need help picking out a bike

[Martin Wilson]

Just a few more questions regarding frames.

Firstly I've read on a few sites about the superior ride quality of
older steel bikes like Raleighs. Obviously retro bike fans but is
there any truth in this? If so what makes the high tensile steel they
use better than the current modern taiwanese/chinese high tensile
steel frames?

Also on a steel frame what gives it its improved ride quality (if
there is any) is it the greater flexing of the rear wheel support
arms or is it an overall effect of the complete frame including the
much thicker tubing or some sort of ratio of the two like 80:20 or
something?

If aluminium is more critical about the quality of welds are there any
visual indications of poor welds that can be seen? How can you
visually inspect a frame either aluminium or steel for build quality?
What do you look for?

Many of the cheaper aluminium frames seem to be 7005 and so do some of
the high up models too. Are there certain aluminiums to be avoided and
others that are preferable to the common 7005?

What are the failure risks of each frame? I mean if a frame fails what
type is the worse to be on? Who has experienced frame failure on a
bike at high speed?

Lastly going back the guarantee question. If you have a manufacturer
making two similar bikes with the same components fitted but one is
steel at a sub £100 price and the other is aluminium at £150 the
reason the guarantee can be 15 to 25 times as long with steel is
because;

a) steel bikes aren't actually ridden by anyone as they are too heavy
and people don't like riding them so they promote them with long
guarantees.

b) aluminium frames are harder to weld on the cheap. So cheap bikes
have rubbish aluminium frames.

c) a marketing ploy so that people spend less money on their bike and
opt for a cheap steel bike instead of the more expensive aluminium
bikes.

So basically am I right in thinking (finally) that b) is the
definitive answer. Cheap aluminium frames have a higher failure rate
and less strength than high tensile steel. Not so much because of the
material but the actual weld.

 

[Peter Clinch]

Martin Wilson wrote:

> Firstly I've read on a few sites about the superior ride quality of
> older steel bikes like Raleighs. Obviously retro bike fans but is
> there any truth in this? If so what makes the high tensile steel they
> use better than the current modern taiwanese/chinese high tensile
> steel frames?

It's not something that's easily quantified, especially when there are
so many other variables to play with. Old steel bikes may well have old
leather saddles which aren't fashionably high tech but are preferred
amongst serious tourists as being more comfortable, and so on.

> Also on a steel frame what gives it its improved ride quality (if
> there is any) is it the greater flexing of the rear wheel support
> arms or is it an overall effect of the complete frame including the
> much thicker tubing or some sort of ratio of the two like 80:20 or
> something?

Again, difficult to quantify, but the triangulation at the rear will
greatly reduce any flex in the chainstays in any case. Basically, I'd
say this is just not something to get hung up about, partly because it's
very hard to quantify but mostly because I doubt that most people find
much difference. There are far, far, far more important things to
consider about bikes than what the frame's made of, assuming a basically
competent job there. Such as the fit of the frame to your body, which
will have an order of magnitude more effect than what flavour of metal
it's made of.

> If aluminium is more critical about the quality of welds are there any
> visual indications of poor welds that can be seen? How can you
> visually inspect a frame either aluminium or steel for build quality?
> What do you look for?

It's not that easy to do it by eye. Aside from seeing that there is a
clear weld the whole way around the tube join there's not much to see.
Better welding tends to be /neater/, but a neat weld can still be badly
done and a messy one can be very strong.

> Many of the cheaper aluminium frames seem to be 7005 and so do some of
> the high up models too. Are there certain aluminiums to be avoided and
> others that are preferable to the common 7005?

Don't know, to be honest, but as above I just don't see it's worth
getting hung up on the frame material unless you are seriously into
weight weenieism, which generally only competition minded folk with deep
wallets truly are.

> What are the failure risks of each frame? I mean if a frame fails what
> type is the worse to be on? Who has experienced frame failure on a
> bike at high speed?

I think Al will fail more horribly than steel, but a weld going isn't
the same as a tube breaking and again I'll stress you're looking at very
unlikely things here. Frames don't have a habit of breaking unless
they're being punished, there's a bad weld or a design fault. Guy's
broken two Al frames due to a (now rectified) design fault and not got
hurt, Jon Senior's homebuilt bust a weld and he rode it home, my old
steel tourer bust a weld and I got it to the kerb safely and then walked
home.

> Lastly going back the guarantee question. If you have a manufacturer
> making two similar bikes with the same components fitted but one is
> steel at a sub £100 price and the other is aluminium at £150 the
> reason the guarantee can be 15 to 25 times as long with steel is
> because;
>
> a) steel bikes aren't actually ridden by anyone as they are too heavy
> and people don't like riding them so they promote them with long
> guarantees.
>
> b) aluminium frames are harder to weld on the cheap. So cheap bikes
> have rubbish aluminium frames.

