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Front Mech Issues

GT-ArrowheadGT-Arrowhead Posts: 2,507
edited May 2013 in MTB workshop & tech
Hi, ive just changed the front mech on my bike, and im having issues with getting it to work properly.

At the moment, ive taken the chain out of the front mech as it only lets me use the granny ring, just until i can find a solution to the problem. Im just using the largest only at the moment.You can see what i mean in the pictures.

I have adjusted the front mech to go as far away from the frame as possible, but still no luck. I think i know what the problem is though. The BB looks to be making the cranks/axle be too far away from the frame.

Before i had the new front mech on there (The new one is a Shimano Nexave) i had an Altus with a sort of "plate" that sits inbetween the BB and the frame. The Altus mech was mounted to this plate via two screws. I also experienced the problem of it not changing to the largest ring, but it wasnt as bad as it is now. (The cranks have been changed, but the ratios are exactly the same) Eventually i had had enough and i ripped the outer guide of the mech off... I could have removed the mech from the plate but the plate would just shake around, so i ripped the outer guide off.

Pictures of the old plate and mech:



I now have a massive gap between the BB and the frame from where that plate used to sit, i think that this is causing my problem of the mech not having enough range to change to the larger chainrings. The BB wont screw into the frame anymore.

If i unscrew the non driveside part of the BB a bit, would it allow me to screw the BB in more from the driveside? Even still i dont think the mech would reach the largest ring...

Is it just that my BB axle is too long or something, and i need to get a new one?

Thanks alot for the help in advance.

Here are some pictures, you can see the gap clearly in the first picture:

This is far out as the mech comes when its shifted to the highest gear
This is it on the lowest gear


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