On 8/29/2019 4:44 PM, jbeattie wrote:
On Thursday, August 29, 2019 at 12:44:33 PM UTC-7, Frank Krygowski wrote:
On 8/28/2019 11:51 AM, Tom Kunich wrote:
On Tuesday, August 27, 2019 at 9:13:57 PM UTC-7, Frank Krygowski wrote:

Explain. If you take a bottom bracket axle made of steel with yield strength
100,000 psi and replace it with an identical part made of steel with yield
strength 120,000 psi, will it transfer more power from the same rider?

Perhaps you'd like to explain to us why that would matter? How many people can cause distortion of the bottom bracket axle in either case?

Sheesh! Tom, that is precisely the point!

It was YOU who claimed "But these higher grade materials allowed for
large improvements in power transfer." That's what I was responding to.
Now you seem to be arguing with yourself!

Care to explain why you said that in the first place? What on earth were
you thinking?

--
- Frank Krygowski

I always wondered how they measured the effect of BB (shell or axle) flex and power output. Power is transmitted from the pedal to the arm to the spider to the ring to the chain -- as the mechanism is rotating on the BB axle. You would have to have one of those complicated equations with fancy symbols to calculate the contribution of flex in the BB axle or shell!

I know it is a big marketing point, but I don't recall going any faster when I went from a PW square drive to an Octalink on the same bike.

Not to resurrect an argument, but just to remind people:

A few years ago here, someone linked to a magazine article where they
had young modern racers do a comparison test of a 1980s or 1990s racing
bike vs. an up to date, modern rigid-yet-compliant, many-more-speeds,
STI equipped, more aero carbon frame racing bike. The test consisted of
repeated runs over a long steady climb.

The young test pilots were indeed faster on the new bikes, and said
everything about the new bike was much better except perhaps the saddle.
They said they were afraid to take their hands off the hoods to shift
the old bike. And yes, they said the rigidity was much better for power
transfer. It "proved" that all of the new technology was the bees knees.

Except the improvement in climbing speeds was precisely what would have
been predicted by just the difference in bike weight. All the other
factors had no demonstrable effect on speed.

--
- Frank Krygowski