Front mech help please
clanton
Posts: 1,289
As part of a project to get my girlfriends old mtb up to speed again we've replaced the front chainset. Unfortunately the new large ring is larger than the old and the front mech is hitting the teeth on the large ring. It is a bb mount type mech and I can't see any way of adjusting the height on it. The mech itself bolts onto the bb mounting plate.
So - shoudl there be a way of adjusting the thing? Or can I buy a new bb mounting plate for it?
It is an old 8 speed compatible mech with no name or markings unfortunatley (I assume Shimano) and I've not been able to find it on wiggle or chain reaction.
So - shoudl there be a way of adjusting the thing? Or can I buy a new bb mounting plate for it?
It is an old 8 speed compatible mech with no name or markings unfortunatley (I assume Shimano) and I've not been able to find it on wiggle or chain reaction.
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Comments
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You will need a new mech compatible with the larger chainring.0
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I've been having a look at the excellent links section and I think the mech is an older version of this one:
http://cycle.shimano-eu.com/catalog/cyc ... 9430480544
which is only compatible with 42teeth. So yes looks like I will need a new mech.0 -
I've not been able to find an Acera in 34.9mm -any reason that this mech won't work?
http://www.chainreactioncycles.com/Models.aspx?ModelID=176540 -
What is your largest chainring? If 48 then n0. Also have to make sure the clamp will fit on the frame. the cable routing can be done, and you may need a spacer for the bottom bracket to replace where the old mech was.0
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It is a 44 tooth chain ring and the seat tube size is 34.9mm as near as I can measure it so think the clamp will fit. I do have a spacer (from a Hollowtech bb) that I can use.
Only thing I'm not sure of: how do I know if I need a top swing or bottom swing type?0 -
Swing is the position of the clamp - you can see this by looking at pics of them both. The are different for clearence purposes ie bottle bosses, suspension. make sure the cable pull is correct too.0
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Thanks for the reply - that is helpful. Trouble is that I'm not replacing like for like so can't compare to previous mech.
It is a hardtail and there are no bosses that I can recall that could get in the way - does this mean I could use either type?
The cable is top pull.0 -
Either type should work fine: conventional (bottom swing) usually offers the best shifting and looking at that mech you linked, its dual pull for cable anyway.0
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Thanks again - have a virtual beer from me!0