Or getting back to the previous incarnations of this subject, cheap
bikes are basically rubbish, so you avoid the questions by not getting
them. They're a false economy in the eyes of most regular cyclists.
For example, to quote the Cycling Scotland website, designed to promote
cycling up here,
"1/ How much to spend.
The answer is "Enough that the bicycle will allow me to do what I need
it to in comfort and safety." If you are looking to buy a first bike, or
a bike to enjoy gentle leisure or fitness riding, then you should expect
to spend around £200"

> So basically am I right in thinking (finally) that b) is the
> definitive answer.

Things aren't that black and white, but probably more of (b) than
anything else. Probably.

> Cheap aluminium frames have a higher failure rate
> and less strength than high tensile steel. Not so much because of the
> material but the actual weld.

AFAICT welds are frames tend to break the most.

But I'll reiterate a couple of salient points.

- cheap bikes are widely regarded as a false economy. Of the cycle
commuters I see in Dundee regularly all through the year(s) on a long
term basis, almost all (actually possibly all) ride bikes that do not
fit the supermarket budget category. Ones I see on cheapies tend to
disappear after a while, usually a short while.

- whatever bike you get, as long as it's basically competent (and if you
rule out these gaspipe specials it very probably will be, so everything
should at least be properly aligned, which is independent of material)
then the frame material is of less importance for general purpose
cycling than how well the frame fits you. Back to the
http://www.cyclingscotland.org/ bike choosing advice, "Whatever bicycle
you end up with, the most important things are to make sure that it fits
you, that it's well maintained and is safe to ride." Note no mention of
frame material in there. There are differences, but IMHO they are not
worth getting hung up on.

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/

 

[Martin Wilson]

>- cheap bikes are widely regarded as a false economy. Of the cycle
>commuters I see in Dundee regularly all through the year(s) on a long
>term basis, almost all (actually possibly all) ride bikes that do not
>fit the supermarket budget category. Ones I see on cheapies tend to
>disappear after a while, usually a short while.
>

I have to say though that where I am I see loads of cheap older bikes
being ridden to work. Presumably steel mountain bikes from universal
and Halfords plus dual suspension and even older classic british
brands. In fact all sorts of cheap bikes in regular use. I've seen
this with my own eyes. I know to many here, a universal type bike
thats being in constant use for commuting and is many years old sounds
too fantastic to believe but I've seen it multiple times. Maybe the
riders aren't enjoying the ride as much as a decent bike would enable
them too and also maybe the bike has had to be repaired or upgraded to
keep working as I haven't got that close but its doing the job it was
bought for (some would say badly of course). Maybe this varies by
region but I don't see much in the way of mid to high brands where I
am but then crime is fairly bad in my area so perhaps this would have
an effect. Anyway I think we all would acknowledge that cheap bikes
from supermakrets or wherever are huge sellers and sell in far greater
numbers than the better brands. So maybe the ones that aren't wheeled
back from Tescos/Asda etc and hidden in people's sheds are actually
ridden where I live. Like a sort of Twilight Zone where people
actually go out on such bikes instead of hiding them away in disgust.

 

[David Martin]

On 29/9/04 9:31 am, in article [email protected],
"Martin Wilson" <[email protected]> wrote:

> If aluminium is more critical about the quality of welds are there any
> visual indications of poor welds that can be seen? How can you
> visually inspect a frame either aluminium or steel for build quality?
> What do you look for?

Failure rates in welds tend to be through overheating of the metal creating
an overlarge heat affected zone [1] or through creation of stress
concentrators[2] through less than skilled welding.

There are no real ways to observe a HAZ by eye so you take the luch of the
draw. Heat in this case means above the point at which the composition of
the steel changes, typically around 12-1300 C. Welding will exceed this.
Ordinary arc welding will produce a large HAZ and ruin any heat treatment in
that area. As most of the stresses are concentrated at the joints, ruining
the heat treatment here is a bad thing. You can reduce the size of the HAZ
by TIG welding or minimise the effects by using a more expensive but cooler
process like brazing. It is still possible to overheat the tubes when
brazing - ideally use a low temperature brazing such as a silver based
filler metal which will be around the 1000C mark. For some tubes this will
improve their characteristics. Cheap hi-ten tubes get their characteristics
from the cold working in creating the tubes. This strength will be destroyed
by normal arc/mig welding in the HAZ (which is why Jon's first recumbent
frame broke so easily).

In summary for steel, get a silver brazed frame from a reputable maker.

For aluminium you don't usually have the option to braze. Welding is
typically TIG and should be neat and small. Irregularities can act as stress
concentrators that initiate cracking. Aluminium can also be work hardened
and heat treated.


