Yet another steel vs aluminium question

Hi Gang,

I'm trying to put together a bike for general leisure and fitness riding but with half an eye on
next years Etape and both eyes on lots of Scottish hills. So basically I want something light and
fun that also looks good. Practicality isn't an issue as I still have my old faithful everyday bike,
with 501 frame and forks, rack and mudguards. This one is just for fun.

I've pretty much decided to go for a mix and match approach to the components and will be using 10
speed Chorus ergo shifters with an 8 speed shimano rear. Wheels will be Open Pro (black) on Dura
Ace hubs with black DT spokes. However, I still can't decide on the frame. Currently I'm looking at
two options.

1. Scandium frame from Ribble. I've read all the threads on Ribble so am prepared for a long fight
if the frame isn't as advertised, but so far most people seem to agree that the frames themselves
are well made and you can't argue with the price. A weight of 1050g sounds impressive but is that
too light to last more than a year or two and is an integrated headset really a sensible idea.

2. Sintesi Pegaso steel (Deda Eom 16.5). I think I've found one of these in my size at the same
proce as the Ribble. Quoted weight is 1520g, so that's a whole extra pound on the total weight.
But steel is real right?

So which would you choose.

Cheers,

Andy

 

[email protected] wrote:
> 1. Scandium frame from Ribble. I've read all the threads on Ribble so am prepared for a long fight
> if the frame isn't as advertised, but so far most people seem to agree that the frames
> themselves are well made and you can't argue with the price. A weight of 1050g sounds
> impressive but is that too light to last more than a year or two and is an integrated headset
> really a sensible idea.
>
> 2. Sintesi Pegaso steel (Deda Eom 16.5). I think I've found one of these in my size at the same
> proce as the Ribble. Quoted weight is 1520g, so that's a whole extra pound on the total weight.
> But steel is real right?

Be wary of those quoted weights. Manufacturers and dealers may be quoting the smallest size (which
may be different in each case) - and without any paint or braze-ons!, or may simply be telling
bare arsed lies! My latest frame was advertised as being "1.5kg" (no size mentioned) but is
actually 1646g for the 60cm, and 1678g for the 62cm, and I've read of much greater discrepencies
with other makes.

Personally, I would look for a third option: an Al or Ti frame that was not Ribble (I'm skeptical
about steel giving a /much/ better ride or being so much more durable that it's worth the extra
weight or expense); or alternatively go up to Ribble and check it out in person rather than
mail-ordering.

~PB

 

On 19-Mar-2003, "Pete Biggs" <pLime{remove_fruit}@biggs.tc> wrote:

> Be wary of those quoted weights. Manufacturers and dealers may be quoting the smallest size (which
> may be different in each case) - and without any paint or braze-ons!, or may simply be telling
> bare arsed lies! My latest frame was advertised as being "1.5kg" (no size mentioned) but is
> actually 1646g for the 60cm, and 1678g for the 62cm, and I've read of much greater discrepencies
> with other makes.
>

Fair point. The Sintesi weight claims to be for a large size painted frame. The Ribble one doesn't
give any info so I guess we can bank on it being closer to 1200g than 1000g but that is still 300g
lighter than the Sintesi.

> Personally, I would look for a third option: an Al or Ti frame that was not Ribble (I'm skeptical
> about steel giving a /much/ better ride or being so much more durable that it's worth the extra
> weight or expense); or alternatively go up to Ribble and check it out in person rather than
> mail-ordering.

Having said that the Sintesi is heavier I guess 300g isn't much so you could argue that steel isn't
significantly heavier and in this case it isn't more expensive either. There is a part of me that is
drawn to the idea of building a lightweight steel bike just to show that it can be done, although
I'm also skeptical about those claims of much better comfort or durability.

Cheers,

Andy

 

<[email protected]> wrote in message

> There is a part of me that is drawn to the idea of building a lightweight steel bike just to show
> that it can be done, although I'm also skeptical about those claims of much better comfort or
> durability.

Don't let me influence your choice here. I only want to satisfy my curiosity.

Conventional steel frames have fairly narrow diameter tubes which are fairly twisty. As the tube
diameter rises, the wall thickness has to go down to keep the weight down. Hence we get a stiffer
frame but it might be more prone to crush damage.

My old 531 tourer is too flexible for comfort (recovery after bump is poor) so I would not consider
similar for a leisure bike. But it will pobably last forever.

