On Wed, 7 Jun 2017 07:20:09 -0700 (PDT), jbeattie
wrote:

On Wednesday, June 7, 2017 at 5:28:46 AM UTC-7, AMuzi wrote:
On 6/7/2017 12:13 AM, John B. wrote:
On Wed, 7 Jun 2017 09:34:58 +1000, James
wrote:

On 07/06/17 08:03, jbeattie wrote:
On Tuesday, June 6, 2017 at 7:09:56 AM UTC-7,
wrote:
On Monday, June 5, 2017 at 7:56:58 PM UTC-7, James wrote:
https://cyclingtips.com/2017/06/cycl...ffness-matter/



Interesting that some pros want a less stiff frame early season, and
more stiff frame later in the season.

Other interesting bits too.

Well, if you're flexing a frame and getting power back that's fine.
But at the same time there are frictional loses and you're only
getting back a portion of it.

There was a noticeable difference between riding a Colnago Dream
with carbon forks and the Colnago C40. The C40 was stiff and I had
to pedal complete circles on a hard climb or the bike would stop at
the point of one down stroke to the next. The Dream did it less. A
steel bike absolutely does not do this.

Now there may be a preference about one way or another but I don't
believe so. I think that this really is something that works better
and while I haven't said anything to the group I generally ride
with most of them are returning to steel.

The podcast is all about BB stiffness which is just one aspect of
frame stiffness.

Of course a soft frame is an energy sponge. Try sprinting on a
double-suspended mountain bike. Small difference in BB stiffness
between racing bikes, however, probably makes little difference.


Dual suspension MTB is a totally different beast. It has built in energy
absorbers (shock absorbers). Rigid frames do not.

I'm far more sensitive to front-end stiffness than BB stiffness. I
had a first-gen Cannondale 2.8 with aluminum forks that was like
sprinting on a pogo stick. I wanted to throw it away after my first
race on it but instead bought a pair of Kestrel forks which rode a
lot like steel (they had a steel steerer). I had a custom steel
sport-touring frame that rode the same way -- lots of slop. My last
steel racing bike was very stiff, but when I resurrected it last and
used it as my winter bike, it was not magical in any way. The
top-tube was too short; it was heavy and probably less "planing" than
my CAAD 3. What steel has going for it is resistance to mechanical
damage.


With thin walled tubes (0.4mm & below), not even that.

This whole steel-is-magical thing reminds me of going back to vinyl
and realizing how many bad recordings there are. It's more about the
implementation than the material.


I agree.

One of the things I've always wondered about when people start talking
about BB flex. It would be a relatively simple problem to built a
steel frame bike with gussets of bracing for the BB, but no one seems
to have. Looking at Eddie Marckx, Sean Kelly or any of the other top
riders of the "steel Era" and none of their bikes seemed to have any
visible BB bracing.

Yoshi Konno of 3Rensho, c.1990:
https://www.pedalroom.com/bike/3rensho-njs-chrome-6748

The linking is odd so in that series go to the BB photo.

The Serotta Colorado used an ovalized seat tube at the BB to add stiffness. That was '86-87. Earlier steel frames also used chain stay bridges. If you wanted a super-stiff BB after the late '70s early '80s, you bought a Klein or Cannondale, assuming you could handle the aesthetic shock of fat tubes.

-- Jay Beattie.

But that was one or two bicycles. I'm looking at bikes ridden by top
riders, I mentioned Eddie Marckx, Sean Kelly, et al, and I don't see
any frame stiffeners or wide tubes on bikes shown in photos of the top
rider of that era.

In fact, based on memory - always a questionable practice - I don't
remember a lot of talk about frame stiffness until about the time that
Cannondale started selling aluminum bikes. .

--
Cheers,

John B.