On 2/16/2020 10:11 AM, Bertrand wrote:
I was replying to your pedantic remark 'As always: Sorry for
introducing real numbers into a discussion. '. Those are not real
numbers and certainly can not be checked. We have to believe you. In
that case we can also believe Tom saying that thy dyno slowed him down
considerably. BTW I think going from 20 to 19 mph is quite a bit for
some. Bottom line is a dyno(hub) cost you 5-10 W, a battery powered
light not.


Putting some numbers into bikecalculator.com suggests that the
difference between 20 and 19 mph is about 26 watts (207 vs. 181), which
is a lot.

Assuming those calculations are correct: Is that "a lot"? How do we judge?

If told "It's enough to slow you down from 20 mph to 19 mph," I think
most people who were not riding to race would say "Oh, that's not so bad."

It's certainly not as bad as Tom pretended to believe, which was my main
point.

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- Frank Krygowski