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Post by brianbutler on Jun 23, 2022 18:29:43 GMT
For a recent post, I measured the bolt circle diameter (BCD) of the Viscount TA crankset. It reminded me of this write-up ( wickwerks.com/bolt-circle-diameter-bcd/), where they say how easy it is to measure BCD for crank sets with an even number of bolts - just measure across. Then they delve into a lot of geometry, formulas, and tables to explain how to get the BCD of a crankset with an odd number of bolts - they warn it is not so easy.
But why not just measure from the crank center to one of the bolts and double it. Indeed, this could be a "universal" solution.
It reminds me of the time in college when 5 of us stopped at a pizza place, ordered a pie, and asked for it to be cut into 10 slices, which was immediately rejected as impossible by the proprietor. He said it would be possible to cut a pie into 4, 6, 8, even 12 slices but not 10. An engineering students among us took one of the circular cardboards they put in the pizza box and with a pen drew 5 lines making 10 slices and numbered them 1-10. After several counts and recounts, it was confirmed and the cardboard was tacked on the wall for future reference.
Brian
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Post by oldroadietehachapi on Jun 24, 2022 5:27:30 GMT
Yes, of course that will work. I like it, plain and simple.
Oh wait, let me think on it. I will need to find the exact center of the crank and chain holes. I suppose I could make a tool that fills each hole as well as for the crank. These tools must indicate the exact center of the hole. Of course, I must buy a mill to make the tool and my machine skills are rusty so I will need to go back to school. The nearest school is 100 miles away and with the price of gas I will need to buy an electric car. Also, my shop is a bit small so I will need an addition to the building. The permitting process is difficult so I will need to hire a consulting service to influence (bribe?) the bureaucrats; after all, this is California. Did I mention that I will need a new computer application to statistically analyze the results? I think I can successfully complete the project for 1.7 million dollars, give or take a few hundred thousand. 
Ride Happy Jim |
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Post by brianbutler on Jun 24, 2022 10:30:28 GMT
Yes, of course that will work. I like it, plain and simple.
Oh wait, let me think on it. I will need to find the exact center of the crank and chain holes. I suppose I could make a tool that fills each hole as well as for the crank. These tools must indicate the exact center of the hole. Of course, I must buy a mill to make the tool and my machine skills are rusty so I will need to go back to school. The nearest school is 100 miles away and with the price of gas I will need to buy an electric car. Also, my shop is a bit small so I will need an addition to the building. The permitting process is difficult so I will need to hire a consulting service to influence (bribe?) the bureaucrats; after all, this is California. Did I mention that I will need a new computer application to statistically analyze the results? I think I can successfully complete the project for 1.7 million dollars, give or take a few hundred thousand. 
Ride Happy Jim Sure, the startup is cumbersome but once you work out the kinks you can sell the idea to Park Tool (BCD-1) for $3.4M.
Brian
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