[Rollin'in'Zona]

Seems my XT front d'er has lost it's spring tension - with only 6 months of use! It does not have enogh contractile power to get the chain off of the middle ring (runnig only two chainrings) when the cain is under even the slightest tension. I resigned to this after spending several hours, over two days, tying to adjust it. It used to work fine.

1) Anyone know where to get another sping?
2) Or is there some cryptic spring tension adjusment I've missed?


When I started biking (95) these components were Deore. When I returned to biking 3 years ago I changed my deraileurs and shifters to SRAM. The only two Shimano products I have purchased, the XT front d'er and XT cassette, have BOTH had serious issues. Both of them! I can't believe this.

 

[Ken2]

Try this

Try disconnecting your cable and then check the FD spring tension... that puppy should be very hard to pull over from the inside position with your bare hand. If it is, I'd suspect crud in your cable housing, or a kink in the cable. I've never heard of a weak FD spring.

 

[Rollin'in'Zona]

Thanks for the reply.
Yeah, I did this - as mentioned above, I spent hours on this over two-days time. New cable, new housing, cable on, cable off, d'er assembly rinsed and dried (no mud here in the desert)... The derailleur will not pull the chain off of the 34 tooth ring even after the cable's been removed - while pedaling - in any rear cog!

Freaky, eh!

 

[the Inbred]

is it sticking? maybe shoot some WD-40 into the pivots

 

[pimpbot]

It has to be crudded up or something

Thanks for the reply.
Yeah, I did this - as mentioned above, I spent hours on this over two-days time. New cable, new housing, cable on, cable off, d'er assembly rinsed and dried (no mud here in the desert)... The derailleur will not pull the chain off of the 34 tooth ring even after the cable's been removed - while pedaling - in any rear cog!

Freaky, eh!

I got the same XT derailleur (front and rear) and don't have issues with either, and I got mad miles on them through mad amounts of crud. Sh¡mano XT stuff is pretty tip top, IMO. I know there is no shortage of people who love to b¡tch and moan about Sh¡mano, but my experience with Sh¡mano on 4 of my 5 bikes (one is a SS) is pretty dang flawless.

Every indexed bike I have ridden won't shift down off the front rings under too much load, but I hear you about 'it used to' so that's prolly not it.

Could it be a worn chain gripping the front ring's hooked teeth, maybe? I hate to get you to throw more money at the issue, but maybe a chain length check is in order along with close inspection of the teeth on your rings. Hooked teeth are bad, so are burrs. You can at least file a burr off, but hooked teeth mean new rings.

Also check how you have the derailleur bolted to your seat tube. I forget which way, but it should be slighly off of parallel from the rings (angled out at the back IIRC) and pretty close to your top ring (or where the big ring was).

 

[Rollin'in'Zona]

Thanks Pimbot for another excellent reply. I love these forums.

I know there is no shortage of people who love to b¡tch and moan about Sh¡mano...

I never had a reason to ***** before this - I actually went out and spent $$ for these parts based on a belief that thety were great components. The jury is still out so I'm not really *****in', but really surpried!

Could it be a worn chain gripping the front ring's hooked teeth, maybe?

New Blackspire SuperPro rings were installed recently, w bashguard so they look amost "to new". In fact, the entire drivetrain is new (built bike in spring), and as I travel all summer for work, it has only abot 15 rides on it in the 7 -12 mile range.

I'll take it apart again today and check the internals. This is great in a way - I'm leaning a lot about the workings and tuning of the front d'er!

 

[Rollin'in'Zona]

XT front d'er FIXED!

I took the d'er off the bike again, removed the black plastic cover, and reinstalled it so I could see the internals in motion. Turns out the "high limit" screw had contact with the curved "bump stop" unit through its entire movement range. This created just enough friction to inhibit the the d'er from pulling the chain.

I picked up a hex head screw from a hardware store, reinstalled it, marked it, then cut it to exact length and ground the last few mm's of the screw into a wedge shape. The "bump stop" mechanism now slides freely where the ground-off screw material used to be, and the screw still engages the high limit stop.

Who would have thunk it?!?