Bike Lust = Derailleur's Bane?

[g_barr]

All right all you bike shop folks and DIYers... How should one adequately prep the mounting area for a front derailleur? I wiped off my new FD (grease) and the seat tube (dirt). The adjustments were 99% perfect on the stand in all 3x9 gear combinations and great on the trail. After about 50 minutes of riding WF, I started getting some chain rub so I adjusted the index barrel adjuster (1-2 turns CW & CCW with no improvement either way). When I finished 10 minutes later, the FD managed to drop and rotate CCW.

It seems to me the top ring tension pulled the FD down on the treated seat tube and the big ring kicked it out. Before the FD moved, there was slight tension on the low end but it was resting on the low stop. I haven't had this happen before but I've also never adjusted a FD on a frame treated with Bike Lust (http://www.pedros.com/products_bikecare.htm).

My install doesn't require spacers and the clamp bolt doesn't feel looser after riding. My plan is to remove the FD and use some painter's wipes (http://www.homaxproducts.com/products/cleanersremovers/05/index.html) or auto wax remover before remounting the FD. I could wrench the clamp bolt down some more but I'm concerned the steel bolt will pull the threads out of the aluminum band. Any thoughts?

[BikerMiker]

Uh, there's probably no way in he(( that the Bike Lust made this happen. Sounds like it wasn't right and was hitting the chainring or the bolt was too loose.

I may be wrong on this but it sounds REALLY unlikely.

mike

[g_barr]

Uh, there's probably no way in he(( that the Bike Lust made this happen. Sounds like it wasn't right and was hitting the chainring or the bolt was too loose.
Okay, I didn't torque wrench it to 60 inch-pounds but a bulging bicep at the end of a 5mm hex wrench should be at least 12 pounds force at the end of a 5-inch wrench right? I'll check the clamp bolt first though.

Everything else was IAW Shimano's 2008 XT FD-M770 directions - 1mm top-front clearance (44T big ring - the rear had plenty of clearance, 360-degree rotation w/no interference), cage parallel to big ring before top end adjustment and minimal tension at the low end.

[DaveG]

Uh, there's probably no way in he(( that the Bike Lust made this happen. Sounds like it wasn't right and was hitting the chainring or the bolt was too loose.

I may be wrong on this but it sounds REALLY unlikely.

mike

I've also had the cable tension move the front der. when I didn't tighten it down enough.

[Brizn]

Just cut a small section of rubber (tube) and wrap around the seat tube where the der mounts. torque it down good and that should prevent the clamp from moving. cut the rubber narrow enough so you couldn't even see it under the clamp.


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