On Thursday, August 29, 2019 at 1:44:10 PM UTC-7, 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.

-- Jay Beattie.

Just five years ago I could tell the difference in flex between an ISO BB and an Octalink. Today I can't. Five years ago when sprinted for a light I could hit almost 40 mph. Today I have trouble getting over 20.

So it doesn't matter what I'm using now but it did only 5 years ago. There is a local hill that I climb coming back from an area where there are many courses. 5 years ago I could go over its 3% grade at 25 mph. Today, it's 8 mph. This is all pretty shocking to me that I would change that much that fast. Of course in two months I'll be 75 but I wouldn't think there would be such a dramatic difference between 70 and 75.