...d

 

[Peter Clinch]

Martin Wilson wrote:

> I have to say though that where I am I see loads of cheap older bikes
> being ridden to work.

If you have every confidence in them then nobody's trying to actually
stop you using one. OTOH if you don't believe the advice you get here
about this, why would the general opinion on frame materials be of any
more use to you? Or are you just sending the topic around until someone
tells you what you want to hear?

Cheap bikes are cheap because they don't have money spent on good
mechanical engineering, which costs. If you want a mechanical device as
good as possible then spending money on good mechanical engineering
makes a lot of sense.

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/

 

[Martin Wilson]

On Wed, 29 Sep 2004 11:49:01 +0100, Peter Clinch
<[email protected]> wrote:

>Martin Wilson wrote:
>
>> I have to say though that where I am I see loads of cheap older bikes
>> being ridden to work.
>
>If you have every confidence in them then nobody's trying to actually
>stop you using one. OTOH if you don't believe the advice you get here
>about this, why would the general opinion on frame materials be of any
>more use to you? Or are you just sending the topic around until someone
>tells you what you want to hear?
>

To be perfectly honest I'm trying to take in as much information as
possible about frames and bikes. As I've said before I tend to like
almost all bikes. I accept practically all thats being said about
frames. However I pointed out that in my area I have seen plenty of
cheap bikes in use every day and years old. Thats my experience. There
is a level of anti-cheap bikes sentiment on this forum and to me
comments about such bikes not being used and going straight into the
shed or soon after the first ride don't really ring true for me. Thats
not to say there isn't some truth to it I suppose in rare cases but to
dismiss them as unusable and unused just doesn't gel with the reality
of my own eyes. I see loads of low cost bikes about all over the
place. I saw an elderly gentleman about to cross a road on my way home
this morning and he had the classic (or not so classic in this case)
low cost Y frame suspension bike. I see quite a few of them about.
These bikes are being used and ridden. So basically on that one point
I disagree which I believe on a forum I'm allowed to do and I'm
comfortable doing so as its reality for me and what I've experienced.

>Cheap bikes are cheap because they don't have money spent on good
>mechanical engineering, which costs. If you want a mechanical device as
>good as possible then spending money on good mechanical engineering
>makes a lot of sense.
>
>Pete.

It certainly does but what if you just want to test the water of
cycling and not spend too much money and don't actually want to buy
secondhand? Lots of people just won't buy secondhand. I realise no
point going over the same ground repeatedly but its fair to say the
people have decided that cheap bikes are worth buying because they
sell so well. Its the same with any goods you can have a quality
Panasonic widescreen tv for £500 or a bottom end Bush for £200. Far
more people in this country will buy the Bush and suffer tinny sound,
slightly worse picture and lesser features but they will still use it
probably as much as a Panasonic owner if not more so. They could have
got a secondhand Panasonic for £200 thats a couple years old but
they'd rather buy the new Bush tv.

 

[Martin Wilson]

On Wed, 29 Sep 2004 11:28:59 +0100, David Martin
<[email protected]> wrote:

>On 29/9/04 9:31 am, in article [email protected],
>"Martin Wilson" <[email protected]> wrote:
>
>> If aluminium is more critical about the quality of welds are there any
>> visual indications of poor welds that can be seen? How can you
>> visually inspect a frame either aluminium or steel for build quality?
>> What do you look for?
>
>Failure rates in welds tend to be through overheating of the metal creating
>an overlarge heat affected zone [1] or through creation of stress
>concentrators[2] through less than skilled welding.
>
>There are no real ways to observe a HAZ by eye so you take the luch of the
>draw. Heat in this case means above the point at which the composition of
>the steel changes, typically around 12-1300 C. Welding will exceed this.
>Ordinary arc welding will produce a large HAZ and ruin any heat treatment in
>that area. As most of the stresses are concentrated at the joints, ruining
>the heat treatment here is a bad thing. You can reduce the size of the HAZ
>by TIG welding or minimise the effects by using a more expensive but cooler
>process like brazing. It is still possible to overheat the tubes when
>brazing - ideally use a low temperature brazing such as a silver based
>filler metal which will be around the 1000C mark. For some tubes this will
>improve their characteristics. Cheap hi-ten tubes get their characteristics
>from the cold working in creating the tubes. This strength will be destroyed
>by normal arc/mig welding in the HAZ (which is why Jon's first recumbent
>frame broke so easily).
>
>In summary for steel, get a silver brazed frame from a reputable maker.
>
>For aluminium you don't usually have the option to braze. Welding is
>typically TIG and should be neat and small. Irregularities can act as stress
>concentrators that initiate cracking. Aluminium can also be work hardened
>and heat treated.
>
>
>..d
>

Excuse my ignorance but I thought my high tensile steel frame was TIG
welded. I thought I'd read it somewhere. What are the options for
steel frames. Is it silver brazed, brass brazed and something else
like TIG? Have I got confused somewhere and it has to be brass or
silver brazed?

