Today while coming downhill I threw the chain of my fixie. looked staright ahead and clamped on the anchors droping my rear end off he back of the saddle as it only has one brake on the front.
what could have caused this I was going down a hill with the legs doing 140-150 rpm and all of a sudden my feet stop turning fortunately the chain dropped onto the crank arm and slipped off the rear onto the space between cog and frame. I had to loosen the rear wheel to get the chain back on and pulled it tight again then gingerly pedaled home avoiding any steep downhill sections does anyone have any idea as to what might have happened.
Today while coming downhill I threw the chain of my fixie. looked staright ahead and clamped on the anchors droping my rear end off he back of the saddle as it only has one brake on the front.
what could have caused this I was going down a hill with the legs doing 140-150 rpm and all of a sudden my feet stop turning fortunately the chain dropped onto the crank arm and slipped off the rear onto the space between cog and frame. I had to loosen the rear wheel to get the chain back on and pulled it tight again then gingerly pedaled home avoiding any steep downhill sections does anyone have any idea as to what might have happened.
Most likely, excessive chain slop built up, and it slung just far enough to snag a tooth at the rear and walk over the sprocket. Anything else would most likely have produced other symptoms that you might have noticed.
Did you notice if you had to move the wheel farther back to get correct tension when you put the chain back on? -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts.
"Werehatrack" <[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Jon_H said:
Today while coming downhill I threw the chain of my fixie. looked
staright
Quoted message said:
Quoted message said:
ahead and clamped on the anchors droping my rear end off he back of the saddle as it only has one brake on the front.
what could have caused this I was going down a hill with the legs doing 140-150 rpm and all of a sudden my feet stop turning fortunately the
chain
Quoted message said:
Quoted message said:
dropped onto the crank arm and slipped off the rear onto the space
between
Quoted message said:
Quoted message said:
cog and frame. I had to loosen the rear wheel to get the chain back on
and
Quoted message said:
Quoted message said:
pulled it tight again then gingerly pedaled home avoiding any steep
downhill
Quoted message said:
Quoted message said:
sections does anyone have any idea as to what might have happened.
Most likely, excessive chain slop built up, and it slung just far enough to snag a tooth at the rear and walk over the sprocket. Anything else would most likely have produced other symptoms that you might have noticed.
Did you notice if you had to move the wheel farther back to get correct tension when you put the chain back on? -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts.
If the wheel is slipping under tension has anyone succesfully used any clamping device for Campy type dropouts to stop the forward creep .
Today while coming downhill I threw the chain of my fixie. looked staright ahead and clamped on the anchors droping my rear end off he back of the saddle as it only has one brake on the front.
what could have caused this I was going down a hill with the legs doing 140-150 rpm and all of a sudden my feet stop turning fortunately the chain dropped onto the crank arm and slipped off the rear onto the space between cog and frame. I had to loosen the rear wheel to get the chain back on and pulled it tight again then gingerly pedaled home avoiding any steep downhill sections does anyone have any idea as to what might have happened.
Most likely, excessive chain slop built up, and it slung just far enough to snag a tooth at the rear and walk over the sprocket. Anything else would most likely have produced other symptoms that you might have noticed.
More likely it climbed over the chainring first. This was discussed here a week or two ago. Chain slop+back torque+high rpm=loose top run flapping around on its way to the chainring. Chain off on a fixie nearly always happens at speed going downhill because the loose run is the one which fails to engage, and derailing off the chainring is much easier than derailing off the sprocket. You only have to look at a geared bike to know this; the front derailleur pushes the tight top run off the chainring quite easily when you shift from big to little under load.
You can cure this completely with side plates on the chainring and sprocket, such as using a DH chain device :-)
Kinky Cowboy*
*Batteries not included May contain traces of nuts Your milage may vary
Most likely, excessive chain slop built up, and it slung just far enough to snag a tooth at the rear and walk over the sprocket. Anything else would most likely have produced other symptoms that you might have noticed.
Did you notice if you had to move the wheel farther back to get correct tension when you put the chain back on?
If the wheel is slipping under tension has anyone succesfully used any clamping device for Campy type dropouts to stop the forward creep .
Um, he did not say that the wheel was slipping under tension. Excessive slop can develop from chain wear. In addition a worn chain is more easily thrown than a new one.
BTW, I use a plain old quick-release and get no slipping.
--
David L. Johnson
__o | The lottery is a tax on those who fail to understand _`\(,_ | mathematics. (_)/ (_) |
"David L. Johnson" <[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Jon_H said:
Quoted message said:
Most likely, excessive chain slop built up, and it slung just far enough to snag a tooth at the rear and walk over the sprocket. Anything else would most likely have produced other symptoms that you might have noticed.
Did you notice if you had to move the wheel farther back to get correct tension when you put the chain back on?
If the wheel is slipping under tension has anyone succesfully used any clamping device for Campy type dropouts to stop the forward creep .
Um, he did not say that the wheel was slipping under tension. Excessive slop can develop from chain wear. In addition a worn chain is more easily thrown than a new one.
BTW, I use a plain old quick-release and get no slipping.
--
David L. Johnson
__o | The lottery is a tax on those who fail to understand _`\(,_ | mathematics. (_)/ (_) |
the chain only has about 200 mainly dry miles and has been cleaned and lubed fairly regularly so i don't think its a worn chain.
"David L. Johnson" <[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Jon_H said:
> Most likely, excessive chain slop built up, and it slung just far > enough to snag a tooth at the rear and walk over the sprocket. > Anything else would most likely have produced other symptoms that > you might have noticed. > > Did you notice if you had to move the wheel farther back to get > correct tension when you put the chain back on?
