Trek oclv front derailier problem

[2cummings]

Last fall I got a 2003 trek 120 frame. I pulled all the components off my old frame (bill holland)
and built up the trek. Everything works fine except for the front derailier. I've found it nearly
impossible to adjust the derailier cage so the chain doesn't rub the cage (first and eighteenth
gears). When the cage is adjusted so the chain doesn't rub when I'm on the inside ring, I can
downshift from the big ring to the small ring and the chain will get thrown off on the inside. I
never had this problem on my other frame. Is there a geometry issue with the location of the front
derailier and how it relates to the cranks? Any help would be graetly appreciated. Rob

 

[daveornee]

Originally posted by 2cummings
Last fall I got a 2003 trek 120 frame. I pulled all the components off my old frame (bill holland)
and built up the trek. Everything works fine except for the front derailier. I've found it nearly
impossible to adjust the derailier cage so the chain doesn't rub the cage (first and eighteenth
gears). When the cage is adjusted so the chain doesn't rub when I'm on the inside ring, I can
downshift from the big ring to the small ring and the chain will get thrown off on the inside. I
never had this problem on my other frame. Is there a geometry issue with the location of the front
derailier and how it relates to the cranks? Any help would be graetly appreciated. Rob

It could be how the Front Derailer arc travels based on it's position relative to the new chain wheel postition.
See Sheldon Brown's article on derailer adustment at URL:
http://www.sheldonbrown.com/derailer-adjustment.html
also some potential help at Park Tool site URL:
http://www.parktool.com/repair_help/clg2.shtml

 

[Mike Jacoubowsk]

> Last fall I got a 2003 trek 120 frame. I pulled all the components off my old frame (bill holland)
> and built up the trek. Everything works fine except for the front derailier. I've found it nearly
> impossible to adjust the derailier cage so the chain doesn't rub the cage (first and eighteenth
> gears). When the cage is adjusted so the chain doesn't rub when I'm on the inside ring, I can
> downshift from the big ring to the small ring and the chain will get thrown off on the inside. I
> never had this problem on my other frame. Is there a geometry issue with the location of the front
> derailier and how it relates to the cranks? Any help would be graetly appreciated. Rob

Nothing special about the OCLV derailleur positioning; it's designed to put it right where Shimano
wants it. UNLESS you're trying to use something other than standard chainring sizes, or a funky
crank that puts the crank too close or far to/from the frame.

What front derailleur, crank & chainrings are you running? And what shifters? Could be a simple
cable adjustment that's throwing things off.

Also, PLEASE install that thin large round washer between the bottom bracket cup and the frame
on the chainring side. If the chain does fall off the inside chainring, it will nicely sit on
that washer until you shift it back up onto the chainring. Without it, it may very well get
nastily jammed.

--Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

 

[2cummings]

"Mike Jacoubowsky" <[email protected]> wrote in message news:<[email protected]>...

>
>
>
> What front derailleur, crank & chainrings are you running? And what shifters? Could be a simple
> cable adjustment that's throwing things off.
>
>
> --Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

I'm using a campy record 7 speed era front derailleur, fsa carbon cranks, 53/39 rings with dura-ace
9 speed shifters. I had this setup on my Holland frame for 8 years with no problems. The cage is set
a bit high in relation to the big ring, so I'll try bringing it down to within 1mm of the teeth.
Thanks for your input. Rob