How much stronger would a a silver brazed weld be compared to brass
typically?

 

[Peter Clinch]

Martin Wilson wrote:

> To be perfectly honest I'm trying to take in as much information as
> possible about frames and bikes. As I've said before I tend to like
> almost all bikes. I accept practically all thats being said about
> frames. However I pointed out that in my area I have seen plenty of
> cheap bikes in use every day and years old. Thats my experience.

I see quite a few too, but as I said I don't see quite a few of the same
ones regularly, which I do for better bikes and not just the ones
ridden by the "all the gear" crowd, and I also don't see anything like
as many as their proportion of the sales market suggests I should.

The students are just back, so there's /lots/ about right now. On my
way to and from work I walk through a hall of residence and by the bike
rack there. I've been doing this for years. It's usually got cheap
bikes in it. And it usually doesn't have vacant spaces at any time and
as the year goes on they get rustier and less usable, and often only
seem to move when the summer vac comes around again.

> is a level of anti-cheap bikes sentiment on this forum

Often based on having ridden the things. I've always bought the best
bikes I could afford. I have had cause to ride budget stuff and I have
/never/ regretted my own spending policy as a result.

> comments about such bikes not being used and going straight into the
> shed or soon after the first ride don't really ring true for me. Thats
> not to say there isn't some truth to it I suppose in rare cases but to
> dismiss them as unusable and unused just doesn't gel with the reality
> of my own eyes.

But you have no real way of telling how many are sitting at the back of
sheds because your own eyes, unless Martin Wilson is a pseudonym for
Clark Kent or you're an expert burglar, don't see there, so you don't
have information on the proportion it's true for.

> It certainly does but what if you just want to test the water of
> cycling and not spend too much money and don't actually want to buy
> secondhand? Lots of people just won't buy secondhand. I realise no
> point going over the same ground repeatedly but its fair to say the
> people have decided that cheap bikes are worth buying because they
> sell so well.

That doesn't make them right, however. I've said it before, and I'll
say it again, in NL where there really /is/ a cycling culture and things
get used, and lots of ancient rusting heaps get used too and relatively
few bikes are making a fashion statement, the average spend on a new
bike is IIRC[1] reckoned to be about £350. It strikes me as making much
more sense to look at the habits of people who famously use bikes for
utility jobs more than just about anyone else (possibly excepting the
Danes) than the British, who by and large don't have a clue about bikes
and appear to think all aluminium frames and all full suspension designs
and implementations are basically the same. These are not people to
take a useful opinion from, IMHO!

> Its the same with any goods you can have a quality
> Panasonic widescreen tv for £500 or a bottom end Bush for £200. Far
> more people in this country will buy the Bush and suffer tinny sound,
> slightly worse picture and lesser features but they will still use it
> probably as much as a Panasonic owner if not more so. They could have
> got a secondhand Panasonic for £200 thats a couple years old but
> they'd rather buy the new Bush tv.

But if you're watching Eastenders over dinner it doesn't really make
much odds, does it? And in the example here you're still looking at
spending £200 for something where construction care is basically a
non-issue. So why not spend that much on something where construction
care is an issue, and where its reliable working may be something that
makes the difference between a pleasurable ride and a fatal accident.

If you really want to test the water of cycling but don't want to buy
secondhand you'd probably benefit from hiring something for a weekend.

Pete.

[1] I think that's what I read in a VV article on Dutch Cycling, but I
don't have it to hand and ICBW.
--
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/

 

[Simon Brooke]

in message <[email protected]>, Martin Wilson
('[email protected]') wrote:

> Just a few more questions regarding frames.
>
> Firstly I've read on a few sites about the superior ride quality of
> older steel bikes like Raleighs. Obviously retro bike fans but is
> there any truth in this? If so what makes the high tensile steel they
> use better than the current modern taiwanese/chinese high tensile
> steel frames?

They didn't use high tensile steel, is the quick answer (well, they did,
of course, since all steel is high tensile) but the steels used in the
classic Reynolds tubesets were highly specialised in the alloying (high
in manganese and molybdenum) and in the heat treatment, and the tubes
were highly specialised in the forming (pierced rather than rolled).
All this meant a springier, lighter, thinner walled tube.

> Also on a steel frame what gives it its improved ride quality (if
> there is any) is it the greater flexing of the rear wheel support
> arms or is it an overall effect of the complete frame including the
> much thicker tubing or some sort of ratio of the two like 80:20 or
> something?