If the wheel is slipping under tension has anyone succesfully used any clamping device for Campy type dropouts to stop the forward creep .
Um, he did not say that the wheel was slipping under tension. Excessive slop can develop from chain wear. In addition a worn chain is more easily thrown than a new one.
BTW, I use a plain old quick-release and get no slipping.
--
David L. Johnson
__o | The lottery is a tax on those who fail to understand _`\(,_ | mathematics. (_)/ (_) |
the chain only has about 200 mainly dry miles and has been cleaned and lubed fairly regularly so i don't think its a worn chain.
cheers Jon_H
What are you using to affix your rear wheel to your frame dropouts?
Today while coming downhill I threw the chain of my fixie. looked staright ahead and clamped on the anchors droping my rear end off he back of the saddle as it only has one brake on the front.
what could have caused this I was going down a hill with the legs doing 140-150 rpm and all of a sudden my feet stop turning fortunately the chain dropped onto the crank arm and slipped off the rear onto the space between cog and frame. I had to loosen the rear wheel to get the chain back on and pulled it tight again then gingerly pedaled home avoiding any steep downhill sections does anyone have any idea as to what might have happened.
Chain not tight enough, and jerky pedalling at high rpms. This makes the chain bounce around and eventually come off. Make sure your chain is as tight as possible without causing binding.
On Thu, 13 Oct 2005 21:01:44 +0100, Kinky Cowboy <[email hidden]>
Quoted message said:
Werehatrack said:
Jon_H said:
Today while coming downhill I threw the chain of my fixie. looked staright ahead and clamped on the anchors droping my rear end off he back of the saddle as it only has one brake on the front.
what could have caused this I was going down a hill with the legs doing 140-150 rpm and all of a sudden my feet stop turning fortunately the chain dropped onto the crank arm and slipped off the rear onto the space between cog and frame. I had to loosen the rear wheel to get the chain back on and pulled it tight again then gingerly pedaled home avoiding any steep downhill sections does anyone have any idea as to what might have happened.
Most likely, excessive chain slop built up, and it slung just far enough to snag a tooth at the rear and walk over the sprocket. Anything else would most likely have produced other symptoms that you might have noticed.
More likely it climbed over the chainring first. This was discussed here a week or two ago. Chain slop+back torque+high rpm=loose top run flapping around on its way to the chainring. Chain off on a fixie nearly always happens at speed going downhill because the loose run is the one which fails to engage, and derailing off the chainring is much easier than derailing off the sprocket. You only have to look at a geared bike to know this; the front derailleur pushes the tight top run off the chainring quite easily when you shift from big to little under load.
You can cure this completely with side plates on the chainring and sprocket, such as using a DH chain device :-)
Good points; when the bike speed is high, the slinging is also greatest as well, and in a downhill situation, it's easy to reach the kind of speed where the bike is outrunning the rider. 140 to 150rpm would be faster than *I* want to pedal.
I've seen one other factor that also contributes to fixie sling; usage of a front sprocket that was made for a der system. Those often have reduced-height teeth in two (or more) places which are designed to aid in shifting...but which end up aiding in chain jump. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts.
thanks for all the tips and advice, the wheel is fixed with an allen key skewer as it appears to tighten better than the normal lever type. My brother reckons I should fit a front derailleur to hold the chain in place anyone else tried this to good effect.
their does seem to be a bit of chain slop but not a great deal.
"Jon_H" <[email hidden]> wrote in message news:[email hidden]... SNIP
Quoted message said:
the chain only has about 200 mainly dry miles and has been cleaned and lubed fairly regularly so i don't think its a worn chain.
cheers Jon_H
I find that my fixed gear chains often strech quite a bit in the initial 200 miles. I always assumed this was some kind of break in period and adjust the rear wheel often during this period.
thanks for all the tips and advice, the wheel is fixed with an allen key skewer as it appears to tighten better than the normal lever type. My brother reckons I should fit a front derailleur to hold the chain in place anyone else tried this to good effect.
_ That's a common trick in cyclocross racing.
Quoted message said:
their does seem to be a bit of chain slop but not a great deal.
_ Ideally you want none, you should be able to "pluck" the chain. I found this article very useful in getting the chain as tight as possible.
their does seem to be a bit of chain slop but not a great deal.
_ Ideally you want none, you should be able to "pluck" the chain.
Yup, no slack is the way to go; I find the only way to consistently achieve this is with chain tugs. Find the tight spot (there nearly always is one) then tighten the chain using the screws on the chain tugs until it's just taut. Secure the wheel with whatever you're using (QR, tracknuts, Allen screws) Now, keeping the crank in the position which gives the most chain tension and holding the bike still, push the pedal in whichever direction suits you using moderate hand pressure; you'll find you can easily get 1/4" of chain slack in the loose run of chain like this. Now imagine how much more slack you'll have when you're really cranking it with leg power.
thanks for all the tips and advice, the wheel is fixed with an allen key skewer as it appears to tighten better than the normal lever type. My brother reckons I should fit a front derailleur to hold the chain in place anyone else tried this to good effect.
their does seem to be a bit of chain slop but not a great deal.
Have you read Sheldon Brown's articles on fixed gear conversion/setup? If not, Google it, it's a wealth of info.
Chain drops on a fixer are not a good thing. You want to get out all the slack and have a perfect chain line. Often chainrings aren't perfectly centered on the crank spindle. You can usually correct this by tweaking the alignment on the chainring bolts, Sheldon explains all this and much more.
I set up my fixer according to his directions and I haven't dropped a chain ever, in several years of riding.
