fundamentally. A
slightly lose spoke yes, a wheel that might need trueing yes. How
would they have got the tyre and tube on without noticing at the
factory?

>As I've explained (sort of) in another post, part of the problem with
>badly made cheap bikes, is that they devalue bikes and cycling. They are
>categorised as toys. I'd rather see them taken more seriously.
>
>Jon

Thats a bit serious isn't it? Cheap bikes devaluing bikes and cycling.