There is no thicker tubing. Indeed on many Reynolds tubesets the walls
of the seatstays will be thicker, not thinner, than the walls of the
main tubes, which may be as little as 0.4mm thick, as against the 1.2
to 1.5mm walls of unbutted 'high tensile' frames.

Older steel frames are also brazed, not welded, and the best ones are
silver brazed. Consequently the temper given to the tubes during heat
treatment is not destroyed in subsequent manufacture.

See
<URL:http://web.archive.org/web/20030608042817/http://www.reynoldsusa.com/history/history.html>

Consequently, the whole structure of a high quality steel frame will be
much springier than an unbutted, welded 'high-tensile' steel frame.
This doesn't mean all old frames are good, of course.

> If aluminium is more critical about the quality of welds are there any
> visual indications of poor welds that can be seen? How can you
> visually inspect a frame either aluminium or steel for build quality?
> What do you look for?
>
> Many of the cheaper aluminium frames seem to be 7005 and so do some of
> the high up models too. Are there certain aluminiums to be avoided and
> others that are preferable to the common 7005?
>
> What are the failure risks of each frame? I mean if a frame fails what
> type is the worse to be on? Who has experienced frame failure on a
> bike at high speed?

Steel frame junkies will tell you steel frames are less likely to fail
than aluminium. I don't believe this is true, but what is true is that
a steel frame which has failed can usually be repaired, while a failed
aluminium frame usually cannot be.

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

;; 99% of browsers can't run ActiveX controls. Unfortunately
;; 99% of users are using the 1% of browsers that can...
[seen on /. 08:04:02]

 

[Martin Wilson]

>Often based on having ridden the things. I've always bought the best
>bikes I could afford. I have had cause to ride budget stuff and I have
>/never/ regretted my own spending policy as a result.
>

what actually is it that you don't like about cheap bikes when you
ride them? At the moment I'm commuting to work on a high tensile
steel rigid mountain bike. I'm 21 stone. The bike cost £60. It has an
oversized frame (Mega Oversized it claims) and 18 gears (shimano
tourney). I've changed the saddle and tyres. It seems very
comfortable. Feels super solid in operation and I've done 40mph on it
(down hill) and about 30mph on flats. I probably average about 6-8 on
the hills though. I came home this morning from my nightshift on it. I
enjoyed the air I was breathing, the view and the sensation of riding
not forgeting the slight high you get from exercising. It may not be
the lightest bike at 15kg but the frame is absolutely solid as a rock.
The journey of 7-8 miles took me 35 minutes. Not amazing but there
were a couple of long hills and a few minor ones and I am 21 stone. I
also have a Kona Lanai which I can't ride as it has an absolute weight
limit of 300lbs and I'm just over that when I add my backpack full of
lunch, drinks, revo, mags and other assorted goodies I take to work. I
also have a Giant Revive and that has an absolute weight limit of
125kg (new models are 120kg I believe). Thats two bikes I have that I
can't ride until I've lost a bit more weight. I don't regret buying
the Pagan Arrow for a second its been a great bike so far. The only
thing I'm tempted to replace is the shimano tourney rear derailleur as
although it works well enough its a little slow changing and frankly I
absolutely hate the look of it. The newer tourney rear derailleurs
look far nicer.

 

[Martin Wilson]

>They didn't use high tensile steel, is the quick answer (well, they did,
>of course, since all steel is high tensile) but the steels used in the
>classic Reynolds tubesets were highly specialised in the alloying (high
>in manganese and molybdenum) and in the heat treatment, and the tubes
>were highly specialised in the forming (pierced rather than rolled).
>All this meant a springier, lighter, thinner walled tube.
>

My old Raleigh Royal frame says 'High Tensile Advanced Steel 20-30'
and that was a great frame. I'm currently restoring it.

 

[Peter Clinch]

Martin Wilson wrote:

> what actually is it that you don't like about cheap bikes when you
> ride them? At the moment I'm commuting to work on a high tensile
> steel rigid mountain bike. I'm 21 stone. The bike cost £60. It hasan
> oversized frame (Mega Oversized it claims) and 18 gears (shimano
> tourney). I've changed the saddle and tyres. It seems very
> comfortable.

Quite often my number one complaint is the saddle, but you've avoided
that one. Beyond that they just don't work nearly as well as good
bikes. Everything about them doesn't work as well. Brakes aren't as
smooth or powerful, gears tend to miss more and go out of adjustment
more, wheels are more prone to going out of true, they feel less an
extension of me (getting into Touchy-feely territory here).
One of the local CTC folk has a very nice Thorn bike which she likes a
lot, but she thought she'd keep that for Serious Cycling and bought an
EBC hybrid for a hack bike. Couple of hundred, nothing /wrong/ with it
at all, but she sold it on because she never used it because it just
didn't do anything as well as the Thorn. It's new owner was very happy
with it.

