View Single Post
  #17  
Old September 9th 17, 05:29 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default program to compute gears, with table

On Fri, 8 Sep 2017 14:32:52 -0700 (PDT), wrote:

On Friday, September 8, 2017 at 10:52:22 AM UTC-7, Emanuel Berg wrote:
Skip Montanaro wrote:

* Why the 1.0 divisor when computing gear?


As explained, otherwise it'll be integer
division. But I think that qualifies as a hack
(not an ugly hack tho) so there is no shame in
spotting it an "error"

* You can skip the radius and use wheel
(diameter) directly in computing
the circumference.


Right!

* It never occurred to me to do this in Lisp.
I always just use an online calculator, like:

http://www.gear-calculator.com/?GR=D...&SL=2.6&UN=KMH

Let's agree there is no need to do it in Lisp.
Only a desire


That's an eight speed setup. For the most part you can REALLY set an 8 speed up nicely to have only two clumsy steps - the two highest gears. And you in general only use these while riding downhills so it is not worth making these ratios closer.

So exactly why are they changing to 10, 11 and now 12 speeds. These have weaker chains, much faster wearing drive components and less sure shifting.


But they do allowed the sales person to say such things as "Of course
it has the new x speed" system. The last time I was at my local bike
shop the sales person said something about, "well, we do still have a
few 9 speed chains left".

I might add that in Bangkok, which is essentially flat, I might use
two gears on a normal ride.
--
Cheers,

John B.

Ads
 

Home - Home - Home - Home - Home