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Shimano freewheel, max coasting RPM?
On Friday, July 18, 2014 11:00:55 AM UTC-7, JoeRiel wrote:
AMuzi writes: John Doe wrote: I just bought a Shimano SF-1200 freewheel. What is the maximum coasting RPM for such a freewheel? If you don't know the specification, can you give me a ballpark estimate? Clive George clive xxxx-x.fsnet.co.uk wrote: I can't see why there would be such a maximum specified. However 60mph is about 700 rpm on a 700c wheel so they'll easily cope with that. What speed are you thinking of? On 7/18/2014 11:32 AM, John Doe wrote: If you must know... I'm building a racing bike for a beloved and unusually talented midget friend. The wheels are tiny but (in spandex) he can pedal up to 2000 RPM. Something's not right, either a typo, an error or a falsehood. I do not believe there is _anything_ a human can do at 2000 rpm= 33 times per second given tour standard issue nervous system. Certainly not move a crank that fast. He's concerned about the rpm of the wheel, not the crank. Presumably it's a small diameter wheel. -- Joe Riel Yes, but let say he has a 20" wheel, 2,000 RPM would yield about 120 mph. Assuming he has a 53/12, he would have to spin at about 650 RPMs, which I can do, but not for more than maybe half an hour. I think the subject of the post needs this: http://tinyurl.com/oadu73j The pictured rider is in wool, however, and the subject of the post may need a different front ring if he is wearing Spandex, particularly if it is purple. -- Jay Beattie. |
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#12
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Shimano freewheel, max coasting RPM?
jbeattie writes:
On Friday, July 18, 2014 11:00:55 AM UTC-7, JoeRiel wrote: AMuzi writes: John Doe wrote: I just bought a Shimano SF-1200 freewheel. What is the maximum coasting RPM for such a freewheel? If you don't know the specification, can you give me a ballpark estimate? Clive George clive xxxx-x.fsnet.co.uk wrote: I can't see why there would be such a maximum specified. However 60mph is about 700 rpm on a 700c wheel so they'll easily cope with that. What speed are you thinking of? On 7/18/2014 11:32 AM, John Doe wrote: If you must know... I'm building a racing bike for a beloved and unusually talented midget friend. The wheels are tiny but (in spandex) he can pedal up to 2000 RPM. Something's not right, either a typo, an error or a falsehood. I do not believe there is _anything_ a human can do at 2000 rpm= 33 times per second given tour standard issue nervous system. Certainly not move a crank that fast. He's concerned about the rpm of the wheel, not the crank. Presumably it's a small diameter wheel. -- Joe Riel Yes, but let say he has a 20" wheel, 2,000 RPM would yield about 120 mph. Assuming he has a 53/12, he would have to spin at about 650 RPMs, which I can do, but not for more than maybe half an hour. I think the subject of the post needs this: http://tinyurl.com/oadu73j The pictured rider is in wool, however, and the subject of the post may need a different front ring if he is wearing Spandex, particularly if it is purple. Being a midget and all, there might be chafing issues with the size of that chain ring---a kevlar skinsuit seems in order. A skateboard-sized wheel may be more practical, though attaching the freewheel to it could be challenging. -- Joe Riel |
#13
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Shimano freewheel, max coasting RPM?
'ahhhh a midjet ! off corso...
question: pedaling a transmission output shaft to 2000 is possible ? No Shimano's work isnot good for high speeds. Bicycle engineering at cycle speeds and temps. Bearing races, pressures, lubricants are no high speed systems. For 1912, outasight. wait what abt 100 mph behind a railroad car ? I dunno ask him. |
#14
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Shimano freewheel, max coasting RPM?
On Friday, July 18, 2014 5:59:58 PM UTC-4, wrote:
'ahhhh a midjet ! off corso... question: pedaling a transmission output shaft to 2000 is possible ? No Shimano's work isnot good for high speeds. Bicycle engineering at cycle speeds and temps. Bearing races, pressures, lubricants are no high speed systems. For 1912, outasight. wait what abt 100 mph behind a railroad car ? I dunno ask him. LLLLLLLLLLLLLLLLLLLLL no argument on that position ? |
#15
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Shimano freewheel, max coasting RPM?
On Friday, July 18, 2014 10:28:25 AM UTC-4, John Doe wrote:
I just bought a Shimano SF-1200 freewheel. What is the maximum coasting RPM for such a freewheel? If you don't know the specification, can you give me a ballpark estimate? Thanks. -9 on the Troll Meter. |
#16
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Shimano freewheel, max coasting RPM?
off-topic Google Groups spam/troll...
-- Sir Ridesalot i_am_cycle_pathic yahoo.ca wrote: X-Received: by 10.50.170.162 with SMTP id an2mr2481206igc.4.1405788447298; Sat, 19 Jul 2014 09:47:27 -0700 (PDT) X-Received: by 10.140.105.200 with SMTP id c66mr181026qgf.4.1405788447198; Sat, 19 Jul 2014 09:47:27 -0700 (PDT) Path: eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!feeder.erje.net!eu.feeder.erje.net!e nother.net!enother.net!news.glorb.com!h18no2319808 igc.0!news-out.google.com!cz11ni6302qab.1!nntp.google.com!v10 no1477015qac.1!postnews.google.com!glegroupsg2000g oo.googlegroups.com!not-for-mail Newsgroups: rec.bicycles.tech Date: Sat, 19 Jul 2014 09:47:26 -0700 (PDT) In-Reply-To: lqbau9$api$1 dont-email.me Complaints-To: groups-abuse google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=174.92.139.52; posting-account=2ScyvAoAAABQnc3o8m-FIpwdnQ-MzjLx NNTP-Posting-Host: 174.92.139.52 References: lqbau9$api$1 dont-email.me User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: 93f84ffe-d8e9-4429-8b9d-8840774e053d googlegroups.com Subject: Shimano freewheel, max coasting RPM? From: Sir Ridesalot i_am_cycle_pathic yahoo.ca Injection-Date: Sat, 19 Jul 2014 16:47:27 +0000 Content-Type: text/plain; charset=ISO-8859-1 Xref: news.eternal-september.org rec.bicycles.tech:161785 On Friday, July 18, 2014 10:28:25 AM UTC-4, John Doe wrote: I just bought a Shimano SF-1200 freewheel. What is the maximum coasting RPM for such a freewheel? If you don't know the specification, can you give me a ballpark estimate? Thanks. -9 on the Troll Meter. |
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