With ally we can combine large diameter tubes with decent wall thickness. Decent stiffness is also
the only option.

If we talk about the durability, steel can obviously do it. It can also be made adequately stiff.
But can it achieve both at the same time? In steel
vs. aluminium, how is like for like performance properly compared?

David Roberts

 

On 20-Mar-2003, "DR" <[email protected]> wrote:

> Conventional steel frames have fairly narrow diameter tubes which are fairly twisty. As the tube
> diameter rises, the wall thickness has to go down to keep the weight down. Hence we get a stiffer
> frame but it might be more prone to crush damage.
>

Sounds sensible although I'm not sure how big the twisting forces are on a bike. Seems like
compression is a big issue and bending around the bottom bracket, but is there mich twisting around
the long axis of the tube?

> My old 531 tourer is too flexible for comfort (recovery after bump is poor) so I would not
> consider similar for a leisure bike. But it will pobably last forever.
>

Interesting observation. I thought 531 was supposed to be the ideal material for a comfortable
tourer. You seem to be saying that you find a stiff frame more comfortable on a long ride than a
more forgiving one.

> With ally we can combine large diameter tubes with decent wall thickness. Decent stiffness is also
> the only option.
>
> If we talk about the durability, steel can obviously do it. It can also be made adequately stiff.
> But can it achieve both at the same time? In steel
> vs. aluminium, how is like for like performance properly compared?

I guess this is the nub of the issue. I suspect that like for like performance is never compared,
which is why we end up with all sorts of unproven "facts" like aluminium frames are harsh or steel
frames are heavy.

I think it is safe to say that you can build a light frame in steel and a flexible frame in
aluminium. I guess my main concern at the moment is whether a 1.5Kg Eom 16.5 steel frame (with thin
tubes) will be a better option for fast day rides in hilly terrain than a 1.1Kg Scandium one (with
fat tubes).

Cheers,

Andy

 

<[email protected]> wrote
> "DR" <[email protected]> wrote:
>
> > Conventional steel frames have fairly narrow diameter tubes which are fairly twisty. As the tube
> > diameter rises, the wall thickness has to go down to keep the weight down. Hence we get a
> > stiffer frame but it might be more prone to crush damage.
>
> Sounds sensible although I'm not sure how big the twisting forces are on a bike. Seems like
> compression is a big issue and bending around the bottom bracket, but is there mich twisting
> around the long axis of the tube?

If you take the four points of a bike - the two tyre contact patches, the handlebar and the saddle -
then, yes it can bend in torsion.

> > My old 531 tourer is too flexible for comfort (recovery after bump is poor) so I would not
> > consider similar for a leisure bike. But it will probably last forever.
>
> Interesting observation. I thought 531 was supposed to be the ideal material for a comfortable
> tourer. You seem to be saying that you find a stiff frame more comfortable on a long ride than a
> more forgiving one.

We know that a frame offers no useful vertical compliance (certainly insignificant wrt tyre
deflection). I don't see how flexibility offers benefit because it is bound to develop as movement
in the wrong plane. Steel also offers very little damping so recovery take time. I think this must
be why it is termed "lively".

I actually do most of my riding on a bike with slightly oversize (1 3/8), steel tubes and
suspension. This is definitely the optimal route to comfort.

Conversely, a fat tubed ally machine with 23mm tyres is the opposite extreme. I might not attack
speed humps in quite the same way but otherwise the sharp responses and fast recovery from most road
defects makes it a quite agreeable ride.

> I think it is safe to say that you can build a light frame in steel and a flexible frame in
> aluminium. I guess my main concern at the moment is whether a 1.5Kg Eom 16.5 steel frame (with
> thin tubes) will be a better option for fast day rides in hilly terrain than a 1.1Kg Scandium one
> (with fat tubes)

As I said, I was satisying my own curiosity. I wish you best of luck.

David Roberts

 

[email protected] wrote in message news:<[email protected]>...
>
> I think it is safe to say that you can build a light frame in steel and a flexible frame in
> aluminium.

Indeed - especially bonded Al frames, which on the whole have a rather "springy" ride quality. This
does help to smooth out rough surfaces, and is presumably why Alan frames built this way have
figured strongly in cyclo-cross for so long.

David E. Belcher

Dept. of Chemistry, University of York