As for comfort, comfort is a relative thing. I ride a full suspension
recumbent tourer when it's comfort I want, and comfort on that is
comparable to an armchair. Really, an armchair.

I guess once you've been spoiled it's difficult to go back, but
comparing cheap MTBs I've ridden to my old high tensile steel framed
tourer with SIS 2x6 gears (£250 back in '89) they're found seriously
wanting in getting from A to B, so I'm not just comparing new and high
end here.

> Feels super solid in operation and I've done 40mph on it
> (down hill) and about 30mph on flats.

If you can do 30 mph on the flats on an 18 speed budget MTB while
weighing in at 21 stone I would say that either you have a career in
cycle racing ahead of you when you've slimmed down a bit more, you had a
storm force tail wind, or your speedo needs recalibrating! Are you sure
you don't mean km/h?

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/

 

[Martin Wilson]

>Quite often my number one complaint is the saddle, but you've avoided
>that one. Beyond that they just don't work nearly as well as good
>bikes. Everything about them doesn't work as well. Brakes aren't as
>smooth or powerful, gears tend to miss more and go out of adjustment
>more, wheels are more prone to going out of true, they feel less an
>extension of me (getting into Touchy-feely territory here).
>One of the local CTC folk has a very nice Thorn bike which she likes a
>lot, but she thought she'd keep that for Serious Cycling and bought an
>EBC hybrid for a hack bike. Couple of hundred, nothing /wrong/ with it
>at all, but she sold it on because she never used it because it just
>didn't do anything as well as the Thorn. It's new owner was very happy
>with it.
>

I won't argue about the saddle. It was totally unsuitable for me.
Brakes seem very powerful but can be a bit screechy when I apply them
hard. Maybe I've not got the toe in quite right. Frankly though if I
have to brake that hard I want people to hear about it (i.e. don't
come out of that junction as I'm here type noises) The front wheel did
go out of true but then I did hit the pavement while doing about 12mph
and I was 26 stone at the time and it was only slightly out of true. I
notice one or two of the Edinburgh bikes do have basic tourney gears
no different to mine.

>As for comfort, comfort is a relative thing. I ride a full suspension
>recumbent tourer when it's comfort I want, and comfort on that is
>comparable to an armchair. Really, an armchair.
>

I'll make no claim that my bike is comparable in comfort to that but
its pretty good considering it has no suspension. Its not unpleasent
to ride at all.

>I guess once you've been spoiled it's difficult to go back, but
>comparing cheap MTBs I've ridden to my old high tensile steel framed
>tourer with SIS 2x6 gears (£250 back in '89) they're found seriously
>wanting in getting from A to B, so I'm not just comparing new and high
>end here.
>

My Raleigh Royal Export of late 80s vintage was also a superb bike of
its day. I wouldn't feel safe on getting back on it until I'm about
16-17 stone though.

>> Feels super solid in operation and I've done 40mph on it
>> (down hill) and about 30mph on flats.
>
>If you can do 30 mph on the flats on an 18 speed budget MTB while
>weighing in at 21 stone I would say that either you have a career in
>cycle racing ahead of you when you've slimmed down a bit more, you had a
>storm force tail wind, or your speedo needs recalibrating! Are you sure
>you don't mean km/h?

I'm pretty sure I've set the computer to mph display but perhaps I'm
being generous in my description of flat as its possibly more like a
slight incline. The 40mph was achieved just coasting and not braking
in the middle of the night with no other traffic about, down a long
steep hill (Bablyon Hill).Obviously 40mph was the peak reading not the
average. It took some nerve/stupidity to do as the brakes took a long
time to stop my mass at that speed. I think a normal relaxed cadence
will take the bike to about 24mph in its fastest gear so to acheive
30mph I had to be a bit silly with my legs going super fast. I
achieved practically 30mph or something like 29.6mph on the read out.
Is this really that impressive? When I was coming back from work this
morning just before I got to the top of Babylon Hill a very serious
looking cyclist with a dayglo treacle **** stuck to his head and
muscles in his legs like Popeye has muscles in his arms overtook me.
It couldn't have been that long before I got to the top of Bablyon
Hill to look down but he was out of sight.He must have been doing
18-20mph up the slight hill to the top of babylon hill compared to my
6-8mph. Of course the frame of his bike was super thin, the sort of
frame I could break with a side swipe of one of my buttocks. Is 30mph
on a relatively flat road that impressive? I find that my cycling
consists of fast level and downhill riding and super slow uphill
riding as would be expected I would have thought. Surely gravity is
working in my favour with any sort of downhill road? As someone who
has been as weighty as 27 stone in recent times (with 13.5 stone on
each leg) but still had a very active life/job in manufacturing and I
have been doing 30 km per day on an exercise cycle with a very high
friction level daily for the last few months to lose the lbs I would
have thought my leg muscles were relatively strong.

