55mph?

keep her down to 30 on the streets at least till ya get to the less watched places, & rotate the pedals when ya see the man! good vibes go a long way for the cause!!
 
you listning?. i do 16 mile there.. chill watch tv.. than take another 16 miles back. i'm sayin 16 miles takes bout 20 mins or less.. in city
 
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16 miles in 20 minutes = 48 mi / hr. Pretty good average, and even better at hitting all the lights unless you are using the bike paths. It has been many moons since I have been in good ol' Anchor Town but they would have had to do some pretty heavy mods on the bike paths to give me the courage to sustain a high rate of speed on them even running from the gestapos.

Speaking of math, perhaps someone can tell me how they figured out the rev factor. Pullin' out my dusty old calculator (puff, *coff* *coff*) it appears to me that 11,500 rpm would be about 180 mph.

Figurin' a 63" circumference and 3,484,800 inches in 55 miles the tire would make 55,314 revolutions in an hour or 922 rev per minute. Assuming 11/42 sprockets 55mph would have the engine running closer to ~3500 rpm by my calculations. Of course, I suck at brain teasers, ignored the little things like clutch slippage, and always manage to miss an important crucial factor or two so feel free to point out where I am going wrong in my pondering.
 
Actually, I might have figured out what I am missing. Is the gear ratio stepped up from the crank? I pictured a direct connection to the output sprocket but that might be a bad assumption. It has been longer since I have been inside an engine than it has since I have used a calculator!
 
these chinese bike engines have an internal gear reduction....roughly 4:1

then, the 2nd reduction is the 10 toothed sprocket coming off the engine, to your choice of rear wheel sprockets....usually 44 tooth. (I like 48 tooth, with my 48cc engines.)
factor in wheel size & rpm's and you get mph.


this is the easy way....
here's a link to jpilot's gear ratio calculator

http://www.motoredbikes.com/showpost.php?p=87814&postcount=1
 
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srdavo said:
these chinese bike engines have an internal gear reduction....roughly 4:1
....
Click to expand...
That alone would kick my calculations into the 14k range. I think I might be wanting some cast iron crotch protection with something going that fast between my knees!
 

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