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#21
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Fixed/free hub opts to be free/free
"Paul Hobson" wrote in message ... Tom Nakashima wrote: I once bet my friend that a fixedgear couldn't freewheel. He also rides without a lockring and he actually unthreaded the cog by standing on the pedals, then quickly forward pedaled retheading the cog before it came off. Guess I lost the bet because I didn't state how long of a freewheel. btw; I ride with a lockring, but only secure it just past finger tight. -tom That's how I started with my lockring/sprocket, but noticed that strong back pedaling unthreaded the cog just slightly, which really threw off my mojo. So as per some advice of Mr. Sheldon, I road up a really stiff hill with some tools in my pocket to really thread the sprocket on tight. At the top of the hill I took off the wheel and then really torqued down the lockring ring hard. I've only felt the sprocket slip a little bit a couple time while skidding (something I *hate* doing). Can you friend who rides sans lockring do track stands when the hill slopes downward? \\paul www.fastermustache.org My friend is a lot heavier than I, and has a lot of power in his legs. I'm really not sure why he doesn't use an inexpensive lock ring since he can also ride his fixie backwards, or at least do a figure 8 backwards. We both can do track stands, but it's a balance thing. I not sure if the track stand you're referring to is making a skid...that I can't do, but my friend will sometimes leave his mark. My fixie is a converted steel frame bike. It has a longish wheelbase and a relaxed rake both headtube and seat-tube, so there is no toe-overlap which makes the wheelstand a lot easier on red-lights. Yes, Sheldon has great cycling information. In his website, I picked up a lot of good advice on fixedgear riding. -tom |
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#22
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Fixed/free hub opts to be free/free
"Luke" wrote in message ... In article , Tom Nakashima wrote: "Luke" wrote in message ... More exactly, that the outcome wouldn't have been different; but I concede your point. I was reasoning (Disclaimer: I'm not an engineer) - along these lines: once the chain jammed and began leveraging the cog off with the force of the bike's momentum behind it, the dynamic at play was essentially a battle of strength between the hub's cog and lockring threaded portions? And wouldn't the cog's greater surface area of thread engagement over the lockring's (one installed to spec), favor the hub's cog threads at the expense of its lockring grooves? Luke How did your chain get jammed? snip Well I was preoccupied with other matters during the duration of the snafu ;-) and so could only surmise the specifics post facto, with the bike roadside, its cog unscrewed and chain swinging freely from the BB shell and wheel's axle. But based on observations from previous - and more innocuous! - derailments and details particular to the event, I've a fair idea. Bear in mind the time span from the chain's derailment and cog unscrewing was little more than an instance; estimated speed was 45 KM/H. Here are the sequence of events: a) loose chain + bumpy asphalt derails chain to the inboard of the chainring. b) chain then derails inboard at the cog c) the chain's top run, now positioned between the cog and flange, is hooked by the wheels outbound spokes; it's pulled down and around the hub, further wedging itself between the cog and flange/spokes. d) Running out of length, the chain jams. At the time this was evidenced by a brief but intense shuddering, grinding protest from the rotating wheel, as the chain and spokes milled themselves. e) Now the chain, with the force of the bike's momentum behind it, was exerting an outbound, counterclockwise force on the cog as the spokes tried to wrap it more tightly around the hub. d) The wheel locks up for an instant; but the path of least resistance is my ersatz lockring/hub combo rather than the friction of rubber on dry asphalt. f) Cog liberated... Luke Pretty awesome Luke, 45 KM/H = 27.9617 mph.. I had to ask about derailing the chain because I did this once at the Hellyer Park Velodrome in San Jose when I had too much slack in the chain. The chain got wedged between the bottom bracket spindle cup and the crank around the curved bank. The sad part was I was strapped in tight and didn't release from the bike. It was more embarrassing than actually hitting the cement. From then on, I always made sure I adjusted the slack to the tightest part of the chain. -tom |
#23
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Fixed/free hub opts to be free/free
"Paul Hobson" wrote in message ... James Thomson wrote: Did you know about the fixed-gear mailing list? Subscription details are at: http://lists.davintech.ca/mailman/listinfo/fixed-gear James Thomson Thanks for that link, I'll check it out \\paul Here's another fun site: http://www.fixedgeargallery.com/ You wouldn't think there was so many of us. -tom |