So I reckon my legs are pretty powerful by any standard. However as
soon as I come to a hill and have to move my own mass up a hill the
speed becomes pitifully low.

>
>Pete.

 

[Peter Clinch]

Martin Wilson wrote:

> I'll make no claim that my bike is comparable in comfort to that but
> its pretty good considering it has no suspension. Its not unpleasent
> to ride at all.

Suspension only makes for much comfort difference over rough stuff. On
typical roads it's of no matter most of the time. Where the 'bent makes
the difference is your weight is supported along your whole back, rather
than on just sit bones and arms.

> I'm pretty sure I've set the computer to mph display but perhaps I'm
> being generous in my description of flat as its possibly more like a
> slight incline. The 40mph was achieved just coasting and not braking
> in the middle of the night with no other traffic about, down a long
> steep hill (Bablyon Hill).

I can top out over 40 going down a long steep hill, pedalling hard in
big gears on a recumbent with high quality high pressure tyres which
almost certainly have lower rolling resistance than yours. 40 on a bike
is fast and generally requires working at it unless you have a very low
rolling and air resistance.

> average. It took some nerve/stupidity to do as the brakes took a long
> time to stop my mass at that speed.

There's the difference between good and indifferent brakes. You weigh
more than me, but my bike weighs more and even with 4 pannier loads of
camping luggage it stops very well. But there again it damn well
*should* do better, as each of my brakes cost more than your whole bike.

> I think a normal relaxed cadence
> will take the bike to about 24mph in its fastest gear

Unlikely on MTB gearing, especially 6 speed. Not impossible, but I'd
think unlikely. Maintaining over 20 is pretty hard work IME.

> frame I could break with a side swipe of one of my buttocks. Is 30mph
> on a relatively flat road that impressive?

It's certainly not slouching about. The UCI hour record, set in a
velodrome on a pure track racing bike designed for the job by a
professional cycle athlete (Chris Boardman) is 32.48 miles. Obviously
keeping up that speed for an hour is /very/ different to keeping it up
for a minute, but it's the fastest possible sustainable pace on the flat
on an upright bike without a fairing, under the best possible conditions.

> riding as would be expected I would have thought. Surely gravity is
> working in my favour with any sort of downhill road?

Not any more than someone light. Heavier objects don't fall any faster.
Also, any bumps that require the bike to go up over them will lose you
more energy than a light bike/rider (that's what suspension is for on a
road).

> has been as weighty as 27 stone in recent times (with 13.5 stone on
> each leg) but still had a very active life/job in manufacturing and I
> have been doing 30 km per day on an exercise cycle with a very high
> friction level daily for the last few months to lose the lbs I would
> have thought my leg muscles were relatively strong.

They'll be very strong, but once you get up past 20 mph (or even near to
20 mph!) then wind resistance is the real barrier to going faster, with
the loss to air drag going up with the square of the speed. Which is
why the UCI hour record is so much lower than the IHPVA record, where
aerodynamic fairings on recumbent bikes are allowed. This doesn't show
up on an exercise bike, for obvious reasons.

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/

 

[Clive George]

"Peter Clinch" <[email protected]> wrote in message
news:[email protected]...

> > riding as would be expected I would have thought. Surely gravity is
> > working in my favour with any sort of downhill road?
>
> Not any more than someone light. Heavier objects don't fall any faster.

So we have drummed into us at physics lessons. However a feather still falls
slower than a cannonball, and a tandem can descend faster than a single
bike.

Yes, a large gentleman such as Martin describes himself will have a higher
top speed than a skinny bloke, because the ratio of weight to wind
resistance is in his favour.

cheers,
clive

 

[Keith Willoughby]

Peter Clinch wrote:

> Martin Wilson wrote:
>> I'm pretty sure I've set the computer to mph display but perhaps I'm
>> being generous in my description of flat as its possibly more like a
>> slight incline. The 40mph was achieved just coasting and not braking
>> in the middle of the night with no other traffic about, down a long
>> steep hill (Bablyon Hill).
>
> I can top out over 40 going down a long steep hill, pedalling hard in
> big gears on a recumbent with high quality high pressure tyres which
> almost certainly have lower rolling resistance than yours. 40 on a
> bike is fast and generally requires working at it unless you have a
> very low rolling and air resistance.

I've managed 37.6mph freewheeling on an mtb (with slicks, though). The
only time the weight is a benefit.

--
Keith Willoughby http://flat222.org/keith/
"You have nothing to fear, but fear itself....and monsters."
- Richard Herring

 

[Gawnsoft]

On Thu, 30 Sep 2004 11:36:23 +0100, Martin Wilson wrote (more or
less):
....
> I find that my cycling
>consists of fast level and downhill riding and super slow uphill
>riding as would be expected I would have thought. Surely gravity is
>working in my favour with any sort of downhill road?

