Front Mech not indexing correctly on to large ring.

beardytwo
beardytwo Posts: 174
edited March 2009 in MTB workshop & tech
Wonder if any one out there can answer this? I have been building up a Dirty Jo which is essentially done but the front mech is causing me grief. Its a brand new deore dual pull but is configured as a top pull. Frame is 31.8 so have used the spacers provided by Shimano so the grip is the right size. Frame is fitted with an Octalink BB (113mm I think!) and Shimano Cranks. when I shift from small ring to middle all is ok and smooth. When I go from middle to large the inner face of the mech chain guide clashes with the inner surface of the large ring before it has clicked and indexed. It appears that the chain ring is not far enough away from the frame to allow the mech to click and hold on the large ring. To this end I have removed half of the frame spacer on the mech so that the mech moves slightly away from the cranks. This worked but I'm not confident that the mech is gripping the seat post well enough. Is it that the BB is not long enough? (118 instead of 113mm) or am I completely out of wack and its something else. Frame seams good so I don't think its just poor tolerences. Sorry for the ramble and hope this makes sense. Any advice would be great as this is the final thing to sort out.. :x Cheers as always...

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