#24
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Fixed/free hub opts to be free/free
Tom Nakashima wrote:
"Paul Hobson" wrote in message ... James Thomson wrote: Did you know about the fixed-gear mailing list? Subscription details are at: http://lists.davintech.ca/mailman/listinfo/fixed-gear James Thomson Thanks for that link, I'll check it out \\paul Here's another fun site: http://www.fixedgeargallery.com/ You wouldn't think there was so many of us. -tom oh man...I've been a regular at that bike porn site for a while now...I never get enough. \\paul |
#25
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Fixed/free hub opts to be free/free
Tom Nakashima wrote:
"Paul Hobson" wrote in message ... Can you friend who rides sans lockring do track stands when the hill slopes downward? \\paul www.fastermustache.org My friend is a lot heavier than I, and has a lot of power in his legs. I'm really not sure why he doesn't use an inexpensive lock ring since he can also ride his fixie backwards, or at least do a figure 8 backwards. We both can do track stands, but it's a balance thing. I not sure if the track stand you're referring to is making a skid...that I can't do, but my friend will sometimes leave his mark. [snip] My question wasn't clear, sorry. When you're doing a track stand (standing still at a red light) facing uphill, you primarily have to apply pressure forward, which would work to tighten the cog. Conversely, a track stand at a light facing downhill, you primarily have to apple pressure *backward*, which would work to *loosen* the cog -- which would in turn have the bike creep foward and the go would not rotate as much as the wheels, thus, unscrewing. So what I was asking was if track standing facing down a hill representive of your area would cause in sprocket to unthread. Does that even make sense? sorry... \\paul -- Paul M. Hobson Georgia Institute of Technology ..:change the words to numbers if you want to reply to me:. |
#26
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Fixed/free hub opts to be free/free
"Paul Hobson" wrote in message ... So what I was asking was if track standing facing down a hill representive of your area would cause in sprocket to unthread. Does that even make sense? sorry... \\paul -- Paul M. Hobson Georgia Institute of Technology .:change the words to numbers if you want to reply to me:. Paul, to answer your question, the answer is "no" there wouldn't be enough backwards force on a down hill slope doing a track stand that would unthread the cog. You really have to put a lot of force on the cog to unloosen it. To install the cog, I give it a good solid turn with my cog chain wrench, and then add the reverse (left hand thread) locking ring a little past finger tight. I then find a hill to climb and most likely I have to ever-so-slightly retighten the lockring. My friend who rides without a lockring has to really stand on the pedals to break loose the cog. Even when I use my cog chain wrench I have to put on a lot of force to remove it. Since I love climbing hills with my fixie, I have a 46t front and a 20t rear which gives me about 62.1 gear inches. I can ride pretty steep hills in the gear, but the downside is on the flats I have a high cadence. The flip-flop makes sense, or even carrying an extra few cogs and wrench, but I'm lazy. -tom |
#27
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Fixed/free hub opts to be free/free
In article , Tom Nakashima
wrote: Pretty awesome Luke, 45 KM/H = 27.9617 mph.. Well, I wish I could attribute the warp speed to my Nothstein-like thighs, but the hill's grade definitely played a part! ;-). Really, at the time, the cadence was managing me as opposed to the reverse: I was in the proverbial ass-pogoing pedalling mode and transmitting no power to the pavement. I'm laughing now just thinking about it. I'd like to believe that a burst of sparks fanned out from my mobile chain grinder as it sped through the night - that would've made it really awesome! Luke |
#28
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Fixed/free hub opts to be free/free
"Tom Nakashima" wrote:
Pretty awesome Luke, 45 KM/H = 27.9617 mph.. Not correct. Tom, if you are either faculty or student at Stanford, you should know something about significant digits. That conversion is a common source of error in many computations. 45.0000 km/h = 27.9617 mph 45 km/h = 28 mph -- Ted Bennett |
#29
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Fixed/free hub opts to be free/free
"Ted Bennett" wrote in message ... "Tom Nakashima" wrote: Pretty awesome Luke, 45 KM/H = 27.9617 mph.. Not correct. Tom, if you are either faculty or student at Stanford, you should know something about significant digits. That conversion is a common source of error in many computations. 45.0000 km/h = 27.9617 mph 45 km/h = 28 mph -- Ted Bennett Sorry Ted, I was only off by -.0383 mph. -tom |
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