It's more that your additional mass lessens the proportionate effect
of air resistance at high speeds.

If you ignore air resistance, heavy things don't go down because of
gravity any faster than light things. (compare a marble and a
cannonball, dropped from a bell-tower, f'rinstance.)

Compare a cannonball and a feather, however, and the cannonball will
fall faster than the feather, because the feather is lighter /and/
much more affected by air resistance.


>As someone who
>has been as weighty as 27 stone in recent times (with 13.5 stone on
>each leg) but still had a very active life/job in manufacturing and I
>have been doing 30 km per day on an exercise cycle with a very high
>friction level daily for the last few months to lose the lbs I would
>have thought my leg muscles were relatively strong.
>
>So I reckon my legs are pretty powerful by any standard. However as
>soon as I come to a hill and have to move my own mass up a hill the
>speed becomes pitifully low.

--
Cheers,
Euan
Gawnsoft: http://www.gawnsoft.co.sr
Symbian/Epoc wiki: http://html.dnsalias.net:1122
Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk

 

[Gawnsoft]

On Thu, 30 Sep 2004 12:21:13 +0100, Peter Clinch wrote (more or
less):

>Martin Wilson wrote:
....
>> Is 30mph
>> on a relatively flat road that impressive?
>
>It's certainly not slouching about. The UCI hour record, set in a
>velodrome on a pure track racing bike designed for the job by a
>professional cycle athlete (Chris Boardman) is 32.48 miles. Obviously
>keeping up that speed for an hour is /very/ different to keeping it up
>for a minute, but it's the fastest possible sustainable pace on the flat
>on an upright bike without a fairing, under the best possible conditions.

The other factor re. Boardman is that, on a velodrome, you're spending
a very high proportion of your time going round hairpin bends. If
Boardman spent an hour on a straight flat road, he'd go faster.

>
>> riding as would be expected I would have thought. Surely gravity is
>> working in my favour with any sort of downhill road?
>
>Not any more than someone light. Heavier objects don't fall any faster.
> Also, any bumps that require the bike to go up over them will lose you
>more energy than a light bike/rider (that's what suspension is for on a
> road).
>
>> has been as weighty as 27 stone in recent times (with 13.5 stone on
>> each leg) but still had a very active life/job in manufacturing and I
>> have been doing 30 km per day on an exercise cycle with a very high
>> friction level daily for the last few months to lose the lbs I would
>> have thought my leg muscles were relatively strong.
>
>They'll be very strong, but once you get up past 20 mph (or even near to
>20 mph!) then wind resistance is the real barrier to going faster, with
>the loss to air drag going up with the square of the speed.

For a constant shape with constant frontal area. As most folk don't
start crouching until after air resistance starts to build up, the
effect of air resistance on a typical bicycle rider is much more
complex.

> Which is
>why the UCI hour record is so much lower than the IHPVA record, where
>aerodynamic fairings on recumbent bikes are allowed. This doesn't show
>up on an exercise bike, for obvious reasons.


--
Cheers,
Euan
Gawnsoft: http://www.gawnsoft.co.sr
Symbian/Epoc wiki: http://html.dnsalias.net:1122
Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk

 

[James Annan]

Gawnsoft wrote:


> The other factor re. Boardman is that, on a velodrome, you're spending
> a very high proportion of your time going round hairpin bends. If
> Boardman spent an hour on a straight flat road, he'd go faster.

Would he? How much? Since his body is actually travelling slower than
the bike wheels (leaning inside the curve) it seems plausible that a
straight ride would be slower.

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

 

[David Martin]

> Excuse my ignorance but I thought my high tensile steel frame was TIG
> welded. I thought I'd read it somewhere. What are the options for
> steel frames. Is it silver brazed, brass brazed and something else
> like TIG? Have I got confused somewhere and it has to be brass or
> silver brazed?
>
> How much stronger would a a silver brazed weld be compared to brass
> typically?

Well, that all depends.
If done properly, the brass would be stronger. There is more scope to do the
brass brazing badly as you are closer to the temperature at which the steel
composition changes. If you go over that temperature then the structure and
properties (and to a certain extent the chemical makeup) of the steel will
change.

This does happen with TIG welding. The difference is that with brazing you
heat a much larger area of the frame, potentially up to several centimetres
either side of the joint. WIth TIG welding you head a very small area
(typically less than 7mm either side of the weld).

The tubing used for bikes can cope with a little bit of overheat, as long as
it is the thick walled part. If your tolerances are fine and you stray into
the thin walled part of a double butted tube then it could cause a very weak
part.

...d