SS Build - Help Needed - PLEASE

[gb155]

Not sure whats causing this

too wide a chain? too tight ? sprocket and ring not compatible ?


I just dunno, PLEASE help

[media]

]View: http://www.youtube.com/watch?v=tpMrKFZ25WE[/media]

 

[DrSquirrel]

If it can lift up on the teeth - its too loose for one.

Other than that - what is the chainline like? SS should be straight - very straight (if this was fixed it would be dangerous).

 

[gb155]

If it can lift up on the teeth - its too loose for one.

Other than that - what is the chainline like? SS should be straight - very straight (if this was fixed it would be dangerous).

Ermmmmmmmmmm...Chainline ?

 

[DrSquirrel]

It's hard to get it in a photo, but this one looks out of line...
http://farm2.static.flickr.com/1352/544936507_02e1557383.jpg (ignore the 2 cogs)

But this one is good...
http://www.fixedgear.co.nz/images_rear/vitus_chainline.jpg

 

[wheres_my_beard]

That looks like the chain is not knitting properly into the teeth of the cog to me. Not so much to do with chainline, more to do with incompatible parts.

 

[gaz]

Do you get this problem when there is enough tension in the chain?
In the video your wheel is only just in the dropouts, surely it can't be tensioned properly.

 

[gb155]

That looks like the chain is not knitting properly into the teeth of the cog to me. Not so much to do with chainline, more to do with incompatible parts.

What do you mean ?

 

[gb155]

Do you get this problem when there is enough tension in the chain?
In the video your wheel is only just in the dropouts, surely it can't be tensioned properly.

Yea, happens all the time, even when super- tensioned

 

[gb155]

It's hard to get it in a photo, but this one looks out of line...
http://farm2.static...._02e1557383.jpg (ignore the 2 cogs)

But this one is good...
http://www.fixedgear...s_chainline.jpg[/quote]


Ah right , ok , I'll look tonight , thanks Doc

 

[gb155]

When it stops and rides up the link that fails to engage the cog is silver. What is different about this one from the others, apart from the colour?

Ahhhhhh , that's a quick link to join the chain

 

[Red Light]

Is it a new chain and new cog to add another possibility to the ones already mentioned? If one or t'other were worn it could do that but my bet would be on chainline with the chain trying to derail.

 

[gb155]

Does it bend freely? Will it sit on the cog OK at all? Can you put another link in to move the wheel back in the drop out?

I shall take a look this evening

 

[DrSquirrel]

I thought at first is was that silver link - but further on into the video (seconds before the end) I see it doing the same on another area without the link.


Do you know how to walk the wheel into the drops to get it tight? I have tried and tested pushing my chain off the cog on my fixed when tensioned and have yet been able to.

If you tighten both nuts, losen the non drive side and push the wheel between the chainstay (near the crank) towards the non-drive side and tighten the non drive nut, and then do this in reverse for the drive side. Without this it's hard to get a good tension on the chain (you can have it too tight as well btw).

http://www.sheldonbrown.com/fixed.html#tension - Rear Wheel Installation

 

[wheres_my_beard]

To eliminate what I have suggested as a problem (cog/chain teeth/gaps not matching) you could remove the cog and chain; lay the chain completely flat on a clean surface and manually roll the cog up the chain and visually check to see if all the teeth move freely into the gaps in the chain links or whether the cog still rises up.

I have set up my SS with a sloppy chainline and didn't have any trouble until test riding, with full pedal strokes. And even then that was after a few revolutions. That vid looks like it barely has 1/2 of the chain going round before disengaging.

 

[Pennine-Paul]

Your not using a 3/32 chain with an 1/8 freewheel are you????

most freewheels are 1/8

had similar problem with a fixed sprocket that was supposed to be 3/32

On changing to an 1/8 th chain worked fine